91 RS Drop Top

Hi guys, new to the DIY PROM section and pretty clueless. I just pulled my ECM out to check the number on it. I have a 91 RS and the previous owner did a Hack-job install of a truck 350. I found the ECM and it says 1228746, which I believe is an F-body ECM. There are some other numbers on the sticker as well. Do any of them identify the PROM? I am trying to find out if I at least have a PROM set up for a 350, or if I have tune that was meant for a 305 running my car. The point of my question is to figure out how urgent it is that I get it re-tuned. I am looking into options to get into tuning and chip burning (leaning towards the EBL flash right now), but it will be a few months before I have the money and I'm sure it will take a while to get it tuned right. I know many folks on here don't think much of mail order tunes like TBI chips, but I'm thinking about getting one as an interim measure until I can get into the DIY tuning. Besides, if I am working from a 305 tune for a baseline I am gonna be lost trying to get my 350 running, especially when it comes to getting everything right for the injectors. Thoughts?

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DM91RS

That sound's like the ecm that came in the car. With the ebl don't be concerned about 305 or 350 as you will set it for what you have.

91 RS Drop Top

Yeah but having zero tuning experience and trying to get a baseline set up for a 350 might be an adventure. Thats why I thinking about gettingf a 350 chip to make sure I can run the car until I get this all figured out. Right now the 305 chip is controlling the 350 and and it pretty sluggish. Thanks for the help.

DM91RS

If you get a stock/generic 350 chip it might not be much better. It's just a crap shoot. Your best bet and cheapest in the long run would be to go ahead and try to tune it your self if you can swing the purchase. There is enough knowledge on this site to help you through it. In the meantime you can answer some basic questions needed for tuning such as what injectors you have and what fuel pressure you are running. If you cannot answer these things you might work towards that goal. IE: install a fuel pressure guage and possibly make your fuel pressure regulator adjustable. [all you need is a 3/8-24 tap, a drill bit and of course a bolt of your choice in the threads listed above.]