Thread: Car running LEAN right after it was running fine for what reason?

Didn't really make a difference. Car feels the same. I assumed it was only limiting the pcm from seeing boost According to the logs it's the same from max vacuum to atmosphere. I'll have to hit the Yard and get another 1 bar. I'm not paying 60 bucks for a new map for this test. I never had luck buying aftermarket sensors from autoparts stores anyways.

Thanks for reminding me! I had thought a few days ago about just setting everything back to stock. My first tune was made for me by a guy here. He sent me a tune before I started the engine, i just wanted a base to learn. I don't have that tune any more, or my stock file. I lost all my tunes from 4 years ago.

So I set all the tables, even spark, back to stock except for what I needed to tune MAF. Car started nice and the afr error didn't jump around. It did keep rising all the way to 180 degrees, though. But at least I have a stable platform to start experimenting now, thanks to you.




Wideband read 16.1 max when warmed.

Also, my idle is closest to matching commanded than its ever been. 700 commanded, 725ish actual.

I decreased AFR : Fuel-Open Loop/Base-OL AFR : to match the scan. That should have been the first thing I did before trying to drive and log. I wonder if the stock VE table played a part. Like you said, it seems to be a mystery what they do on some cars.

Still getting lean the longer I run the car. My untrained eyes can't spot anything in the tune. I'm guessing...either a sensor is losing resistance as it gets heat soaked, or the injectors. The ECT is stable, but the wideband is seeing lean creep in the longer I drive. Wish I had a fuel pressure gauge I could use when driving. My harbor freight gauge show 63psi at idle. Fuel pump is fairly new aem e85 pump.

Another thing I am thinking. Is it Possible that the PCM is getting heatsoaked and causing issues? Stock location is in the airbox, where hot air is being pulled away. Since my box was removed, it's just sitting vertical where it was on a bracket i made. I mean, it's a computer, computers don't like too much heat, and the factory put it in the flow of cooler air. I'm gonna rig up some cooler air ducting and test.

No. My computer sat for 4 years on the frame where the air box used to be. Never once ran into any problems.

Well I'm stumped then. If anyone wants to look, here's a new log. I left my parents home, 20 minute drive. At first I was happy, error was small. By the time I got home it was running lean. I had thought maybe my wideband was failing, giving false numbers, but i can definitely feel and hear the leanness.

I have 42lb injectors I could swap back in. Don't think they will be enough for e85, but enough to test for this issue.

Scan

Tune

Originally Posted by SgtMarshal

your fuel trims are 0 across the board? did you hit relearn fuel trims on the scanner? or reset fuel trims

I'm doing an O/L MAF tune. PE set to zero, 14.7 commanded, closed loop disabled by setting enable to 284°. Commanded still bounces around until I'm at around 24% throttle. Shouldn't make a difference I think, because I'm tuning wideband/commanded error.

i think your still trying to ve tune and dont know it. cause thats not how to tune a maf. thats how you tune VE. wb err means about nothing for maf tuning.

This is the guide I am trying to follow. Makes the most sense to me.

He is using the MAF. This method works really well and is a lot faster than using the stock narrowband. The wideband is just slightly less accurate at lamba than the narrowband is.

Originally Posted by GTPpower

He is using the MAF. This method works really well and is a lot faster than using the stock narrowband. ..

Works a lot faster, lol! I've probably scanned and adjusted maf 30 times now. I know what your saying though. It most definitely should be a quick process. Russ, the guy who made the write-up, said it takes him minutes. 2-3 sub 7000hz tunes, and a wot tune.

I'll unplug my o2 tonight and see what happens. I considered it because that was his preferred method, but I'm definitely in open loop, no trims. So not sure why it would matter. Then again, I am always suspicious of the hidden tables in the PCM. Might still be some weird corrections happening with o2?

@GTPpower....


upload

My O2 harness. I think we found our issue, lol. Gonna separate the wires, leave it unplugged and go for a drive. Would definitely explain why it gets leanner the longer it runs. Was sitting right on top of my header.