Hey all,

I am looking to do some tuning to my 85 iroc. First and foremost, i need to figure out what kind of prom the 85 ecm uses, and where i can buy an eprom for it. So far the only place i have found that will sell me an EPROM has a 25 dollar minimum order, and a prom only costst 2 dollars and some change. I dont even know if the part number was correct, i just recieved an email from a company called sinister performance and the gentlemen sent me a link saying that it was the prom i needed. Once i have the prom i suppose i am ready to start tuning. I have a 355 tpi set up, with the largest cam i could have without giving the cmoputer a headache. I made the mistake of putting larger injectors into a mass air car without tuning th computer which is the largest reason i am wanting to tune it. but yes my set up is, 355 with 305 heads, 4x4 cam(if anyone is interested in really helping me out i can get the cam specs), short tube headers, high flow cat and flowmaster. it is bolted to a built 700r4. if there are any tuning tips you can offer me, or if anyone can tell me where to get a prom, please let me know thanks

 

Unfortuanatly for you '85 Uses 1226870 MAF ECU. General consensus is that the '870 is "goofy" and no one really likes to tune it. This page here goes more into detail about that and how to convert to '86-'89 1227165 MAF there is also info on that site to convert to '90-'92 1227730 MAP.

You can buy everything to tune it from www.moates.net, you will need:
A chip adapter (G1, G3 , GP1, or GP3)
A datalog cable (ALDU1+CABL1 Combo)
An emulator and/or chip burner (Ostrich just Emulates i.e. acts as a chip) (AutoPROM emulates, burns and datalogs; no need for an extra datalog cable)
EPROMS or EEPROMS if you want to burn a chip with the AutoPROM
And you can download TunerPro at www.tunerpro.net

Everything I just said is also covered in the stickies. I'm also in the research and learning phase, this is what I have found so far.

 

If you can find a harness from an 86 and up TPI i think it might be a little easier than repinning the harness, but if you are up to it...modifying the existing 85 harness to accept a 1227165 computer would be a beneficial upgrade.

The '165 ECM allows you to use any of the MAF programs from 86 to 89, including the versatile ARAP bin. The ARAP bin was the last year of the MAF program and had the most stuff to tweak and a very aggressive timing curve that you are probably going to love.

I just got into tuning recently and noticed a big difference from the stock 86 tune and the 89 tune. The best thing i liked about it is the control over the timing curve and the addition of the highway mode.

 

my friend has a program he used on his 93 formula called tuner car...do you know if this program will burn my chip while its in the car, or will i have to buy a programmer and all. also what kind of chip will work with my car i know it needs a 2732a eprom, but they do not say what that is equivalent to on the website

 

Tuner Car? Or do you mean TunerCat? If Tuner Cat I do believe they have realtime ability. Never heard of Tuner Car. Either way you will need a chip burner/emulator, chip adapter, ect. that I listed.

You should look more into converting to a '165 or '730 before you decide you are going to keep your '870. If you still want to keep your '870, I'm willing to bet that you will regret it later.

 

TunerCat (or anyother Real Time Programmer) only EMULATE an eprom for modifying on the "fly" to test changes without having to "re-burn" everytime you make a quick change. And this is ONLY while you have your laptop computer hooked to the ECM.

You still must burn an eprom once you have done your changes. Also, a 1993 uses a COMPLETELY different calibration.

Your best bet is to follow the advice given above and to convert to the later '165 ECM MAF system and use the $6E calibration. The ECM used in your car is the most "primative" and was a "one year only". If it dies, you are probably going to find it very hard to find in a wrecking yard and may even be discontinued at GM.