I was just monitoring my car's BLMs because I just got my madz28 tuned pcm in and saw that while using pcmcomm my right BLMs were at 108 and my left was at 12X and but my right and left DEL values were at 124-122. I'm guessing one is the L and one is the S term, but I'm not sure which. Just curious I looked under my hood to listen because prior to the tune, I could hear A LOT of rocker noise with stock rockers, now it seems to be a lot quiter, not sure why. Anyways, while I was under there looking at the left side of the motor, I saw my number 1 cylinder arc every couple of seconds, I'd say once or twice in 10 seconds. So I looked at the right to see how that side was and man, fricken fourth of july. The back left one (#8 i think and the #4 cylinder have arcing every cycle it seems, constant lighting up. The arc looks like it is inside the cylinder because its coming from the base of the plug that is visible. The plugs and plug wires are brand new, less that 1000miles on them. I'm going to take them all out tomrrow and see what is going on. My questions are could the right side be richer because they plugs are arcing so much worse on that side and what could be causing my plugs to arc? Could a miss gapped plug make them arc? And finally what is the best gap to use?

 

The BLM (block learn multipliers) are the long term (learned) fuel corrections. The short term corrections are usually call "INT" for integrators. I have never heard them called DEL. The short terms should be averaging 128 on the left side, but could be averaging less than 128 on the right side, since the right side BLM has reached its lower limit at 108. What "cells" are you reading the BLM's from (they will be different in each cell)?

108 indicated it would be running rich on the right side, if the PCM wasn't pulling out 15% of the fuel it would normally supply. A 108 BLM is not caused by misfires. When you have a misfire, the unused air goes out the exhaust and fools the O2 sensor into thinking its running lean, and the PCM starts to raise the BLM's to compensate, not lower them.

I would check the O2 sensors first. Swap the sensors side to side. Reset the BLM's to 128 by pulling the "PCM BAT" fuse for 30 seconds (key at "off"). Then drive it for a while. If the 108 BLM moves to the left side of the engine, you have a faulty O2 sensor. If you had to extend the O2 sensor wiring for the headers, it could be a wiring problem on the right side.

If the O2 sensors and the wiring are OK, look for a leaking injector. The excess fuel goes out the exhaust and consumes the residual oxygen from the other three cylinders, and the PCM thinks it running rich and lowers the BLM's.

 

well i just replaced the o2 sensor with a bosch sensor because my old ones harness got eaten up by the headers.

 

took out all the plugs and regapped them to .045, while i was there i saw the plugs were all kinda brown on the tips but black on the circle edge that's inside the cylinder. also one or two of the plugs looked kind of white/grey on the tip.

 

What have you done regarding the "arcing"?

 

i took all the plugs out and regapped them to .045, the "light" I am seeing is coming from the bottom of the plug, like it's coming out of the cylinder head. Is that just normal because there is the spark going off inside the head?

Update: After I cleaned the plugs and regapped, my BLM on the right bank rose to 117 much better, but still rich.

 

nvm, the BLM dropped back to 109 when I just checked. Here is a run I did on TTS before I got my MadZ28 tune (BLM same)
http://fb.esnips.com/doc/552d5707-53...aftero2replace

Here's Comm? from pcmcomm that I just did.
http://fb.esnips.com/doc/5eba72dd-96...unningrichCOMM