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Low kPa stutter


jacob80

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Hey guys,

 

Just getting my car back together and will resume tuning shortly. One thing I did notice within my tune is that when I keep the car at a low kPa and keep increasing RPMs, right when I reach ~3000 RPM the car starts stuttering. There is no detonation, but a stutter. Is this cause by the ignition map being too retarded? From what I gather, if I have too much advance, it would detonate. I know I'm not going lean because when I step on it at the same RPM but obviously higher kPa, there are no problems. Thanks for your help guys!

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Couple of thoughts...

 

Same RPM but low and high kPa will be looking at different cells on your VE table, so it could be lean, or rich for that matter. Do you have a wideband to check this?

 

Also, what is the advance in this area? Did you check with a timing light to make sure that the advance MS thinks it is putting out is correct?

 

Finally, are your acceleration enrichments turned on? If they are, when you step on the gas it will make the mixture more rich than if you just cruising at 3k RPM.

 

Good Luck!

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My thought is that my timing may be too retarded. This isn't a "step on the gas" situation. This is simply me sitting in first gear and slowly and very steadily increasing RPMs and then right around this specific RPM range, it hesitates. No popping or backfiring, just stuttering. Alternatively, when I accelerate more aggresively, I blow by that RPM all the way up to 6800 RPM with no problemo. Perhaps I should advance my timing a little?

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  • 2 weeks later...

Does anybody have any other advice for me before I start messing with timing? What should be my method of tuning this point in the map?

First gear under a no load situation, I would say wouldn't be damaging to get this a little wrong with experimentation. Some times you have to quit asking, suck it up... and jump. If you asked about under full boost hesitation id be more hesitant, But what you describe is just for you anyways right? When do you ever see yourself in that driving situation?

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