Bradsaundry

Hey guys
Ok so I've swapped a 91 L98 350tpi into my 85 trans am which had the 305LB9. There was a ton of re wiring and pin out changes and running the 91 pcm. Car runs and drives great. Only issue I'm having is if I shut the car off when warm and restart it. I think the computer keeps doing a re learn cause it idles sporadic and sometimes dies. I've changed TPS, IAC etc and leads me down to something not giving the computer constant power to keep its memory?? Maybe?? . I am by no means a pro with all this computer crap and was wondering if someone can help me out with where that wiring should be going? Or how’s to solve this problem

Vader

Constant battery voltage is required by the ECM to maintain memory. I believe a '91 would have that power on B1, presuming it is the '730 ECM.

ULTM8Z

Curious that it only does that on a warm restart....
On a cold restart it's fine?

Bradsaundry

only on a warm restart. for some reason at dead cold it runs great. say i need to get gas and shut it down. when i restart it, it will surge on idle. stopped at a red light it will surge and may or may not stall out. its kinda strange

ULTM8Z

sounds like an issue with the open loop AFR at warm temps. Engine will always start out in closed loop upon restart.

everything about the engine and chip is stock?

Bradsaundry

okay! how do i go about solving that problem? it does have a performance chip but chip in or out it does the same thing. no major upgrades other than injectors,headers, minor tweaks here and there. it was a fairly extensive pin out and electrical change that was done. (fairly extensive more me anyways)

ULTM8Z

Injectors? As in bosch-III injectors?

Bradsaundry

yes!

ULTM8Z

You may have issues with the voltage offsets in the calibration. Do a search on Bosch-III.

If true, at worst you' require a calibration change to correct, at best maybe a tweak of the fuel pressure.

are you able to take data with tunerpro? Or at all,

Bradsaundry

i cant take any data off it myself, maybe a local tune shop can do this? if i even have anyone local lol