So I've been trying to tune this for a while on my LT1. My long term fuel trims are split and my short term fuel trims are fine at +/-5% of 128. My LTFTs are lean on the drivers side 130-145 range while the passenger side is rich at 115-120 range.

The splits were worse but I sent my injectors to get cleaned and now I'm at the above ranges. I've tried playing with all kinds of different things but I haven't really been able to get this problem fixed. I'm going to seafoam the car to see if I have any leaks which I'm not hearing or seeing. Anybody have any ideas of what else I can do to try to get this corrected?

 

In what Cells are those LT's? If its primarilly at idle (Cell 16) it may be the result of the size of the cam. You may need to bypass more air through the throttle blades, and less through the IAC passages.

There's a writeup on the fix on the para-noid website, but I can't find the link.

 

Hi Injuneer its in all the cells. At WOT its okay by my left ST is a little erratic, it adds fuel. I have a great graph of what they look like but i don't know how to attach it to the post.

I modified my TB and IAC paasage but that didn't help. I have then opened the blades a little that's what got my STs in line. I'm afraid if I open it more my STs might get thrown out of wack and my MAP values may suffer. any thoughts?

 

The short terms should stay locked at 128 (0%) when the PCM goes into PE mode (~WOT). How is your left ST looking erratic at WOT?

If you've got that split through all the Cells, its not an idle air problem. Have you tried swapping the O2 sensors side-to-side to see if its an O2 sensor problem?

 

My left ST is lean at WOT. I just downloaded BLM locker to prevent that from happening.

Yeah the split is through all cells. When I got my motor back and I noticed the bad split I bought two new O2s thinking that would fix it. It didn't help out. They are only like 3 or 4 months old. Should I still switch them from side to side?

 

might just want to get some carb cleaner and check for a small vacuum leak on the side of the engine that is running lean (maybe a intake gasket is nicked in one place on that side or something), now that you've ruled out the O2 sensors. Could also be a small exhaust leak... unfortunately, i think what you are looking for will probably be pretty small and hard to find.

 

i'm going to seafoam the car this week to try to build up some smoke to see if i have better luck finding a leak. i've tried the carb cleaner but the car didn't react so i don't think it is a vacuum thing.

 

C Rules, just a quick tip, what I do is reset the PCM (pull fuse or battery 30 seconds) between changes.. That will reset the LT's . The ST's will then update the LT's as you drive and show more accurate readings.. What are you using to scan, if it's Datamaster you can e-mail me the log..

 

hi bobdec whats your email? i've been flashing the pcm from time to time to upload different tunes. wouldn't that also reset the pcm? i've pulled the fuse in the past as well with little results unfortunately.

 

C Rules,, Took a quick look, your left injector DC and BPW are running consistantly 2-5% higher (more fuel) than the right across all BLM cells. I would follow previous recommendations first, seafoam intake, run some injector cleaner , then swap O2's left to right to see if things move or stay the same. Suspect intake gasket leak that effects cylinder or one side, exhaust leak on one side. Could be sticky or defective injector. If you had a IR thermometer and headers you could look for a cold (rich) or hot (lean) cylinder. Could swap injectors side to side. Could inspect plugs for rich, lean misfire conditions for one or a couple of cylinders. Last resort is to alter Individual Cylinder fuel trim but that can be tricky as you don't want to lean a cylinder out to much. By the way your trace shows (MAF) AFGS as 0 through the entire trace, are you running this in SD mode. If so you do have a lean spot from 2600-3150 RPM in your VE table, but that's not effecting the split BLM's.

 

Hi Bobdec,

Yes, I run in SD mode I just like it better. The car is more responsive and it gives me one less thing to worry about. I did send my injectors to get cleaned and flow tested. They are now all good and flow matched. That actually helped the split as it was worse before. I did this after using an IR thermometer and finding headers 1 and 7 were really lean.

I will seafoam the car next as I already have the seafoam. I'll also check the plugs. If I don't find a leak I'll swap O2s arounds. The O2s are only a few month old. Will also try to move my wideband from the y pipe to the actual header banks to see what readings i get.

 

Even with the BLM locker on my tune the WOT BLMS are not at 128. Long Term Left at 140+. WTF??? Gotta sea foam this thing asap to see if I got any leaks.

 

Turns out cylinder 1 & 7 are dead. Pulled off the injector harness and no response from the engine. Taking it to get checked out today to see what the exact problem is.

 

cylinder 1 back up and running. 7 seems to be internal possibly a bad valve or ring.

 

C, Been following this, here and over on Monodax, what was wrong with #1 cyl.