Misfiring/stalls-what to do
Feb 7, 2008, 12:58 AM
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Misfiring/stalls-what to do
When I rev my 8 MR up, around 4500 rpm engine stalls as if there is some fuel cut or boost cut. This happens when boost hits like 15psi then neither engine revs up due to stalling nor boost goes up. If I keep pedal floored, engine does go up but with lots of jerks and stalling.
I've set boost at 1.2 bar on AVCR with duty cycle around 45%. When I decrease set boost, engine does same thing on lower boost. That time jerks are not that hard.
Boost pipes are perfectly intact. Fuel pressure is ok. This usually happens when I start car from cold. I floor the pedal once engine is at normal temp. This happens during first few runs say 3 4. After making some runs, car gets normal. Hits full boost (18psi) without any issues.
Now I am not getting where the problem lies. Is it because of cold weather (nowadays it is ~10 degrees celcius) or some other issue?
During night time, this happens alot & jerks very hard and day time it does do this but car gets ok after 2 3 runs.
I even changed plugs but nothing worked out.
Sometimes I think its either ignition issue or injectors issue but car has just done 13000miles. When it was total stock, it used to do the same but car used to get OK after a little accelartion in any gear. Now this thing is getting worse day by day.
Any idea what problem my car has?
I'm running 3inch turbo-back and Apexi AVCR wih boost at 1.2 bar and 93 octane gas.
I've set boost at 1.2 bar on AVCR with duty cycle around 45%. When I decrease set boost, engine does same thing on lower boost. That time jerks are not that hard.
Boost pipes are perfectly intact. Fuel pressure is ok. This usually happens when I start car from cold. I floor the pedal once engine is at normal temp. This happens during first few runs say 3 4. After making some runs, car gets normal. Hits full boost (18psi) without any issues.
Now I am not getting where the problem lies. Is it because of cold weather (nowadays it is ~10 degrees celcius) or some other issue?
During night time, this happens alot & jerks very hard and day time it does do this but car gets ok after 2 3 runs.
I even changed plugs but nothing worked out.
Sometimes I think its either ignition issue or injectors issue but car has just done 13000miles. When it was total stock, it used to do the same but car used to get OK after a little accelartion in any gear. Now this thing is getting worse day by day.
Any idea what problem my car has?
I'm running 3inch turbo-back and Apexi AVCR wih boost at 1.2 bar and 93 octane gas.
Feb 7, 2008, 04:27 AM
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When I rev my 8 MR up, around 4500 rpm engine stalls as if there is some fuel cut or boost cut. This happens when boost hits like 15psi then neither engine revs up due to stalling nor boost goes up. If I keep pedal floored, engine does go up but with lots of jerks and stalling.
I've set boost at 1.2 bar on AVCR with duty cycle around 45%. When I decrease set boost, engine does same thing on lower boost. That time jerks are not that hard.
Boost pipes are perfectly intact. Fuel pressure is ok. This usually happens when I start car from cold. I floor the pedal once engine is at normal temp. This happens during first few runs say 3 4. After making some runs, car gets normal. Hits full boost (18psi) without any issues.
Now I am not getting where the problem lies. Is it because of cold weather (nowadays it is ~10 degrees celcius) or some other issue?
During night time, this happens alot & jerks very hard and day time it does do this but car gets ok after 2 3 runs.
I even changed plugs but nothing worked out.
Sometimes I think its either ignition issue or injectors issue but car has just done 13000miles. When it was total stock, it used to do the same but car used to get OK after a little accelartion in any gear. Now this thing is getting worse day by day.
Any idea what problem my car has?
I'm running 3inch turbo-back and Apexi AVCR wih boost at 1.2 bar and 93 octane gas.
I've set boost at 1.2 bar on AVCR with duty cycle around 45%. When I decrease set boost, engine does same thing on lower boost. That time jerks are not that hard.
Boost pipes are perfectly intact. Fuel pressure is ok. This usually happens when I start car from cold. I floor the pedal once engine is at normal temp. This happens during first few runs say 3 4. After making some runs, car gets normal. Hits full boost (18psi) without any issues.
Now I am not getting where the problem lies. Is it because of cold weather (nowadays it is ~10 degrees celcius) or some other issue?
During night time, this happens alot & jerks very hard and day time it does do this but car gets ok after 2 3 runs.
I even changed plugs but nothing worked out.
Sometimes I think its either ignition issue or injectors issue but car has just done 13000miles. When it was total stock, it used to do the same but car used to get OK after a little accelartion in any gear. Now this thing is getting worse day by day.
Any idea what problem my car has?
I'm running 3inch turbo-back and Apexi AVCR wih boost at 1.2 bar and 93 octane gas.
Feb 7, 2008, 04:32 AM
#5
My 0.02!
1. Check for boost leask and a faulty BOV.
2. I would install a Wideband. It will pay itself in the long run. Also, will help you diagnose many problems.
3. Have you checked your AFRs? Because of the weather it may be possible that very rich\lean conditions are happening and the car is messing up until is fully warmed.
4. Replace spark plugs and/or re-check the gap on them.
Sounds to me like a boost or fuel issue! The reasoning is that you are getting that behavior around peak TQ on the car.
Good luck and keep us posted!
1. Check for boost leask and a faulty BOV.
2. I would install a Wideband. It will pay itself in the long run. Also, will help you diagnose many problems.
3. Have you checked your AFRs? Because of the weather it may be possible that very rich\lean conditions are happening and the car is messing up until is fully warmed.
4. Replace spark plugs and/or re-check the gap on them.
Sounds to me like a boost or fuel issue! The reasoning is that you are getting that behavior around peak TQ on the car.
Good luck and keep us posted!
Feb 7, 2008, 05:27 AM
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@ Burklow: It is 2004 model, 8 MR. No codes.
@ Cheb evo: Difference is around 15 degrees during day & night timings. I even turned boost off from AVCR. Previously, it used to hold boost at 10psi, when turned off, but last night boost was spiking around 14psi. At that time, engine was having very little missing and running better. I had same idea that it runs better on lowering boost but you know I am not going to drive my car like this.
I want to increase boost but if this missing allows me to
and why would it run lean as it is total stock? Even if i run stock boost, problem is there.
@ joedr: I have ordered wideband kit, untill it reaches me I have to find out the culprit. I have installed prosport NBo2 guage, connected to 02 sensor, which shows "stoich or rich" when TPS is 100% so I think fueling is ok. I have installed iridium but result is same. so plugs is out of question.
@ Cheb evo: Difference is around 15 degrees during day & night timings. I even turned boost off from AVCR. Previously, it used to hold boost at 10psi, when turned off, but last night boost was spiking around 14psi. At that time, engine was having very little missing and running better. I had same idea that it runs better on lowering boost but you know I am not going to drive my car like this.
I want to increase boost but if this missing allows me to
and why would it run lean as it is total stock? Even if i run stock boost, problem is there.@ joedr: I have ordered wideband kit, untill it reaches me I have to find out the culprit. I have installed prosport NBo2 guage, connected to 02 sensor, which shows "stoich or rich" when TPS is 100% so I think fueling is ok. I have installed iridium but result is same. so plugs is out of question.
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Feb 7, 2008, 10:09 AM
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Feb 7, 2008, 11:41 PM
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Today, I made a run without doing anything.
I noticed that if I accelerate gradually from lower range rpm, car runs fine and boost runs ok till rev cut and when I pedal down fully (TPS 100%) from lower range, say 3000rpm, car runs ok till 15psi.. rpm stalls from 5000 to 6000rpm then it goes further up smoothly plus boost goes up as adjusted.
Either it's some boost lock or spark blowout.
I will reduce the plugs gaping today and will check again.
I noticed that if I accelerate gradually from lower range rpm, car runs fine and boost runs ok till rev cut and when I pedal down fully (TPS 100%) from lower range, say 3000rpm, car runs ok till 15psi.. rpm stalls from 5000 to 6000rpm then it goes further up smoothly plus boost goes up as adjusted.
Either it's some boost lock or spark blowout.
I will reduce the plugs gaping today and will check again.
Feb 8, 2008, 05:45 AM
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I installed back stock NGK plugs, that I replaced with iridium. Car's better now. Seems iridium ain't good for turbo.
Coils are fine. Will put new NGK to see if things work out.
Stalling is there but not that hard, plus engine smooths out after 6000 rpm and runs perfect there on.
I think its ignition/plugs issue. Will keep you guys updated.
Wish me good luck
Coils are fine. Will put new NGK to see if things work out.
Stalling is there but not that hard, plus engine smooths out after 6000 rpm and runs perfect there on.
I think its ignition/plugs issue. Will keep you guys updated.
Wish me good luck