calys968

With my Granatelli MAF my LTFT readings were constantly at 25%. Today I swapped the Granatelli MAF for a stock MAF and now my LTFT readings range from about 3% to 15%.
Only mods are a lid, K&N filter and Flowmaster muffler. What could be causing my car to still run lean?

Thanks.

jimmyblue

iTrader: (11)

I think you may need to give it more learn time.
Especially for the cells that you spend very little
continuous time in, the trim process can take a
while to settle them into their new value. Once
you see that the average STFT for a cell is zero
then you can conclude they're done drifting for a
while.

calys968

Okay, it's been almost 2 weeks now and my car is still running lean
I've attached a Carchip log...I know it's not much but if somebody could take a look I'd appreciate it.
Does it look like it could be bad O2 sensors?

white2001s10

iTrader: (4)

can we assume this is a screened MAF, and that you cleared all the LTFTs after the swap?

calys968

It is a screened MAF and I used the Carchip to reset the check engine light after I swapped the MAFs...am I correct in assuming that resetting the light also clears the LTFTs?

white2001s10

iTrader: (4)

Never had a carchip, but I wouldn't assume so. Sounds like it just clears DTCs to me.

calys968

How would I clear the LTFTs?

Thanks for your help.

horist

Pull PCM Bat and PCM Ign fuses (under hood) while key is in run position, leave for 10-15 seconds and LTRIMs will be reset to 0 and need a relearn

calys968

Thanks, I'll give that a try!

calys968

Alright, the LTFTs have been cleared. Here is a new Carchip file from today. If somebody could look at it and give my their opinion I'd appreciate it, even though it's not much to work with Would bad O2 sensors cause my car to run lean like it is?

Another_User

Lid. Replace aftermarket lid with stock lid. Re-test.

calys968

Ok, I'll try that tomorrow. My car was running lean even before I installed the lid though

92SilverSHO

iTrader: (3)

how lean are you running, im having similar problems, but mine just started happening within a few months for no reason, my mileage took a huge hit, throwing no codes, i just have lid/cutout, i have efi logs, noone can figure out, i get KR in weird places also. Whats your mileage? getting KR?

calys968

My LTFTs range from 0% all the way up to high teens. When the Granatelli MAF was installed they were at 25%.
I get about 15 mpg in town and about 25-30 on the highway. It's throwing a code for my knock sensor and 2 codes for my cats. I had a friend in Arizona that had HP Tuners and when he hooked it up a few months ago it showed some knock retard at wide open throttle.
If you figure out what's wrong with your car definantly let me know! Maybe we're having the same problem?

WAHUSKER

iTrader: (4)

Well, since it's throwing a code for the knock sensor, maybe that's it. If that has gone bad & is giving false knock signals, the car could be pulling timing & dumping fuel to compensate. Which could make your ltft's whacked & throw the cat codes.

On the other hand, if it truly IS running lean, then that could cause knock AND the fuel trim issue. You really need to throw it on a wideband equipped dyno to figure it out.

92SilverSHO

iTrader: (3)

well, this is how it started, i moved to montreal, quebec, started using the gas, after the first fillup, mileage took a hit, next fillup, took another 1-2mpg, then finally car threw a bad cat code, they replaced the cat, however mileage dropped to 10mpg, and thats where i am right now, my ltrims dont go as high as yours but my KR is worst that yours bigtime, either way theres something odd with my car, im gonna clean the maf when i take it out for the spring, but after that im at a loss to what to do.