Need help with rough idle, no stalling and no mods
12-26-2006, 07:13 PM
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Need help with rough idle, no stalling and no mods
I need help with a 98 Civic EX. I have a rough idle under 1000 that makes my whole car kinda shake, although it doesn't stall or anything, but it has a hard time with pickup now too. I've got a stock D16 with just a header and CAI, no exhaust. I do regular oil with Mobil 1 and Honda Filters, I did a timing belt, water pump and fuel filter at 100K, and Ive got 160K on it now. I've done my tune-ups and had my last one at 152K, and the plugs looked a little worn with a tinge of green but otherwise ok. No codes on ECU, the injectors sound fine with a mech. steth. and my compressions are 151, 145, 153, 153, cylinders 1-4 respectively. Can anyone tell me what else to check or what the problem most likely is? Im out of options here, and I want to go turbo but not on a rough idling engine. Thanks, hope everyone had a good christmas
12-26-2006, 08:34 PM
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Re: (sddrift)
cai has nothing to do with vacuum, that would be a manifold problem, and it's only on idle so I doubt its vacuum that would show the whole time and probable throw a code.
12-26-2006, 08:40 PM
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Re: (dema12co)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dema12co »</TD></TR><TR><TD CLASS="quote">cai has nothing to do with vacuum, that would be a manifold problem, and it's only on idle so I doubt its vacuum that would show the whole time and probable throw a code.</TD></TR></TABLE>
Wrong. A vacuum leak will only be present at idle. At high RPM the opening of the throttle plate causes vacuum to dissipate. A vacuum leak will cause the motor to run lean but depending on the size of the leak it may or may not throw a code.
Two things I want you to check.
1. Take a squirt bottle (windex) full of water and spray the spark plug wires while the car is running. Sparks and bogging during this indicate bad wires.
2. Take a can of carb cleaner and spray all around the intake manifold while the vehicle in running. In the case of a vacuum leak the carb cleaner will enter the engine causing an ever so slight increase in RPM that you will have to listen for.
Wrong. A vacuum leak will only be present at idle. At high RPM the opening of the throttle plate causes vacuum to dissipate. A vacuum leak will cause the motor to run lean but depending on the size of the leak it may or may not throw a code.
Two things I want you to check.
1. Take a squirt bottle (windex) full of water and spray the spark plug wires while the car is running. Sparks and bogging during this indicate bad wires.
2. Take a can of carb cleaner and spray all around the intake manifold while the vehicle in running. In the case of a vacuum leak the carb cleaner will enter the engine causing an ever so slight increase in RPM that you will have to listen for.
12-27-2006, 04:21 AM
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Re: (dema12co)
You didn't really elaborate on how the car runs otherwise. Does it seem torqueless, then pick up as you get into upper rpm...or does the car run bad overall? Any codes?
Good advice from above...but if you can't find anything more information would help.
Good advice from above...but if you can't find anything more information would help.
12-27-2006, 07:50 AM
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Re: (RC000E)
yeah, thats pretty much it. It lags at the start but then as I rev through the gears it runs fine. No codes, no trouble codes at least, the scanner I have only pulls trouble codes.
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12-27-2006, 01:32 PM
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Re: (JDM-97CX)
No sparks or stuttering with water sprayed on plugs, (they're new NGK plugs with only about 7000 miles on them) and no acceleration or change in RPM at all with carb cleaner sprayed all around manifold.
12-27-2006, 04:56 PM
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Re: (dema12co)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dema12co »</TD></TR><TR><TD CLASS="quote">No sparks or stuttering with water sprayed on plugs, (they're new NGK plugs with only about 7000 miles on them) and no acceleration or change in RPM at all with carb cleaner sprayed all around manifold.</TD></TR></TABLE>
You are supposed to spray the plug WIRE while the car is running not the spark plug.
You are supposed to spray the plug WIRE while the car is running not the spark plug.
12-28-2006, 08:09 PM
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Re: (som3on3_10)
Nah it just started happening over time, and I thought it was a tune up so I did that anyway, then I thought maybe engine mounts just made it seem rough, so I bought engine mounts and stiffeners, I replaced a rusted exhaust and a bunch of other maintenance, but nothing fixed the rough idle.
12-29-2006, 11:27 PM
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Re: (som3on3_10)
Nah it just started happening over time, and I thought it was a tune up so I did that anyway, then I thought maybe engine mounts just made it seem rough, so I bought engine mounts and stiffeners, I replaced a rusted exhaust and a bunch of other maintenance, but nothing fixed the rough idle.
12-30-2006, 05:53 AM
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ive had the same problem guaranteed its ignition go through everything thats what i did it turned out the rotor in my dizzy was melted/ worn down to **** i got a new cap and rotor and did a full tuneup on it .. sparkplugs,wires and the car runs fine now
01-04-2007, 02:59 PM
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Re: (dema12co)
OK since noone has any definitive answers on this on HT, I decided to write my findings to help anyone else out that might have this problem.
I have stiff engine mounts to begin with so I was expecting a rough idle, but mine was far worse than it should have been, so I decided to go at it step by step.
1. Plugs - mine were a little worn but ok, and I had just changed them so this wasn't it.
2. Plug Wires - I sprayed mine as a recommendation by someone on here, but they were fine and thats where he ran out of ideas so that wasn't it either.
3. Manifold leak - I sprayed carb cleaner all around my manifold, and with no increase in idle, there was no vacuum leak on the outside of the manifold.
4. Timing - Mine checked out perfect, it should be 12 degrees +/- 2 degrees BTDC at idle after warming up on the D16Y8
5. Double checking idle speed - the manual says to warm up the car, and after its warm to pull the connector off of the IACV valve (will cause the MIL to come on, which will go away when you reconnect and restart the car). The idle should be at 450 degrees. Then when reconnected go to 650 and then 750 and 850 with headlights and AC on.
6. Compression - All of mine checked out with 151, 145, 153, and 153, on cylinders 1-4 respectively. 2 seems low but its within spec. Honda says minimum 135 on all 4 and max variation of 28 on a D16Y8.
7. Coolant - I double checked my coolant and hoses and connections for any leaks, and also burped my coolant again just to see if there was anything I had missed from that last time I changed it.
8. Gas additive - I had been told before by a *GOOD* mechanic that there was really only one additive that worked well, its by BG and its called 44K. Its about $25 a can, but everyone that I know that actually *KNOWS* anything swears by it. I bought three cans, and I put one in my gas tank with it almost empty. This takes a little while to work, but it helps a little. The other two cans are for steps 9 and 12.
9. Throttle/Intake cleaning - This is my version of the IV drip that a lot of mechanics use this 44K for, instead of an IV though I bought one of those little refillable aerosol cans from Harbor Freight, it was about 9.99 and I poured a can of the 44K into it and pressurized the can to about 75 PSI (the max is 90). Then, I removed the intake from the throttle, cleaned the neck just inside the opening, and while revving the engine a little by pulling on the cable, I started spraying the 44K in. With breaks every few seconds, and wiping off the stuff flowing out, I sprayed the whole can in and let it run for a couple seconds then turned it off and let it sit. They also recommend an oil change immediately after this, as it takes so much carbon off it will ruin your oil right away.
10. Ground wires - This may have been the simplest thing I did, but made the biggest noticeable difference. I made all new ground wires using 4 gauge wires I had left over from a stereo system, and 4 gauge 1/4" ring terminals from AutoZone. I only replaced the stock ground wires, and I used a Dremel to take a little of the corrosion and factory paint away where the terminal would touch the body. Then I sprayed a little bit of of the silver paint over the connectors (covering everything else with cardboard) to keep any more corrosion or rust from forming. This improved the idle a little and improved the throttle response A LOT (everyone says it, but you have to see it to believe it)
11. Resetting ECU - after all of the above tests/cleanings were done I disconnected the battery cable for about an hour, and then reconnected it and let my car idle for about 20-30 mins to let the ECU relearn the idle.
Still to do...
12. Injector cleaning - shops do this for about $125, but I decided I wanted to try it on my own. I bought a canister injector cleaning kit, (about $110 from astro pneumatic via tooltopia.com). You fill half of the cansiter with the 44K (about a can anyway), and the rest with gas (obviously at your own risk). Then you have to cut off the fuel pump with the fuse under the dash, and the return line from the bottom of the regulator, and take off your gas cap (the canister pushes pressurized concentrated cleaning solution through your fuel rail, and some of the pressure could end up at your filter or if you don't disconnect the return, at your tank) There are two ports on the canister, the top one you hook up to shop air, and the one on the end of the hose you have to connect to your fuel system somewhere. I am going to connect it to the end of the fuel rail where the Banjo bolt is, I just have to find the adaptor to fit there as the canister comes with a schrader type valve for domestic cars. You could also connect it to the banjo bolt on top of the filter using that service bolt hole, but Id rather keep it at the rail. I'll update everyone on this when I do it.
13. IACV cleaning - this should have been one of the first, but I'm waiting on the gasket I ordered to arrive, and I'm going to use Intake cleaner to clean it as I've been told by everyone who *KNOWS* that over time brake cleaner or carb cleaner will ruin the seals and parts inside. I also have to check the resistance across the connectors, which should be between 8-15 Ohms according to someone on here, but its not listed in the manual. The manual says to short two terminals on the ECU and listen for clicking in the IACV, if it clicks its fine, if not replace. Ill update after this one too.
I hope this helps anyone with idle problems at least get a start into troubleshooting. It's definately not an end all. All of the steps above helped my idle little by little, so mine was obviously just due to age and needed some TLC.
I have stiff engine mounts to begin with so I was expecting a rough idle, but mine was far worse than it should have been, so I decided to go at it step by step.
1. Plugs - mine were a little worn but ok, and I had just changed them so this wasn't it.
2. Plug Wires - I sprayed mine as a recommendation by someone on here, but they were fine and thats where he ran out of ideas so that wasn't it either.
3. Manifold leak - I sprayed carb cleaner all around my manifold, and with no increase in idle, there was no vacuum leak on the outside of the manifold.
4. Timing - Mine checked out perfect, it should be 12 degrees +/- 2 degrees BTDC at idle after warming up on the D16Y8
5. Double checking idle speed - the manual says to warm up the car, and after its warm to pull the connector off of the IACV valve (will cause the MIL to come on, which will go away when you reconnect and restart the car). The idle should be at 450 degrees. Then when reconnected go to 650 and then 750 and 850 with headlights and AC on.
6. Compression - All of mine checked out with 151, 145, 153, and 153, on cylinders 1-4 respectively. 2 seems low but its within spec. Honda says minimum 135 on all 4 and max variation of 28 on a D16Y8.
7. Coolant - I double checked my coolant and hoses and connections for any leaks, and also burped my coolant again just to see if there was anything I had missed from that last time I changed it.
8. Gas additive - I had been told before by a *GOOD* mechanic that there was really only one additive that worked well, its by BG and its called 44K. Its about $25 a can, but everyone that I know that actually *KNOWS* anything swears by it. I bought three cans, and I put one in my gas tank with it almost empty. This takes a little while to work, but it helps a little. The other two cans are for steps 9 and 12.
9. Throttle/Intake cleaning - This is my version of the IV drip that a lot of mechanics use this 44K for, instead of an IV though I bought one of those little refillable aerosol cans from Harbor Freight, it was about 9.99 and I poured a can of the 44K into it and pressurized the can to about 75 PSI (the max is 90). Then, I removed the intake from the throttle, cleaned the neck just inside the opening, and while revving the engine a little by pulling on the cable, I started spraying the 44K in. With breaks every few seconds, and wiping off the stuff flowing out, I sprayed the whole can in and let it run for a couple seconds then turned it off and let it sit. They also recommend an oil change immediately after this, as it takes so much carbon off it will ruin your oil right away.
10. Ground wires - This may have been the simplest thing I did, but made the biggest noticeable difference. I made all new ground wires using 4 gauge wires I had left over from a stereo system, and 4 gauge 1/4" ring terminals from AutoZone. I only replaced the stock ground wires, and I used a Dremel to take a little of the corrosion and factory paint away where the terminal would touch the body. Then I sprayed a little bit of of the silver paint over the connectors (covering everything else with cardboard) to keep any more corrosion or rust from forming. This improved the idle a little and improved the throttle response A LOT (everyone says it, but you have to see it to believe it)
11. Resetting ECU - after all of the above tests/cleanings were done I disconnected the battery cable for about an hour, and then reconnected it and let my car idle for about 20-30 mins to let the ECU relearn the idle.
Still to do...
12. Injector cleaning - shops do this for about $125, but I decided I wanted to try it on my own. I bought a canister injector cleaning kit, (about $110 from astro pneumatic via tooltopia.com). You fill half of the cansiter with the 44K (about a can anyway), and the rest with gas (obviously at your own risk). Then you have to cut off the fuel pump with the fuse under the dash, and the return line from the bottom of the regulator, and take off your gas cap (the canister pushes pressurized concentrated cleaning solution through your fuel rail, and some of the pressure could end up at your filter or if you don't disconnect the return, at your tank) There are two ports on the canister, the top one you hook up to shop air, and the one on the end of the hose you have to connect to your fuel system somewhere. I am going to connect it to the end of the fuel rail where the Banjo bolt is, I just have to find the adaptor to fit there as the canister comes with a schrader type valve for domestic cars. You could also connect it to the banjo bolt on top of the filter using that service bolt hole, but Id rather keep it at the rail. I'll update everyone on this when I do it.
13. IACV cleaning - this should have been one of the first, but I'm waiting on the gasket I ordered to arrive, and I'm going to use Intake cleaner to clean it as I've been told by everyone who *KNOWS* that over time brake cleaner or carb cleaner will ruin the seals and parts inside. I also have to check the resistance across the connectors, which should be between 8-15 Ohms according to someone on here, but its not listed in the manual. The manual says to short two terminals on the ECU and listen for clicking in the IACV, if it clicks its fine, if not replace. Ill update after this one too.
I hope this helps anyone with idle problems at least get a start into troubleshooting. It's definately not an end all. All of the steps above helped my idle little by little, so mine was obviously just due to age and needed some TLC.
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