1998 CRV high-load low-RPM misfires. Please help.
10-26-2011, 05:03 PM
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1998 CRV high-load low-RPM misfires. Please help.
Hi, all. Anyone wanna put their brain around this one?:
My 1998 CR-V LE 2WD (176,600 mi) has a high-load low-RPM random misfire, both by feel and by OBD2, slowly getting worse (started a couple of weeks ago). When the MIL lights, it throws codes P0300-304, usually 301 and 303 (1st and 3rd cylinder), most recently 303 and 304, so it varies. If I load it at all, I get transient misfires with no MIL. If I go WOT more than a couple of seconds, I get the blinking MIL, always throwing the same general type of code (P0300s).
Here is the most interesting thing: I've figured out that I can drive to work and back (35 minutes on the Fwy) without ANY engine light by simply starting out gently in 1st (automatic), then upshifting when the RPM are around 4-5k, and keeping the RPM high at all speeds. If I keep the RPM up and don't load it too hard, no misfire at all -- perfectly smooth, even as it winds down to slower speeds. At high RPM (above 3500-4000) I can even tap the pedal and get bursts of power without misfiring. BUT, if I load it moderately hard for more than a split second, it will misfire, even at high RPM. If I do it enough, it will keep misfiring even at high RPM and low load (cylinder walls heated up?). If I then drive at low load/high RPM for a few minutes, the high-RPM misfire goes away (hence, my thought about heating, cooling).
I've Sea Foamed it three times, and now I don't get any more smoke out the back after start up. All the carbon than can be reached by Sea Foam (via the brake vacuum line) is gone. I think I had a transient improvement in misfires, but maybe it was just that the car had cooled. Oil is full synthetic, due for change, but looks relatively good, normal level, shouldn't cause misfire. I plan on Sea Foaming the crankcase and changing oil/filter once I fix the misfires problem. I just replaced the fuel filter last night (REALLY needed it); again, only transient improvement attributable to cool-down. I've been running fuel injector cleaner for a tank and a half now. Plenty of spark at the plugs. New plugs didn't do anything. Plug wires seem to connect fine; no jumping. It idles fine when in neutral (no load). Compression was a little variable before I Sea Foamed, but I haven't checked again. Air filter isn't too old and I don't drive in dust, so that's not likely the problem. Coolant level is fine; fluid looks normal.
Not sure what is going on. I don't want to just replace O2 sensors and coils and stuff and "hope."
My plan: pull the fuel rail and check pressure, make sure no leaks at the injectors; replace if needed. Check under the valve cover (check valve appearance, etc; never done that before.). Also, I bought an ohmeter, but haven't ever used it. I could start checking some resistances, but checking voltages is kinda freaky. Eventually I'll get a valve adjustment (will do myself if I can find out how), maybe get a pro electrical diagnostic workup (if I can find someone competent; how?).
Any other thoughts? What should I do next? I'm trying to avoid "giving up" and taking it to some unknown mystery mechanic at the dealer or anywhere else and pay some mystery cost for mystery service.
My 1998 CR-V LE 2WD (176,600 mi) has a high-load low-RPM random misfire, both by feel and by OBD2, slowly getting worse (started a couple of weeks ago). When the MIL lights, it throws codes P0300-304, usually 301 and 303 (1st and 3rd cylinder), most recently 303 and 304, so it varies. If I load it at all, I get transient misfires with no MIL. If I go WOT more than a couple of seconds, I get the blinking MIL, always throwing the same general type of code (P0300s).
Here is the most interesting thing: I've figured out that I can drive to work and back (35 minutes on the Fwy) without ANY engine light by simply starting out gently in 1st (automatic), then upshifting when the RPM are around 4-5k, and keeping the RPM high at all speeds. If I keep the RPM up and don't load it too hard, no misfire at all -- perfectly smooth, even as it winds down to slower speeds. At high RPM (above 3500-4000) I can even tap the pedal and get bursts of power without misfiring. BUT, if I load it moderately hard for more than a split second, it will misfire, even at high RPM. If I do it enough, it will keep misfiring even at high RPM and low load (cylinder walls heated up?). If I then drive at low load/high RPM for a few minutes, the high-RPM misfire goes away (hence, my thought about heating, cooling).
I've Sea Foamed it three times, and now I don't get any more smoke out the back after start up. All the carbon than can be reached by Sea Foam (via the brake vacuum line) is gone. I think I had a transient improvement in misfires, but maybe it was just that the car had cooled. Oil is full synthetic, due for change, but looks relatively good, normal level, shouldn't cause misfire. I plan on Sea Foaming the crankcase and changing oil/filter once I fix the misfires problem. I just replaced the fuel filter last night (REALLY needed it); again, only transient improvement attributable to cool-down. I've been running fuel injector cleaner for a tank and a half now. Plenty of spark at the plugs. New plugs didn't do anything. Plug wires seem to connect fine; no jumping. It idles fine when in neutral (no load). Compression was a little variable before I Sea Foamed, but I haven't checked again. Air filter isn't too old and I don't drive in dust, so that's not likely the problem. Coolant level is fine; fluid looks normal.
Not sure what is going on. I don't want to just replace O2 sensors and coils and stuff and "hope."
My plan: pull the fuel rail and check pressure, make sure no leaks at the injectors; replace if needed. Check under the valve cover (check valve appearance, etc; never done that before.). Also, I bought an ohmeter, but haven't ever used it. I could start checking some resistances, but checking voltages is kinda freaky. Eventually I'll get a valve adjustment (will do myself if I can find out how), maybe get a pro electrical diagnostic workup (if I can find someone competent; how?).
Any other thoughts? What should I do next? I'm trying to avoid "giving up" and taking it to some unknown mystery mechanic at the dealer or anywhere else and pay some mystery cost for mystery service.
10-27-2011, 03:40 AM
#2
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Re: 1998 CRV high-load low-RPM misfires. Please help.
Since those are the only codes you are throwing I would start by checking the Ignition Coil. Since you say you haven't done anything to a vehicle before and checking voltage is "freaky", you may as well just take it to a mechanic. There are wires that are hot even with the vehicle off... 12v DC is nothing to be concerned about.
10-27-2011, 11:04 AM
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Re: 1998 CRV high-load low-RPM misfires. Please help.
I'm not giving up that easily. 
The misfire is much better when I start up the car cold. Once it warms up, the misfires are pretty bad even at idle, but go away at high RPM, low load. Would the ignition coil function change as the car warms up? That isn't intuitive to me, but I'm open to learning more.
Indeed. Not too worried about 12V, and thank you for the reassurance. It's the post-coil voltage in the plug wires I'm more concerned about when the car is running. Don't think I'll mess with that for now. Might replace the wires, but they seem to all carry current fine.
I'll tinker with it this weekend, maybe replace the coil and see what happens. Buying parts and replacing stuff I'm not absolutely sure is broken is not my favorite way to trouble-shoot, though. If anyone else has suggestions, please share.
The misfire is much better when I start up the car cold. Once it warms up, the misfires are pretty bad even at idle, but go away at high RPM, low load. Would the ignition coil function change as the car warms up? That isn't intuitive to me, but I'm open to learning more.
I'll tinker with it this weekend, maybe replace the coil and see what happens. Buying parts and replacing stuff I'm not absolutely sure is broken is not my favorite way to trouble-shoot, though. If anyone else has suggestions, please share.
10-27-2011, 01:35 PM
#4
Honda-Tech Member
Re: 1998 CRV high-load low-RPM misfires. Please help.
honestly i would start off with a compression test. If that comes back good, do a valve adjustment. if you still have missfire issues (and the exhaust valves were very tight) I would move to a leakdown test. If leakdown test comes back good (ruling out burnt valves which are the MOST common culprit of misfire codes) THEN i would start looking at ignition/sensor related items.
you get misfire codes from the crank angle sensor...not from any ignition sensor. your probably getting misfires because one of the exhaust valves is burnt up and the edges of it are staying extremely hot and acting as glow plugs, ignition the mixture before the spark plug can. high rpm/low load situations are where the combustion is at its least volatile state (lowest cylinder pressures) so the crank isnt fluctuating as much as it does in high cylinder pressure situations.
sounds like the all too common "tight exhaust valves" or a burnt exhaust valve (which is a result of running too long with tight exhaust valves)
you get misfire codes from the crank angle sensor...not from any ignition sensor. your probably getting misfires because one of the exhaust valves is burnt up and the edges of it are staying extremely hot and acting as glow plugs, ignition the mixture before the spark plug can. high rpm/low load situations are where the combustion is at its least volatile state (lowest cylinder pressures) so the crank isnt fluctuating as much as it does in high cylinder pressure situations.
sounds like the all too common "tight exhaust valves" or a burnt exhaust valve (which is a result of running too long with tight exhaust valves)
11-02-2011, 09:01 AM
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Re: 1998 CRV high-load low-RPM misfires. Please help.
Hey, all.
First of all, thanks for the help and feedback. Here's an update:
11/1/11. My birthday and day #3 of my vacation, so far spent tinkering on my car (in summary, a 1998 CRV with 176,754 mi and a high-load low-RPM random misfire problem, worse when warm, which started when changed the spark plugs but grew slowly and steadily worse over time). But I think I solved the problem. Here’s what I did:
Removed distrib cap, rotor, leak cover, and coil. My rotor fastener screw was so tight I stripped it trying to get it off, which required a stop at Sears to get a stripped screw/nut remover. I eventually inspected the coil; nothing obvious but there was a rainbow discoloration on the top and some irregularity to the black plastic on one side. Sorry, no pics. Also, there was some carbon on the leak cover, which I cleaned with 90% isopropyl alcohol not being sure if brake/parts cleaner would hurt the plastic. Wife had the other car, so I couldn’t go out and buy any replacements yet.
Removed valve cover to see how things looked. Nothing obvious. Looked up valve adjustment instructions. Found Michael Keefe’s website (http://home.earthlink.net/~michaelpkeefe/), some other good posts at various forums (fora?), and a PDF of the CRV 1997-2000 service manual. Google “1997-2000-HONDA-CRV-SERVICE-MANUAL.pdf” and you’ll find it. Wife came home, so I went out and bought a feeler gauge with the appropriate thicknesses, a 3/8 inch drive torque wrench, and replacement parts. Did my own valve adjustment. Spec is 0.003-5 inches for intake and 0.006-8 inches for exhaust, loose end of spec preferred. Some of my exhaust valves were VERY tight. Burned valves? I’ll address that later. Here are my valve clearances before and after adjustment:
Cylinder#, Intake(I)-Exhaust(E), valve A/B: before after
1IA: 0.005 0.005
1IB: 0.004 0.005
1EA: 0.0020 0.008
1EB: 0.003 0.008
2IA: 0.004 0.005
2IB: 0.004 0.005
2EA: 0.0015 0.008
2EB: 0.004 0.008
3IA: 0.0025 0.005
3IB: 0.0025 0.005
3EA: <0.0015 0.008
3EB: 0.0025 0.008
4IA: 0.004 0.005
4IB: 0.004 0.005
4EA: 0.003 0.008
4EB: <0.0015 0.008
I tightened all jam nuts to spec torque and rechecked each valve clearance, readjusted if needed (and retorqued, rechecked). The values above are spot on.
A new stock coil was $144 at Honda, so I thought I would wait and see if I really needed it. I replaced the original coil, then replaced dizzy cap and rotor with Honda (dealer) brand. I thought I would try aftermarket wires (how bad can that be screwed up?), so I bought the “premium” wires available at O’Reilly auto parts. Also, a Fram “equivalent” PCV valve.
After the valve adjustment and replacing the cover per instructions, installing the new dizzy cap, rotor, wires, PCV valve, and single-platinum Autolite plugs (virtually new), I started it up. TERRIBLE!!! I had MAYBE two pistons firing. Opening the throttle resulted in horrible popping sounds in the intake system. Engine OFF! WHAT DID I DO!!!!?
I thought maybe it was something with the plug wiring (a simple problem with catastrophic effect). The aftermarket wires seemed to slip off of the dizzy cap pretty easily. Connections at the plug were fine. I unplugged the new wires and reinstalled the old wires. Either the new wires were not connecting right or I had somehow screwed up the wiring order with the new wires, because the engine started up fine. YAY!!!! I let the car warm up, then did a Sea Foam spray intake system cleaning per on-can instructions (I had heard good things about it, and I saw that my throttle body was pretty dirty with carbon deposits). Then, for some reason, I decided to do a compression test while the car was warm (I should have waited, for reasons I’ll explain later).
Before I go on, I have to tell you about a compression test I did back on 10/20/11:
Spec: at least 132-150 psi, depending on who you talk to and how you calculate the compression ratio to “psi” conversion.
Cylinder 1: 165 psi
Cylinder 2: 145 psi
Cylinder 3: 140 psi
Cylinder 4: 155 psi
On this one, I had used a rubber-hose tester I borrowed from O’Reilly auto parts. Not sure if I got good seal (hard to torque a rubber hose). Also, the bolt depth doesn’t match the plug thread depth, so the effective cylinder volume was higher than it should have been (reducing compression ratio). At a minimum, I can say my valves weren’t burned through at that time.
Here’s the “new” compression test, after adjusting valves, warming up the engine, and Sea Foaming the throttle body. This one was with a new Innova compression tester I picked up on Amazon. Go with the steel bound hose. It helps with screwing it into the plug hole.
Cylinder 1: 200 psi
Cylinder 2: 177 psi
Cylinder 3: 195 psi
Cylinder 4: 190 psi
???? What? The compression shouldn’t be any higher than 180-185 psi! How would I get that much of an increase? Was it the tester difference? Maybe some of the difference, but not that much. I noticed when I pulled the plugs for this compression test, the piston tops were wet, presumably with Sea Foam. Built up unburned/nonexpelled Sea Foam in the cylinders could have reduced the cylinder volumes (and also effectively increased the seal at the piston rings, like a squirt of motor oil would). Reduce the volumes for any given displacement, and you increase the compression ratio. That’s simple physics. Piston-top volume reduction would especially have a significant increase in compression, up to the point of hydrolocking the cylinder (very bad). LUCKILY, my cylinders didn’t have enough volume of Sea Foam to hydrolock. Something to be aware of though. Again, I can at least say my valves weren’t burned through.
After the compression test, I started the engine with no problems. In fact, at idle it ran smoother than ever before, which I attributed to the valve adjustment. But was my low-RPM high-load misfire gone? It was late at night, but I had to see! (I needed to burn out the Sea Foam anyway.) A brief test down a few roads showed no problems at all! No misfires, even under load! Just a lot of smoke for awhile from the carbon deposits coming off in the Sea Foam.
Lessons learned:
1. Don’t make too many changes at once if you don’t know what the problem is.
2. Don’t do a compression test after Sea Foaming the engine until all of the Sea Foam and carbon deposits have been passed through.
3. Never take all of your distributor cap plug wires off without writing down EXACTLY how they all should be reconnected. I had to look up the order and I may have connected two wires incorrectly the first time (either that or my new wires were not connecting right).
4. With the help of Google, Honda-tech.com, Wikipedia, and the rest of the ‘net, anyone who enjoys tinkering and wants to save money can do their own valve adjustment and many other car repairs for pennies on the dollar compared to taking it to a mechanic or (especially) the dealer!
5. There is NO excuse for a professional mechanic not to know this stuff, and there are too many who really don’t know, throw a lot of BS at customers, and aim for big repairs that bring in cash. And now I know a bit more of what to ask to separate the wheat from the chaff next time I need a mechanic.
In the end, I think my low-RPM high-load misfire was due to tight valves, a bad dizzy/rotor, or something with my previous plug or wire installation (but my most recent installation of the new plugs and ORIGINAL wires seems to produce no problem). I’ll check the compression again to get some more representative values after driving the CRV around a bit to test out the power and load-handling. I may also pick up a Honda OEM plug wire set. For now, I think I can safely say my valves were not burned all the way through or I would not be getting such high compression values. It would be interesting to see what the valves look like, but a fiber-optic isn’t in my budget for now.
I hope my little adventure here helps someone. Cheers.
First of all, thanks for the help and feedback. Here's an update:
11/1/11. My birthday and day #3 of my vacation, so far spent tinkering on my car (in summary, a 1998 CRV with 176,754 mi and a high-load low-RPM random misfire problem, worse when warm, which started when changed the spark plugs but grew slowly and steadily worse over time). But I think I solved the problem. Here’s what I did:
Removed distrib cap, rotor, leak cover, and coil. My rotor fastener screw was so tight I stripped it trying to get it off, which required a stop at Sears to get a stripped screw/nut remover. I eventually inspected the coil; nothing obvious but there was a rainbow discoloration on the top and some irregularity to the black plastic on one side. Sorry, no pics. Also, there was some carbon on the leak cover, which I cleaned with 90% isopropyl alcohol not being sure if brake/parts cleaner would hurt the plastic. Wife had the other car, so I couldn’t go out and buy any replacements yet.
Removed valve cover to see how things looked. Nothing obvious. Looked up valve adjustment instructions. Found Michael Keefe’s website (http://home.earthlink.net/~michaelpkeefe/), some other good posts at various forums (fora?), and a PDF of the CRV 1997-2000 service manual. Google “1997-2000-HONDA-CRV-SERVICE-MANUAL.pdf” and you’ll find it. Wife came home, so I went out and bought a feeler gauge with the appropriate thicknesses, a 3/8 inch drive torque wrench, and replacement parts. Did my own valve adjustment. Spec is 0.003-5 inches for intake and 0.006-8 inches for exhaust, loose end of spec preferred. Some of my exhaust valves were VERY tight. Burned valves? I’ll address that later. Here are my valve clearances before and after adjustment:
Cylinder#, Intake(I)-Exhaust(E), valve A/B: before after
1IA: 0.005 0.005
1IB: 0.004 0.005
1EA: 0.0020 0.008
1EB: 0.003 0.008
2IA: 0.004 0.005
2IB: 0.004 0.005
2EA: 0.0015 0.008
2EB: 0.004 0.008
3IA: 0.0025 0.005
3IB: 0.0025 0.005
3EA: <0.0015 0.008
3EB: 0.0025 0.008
4IA: 0.004 0.005
4IB: 0.004 0.005
4EA: 0.003 0.008
4EB: <0.0015 0.008
I tightened all jam nuts to spec torque and rechecked each valve clearance, readjusted if needed (and retorqued, rechecked). The values above are spot on.
A new stock coil was $144 at Honda, so I thought I would wait and see if I really needed it. I replaced the original coil, then replaced dizzy cap and rotor with Honda (dealer) brand. I thought I would try aftermarket wires (how bad can that be screwed up?), so I bought the “premium” wires available at O’Reilly auto parts. Also, a Fram “equivalent” PCV valve.
After the valve adjustment and replacing the cover per instructions, installing the new dizzy cap, rotor, wires, PCV valve, and single-platinum Autolite plugs (virtually new), I started it up. TERRIBLE!!! I had MAYBE two pistons firing. Opening the throttle resulted in horrible popping sounds in the intake system. Engine OFF! WHAT DID I DO!!!!?
I thought maybe it was something with the plug wiring (a simple problem with catastrophic effect). The aftermarket wires seemed to slip off of the dizzy cap pretty easily. Connections at the plug were fine. I unplugged the new wires and reinstalled the old wires. Either the new wires were not connecting right or I had somehow screwed up the wiring order with the new wires, because the engine started up fine. YAY!!!! I let the car warm up, then did a Sea Foam spray intake system cleaning per on-can instructions (I had heard good things about it, and I saw that my throttle body was pretty dirty with carbon deposits). Then, for some reason, I decided to do a compression test while the car was warm (I should have waited, for reasons I’ll explain later).
Before I go on, I have to tell you about a compression test I did back on 10/20/11:
Spec: at least 132-150 psi, depending on who you talk to and how you calculate the compression ratio to “psi” conversion.
Cylinder 1: 165 psi
Cylinder 2: 145 psi
Cylinder 3: 140 psi
Cylinder 4: 155 psi
On this one, I had used a rubber-hose tester I borrowed from O’Reilly auto parts. Not sure if I got good seal (hard to torque a rubber hose). Also, the bolt depth doesn’t match the plug thread depth, so the effective cylinder volume was higher than it should have been (reducing compression ratio). At a minimum, I can say my valves weren’t burned through at that time.
Here’s the “new” compression test, after adjusting valves, warming up the engine, and Sea Foaming the throttle body. This one was with a new Innova compression tester I picked up on Amazon. Go with the steel bound hose. It helps with screwing it into the plug hole.
Cylinder 1: 200 psi
Cylinder 2: 177 psi
Cylinder 3: 195 psi
Cylinder 4: 190 psi
???? What? The compression shouldn’t be any higher than 180-185 psi! How would I get that much of an increase? Was it the tester difference? Maybe some of the difference, but not that much. I noticed when I pulled the plugs for this compression test, the piston tops were wet, presumably with Sea Foam. Built up unburned/nonexpelled Sea Foam in the cylinders could have reduced the cylinder volumes (and also effectively increased the seal at the piston rings, like a squirt of motor oil would). Reduce the volumes for any given displacement, and you increase the compression ratio. That’s simple physics. Piston-top volume reduction would especially have a significant increase in compression, up to the point of hydrolocking the cylinder (very bad). LUCKILY, my cylinders didn’t have enough volume of Sea Foam to hydrolock. Something to be aware of though. Again, I can at least say my valves weren’t burned through.
After the compression test, I started the engine with no problems. In fact, at idle it ran smoother than ever before, which I attributed to the valve adjustment. But was my low-RPM high-load misfire gone? It was late at night, but I had to see! (I needed to burn out the Sea Foam anyway.) A brief test down a few roads showed no problems at all! No misfires, even under load! Just a lot of smoke for awhile from the carbon deposits coming off in the Sea Foam.
Lessons learned:
1. Don’t make too many changes at once if you don’t know what the problem is.
2. Don’t do a compression test after Sea Foaming the engine until all of the Sea Foam and carbon deposits have been passed through.
3. Never take all of your distributor cap plug wires off without writing down EXACTLY how they all should be reconnected. I had to look up the order and I may have connected two wires incorrectly the first time (either that or my new wires were not connecting right).
4. With the help of Google, Honda-tech.com, Wikipedia, and the rest of the ‘net, anyone who enjoys tinkering and wants to save money can do their own valve adjustment and many other car repairs for pennies on the dollar compared to taking it to a mechanic or (especially) the dealer!
5. There is NO excuse for a professional mechanic not to know this stuff, and there are too many who really don’t know, throw a lot of BS at customers, and aim for big repairs that bring in cash. And now I know a bit more of what to ask to separate the wheat from the chaff next time I need a mechanic.
In the end, I think my low-RPM high-load misfire was due to tight valves, a bad dizzy/rotor, or something with my previous plug or wire installation (but my most recent installation of the new plugs and ORIGINAL wires seems to produce no problem). I’ll check the compression again to get some more representative values after driving the CRV around a bit to test out the power and load-handling. I may also pick up a Honda OEM plug wire set. For now, I think I can safely say my valves were not burned all the way through or I would not be getting such high compression values. It would be interesting to see what the valves look like, but a fiber-optic isn’t in my budget for now.
I hope my little adventure here helps someone. Cheers.
11-02-2011, 11:54 AM
#6
Honda-Tech Member
Re: 1998 CRV high-load low-RPM misfires. Please help.
BRAVO Sir, Bravo!!!
I am glad it seems as though a valve adjustment cured your issue (its VERY common in b20 motors, for the exhaust valves to get really tight) I had the same issues when I bought my CRV...I did some research and concluded that this particular CRV was probably suffering from valves that were out of adjustment, so I picked it up for a steal. Well Some things are just too good to be true, and mine ended up having a burnt valve on cylinder 1. (btw, if you did have a burnt valve, your compression test would immediately confirm it)
Also, over my 15+ years of working on Honda's as a hobby i've learned this....ANYTHING electrical that fails, or isnt operating correctly on a Honda...needs to be replaced with ONLY OEM Honda parts. Especially anything that has to do with the distributer. I read once that there are subtle differences in the "shape" of the electrical current that comes from genuine Honda components vs other types of mfg'ers components...which often leads to the break down or failure of other components, or the replaced component itself. (ive heard soooo many times..."it cant be the coil/ignitor, I know its good, I just replaced it!" lol) 9 times out of 10 a known good, USED OEM electrical component will outlast a NEW aftermarket brand component. Very well could have been your wires that werent any good, or just had too much resistance in them from cheaper mfg materials.
At any rate...Nice Job all the way around
I am glad it seems as though a valve adjustment cured your issue (its VERY common in b20 motors, for the exhaust valves to get really tight) I had the same issues when I bought my CRV...I did some research and concluded that this particular CRV was probably suffering from valves that were out of adjustment, so I picked it up for a steal. Well Some things are just too good to be true, and mine ended up having a burnt valve on cylinder 1. (btw, if you did have a burnt valve, your compression test would immediately confirm it)
Also, over my 15+ years of working on Honda's as a hobby i've learned this....ANYTHING electrical that fails, or isnt operating correctly on a Honda...needs to be replaced with ONLY OEM Honda parts. Especially anything that has to do with the distributer. I read once that there are subtle differences in the "shape" of the electrical current that comes from genuine Honda components vs other types of mfg'ers components...which often leads to the break down or failure of other components, or the replaced component itself. (ive heard soooo many times..."it cant be the coil/ignitor, I know its good, I just replaced it!" lol) 9 times out of 10 a known good, USED OEM electrical component will outlast a NEW aftermarket brand component. Very well could have been your wires that werent any good, or just had too much resistance in them from cheaper mfg materials.
At any rate...Nice Job all the way around
11-02-2011, 12:45 PM
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Re: 1998 CRV high-load low-RPM misfires. Please help.
honestly i would start off with a compression test. If that comes back good, do a valve adjustment. if you still have missfire issues (and the exhaust valves were very tight) I would move to a leakdown test. If leakdown test comes back good (ruling out burnt valves which are the MOST common culprit of misfire codes) THEN i would start looking at ignition/sensor related items.
you get misfire codes from the crank angle sensor...not from any ignition sensor. your probably getting misfires because one of the exhaust valves is burnt up and the edges of it are staying extremely hot and acting as glow plugs, ignition the mixture before the spark plug can. high rpm/low load situations are where the combustion is at its least volatile state (lowest cylinder pressures) so the crank isnt fluctuating as much as it does in high cylinder pressure situations.
sounds like the all too common "tight exhaust valves" or a burnt exhaust valve (which is a result of running too long with tight exhaust valves)
you get misfire codes from the crank angle sensor...not from any ignition sensor. your probably getting misfires because one of the exhaust valves is burnt up and the edges of it are staying extremely hot and acting as glow plugs, ignition the mixture before the spark plug can. high rpm/low load situations are where the combustion is at its least volatile state (lowest cylinder pressures) so the crank isnt fluctuating as much as it does in high cylinder pressure situations.
sounds like the all too common "tight exhaust valves" or a burnt exhaust valve (which is a result of running too long with tight exhaust valves)
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11-02-2011, 05:11 PM
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Re: 1998 CRV high-load low-RPM misfires. Please help.
OOPS. I think I spoke too soon. I DEFINITELY got an improvement, but when warmed up I still get the misfires. Again, low RPM and high load (although now it's pretty much only when I start out from a dead stop, or sit idling in drive. I'll change the plug wires out for OEM and go from there. ????? Why, though? Also, I've noticed a funny sound coming from underneath the car around the catalytic converter when it misfires while it is idling in drive (parking brake on, chocks in). Sort of a squeek. Can the alternator have fits of no juice? Could it be the cat? O2 sensors? Just a rattle due to the misfire and loss of torque? I'm hoping it's the latter.
11-02-2011, 05:44 PM
#10
Honda-Tech Member
Re: 1998 CRV high-load low-RPM misfires. Please help.
hmmm...interesting. swapping the wires back to the OEM wires would be a quick easy test if you havent already...
But beyond that, the service manual says
p0300 and some of, p0301, p0302, p0303, p0304 = ignition system, fuel supply system, map sensor, iac valve, contaminated fuel, lack of fuel.
So maybe the seafoam had a negative effect on the sensors, or maybe the seafoam is still in the fuel causing the misfire codes? I would swap the wires, and after doing so, pull a plug, attach it to teh wire in your hand...then turn the lights off and have someone start the car and get a good estimate of the spark, and make sure all 4 cylinders have equal spark. you could probably do that with both sets of wires to see if there is a difference. above that, maybe just run teh fuel out and after a refill, reset the ECU and see if codes continue?
I have a sneaky feeling your problem was taken care of with the valve adjustment and you are now getting some residual effects from the multiple seafoam sessions.
Also, have you replaced the plugs after the last seafoam session??? VERY good idea to do that...I only use NGK plugs also. i've had issues with other brands of plugs before.
Good Luck!
But beyond that, the service manual says
p0300 and some of, p0301, p0302, p0303, p0304 = ignition system, fuel supply system, map sensor, iac valve, contaminated fuel, lack of fuel.
So maybe the seafoam had a negative effect on the sensors, or maybe the seafoam is still in the fuel causing the misfire codes? I would swap the wires, and after doing so, pull a plug, attach it to teh wire in your hand...then turn the lights off and have someone start the car and get a good estimate of the spark, and make sure all 4 cylinders have equal spark. you could probably do that with both sets of wires to see if there is a difference. above that, maybe just run teh fuel out and after a refill, reset the ECU and see if codes continue?
I have a sneaky feeling your problem was taken care of with the valve adjustment and you are now getting some residual effects from the multiple seafoam sessions.
Also, have you replaced the plugs after the last seafoam session??? VERY good idea to do that...I only use NGK plugs also. i've had issues with other brands of plugs before.
Good Luck!
11-03-2011, 08:21 PM
#11
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Re: 1998 CRV high-load low-RPM misfires. Please help.
Update:
Before trying to take the aftermarket plug wires back to O'Reilly in preparation for buying OEM wires, I thought I'd try one last thing: Clean off the small amount of silicone grease I had put on the distributor plug wire terminals and from the inside of the plug wire ends (the new ones), so that they wouldn't slip off so easily when I put them on the distributor (that was a problem the first go-around). Then I tried again with the new wires, making sure the wires went to the right cylinders, double checking all the connections, and routing the wires neatly in their brackets. It worked. Haven't had a misfire at all while buzzing around town running errands (car fully warmed up, wires hot, etc).
I'm eating humble pie, because I honestly don't understand what in the spark plug wires would cause problems at low-RPM high-load. I can intuit that the worsening with warming up was due to a conduction decrease at higher temps, since I have been noticing that the misfires seemed to significantly trail the water temperature warming up. Could it be that at high wire temps, the conductor in the wires (some kind of carbon paste) had breaks in the conduction that would be overcome by high firing rates (at high RPM) causing persistent ionization of the gaps in the conduction chain (hence, no misfire)? But why would load have anything to do with the misfire? I still don't get that part. Mixture changes? Voltage changes? Current changes? What really goes on here under load?
Lesson's learned:
1. Don't put silicone grease on the distributor terminals. Just the plugs boots. And not on the actual electrical conductive connectors (Important to understand that silicone grease is NOT a conductor, despite being called "dielectric.").
2. Believe the word on wires/cap/rotor. They do go bad and cause random misfires. How, exactly, I'm not sure.
3. Make sure the wiring order is PERFECT. I'm pretty sure I goofed it the first time and had just two pistons firing (and probably detonations in the intake system causing the horrible popping sounds when I revved it). Still makes me cringe to think about it. No major damage as far as I can tell though.
Before trying to take the aftermarket plug wires back to O'Reilly in preparation for buying OEM wires, I thought I'd try one last thing: Clean off the small amount of silicone grease I had put on the distributor plug wire terminals and from the inside of the plug wire ends (the new ones), so that they wouldn't slip off so easily when I put them on the distributor (that was a problem the first go-around). Then I tried again with the new wires, making sure the wires went to the right cylinders, double checking all the connections, and routing the wires neatly in their brackets. It worked. Haven't had a misfire at all while buzzing around town running errands (car fully warmed up, wires hot, etc).
I'm eating humble pie, because I honestly don't understand what in the spark plug wires would cause problems at low-RPM high-load. I can intuit that the worsening with warming up was due to a conduction decrease at higher temps, since I have been noticing that the misfires seemed to significantly trail the water temperature warming up. Could it be that at high wire temps, the conductor in the wires (some kind of carbon paste) had breaks in the conduction that would be overcome by high firing rates (at high RPM) causing persistent ionization of the gaps in the conduction chain (hence, no misfire)? But why would load have anything to do with the misfire? I still don't get that part. Mixture changes? Voltage changes? Current changes? What really goes on here under load?
Lesson's learned:
1. Don't put silicone grease on the distributor terminals. Just the plugs boots. And not on the actual electrical conductive connectors (Important to understand that silicone grease is NOT a conductor, despite being called "dielectric.").
2. Believe the word on wires/cap/rotor. They do go bad and cause random misfires. How, exactly, I'm not sure.
3. Make sure the wiring order is PERFECT. I'm pretty sure I goofed it the first time and had just two pistons firing (and probably detonations in the intake system causing the horrible popping sounds when I revved it). Still makes me cringe to think about it. No major damage as far as I can tell though.
11-04-2011, 03:41 AM
#12
DO IT ON ALL FOURS
Re: 1998 CRV high-load low-RPM misfires. Please help.
My logic would be that the "new" wires are of a higher resistance than the OEM spark plug wires. This being paired with a potentially weak coil could cause your problem. A coil has a set range to operate in and puts out a steady voltage. Obviously firing when it is told to, but not having different outputs for different engine loads. Why would there be a misfire only at a load? The spark is too weak under those cylinder pressures to ignite the mixture.
This is all assuming that the fuel pressure/supply is sufficient - I would assume so since there aren't other signs that would point me in that direction. As well as everything else being in order.
This is all assuming that the fuel pressure/supply is sufficient - I would assume so since there aren't other signs that would point me in that direction. As well as everything else being in order.
11-04-2011, 07:10 AM
#13
Honda-Tech Member
Re: 1998 CRV high-load low-RPM misfires. Please help.
My logic would be that the "new" wires are of a higher resistance than the OEM spark plug wires. This being paired with a potentially weak coil could cause your problem. A coil has a set range to operate in and puts out a steady voltage. Obviously firing when it is told to, but not having different outputs for different engine loads. Why would there be a misfire only at a load? The spark is too weak under those cylinder pressures to ignite the mixture.
This is all assuming that the fuel pressure/supply is sufficient - I would assume so since there aren't other signs that would point me in that direction. As well as everything else being in order.
This is all assuming that the fuel pressure/supply is sufficient - I would assume so since there aren't other signs that would point me in that direction. As well as everything else being in order.
11-08-2011, 12:22 AM
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Re: 1998 CRV high-load low-RPM misfires. Please help.
I use to have the same problems with my 98 crv, I changed my spark plug wires to ngk and got a new dizzy and I didn't have that problem any more.
12-31-2016, 12:19 PM
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Re: 1998 CRV high-load low-RPM misfires. Please help.
Hi Matt,
Thanks for your reply.
I subsequently went for a 70 km drive to the city and it started to misfire again. I replaced the plu leads and the problem has gone.
I will try to send photos when I get time.
Thanks for your reply.
I subsequently went for a 70 km drive to the city and it started to misfire again. I replaced the plu leads and the problem has gone.
I will try to send photos when I get time.
02-20-2017, 06:14 PM
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Re: 1998 CRV high-load low-RPM misfires. Please help.
Hi there, I have a 2000 Honda Civic EX 1.6L SOHC Automatic
just got 6 different codes today P0301
P0302
P0303
P0304
P0300
P1399
P1399 says all cylinders are misfiring, I have replaced... Fuel pump, Fuel filter, Air filter, spark plugs, o2 sensor. And have cleaned just yesterday the throttle body and injectors.
When im stopped at a red light or am just in park, my car will have a really bad idle and want to stall, the headlights will even dim. But once I put it in Drive and get over 1000 rpm's it drives like a dream. Would love to know how to get it fixed, any help would be much appreciated!
just got 6 different codes today P0301
P0302
P0303
P0304
P0300
P1399
P1399 says all cylinders are misfiring, I have replaced... Fuel pump, Fuel filter, Air filter, spark plugs, o2 sensor. And have cleaned just yesterday the throttle body and injectors.
When im stopped at a red light or am just in park, my car will have a really bad idle and want to stall, the headlights will even dim. But once I put it in Drive and get over 1000 rpm's it drives like a dream. Would love to know how to get it fixed, any help would be much appreciated!
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