Hesitation on throttle when warm, negative LTFT (datalogs and vids)

[kev0]

My LTFT/STFT bounced around for thousands of miles until I had enough of it. I switched to CSG and Zach stabilized it throughout the RPM band. He fixed a lot of other issues I had with the car too. I had a problem that my RPM dropped really low for a split second the moment I gave the car some gas and Zach took care of it as well without me having to ask.

I say get a second opinion. It may not be hardware related but software related as long as you're sure that you have no intake leaks or a bad o2 sensor.

[Grant Runion]

Small revelations! But first...

Originally Posted by kev0

My LTFT/STFT bounced around for thousands of miles until I had enough of it. I switched to CSG and Zach stabilized it throughout the RPM band. He fixed a lot of other issues I had with the car too. I had a problem that my RPM dropped really low for a split second the moment I gave the car some gas and Zach took care of it as well without me having to ask.

I say get a second opinion. It may not be hardware related but software related as long as you're sure that you have no intake leaks or a bad o2 sensor.

Not sure who this Zach guy is but it sounds like the kind of person that really should be looking at this for me. Part of me wants to keep tinkering but the first Ontario Time Attack of the season is coming up and I may have to tap out and take it to a professional.

With that said, I did have a small revelation tonight. Just because, I unplugged the MAF to either eliminate it or focus in on it. Low and behold, the hesitation disappeared when the ECU was no longer using readings from the MAF. The car even seemed to idle more consitently. This is great, because I can stop asking myself if it is injectors, or vacuum leak, or any other parts I can think to throw money at. Unless I am misunderstanding something, I can think of only three possible causes now:

1. MAF scaling is still not correct and needs to be done again
2. MAF sensor is bad or damaged
3. Wiring harness to the MAF sensor is bad or damaged

I'm not sure why I had not thought to do that earlier, but super glad I did. Hopefully next post will be a resolution of some sort.

[Dzmitry]

Originally Posted by Grant Runion

Small revelations! But first...



Not sure who this Zach guy is but it sounds like the kind of person that really should be looking at this for me. Part of me wants to keep tinkering but the first Ontario Time Attack of the season is coming up and I may have to tap out and take it to a professional.

With that said, I did have a small revelation tonight. Just because, I unplugged the MAF to either eliminate it or focus in on it. Low and behold, the hesitation disappeared when the ECU was no longer using readings from the MAF. The car even seemed to idle more consitently. This is great, because I can stop asking myself if it is injectors, or vacuum leak, or any other parts I can think to throw money at. Unless I am misunderstanding something, I can think of only three possible causes now:

1. MAF scaling is still not correct and needs to be done again
2. MAF sensor is bad or damaged
3. Wiring harness to the MAF sensor is bad or damaged

I'm not sure why I had not thought to do that earlier, but super glad I did. Hopefully next post will be a resolution of some sort.

Just as a side note, Zach is a well renowned tuner for this platform and works for CSG (CounterSpace Garage).

[Grant Runion]

TENATIVELY SOLVED
I tried one more MAF scaling with 6 good datalogs to make sure the data was clean and it was still no good, even got as bad stalling out at stop lights. I bit the bullet and bought a new MAF sensor, installed it and reflashed with the off the shelf Stage 2+ tune. Right off the bat the the throttle response was great, idle was steady and it shifted much smoother. I only have about 30kms on it but my confidence is pretty high that this is resolved now. So, the takeaway:

If you are having issues with bogging at low load situations and have sketchy LTFT readings, try disconnecting the MAF and see if the problem goes away in the absence of MAF readings. If that is the case and scaling gets you nowhere, you may have a bad MAF sensor.

Thanks to everybody who chimed in with advice, much appreciated!!!