I have heard that programming the chip for an '85 ECM is very difficult. WHY? What is the difference between '85 and later model ECM? Is it possible to switch to a later model ECM and just reprogram a chip for it?

 

Tuning is tuning.
The difficult part is learning to tune EFI.
Some of the strategies have changed over the years, so you have to readjust your thinking at times, but that's about it.

The actual programming of the chip from 85 to 92, is the same.

Yes you can swap over to a 86-89 ecm. The later the ecm the more refined the code, and calibrations.

 

Quick correction. the 1985 model yr ECM is a 122870 is uses a 732 eprom. its a kissing cuosin of the $3a code i did a post about a year back called MAF and why its such a pita. the mask ID is $1f.

ok quick review

122870 ecm
$1f mask id
2732 eprom

what would i do. read my post MAF and why its such a pita!! good tunngin post for this ecm. i cover al the basics

 

Quick correction to what?.
No one had mentioned the ecm part number or prom.

Anyway now that you mention it,

It's a 1226870 ecm,
and it uses a 2732 series of prom.

 

I think you are referring to the specific ECM and calibrations which is unique for the '85.

Bruce was talking about the concept of "EFI tuning" in general (and I would say just tuning in general). I still say, that if you can tune an old fashion carb/dissy combo, that once you grasp the concepts of using a computer to modify the calibration - that tuning EFI becomes a snap.

The biggest problem with the 870 in the past was the limited information on it. TunerCat's TDF for the 870 has really come a long way in the last year or so. The 870 is now just as viable to tune as any of the other TPI ECMs and calibrations.

But heck, a mere 5 years ago, the number one "tuning tip" was "bumping up your base timing and adjusting your fuel pressure - avoid the eprom unless you absolutely have to". A mere 15 years ago, people were telling me that "there is no way you can modify an EFI engine because of the computer".

EFI knowledge has grown leaps and bounds as more people get into it. Today, I feel that "eprom burning" is the FIRST place to go if you want to start "modifying" your engine.

 

wait till you see the new stuff comming. thats all i can say. however id like to see the interest in a 90mm maf ?? any interest. itll be cheaper then a stock maf.