misfire

[mdss]

Hi guys looking for some of your expert help

Today when i turned the car on it seemed fine and then after 100 meters it started to misfire and stutter and would not rev properly.
I floored the throttle and it kicked down a few gears and misfired once and then it was fine. Almost like the plugs were fouled or faulty.


It had been doing something similar for the last two weeks immediately after turning on, on the first press of the throttle but after a second it cleared but today it was more prolonged before clearing.

Has anyone experienced this and are my suspicions correct that it may need a set of plugs?

Any help is much appreciated

 

[weiye]

Hi, could be plugs misfiring but I would suggest you take them out to check before you swap them completely. Could also be that your engine bay is somehow flooding with fuel or methanol (if you use it). Does not sound like a boost or vacuum leak to me.

 

[vr2turbo]

If using normal plugs they are not too expensive, so i suggest you change them and see if you still encounter the same problem. If not, solved. If yes, then move on and check some thing else

 

[mdss]

Hi changed the plugs today and although it runs smoother now the car once again from cold was stuttering/misfiring until it was driven for around 5-6 mins then it was fine again.

Very frustrating any ideas guys?

Oh yes and checked they were gapped correctly before installing them, feels like a fueling type problem/electrical thing but hell what do i know!

 

[weiye]

Since plugs have been gapped and changed. I would try to check if fuel was flooding your engine. Your car would seem like its going to stall if there was flooding of fuel in your engine and it would be fine after all the excess fuel has burnt up. You might even face difficulties starting your car due to flooding of engine. I would suggest you park your car at the garage for 5-6 hrs. Before you start the engine, take out the spark plugs and check for fuel flooding in the engine. The mechanics should know how to check that. If there was flooding, you would have to check if your fuel regulator or pump is leaking fuel.

Unlikely to be electrical issue. Not sure if it would be vacuum/boost leak but quite unlikely if the drive becomes fine after 5-6 mins.

 

[mdss]

Thanks for the reply i appreciate the help.

Its not flooding as it starts fine and the mechanic checkked the plugs to see if they were showing signs of flooding. I have just pulled the coil packs off my evo and intend to swap them over in the morning when the car is totally cold. I will then see if i get the same problem.
If that does not fix it i took the crank sensor off also and will then swap that also.

If both these swaps dont work, i will take the car back to the workshop and he will have to do some fault finding.
I know its something simple but very irritating because after a few mins the car is perfect.

Thanks again for all the help, i will report back once i find the fault

 

[vr2turbo]

Yup, try to eliminate one by one, then at least will know what went wrong......

 

[weiye]

yeah. no prob. keep trying. last resort, get a tuner to plug into the obd II and try to read what's happening. Have you tried boosting the car and notice any boost drop? I don't think its boost/vacuum leak but nonetheless I think worth a shot. Or, it could just be the idle control valve. But usually when its the idle control valve, the car would stall even after warming up.

 

[vr2turbo]

Check the auto choke also since if refers to cold start.....

 

[arvinm]

I feel it sounds like an air flow problem.

If shuddering alone, could be due to a clogged/faulty air flow sensor. Might be worth a try to clean with high pressure air it to see if this solves the problem. i
At the same time, it's worth to give your throttle control valve a cleaning too.

 

[Shinjite]

I feel it sounds like an air flow problem.

If shuddering alone, could be due to a clogged/faulty air flow sensor. Might be worth a try to clean with high pressure air it to see if this solves the problem. i
At the same time, it's worth to give your throttle control valve a cleaning too.

Aahh yes, that too can cause misfiring. If cleaning can't solve it, change it to another MAF sensor

 

[vr2turbo]

If MAF sensor problem, why only when cold?

 

[weiye]

yeah I don't think its maf. if maf sensor, problem likely to happen not just when cold. Also quite dangerous to try to clean maf sensor as it is very sensitive. If we are not careful, we may end up really breaking the maf sensor. hmmm

 

[vr2turbo]

yeah I don't think its maf. if maf sensor, problem likely to happen not just when cold. Also quite dangerous to try to clean maf sensor as it is very sensitive. If we are not careful, we may end up really breaking the maf sensor. hmmm

But many members seems to clean on their own DIY, even my mechanic warn me to be gentle if need to clean, but better not to touch......lol

 

[stutzedward]

Sounds like airflow going to die... Airtrek is old and airflow meter needs replacement every 5-7 years. DO NOT CLEAN IT. Some member did and made it worse. It could also be the ignition coil about to die too....

 

[mdss]

Hi guys thanks for all the replies. The problem still persists!

I have tried the other coils from my evo that did not work.
I have put on another maf and again this has not worked.
I am now going to try and replace the injector pack as I have a spare somewhere.

Its very odd as it only happens as soon as you turn the car on, once you press the accelerator hard it clears and is fine, more odd is that it does not do it everyday, there seems to be no pattern to this odd behaviour.

Can anyone think what else it could be? As I said its fine on full throttle no misfires but on the first few presses of the throttle when cold it misfires then clears.

I am becoming very frustrated with it to be honest as the car is great and was hoping to keep her for at least another 2 years.

Any help is always appreciated.

 

[weiye]

If you swapped the MAF, it might need some re-scaling by a tuner. Anyway, I suggest to get a tuner to plug in and start the car when cold. Then get the tuner to log the whole process to see if the fuel is to rich or something. If you haven't tried swapping out the idle control valve, you could try that with a used idle control valve that is working fine - don't think this is the issue but seems like you don't have much options left to try. Good luck!

 

[vr2turbo]

Have you tried cleaning the throttle body?

 

[stutzedward]

I don't really rev the car hard when it's cold. So if this is happening only when cold, I have similar experience with my current Airtrek too... after it's warm, then car is normal.

 

[vr2turbo]

I don't really rev the car hard when it's cold. So if this is happening only when cold, I have similar experience with my current Airtrek too... after it's warm, then car is normal.

Sounds more like auto choke problem. Running lean when cold will cough and shudder, and when step on accelerator slightly will idle properly.....