Inconsistent Acceleration w/ SBD 500x
 

Everyone:

I've been trying to iron out an issue with my car since my tune was completed with James (HRI). Car seems to stumble randomly at partial throttle with respect to acceleration. Doesn't always seem to happen. Feels like it's losing/gaining a significant amount of power in a ~500-1k rpm band right below when boost starts to build (~3-4k). Problem doesn't seem to be nearly as noticeable, if at all, when it's WOT or even moderately pressed on. Only during a normal, driving two minutes to a gas station, kind of gentle acceleration does it stumble. James says the tune looks fine based on my logs. Anyone have this issue?

PTuning suggested my Primary O2 on the log file didn't look great, but I'm not educated enough on tuning to make a judgement for myself. I can e-mail tunes to anyone. The logs are too large for datazap.

Thanks!

Worth noting: I've checked all of my piping, the BOV multiple times, all bolts and hoses. No leaks that I can find.

MAF scaling maybe

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Is that connection under the manifold clamped? I know these can pop up when boosted..

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Im going to have to agree on maf scaling. If your on ecutek or maybe oft has speed density but when the engine is inside the maf range it could use the maf still. Tuning for the turbo would mainly focus on the speed density tables in order to make it safe but maybe the maf got skipped. If you want to check record a log and see if your LTFT (Long term fuel trim) + STFT(Short term fuel trim) are greater than a 5% value or less than a -5% value. If that is the case then your maf scaling is off.


If your on oft it might be all speed density and the stumble you feel might be temp. based. Speed density doesnt do well with variations in air density such as altitude or temp. If you say it happens after stopping at a gas station it might be heat soaking temp on your intake causing the issue. If thats the case than ECUTEK is probably the solution your looking for.


If not then im out of ideas.