pcmhacking.net

So ive had a customer today requiring relinking of another second hand PCM on his VZ LS1.

Long story short guy spent 15g on a cammed motor install and got it tuned by a company here in NZ, turns out he didnt like it so is getting his mechanic to swap out the cam for a standard one hence why a replacement standard PCM has been relinked.

Trouble is ive done the relink, but was not getting a MAF Hz reading.
Went to loom to find they had depinned the pink wire ( ignition ) and the brown/white ( airflow signal ) and folded them back and taped them in loom

First question:- Why would they depin those wires? (IAT wires were still plugged in and i think still functioning unless theres an external IAT sensor away from MAF, his mechanic is adament that they never touched the wires and apparently watched them the whole time which i doubt )
I thought just failing it, and masking it in the software would work unless theres certain software that require MAF to be physically disabled?

question 2 :- could it be the wiring thats at fault after i put the pins back into there correct locations or can the maf be damaged by not being connected and run through (like WBO2 sensors for example running then without being powered?

I'd say it's not a custom MAFless tune loaded. And as the VZ runs the IAT from the MAF they've been smart enough to work that out. Usually you will wire in a separate IAT from the VT-VY models. A custom MAFless OS let's you use the high octane table still. Disconnecting the MAF like this you will most likely not be able to use the high octane table. Possibly it is a custom OS and they've just disconnected it for no reason.

Dylan wrote:I'd say it's not a custom MAFless tune loaded. And as the VZ runs the IAT from the MAF they've been smart enough to work that out. Usually you will wire in a separate IAT from the VT-VY models. A custom MAFless OS let's you use the high octane table still. Disconnecting the MAF like this you will most likely not be able to use the high octane table. Possibly it is a custom OS and they've just disconnected it for no reason.

So you recon they have used a standard operating system instead of a 1/2 bar and pulled the signal and ignition wires from the plug to force the MAF to fail and run in speed density mode and just masked the SES light?
Which would explain why the MAF is still in place to utilise the IAT sensor?

Couldn't be sure on there OS. They may have masked the code to save some credits for the custom OS and bumped up the low octane spark table. Can you read the tune?