Random Misfire
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Random Misfire
ok, Just today when I was warming up my car this morning my check engine light came on. Luckily I had an OBD2 monitor to check out the code. It said that I was having random misfire. What is the first step to check in my situation. I drove around my neighbor hood and the car doesn't seem like it loss any power nor feels like the car is running terrible. Car runs fine....So I deleted the check engine light and 5mins later it came back on. What could cause this and how do I fix it?
#2
Re: Random Misfire
random misfire can be caused by a couple of things.. i would first check you ditzy.. check all your wires... make sure there is a firm connection at the cap and the plugs... all n all you might jus need a ditzy
#3
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Re: Random Misfire
ok, Just today when I was warming up my car this morning my check engine light came on. Luckily I had an OBD2 monitor to check out the code. It said that I was having random misfire. What is the first step to check in my situation. I drove around my neighbor hood and the car doesn't seem like it loss any power nor feels like the car is running terrible. Car runs fine....So I deleted the check engine light and 5mins later it came back on. What could cause this and how do I fix it?
Use OEM recomended plugs.
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Re: Random Misfire
ok, Just today when I was warming up my car this morning my check engine light came on. Luckily I had an OBD2 monitor to check out the code. It said that I was having random misfire. What is the first step to check in my situation. I drove around my neighbor hood and the car doesn't seem like it loss any power nor feels like the car is running terrible. Car runs fine....So I deleted the check engine light and 5mins later it came back on. What could cause this and how do I fix it?
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Re: Random Misfire
Ok today i swapped out my old plugs and "o" man they were black.... Swapped in some new colder ngk and erased the engine light... After turning the car on 3x check engine light came back on.. Checked the engine light with the scanner and said there was a misfire on cylinder 2. Checked all the spark plugs to make sure every one of them were snugged tight. Checked all the wires to see if they were all on. Which all of them were!... Should I go ahead and replace the cap and rotors or could it be that my wires are gone to sh!tZZ...What to do? o 0 0 0 and whats a ditzy?
Last edited by Christopherian1982; 12-30-2008 at 08:21 PM.
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Re: Random Misfire
Alright... My car is coming to shitz. I just got back from autozone buying a cap and rotor.I installed the new cap and rotor and before starting the car I erased the code again to see if it will reappear. Started the car ran it for ten minutes and the check engine light appeared again. Saying that i have a misfire on cylinder 2. So the car is started and I pulled out cylinder 2 plug to see if any sorts of power is going threw it and there was. Half way pulling the plug out the cars stalls. Plugged the wire back in and the car wont start....wtf. Now what happen? someone please HELP....
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Re: Random Misfire
Alright... My car is coming to shitz. I just got back from autozone buying a cap and rotor.I installed the new cap and rotor and before starting the car I erased the code again to see if it will reappear. Started the car ran it for ten minutes and the check engine light appeared again. Saying that i have a misfire on cylinder 2. So the car is started and I pulled out cylinder 2 plug to see if any sorts of power is going threw it and there was. Half way pulling the plug out the cars stalls. Plugged the wire back in and the car wont start....wtf. Now what happen? someone please HELP....
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Re: Random Misfire
So you're saying you replaced your plugs, wires, cap, and rotor? What brand parts did you use for all the stuff? Please tell me you didn't buy the ****in' junk Bosch +2 or any other crap like that. That stuff alone is enough to cause a headache when you replace it with shitty parts.
Anyways, usually a random misfire starts by replacing plugs and wires and see if you can then pinpoint it down to a specific cylinders. Since yours seems to be cylinder 2 in this case, start the car and let it run, then pull the wire for cylinder 2 and see what happens. If the misfire doesn't go away, then you know it's that cylinder for sure. Then you need to make sure you've got spark through that wire, which obviously is easy to tell if you do or don't. If you've got spark, then you need to make sure it's getting fuel, which is also easy to figure out. If you've got fuel and spark in that cylinder, I'd then perform a compression test to see if anything goofy is going on inside that cylinder (sticking valve, valves not closing or opening properly due to carbon build-up, etc. etc.).
Start with those tests and report back.
Anyways, usually a random misfire starts by replacing plugs and wires and see if you can then pinpoint it down to a specific cylinders. Since yours seems to be cylinder 2 in this case, start the car and let it run, then pull the wire for cylinder 2 and see what happens. If the misfire doesn't go away, then you know it's that cylinder for sure. Then you need to make sure you've got spark through that wire, which obviously is easy to tell if you do or don't. If you've got spark, then you need to make sure it's getting fuel, which is also easy to figure out. If you've got fuel and spark in that cylinder, I'd then perform a compression test to see if anything goofy is going on inside that cylinder (sticking valve, valves not closing or opening properly due to carbon build-up, etc. etc.).
Start with those tests and report back.
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Re: Random Misfire
is the distributor original? are you boosting? i have a brand new distributor king. boosted my car and now it misfires a little at about 2200 rpm. runs fine under boost though. my tuner told me that any dizzy other that stock or msd will fry the ignitor module eventually. lots of people just prefer the oem ones. you could try to rebuild it. easier to buy a new one though.
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Re: Random Misfire
is the distributor original? are you boosting? i have a brand new distributor king. boosted my car and now it misfires a little at about 2200 rpm. runs fine under boost though. my tuner told me that any dizzy other that stock or msd will fry the ignitor module eventually. lots of people just prefer the oem ones. you could try to rebuild it. easier to buy a new one though.
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Re: Random Misfire
k guys i did a compression check and this is what turned out....I got 175, 175, 115, 160
Whats been changed:
-New Distributor
-Spark plugs
-Wires
Problems: Misfire on cylinder 2
Mods:
B16
greddy turbo kit
How can I fix my problem?
And how does a compression test determined a misfire?
Whats been changed:
-New Distributor
-Spark plugs
-Wires
Problems: Misfire on cylinder 2
Mods:
B16
greddy turbo kit
How can I fix my problem?
And how does a compression test determined a misfire?
Last edited by Christopherian1982; 01-01-2009 at 04:20 PM.
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Re: Random Misfire
do a dry then a wet compression test the 115 cylinder something is obviously wrong
if your compression goes to normal when you add oil to the cylinder in question rings are problably your problem if it does little to nothing your top end is the culprit (burned valves, bent valves, ect) either way dosent sound fun GL
if your compression goes to normal when you add oil to the cylinder in question rings are problably your problem if it does little to nothing your top end is the culprit (burned valves, bent valves, ect) either way dosent sound fun GL
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Re: Random Misfire
do a dry then a wet compression test the 115 cylinder something is obviously wrong
if your compression goes to normal when you add oil to the cylinder in question rings are problably your problem if it does little to nothing your top end is the culprit (burned valves, bent valves, ect) either way dosent sound fun GL
if your compression goes to normal when you add oil to the cylinder in question rings are problably your problem if it does little to nothing your top end is the culprit (burned valves, bent valves, ect) either way dosent sound fun GL
#21
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Re: Random Misfire
If you put oil in and your compression goes up a lot, it shows that your rings/walls are worn. If you do this, only put a couple drops because oil is a liquid and you can't compress liquids. With the information you have presented us, I am pretty sure that the lack of compression in #2 is the cause of the misfire. To pinpoint the problem, you'll have to do a leak down test.
#22
Re: Random Misfire
the one with 115 in apparently no.2 and why its misfiring is either the lack of combustion pressure or if they rings are bad in that oil could be getting on the plug too
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Re: Random Misfire
I'll go buy a leak down tester tomorrow and I will see what the results will be. I've never used this tool and how do i go about using it and what do I look for? Now if I do get an issue for using the leak down test what is the worse Scenario that could happen to the engine and what might need to be replaced? Stay tuned till tomorrow!!!!
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Re: Random Misfire
115 is extremely low. The lowest you should see is around 130. Also, all cylinders should be within 21 PSI of each other at the MOST. I'd definitely say the low compression on cylinder 2 is causing the misfire. Either you've got a valve acting up or the rings are shot. I'd vote closer to rings due to you running a turbo.
You can use your compression tester to read things pretty easily. If you've got bad rings, you'll see the first bounce on the compression test read low, followed by it slowly building up to final compression. Your first bounce should be roughly half of the final number. Another way to tell if the rings are bad is if you put a tablespoon of oil into the cylinder through the spark plug hole and run the compression test again. If the numbers increase drastically most likely the rings are the culprit. If you just plan get low readings it's usually a problem with the valves not seating at the proper times or not seating at all. If you get no compression it's most likely a bent valve or valve stuck open.
Just to make sure - is the engine at operating temp when performing the test? Do you have the throttle wide open? Fuel/spark disabled? Do you have all the plugs pulled out? Battery pack on the battery or another car jumping the battery? These are all things that can show lower numbers if not done.
Essentially all the leakdown tester does is pressurize the cylinder and allow you to see how much it's leaking and where it's leaking to. You simply set each cylinder you're testing to TDC, then listen for where the air is leaking. IIRC 10% is normal leakage since no engine is perfect at sealing. Most of the time your leakage will be passed the rings, which is the reason that cars are fitted with PCV systems.
You can use your compression tester to read things pretty easily. If you've got bad rings, you'll see the first bounce on the compression test read low, followed by it slowly building up to final compression. Your first bounce should be roughly half of the final number. Another way to tell if the rings are bad is if you put a tablespoon of oil into the cylinder through the spark plug hole and run the compression test again. If the numbers increase drastically most likely the rings are the culprit. If you just plan get low readings it's usually a problem with the valves not seating at the proper times or not seating at all. If you get no compression it's most likely a bent valve or valve stuck open.
Just to make sure - is the engine at operating temp when performing the test? Do you have the throttle wide open? Fuel/spark disabled? Do you have all the plugs pulled out? Battery pack on the battery or another car jumping the battery? These are all things that can show lower numbers if not done.
Essentially all the leakdown tester does is pressurize the cylinder and allow you to see how much it's leaking and where it's leaking to. You simply set each cylinder you're testing to TDC, then listen for where the air is leaking. IIRC 10% is normal leakage since no engine is perfect at sealing. Most of the time your leakage will be passed the rings, which is the reason that cars are fitted with PCV systems.
#25
Re: Random Misfire
its ur map sensors its going out cuz my car does but it got to the point where if i use my old map sensor it bogs very bad so when i run without it i get engine light a lil back fire only becuz its running rich soo i think its the map or tps and if it was a spark plug or spark plus wire it would bog