Need to know where to start looking into fixing this problem. My scanmaster shows that @ WOT both my right and left sides wont pulse over 10.2. I seen some place a stock lt1 should be 15.x @ WOT. My car is a cc503 with full bolt-ons, and a tune. So something got to be off, I also pull 5* KR every time I go wot.

 

Are you running stock fuel injectors? Who tuned it for the cam? At what RPM is the pulse width 10.2mSec at WOT? What do the BLM's look like in Cell 15? What is the MAF sensor reading at max RPM/WOT?

The pulse width is calculated by the PCM based on the injector size constant, the target A/F ratio (detemined from the PE tables), the BLM's and the MAF sensor reading. If it has stock injectors and the the stock flow constant in the program, I'd suspect the MAF sensor reading it low, but you should be able to determine that from the ScanMaster readings.

 

Stock injectors, Tuned by Ion for a hotcam "just swapped over the 503 did the same with the hot cam". I'de say from 4,000rpms all the way to 6,200 it stays around 10.2. Never checked the blm's or the cell at wot. What should they be reading? The maf I think is fine its been a while sence I scanned it at wot but I think it went over 300gr's last time I did.

 

At WOT, you will be in either Cell 15 or Cell 18. Cell 15, and the Cell 15 BLM's are typically used only of the PCM is "adding" fuel to compansate for a lean mixture in closed loop. That would mean BLM's above 128. If the Cell 15 BLM's are below 128, and you go WOT, the PCM seems to either lock the Cell 15 BLM's at 128, or use Cell 18 and 128.

If you are getting 300gps at max RPM, your MAF sensor isn't reading low.

You've basically ruled out all the things I could think of that would cause the PCM to set pulse widths that are too low. The 15mSec typical pusle width came out of my online Scanmaster writeup.

 

As long as it's not running lean, it doesn't matter what the PW are.

Rich

 

I scanned it last night and the cell stuck at 15. Didnt get a good chance to scan the maf, so i'll do that today.



My goal is to find my 5* kr so I can spray the hell out of the car.

 

Ok scanned it again today. BLM's @ 128, Cell @ 15, Maf @ 285ish "i've seen it go well over 300 with a smaller cam". Maybe the maf needs cleaned....


This kr is really ticking me off. I have a lt4 KM, and had Ion do the kr desensitizing in the tune. I have no clue why I keep getting knock.

 

With regards to the knock retard, you need to determine if it is "false" knock or the real thing. Try running some fuel with a higher octane rating than what you normally run. If the pcm stops pulling away timing with better fuel, the system is probably doing just what it is suppose to.

As Rich said, as long as the motor isn't experiencing a lean condition, I wouldn't be too concerned with the pw.

I'm sure you know it is stronly advised to purposely pull adequate amounts of timing when you "spray the hell out of the car".

 

I cleaned the air filter, and maf today. I think its cleared the problem up. I also found and fixed an exhaust leak at my driver side header at the plug for the air pump line.


I only logged 2 wot runs. One was showing well over 300 on the maf "was only 280's before the cleaning and I didnt even take it to the redline". The other showed 0.7kr. The 0.7 kr is awesome considering i'm running 87oct on a 93 tune"I run 93 99% of the time". I also hit the throttle for a second while I was idling after I took care of the stuff and at 4,500 it showed 12.6 on the injector pulse.

Hope this helps anyone with this pos problem in the future. Clean air filter, maf, and check for exhaust leaks.