S300v2 E85 B16a leaning out when fully warmed up

[Coombs_43]

What's up guys. In need of some help here with this weird issue I've been having lately. So, when I start the car dead cold the tune is all good (rich to start but AFR slowly creeps up to 14.6-15.2) Now, when the ECT reaches 170+F the motor slowly begins to lean out and by the time operating temp is reached the AFR sits between 16.2-17.0 or sometimes even ---. When cruising at light load the AFR's float between 16.5-18.00+. Under partial throttle the AFR's seem to be perfectly normal between 13.5-15.5 depending on the throttle input. Under WOT the AFR's are in 13's until boost really comes in and then AFR starts to rise to 14+, at which I immediately back off. Pretty stumped on why this is happening. Just had the car tuned like two weeks ago and seemed great for a bit. We did swap wastegate spring from 14 psi to 8.7 psi but boost parameter were adjusted accordingly and everything seemed to be great after that. But now this problem has started. I've also attached a Datalog of the car after fully warming up and going on a 7 min cruise. Let me know your thoughts and any help is much appreciated. Thanks! -Zack

[Coombs_43]

Bump! Any ideas are appreciated!

*EDIT* Added a file of the calibration for people to take a look at to help figure out this issue.

[Spunkster]

Have you talked to the tuner that did the tuning about this issue? It could be the compensations.

[Coombs_43]

Have you talked to the tuner that did the tuning about this issue? It could be the compensations.

Yes I have, I plan on heading over there tomorrow with the car to see if we can sort out the issue. Justed wanted to get some more opinions or ideas to maybe help the process of elimination. Have you taken a look at the Datalog and calibration? Notice anything unusual except for the high AFR readings? I did also think it may be compensations but saw that they're all set to 0 by operating temp, so I don't believe it could be that.

[Coombs_43]

*UPDATE*. So went to the tuner and try and solve this issue and instantly he noticed my fuel pressure at idle was almost 10psi down from when he had tuned it a couple weeks ago. Bumped up the pressure a bit to at least make it home, still had crazy AFRs but not as lean. It then came to me that I had totally forgot I used the same fuel strainer from my old setup, which was very old. Replaced it and fuel pressure bumped up to about 60psi (started at 51psi).

Went ahead and dropped the fuel pressure back down to 51psi and before starting it I realized the TPS sensor was very loose. Went ahead and calibrated it and tightened it up. Finally got the car started and instantly I could tell the car was acting much better. AFRs looked perfect at idle during cold and when completely warm. Went out for a cruise and AFRs were also spot on! Buttt when I went to do a third gear pull my AFRs started reaching the 13s at which I backed off. 2nd gear was the same deal.

My tuner did mention something about the fuel pump I currently have (Aeromotive stealth 340) and said that they seem to crap out very often, even when fairly new. Anyone have any experiences with this pump and would please chime in??? Also, I'm wondering if this pump is too much for the stock wiring and isn't getting enough voltage, causing a pressure drop in higher RPM.

[Coombs_43]

Bump. Any ideas? I'm gunna try burning off the rest of this tank of E85 and go back to the gas station I usually buy from. Thinking I might of just got a bad mixture of E85 cause the lean at WOT problem didn't seem to happen until my last fill up.

[Coombs_43]

Alright guys so I got another update. Since my last post I have filled up with a fresh tank of E85, put in a Walbro 416 with a relay setup through my battery to help eliminate voltage drop, installed and calibarated a new OEM TPS (which was wayyyyy more accurate and steady when calibrating), checked online fuel filter (clean) and even took apart my regulator to see if there was maybe a machining defect, of course there wasn't. After doing all this I took it out and tho throttle response is even better and it doesn't hesitate or buck under light throttle condition, I still have the same problem with it leaning out in boost. Pretty stumped on what it could be now. Anyone's help is much appreciated as I am not able to get ahold of my tuner.

Notes:

*After turning off the car, my fuel pressure drops down to about 20 psi within a min or two. I've always seemed to have this occurrence tho and didn't affect anything before.

*When cruising, lifting off the throttle slowly causes my AFRs to slowly keep getting more and more rich, which to me makes no sense? And when slowly giving it more throttle it will lean out in 16-17 until I give enough as then it goes i to normal 14-15. Also, there is only a certain point in the peddle that the AFRs will stay steady between 14-15 while crusing. If I start to let off it will richen up like stated above and if I give it too much it will go lean (16-17). I think this has something to do with the TPS being loose when tuning it before but I could be wrong.

*AFRs are great until boost comes in, then they shoot quickly up to 13-14. Unfortunately I cannot get onto a dyno to see if my fuel pressure is dropping. Don't even know what could cause it to drop at this point since everything fuel related has checked out or been replaced.

[Mafia]

I would take the car back to tuner or just add fuel under boost. If you use the help drop down in smanager it explains how to add and take away fuel.

[Coombs_43]

Ya I'm trying to get back to the tuner ASAP. With the TPS being off during tuning my whole partial/cruising AFRs are outta wack at times since I had installed a OEM unit and calibrated it. I did replace my regulator also and still same issue. Decided to utilize the Walbro 416 I had installed and also lower the duty cycle of my injectors. So I went ahead and Bumped up the fuel pressure from 51 psi to 57-58psi to see if it would make a difference and it deff did. AFRs were decent until higher psi was reached, then it stars to lean into the high 12s. I do wanna try and add fuel up top tho, just to see if it will fix my lean issue. Just concerned about trying to re-tune partial throttle.

[Coombs_43]

Bump! Could this be caused by a bad map sensor? I have a omni 3 bar in right now, but wonder if that would cause it to lean as soon as boost comes in...

[Spunkster]

Is it reading less boost than when tuned?

[Coombs_43]

Not from what I can tell. The only thing I changed before this all happened was the wastegate spring from a 14 pound to a 8.7 pound spring and adjusted the duty cycle trough hondata to get the desired pressure (around 19 psi which the car was making before). Unfortunally I can't even see where it spikes since it starts leans out pretty much as i start getting into higher psi. Either way I'm set up to be on the dyno again on Saturday so hopefully we can sort this out. Is there anyway I could have messed something up in the process of changing the parameters? Or maybe need to be retuned with this new spring and duty cycle?

[Coombs_43]

Update: Got the car on the dyno yesterday and tuner worked his magic. Car pumped out 453whp 298 trq at 20 psi. (PTE 5431E turbo) Said the car had a lot more room when it came to fuel since the last time it had been there and just pretty much did a retune. it's great so far and hasn't lean out once since.

I do still seem to have the problem with AFRs richening when having the throttle position in the 0-20% range. He did say he noticed how much more defined the resolution was when it was in that range compared to 20-100% range. Any knowledge of this problem and how I could go about solving it?

Also, I deleted the IACV because the new billet TB I had purchased didn't come with a port for it. I got the idle down when warmed up but the thing runs pig rich (10.0-10.5) until it pretty much completely warms up. I don't mind having to keeping my foot on the throttle so it won't die when cold starting, just want to see if I can have it idle not as rich during the warm up cycle. Almost stalls the car out and the car is always in open loop btw. All help is appreciated, thanks!

-Zack

[Spunkster]

Was it tuned at part throttle or only at WOT?

Without an idle controller then you will have difficulty getting it to idle properly when cold or warm. I personally would get a proper throttle body that can be used with an idle controller.

[Coombs_43]

It was tuned at both part and wide open throttle. He had mentioned tho that he noticed it would richen lower and lower as you went anything below 20% throttle input. Once I get past that amount of throttle input the AFRs lean back out to the normal (14.0-15.5). Literally starts at 13.5 or so when you come to that point and lowers as I slowly lift off the pedal and vise versa until past that point again. Doesn't matter how much load or what gear you're in when cruising. He said he had tried re calibrating it when he noticed and still same thing. But I mean everything else throttle wise is spot on especially responsiveness. Just aggravating trying to keep my AFRs up with the throttle while crusing. Pretty confused at this point!!