Why am I lean at WOT???? PL file inside. HELP!!

[gunslinger]

I've been fighting a lean at WOT condition for a while now.
Fuel pressure wasn't rising 1:1 with boost, so I changed the pump, and that has been taken care of. Max fuel pressure on this run was about 65lb.
The O2 sensor was reading strange. When I'm just cruising down the highway, it's sticking between 530 and 560mv. It doesn't seem to be in good fuel control. I changed it, and it is a little better, but it's not switching like it should.
The only thing I'm seeing strange is the MAF reading. I thought it was supposed to lock at 255 @ WOT. Mine's not.
I had to ease into the throttle an pedal it once. You'll see that in the file. Damn street tires.

Combination is in my sig. Any suggestions would be helpful.

Thanks.

 

[Pronto]

Hi Eric. From what I see your running pretty lean still. I would seriously consider a fuel pressure transducer so you can log that and wb O2 to verify your lean condition. Does the O2 cross counts cycle steadily or is it lazy or stuck? You do has a quick MAF dropout. I had that happen too but it was a deeper drop so I just got rid of the stocker and went with a Translator and LT1 MAF. No dropouts since.

 

[gunslinger]

I've got a fuel pressure gauge on the A-Pillar, so I keep a very close eye on that.
The O2 doesn't cycle like it should. No nice sine wave, just pretty much flat lined.

 

[Pronto]

O2 time.

 

[QWKRTNU]

Get a new o2.. also i take it you do not have a wideband so you should get one of those... Also i would look at your battery or alternator becasue your volts are getting low too.. They should be at13.0 or above and there getting to 12.. That can also effect your fuel pump

 

[gunslinger]

The O2 is a brand new Bosch sensor. I have a new 140A alternator too. It's 14.5V at the battery, and at the pump. Scanmaster voltage since the day I got this car has been at least 1V lower than the alternator is putting out. It doesn't help that I've got underdrive pulleys on it.

 

[QWKRTNU]

I would get a wide band it is very very hard to tune a car when you only have a scan master... what is your injector duty cycle? I bet with the 42's you might be maxed out

 

[gunslinger]

I would get a wide band it is very very hard to tune a car when you only have a scan master... what is your injector duty cycle? I bet with the 42's you might be maxed out

There's an attached powerlogger file.
I thought I had maxed the injectors too, but it's only a low12 high 11 second car. 42s with alky should be plenty.
Injector duty cycle peaked at 81.6%

I think the MAF drop out is where I had to pedal the car.

The flat lined O2 has me puzzled. Cruising down the hwy at 75 mph there should be a nice clean wave. It's not there. I'm not sure I believe the data coming out of the computer. I think I'll hook a scope up to the O2 at the ECM and see what it's really reading.

 

[QWKRTNU]

There is one more thing I think it could be becasue I had the same issue last time I drove my car.. I changed the o2 and it seemed to help but when I got on it had issues like you. I replaced my maf and all was good again. I had drove the car the day before fine and parked it the next day the maf went bad just sitting

 

[TurboDave]

Personally I would suspect the MAF. At your boost levels it should hit 255 and stay there, then near the end of the run it started looking flaky.

 

[gunslinger]

I may have to try a MAF. A major input like that would definitely screw with O2 readings....Maybe I'll just go mafless....

I was also thinking that if the cam sensor was flaking out, it could also explain the O2 flat-lining. Does anyone have a good picture of what the cam and crank signal should look like on a scope? Where should they synch?

 

[Pronto]

Checking the "CC" on the Scanmaster showed me when my O2 got lazy years ago. It would change but real slow. It is possible the new O2 is bad but not likely. Maybe the wiring to it is damaged? Voltage at the alt vs the ecm are always different, some worse than others. The main thing is how much it drops at WOT. You could go with the SD chip, looks like it would work with 42s. Those injectors+alky should be plenty to low 11s but they do limit you as far as the upgrades the the new 6.1 chip can do with the O2 and fueling. Need a minimum of 50s for that chip.

 

[TurboDave]

Want to prove it's the MAF? Reduce your boost back to about 18 lbs. The maf should still easilly hit 255!! I'l bet it's no where near close.

 

[huntsg]

I had a very similar issue in the past. Either get a known good original MAF (remans usually do not hold up) or go with something like a gen2 and a LT 1.