badhombre

iTrader: (4)

so we ran into this problem before and seemingly fixed it by accident. now it has come up again. I have a stock PCM and using HPtuners. I recently switched from a regular MAF tune to SD with 3 bar map. Purchased the extra credits for 3 bar SD tuning etc. It would cough and sputter but only fire on cylinders 1, 2,4, and 8. My tuner and I spent nearly 10 hours going over everything, mechanical, electrical, tune etc trying to figure this out. I even contacted denmah who sent me a base file to try. Same result. Finally, out of borederline insanity, I made the old joke about chevy's having to have the check engine light on to run. so he turned the CEL light command for the MAF back on and it fired right up and began running normally. Just, with the CEL on. W T F?!?

sicksspeed

iTrader: (2)

Check ground grounds and all the grounds.

SSellers

I think the CEL function just provides ground to one side of the light bulb when turned on. Must have something connected to that wire that should instead be connected directly to ground.

badhombre

iTrader: (4)

all ground wires are uncut and run to stock location on the head, and the CEL is wired off of the single signal wire from the pcm to an led in the dash about 6" away. and it is wierd, we can turn off all the lights for everything else. it was just the ones for the MAF that makes it not run

SSellers

Does that also force it into some kind of limp mode?

salemetro

iTrader: (5)

Post your tune file. I know....standard request, but it might help get some insight. Or, PM me, and you can email it to me.

2xLS1

iTrader: (25)

Sounds like you don't know how to force it into SD mode. You have to fail the MAF.

salemetro

iTrader: (5)

Exactly. However, he said that Denmah sent him a base tune to try with the same result....so I'm curious to see what he's running currently. Denmah is no idiot, but sometimes things get messed up.

DMM

MAF has to be set to fail at 1Hz and must have the "turn CEL" unchecked. The MAF codes must set or you will be using MAF and not he MAP which is why you are having issues.

Disconnect and/or remove the MAF if possible and zero out all of the MAF tables.

badhombre

iTrader: (4)

that's the problem, we failed the maf but turned the CEL light off for it and it wouldn't run. with the MAF failed but the CEL light for it on, it does run. he is sending me a copy of the tune now to post up. bear in mind, it is not complete. it was just to get it up and running. we haven't done any driveability/boost tuning yet

salemetro

iTrader: (5)

This might sound like an odd question....but do you still have the original "read entire" tune file from the PCM? The reason that I ask, is that I recently had a really strange corrupt tune file issue on a customer's car....that was only solved by copying the files that I had been tuning into the old/original initial-read tune file. After I flashed the updated "original" tune file back in, all issues that I was having with the car disappeared.

Just throwing it out there...

badhombre

iTrader: (4)

I believe so. My tuner is good about backing everything up and saving copies of stuff before making changes. we had a similar issue getting the truck running originally on all stock parts. fought it for weeks, and finally one day just re-burned the same tune back into it and it started and ran fire since. still no idea why. I have had some other odd happening with this PCM which are starting to make me suspect it may have damage or internal issues. I have tried, repeatedly and in various ways to get the one wire p/n rev limiter to work with no success

scotte

this is what your maf codes need to be set to

in order for the pcm to be is speed density the codes need to be enabled and set, the codes are then set to 2- no mil light so you dont have to stare at a cel and it will still be fully functional when something else fails

badhombre

iTrader: (4)

^thanks, I will pass that along to my tuner and see if that fixes it.