bmarino1974

Hey fellas, I got a log here with some weird action in the upper rpms. For some reason my fuel is leaning out and well..you'll see. the maf and other junk just looks kinda wacky. Help me out here guys. There are two "pulls" toward the end of the log.

Thanks,

Ben Marino

bmarino1974

Anyone?? I'm wondering if I have valve float as well with that MAF reading.

GT12 Lingenfelter Camshaft
Comp Beehive Springs

RonSSNova

I don't' see anything unusual with the MAF reading. Looks smooth to me.
Your fuel is commanded at 12.4 and is rich at lower rpm and lean at higher rpm.
Perhaps it's just not tuned real well?

bmarino1974

Well it's a mail tune but here's an updated log. My wideband was in a bad spot..now this is dead accurate. And the maf is surging up and down through second and third gear around 5000 rpm.

bmarino1974

Fixed wideband location.

RonSSNova

This is what I see.
Commanded fuel is 12.49:1 (Green)
Actual by your wideband is mid 11's. (Yellow)

The MAF freq and flow look normal to me. I never see perfectly smooth MAF curves.

Ron

bmarino1974

Okay I was wondering because through first gear the MAF seems perfectly smooth but through higher gears at sustained rpms, it starts bobbing, which led me to believe there is some turbulence or valve float. I have a volant dual cone air intake so maybe thats causing some air flow issues. The filtered MAF reading is fine so I guess its all good. But I definitely need to lean out the WOT a bit, I'm NA so thats a bit rich for sure.

Thanks for the input!

Ben Marino

NJ_phil

I don't post here in the C5 section but happened to look at that 1st log and was stumped by the leanout because it only happens only when the vehicle speed increased.

Just curious, where was your WB sensor located to cause this??

bmarino1974

Someone had put a bung in the header that was basically pointed at the ground so I bought a angled adapter to move it away from the ground. The only thing I can think of is that staying at high rpm constantly (shifting through gears) and high exhaust flow slowly removed the concentration that I guess had built up in the adapter, leaning out the reading. or something like that lol. I finally tore my exhaust apart and added a bung in the cat, before the catalyst. It's way more sensitive now, and accurate.

RonSSNova

You're welcome!

My headers conviently had the bung in the center of the X-pipe.

WB readings are probably best observed in third and 4th gear.
i know in my auto, low gear is always a smidge leaner than 2nd and third despite the airflow falling in the same MAF range.

Ron

NJ_phil

Maybe the high vehicle speed cooled off the sensor and threw off the readings. They're pretty temperature sensitive and assume it was hanging down in the airflow under the car. Glad you got it sorted out.

Regardless, the car seems to be running great.

bmarino1974

Oh okay..I'll have to keep that in mind when something else seems off.

Thanks

bmarino1974

Yeah it seems to be fine now. I actually think its a bit slow lol. I wanna turbo the thing, there's not enough wheel spin for my liking.

bmarino1974

yeah so..what the fun sticks happened lol? Take a look. Reloaded an older tune with the same VE table...and this happened. I then went back and loaded the one used in the WOT scan..did the same thing. Any ideas????

0Tampa Tuning

For more help, you should post the tune related to the scan.

bmarino1974

Thanks for the reply, but it seems a line had come off of the intake causing a massive vacuum leak. It's fixed and running fine.