A/F is WAY off

[Hoboattacker]

Hey guys, I need some help on diagnosing a problem with my a/f that I am having.

I'll start with all the symptoms starting from idle and then going to WOT.

At idle, my a/f gauge is reading 13.8-14.3 with it staying around 14.1-14.3 most of the time. A week or so ago it was right at the 14.5-14.6 mark.

While cruising (not under load) it reads around 13.4-14.2 with it mostly around 13.7-14.1

Under light load (still cruising) it reads 12.9-13.8 with it mostly around 13.4-13.6

My BIGGEST concern is WOT. Last night I was getting on the interstate I went WOT. It started off normally around 11.5 and then climbed to the normal 11.7-11.8 range. About a second later it jumped to 12.2 and then to 12.4. I shut it down immediately and called my tuner. He said to check for loose connections under the hood. I found none.

I just had a header leak fixed on the passenger side (reading is from the driver side). My car was reading a/f normally before the fix. I wouldn't think this is a problem because a leak would mean it would run leaner. By fixing it, it should run richer. I also don't think it's bad gas since I just filled up with Shell V-Power 93 and I had 3/4 tank of gas left when I went WOT.

Any input is appreciated. Thanks guys!

 

[DarkFireGT]

Actually, even stock, my AFR was crazy rich when I was running the Shell gas. I tried 2 different stations and had the same problem. Switched to BP and everything was solved. I would try different gas, first. Shell is good gas, but because of their additive mixture, it really can cause some AFR issues. If that doesn't help, it's most likely your tune, or a leak somewhere between your MAF and TB.

 

[Hoboattacker]

What are the best gas stations? We have Exxon/Mobil, Shell, and Chevron that I know of. I've heard Exxon isn't great, but I'm not sure.

 

[anthony05gt]

I like Sunoco gasoline. My car runs great with it. 3 years ago when I just had a hand tuner and a CAI the engine would just shut down once in a while sometimes with and sometimes without the engine light. It was because my tune was lean. Whatever you do stay away from WOT until you get this cleared up. Good luck with it.

 

[Hoboattacker]

Yeah, I figured staying away from WOT was the best idea, but...

I just did a 3rd gear pull and kept my eyes on the fuel pressure and A/F gauge. It was pegged at 11.0-11.1 the entire time (up to 5500 rpms where I let off since there was a red light). Fuel pressure was good too around 60lbs (39lb injectors).

 

[DarkFireGT]

Whose tune are you running? We had Bamachips previously, and had trouble with the AFR on both cars. Lean on one, rich on the other. Even after updated tunes, we still had problems. Switched to Brenspeed and AFR was dead on.

In any case, the easy fix is to try different gas. Like I said, I do great with BP. Sonoco is fantastic if you can find it. I think Chevron is fine as well.

 

[Hoboattacker]

I am running a custom tune through RWTD (runnin' with the devil). The tune was spot on coming from the shop so i don't know what is up right now. I'm NOT blaming the tuner and have 100% faith that he can fix this. I might be doing a datalog and emailing it to him. I just don't know the parameters I should datalog

 

[2k05gt]

if you think you got bad gas you can try the following,
add 6 oz of acetone to a full tank this tends to clean it up.
DO NOT GET ON YOUR PAINT...

I have heard adding a Gal of Toluene or Xylene does wonders as well

I know what you are all thinking

google it this stuff does work and you can buy it at any paint store.