99 A4 T/A LQ4 with H/C/I and LTs and 3200 stall, 3.73 gears

Fine tuning/scanning for a track day yesterday car was found to be very RICH, like low 11 high 10 AFR. I'd swear on last track run it was around mid/high 12s AFR. PE tables were around 1.17xx range.

But yesterday in order to get the AFR on the wideband to be in the high/mid 12's where I wanted it I really had to pull a lot of fuel from the PE table especially near the top, and it's STILL a bit rich (but close enough, lowest points are 11.6 but almost all in the 12's now):



The only change I think I made was a HOTWIRE kit for the SAME STOCK fuel pump, could that make this much difference? I know the computer is somewhat blind at WOT and it's mostly guessing for AFR based on my PE multiple.

COT is off (no cats) and the Open Loop F/A vs. Coolant Temp vs. MAP is all 1's. Temp Delta is zeros all around the temp range car was operating in. From what I am reading here, with COT off the car will choose richest value between PE and OLFA (unless I'm referencing the wrong table...? I think that's what OLFA is). I don't yet have fuel pressure because I don't have a gauge handy but that's my next step when I can.

Car starts/idles/runs/shifts great hot or cold, all tuned by me with help from here of course. No detonation heard at all so far ever. Fuel Trims all seem within tolerable ranges, less than +/- 10% from what I have seen.

Here is what it looked like at the track (below). (Note that the above PE table is actually pulled down maybe another 10% since the below track run but they're close, it's all in the 12's now, this is the graph from the track because it has more data than my tiny test pulls).

I have AFR graphed twice, once with a 14.7 reference line and the other is a 12.8 reference line.



Any thoughts? Prior to this I felt very confident in the tune but now I feel like I need to start over because this sounds hacky. I kinda don't want to retune those VE tables again if I don't have to.

BTW car ran great, posted best time yet of 12.3 at 112.9mph with 1.8 sixty foot.

All thoughts and opinions appreciated!!

 

You were probably dropping fuel pressure before when you tuned it. Correct the VE table and then set the PE back to the desired afr

 

LOL actually, that is ONE thing I really don't think happened, because ironically I had that low pressure problem at the start of my tuning. Matter of fact, I blame that for blowing the original engine that caused me to build the LQ4 LOL

https://ls1tech.com/forums/pcm-diagn...track-day.html

I know my Fuel Pressure was at lowest 55PSI during my entire tuning process, not just the MAF tuning. I was pretty careful about that knowing I already blew one engine, but I guess it's possible the old stuff got mixed in there. Funny how I now have the OPPOSITE problem.

I guess it possible I got some tune files crossed or something from this and had the low pressure numbers in there. It is curious that you suggest something that DID actually happen. If I get a chance I'll try to dig up those old tunes and see if the tables were indeed changed compared to my tables right now. But good theory!

Any other ideas? Also, is having PE down in the 5's necessarily a bad (hacky) thing to do?

EDIT: I guess I'm not running PE in the 5's because I'm only spinning to 6500RPM.. but question remains. Should I back out and do tables again and PE again or is this OK? Note it's a DD bomber with 1/4 million miles on it.

 

Mystery solved.

Pulled my old tunes and actually even had a log from my last track day. One thing I forgot. Between then and now I decided to bump up shift points and rev limiter (was stock, went to 6600ish), and never tuned the PE for those high RPM areas because the car never revved that high at the time I was tuning with the wideband.

At least it was erroring on the RICH side not the LEAN side LOL. This is a good excuse to get a wideband gauge I guess.

Still would like to know if having 0.6xx numbers in PE is bad voodoo. Seems other tunes I see are all greater than 1.00

 

Just had a friend explain this to me in a way I never thought of, you professional tuners probably had this in your head from the beginning.

One reason to fix the VE tables would be because under conditions where PE doesn't kick in and I happen to hit those RPMs and other criteria, the VE fueling could be way off and the fuel trims will have to kick in to fix, and if it's off enough (I think 25% if I recall) it could even throw a code (engine running rich)

Since the VEs are throwing too much fuel (versus lean) I don't think it's risky to the engine, but it shouldn't be in that situation under load without PE typically so I will wait to tune this out later this summer.