Car sputters when cold?
May 16, 2007, 04:21 PM
#18
The reason why you guys have this problem is simple...It's actually not a "problem" it's there by design.
When you first crank your engine up, the ECU retards the hell out of the ignition timing and keeps it semi retarded until the engine coolant temp(ECT) reaches a certain temp. THis is for emissions and facilitates fast catalytic "light-off" from elevated EGT's.
During which time, the engine feels slugish and can "break-up" due to the retarded ignition timing.
You guys need to be letting your engine warm up for several reason, not just because of this issue alone. The harshest time for your engine is at a cold start and the moments following the cold start.
Let your engine warm up to the point where RPM's drop to the desired level and your temp gauge is above the first hash mark.
CJ
When you first crank your engine up, the ECU retards the hell out of the ignition timing and keeps it semi retarded until the engine coolant temp(ECT) reaches a certain temp. THis is for emissions and facilitates fast catalytic "light-off" from elevated EGT's.
During which time, the engine feels slugish and can "break-up" due to the retarded ignition timing.
You guys need to be letting your engine warm up for several reason, not just because of this issue alone. The harshest time for your engine is at a cold start and the moments following the cold start.
Let your engine warm up to the point where RPM's drop to the desired level and your temp gauge is above the first hash mark.
CJ
May 16, 2007, 05:28 PM
#19
The reason why you guys have this problem is simple...It's actually not a "problem" it's there by design.
When you first crank your engine up, the ECU retards the hell out of the ignition timing and keeps it semi retarded until the engine coolant temp(ECT) reaches a certain temp. THis is for emissions and facilitates fast catalytic "light-off" from elevated EGT's.
During which time, the engine feels slugish and can "break-up" due to the retarded ignition timing.
You guys need to be letting your engine warm up for several reason, not just because of this issue alone. The harshest time for your engine is at a cold start and the moments following the cold start.
Let your engine warm up to the point where RPM's drop to the desired level and your temp gauge is above the first hash mark.
CJ
When you first crank your engine up, the ECU retards the hell out of the ignition timing and keeps it semi retarded until the engine coolant temp(ECT) reaches a certain temp. THis is for emissions and facilitates fast catalytic "light-off" from elevated EGT's.
During which time, the engine feels slugish and can "break-up" due to the retarded ignition timing.
You guys need to be letting your engine warm up for several reason, not just because of this issue alone. The harshest time for your engine is at a cold start and the moments following the cold start.
Let your engine warm up to the point where RPM's drop to the desired level and your temp gauge is above the first hash mark.
CJ
I believe mine has more to do with my injectors or injector scaling or something along those lines. When I have a nice cold start (again, overnight or when I come out from work) the car starts right up on the first crank - which is also when this condition of going extremely lean occurs. If the car is warm at all, it takes a couple of cranks and some gas to get it started, however I do not have the lean issue. It's weird, but I am CERTAIN it is not because I don't let the car warm up.
Any input besides "let it warm up" would be appreciated.
May 16, 2007, 06:12 PM
#20
iTune...I've seen many of your posts, agree with you almost always, and I know you know your ****, but I do disagree with you on this one - at least for my car. I know exactly what you guys are talking about when you say the car needs to warm up (which I do), however that is not the issue I'm experiencing.
I believe mine has more to do with my injectors or injector scaling or something along those lines. When I have a nice cold start (again, overnight or when I come out from work) the car starts right up on the first crank - which is also when this condition of going extremely lean occurs. If the car is warm at all, it takes a couple of cranks and some gas to get it started, however I do not have the lean issue. It's weird, but I am CERTAIN it is not because I don't let the car warm up.
Any input besides "let it warm up" would be appreciated.
I believe mine has more to do with my injectors or injector scaling or something along those lines. When I have a nice cold start (again, overnight or when I come out from work) the car starts right up on the first crank - which is also when this condition of going extremely lean occurs. If the car is warm at all, it takes a couple of cranks and some gas to get it started, however I do not have the lean issue. It's weird, but I am CERTAIN it is not because I don't let the car warm up.
Any input besides "let it warm up" would be appreciated.
Now, after reading your posts again, seems as though your problems lie more in ECT temps compensation factors, which we don't have control of yet using ECU flash.
or even more possible....."min coolant temp for closed loop". Try setting this lower. It's possible that your ECU is staying in open loop too long after startup and you fuel tables in the idle and part throttle/low rpm areas are a little leaner than is needed at that ECT, while in open loop....causing the lean condition and the breaking up. This can be fixed now....the first thing i stated is something we don't have control over yet(if ever) with the stock ECU.
You might want to force open loop and tune these areas manually, then revert back to closed loop feedback. The easist way to force open loop is to set the "min temp for closed loop" higher than the engine can reach...then tune idle and part throttle...then revert back to original setting.
CJ
May 16, 2007, 06:45 PM
#21
I was mainly reffering to the other guys that were chiming in saying they had the same feel after a cold start. I can promise you that all modern EFI engines do this from the factory. I have seen it and logged it on many many cars. It's a way to lower emissions from faster catylitic light off.
Now, after reading your posts again, seems as though your problems lie more in ECT temps compensation factors, which we don't have control of yet using ECU flash.
or even more possible....."min coolant temp for closed loop". Try setting this lower. It's possible that your ECU is staying in open loop too long after startup and you fuel tables in the idle and part throttle/low rpm areas are a little leaner than is needed at that ECT, while in open loop....causing the lean condition and the breaking up. This can be fixed now....the first thing i stated is something we don't have control over yet(if ever) with the stock ECU.
You might want to force open loop and tune these areas manually, then revert back to closed loop feedback. The easist way to force open loop is to set the "min temp for closed loop" higher than the engine can reach...then tune idle and part throttle...then revert back to original setting.
CJ
Now, after reading your posts again, seems as though your problems lie more in ECT temps compensation factors, which we don't have control of yet using ECU flash.
or even more possible....."min coolant temp for closed loop". Try setting this lower. It's possible that your ECU is staying in open loop too long after startup and you fuel tables in the idle and part throttle/low rpm areas are a little leaner than is needed at that ECT, while in open loop....causing the lean condition and the breaking up. This can be fixed now....the first thing i stated is something we don't have control over yet(if ever) with the stock ECU.
You might want to force open loop and tune these areas manually, then revert back to closed loop feedback. The easist way to force open loop is to set the "min temp for closed loop" higher than the engine can reach...then tune idle and part throttle...then revert back to original setting.
CJ
Thanks very much, and I will take a look at your suggestions tomorrow. 
Apr 27, 2013, 04:21 AM
#23
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Anyone have any resolution on this? I have a car that recently developed identical symptoms....
I disagree that the car needs to " warm up" to not break up at 20 mph off boost rolling down the street. 60 seconds of warmup for oil pressure, and a little heat in the head and you should be able to drive the car gently off boost with no issue until it is warm enough to rag on (1/4 temp). If your **** is breaking up on cold starts you have fueling, ignition, or timing issues. Cold temps expose these problems because it is much harder to keep a cold cylinder firng.
Bottom line is my car never did this at all last year, it started minor and has gotten worse over time. Something is quite wrong.
I disagree that the car needs to " warm up" to not break up at 20 mph off boost rolling down the street. 60 seconds of warmup for oil pressure, and a little heat in the head and you should be able to drive the car gently off boost with no issue until it is warm enough to rag on (1/4 temp). If your **** is breaking up on cold starts you have fueling, ignition, or timing issues. Cold temps expose these problems because it is much harder to keep a cold cylinder firng.
Bottom line is my car never did this at all last year, it started minor and has gotten worse over time. Something is quite wrong.
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