Whats up guys, I haven't really seen or heard of anyone doing this exact swap but here it is. My 87 iroc-z tpi runs great, but the computer is noticably slower to respond to tuning than my 89 formula 350's is.

So this is what I'm wondering, can I get an 89 tpi ecm and put it in place of my 87 tpi ecm, and install the original eprom that came in my 87, since the 89's had vats, I believe the wiring on the computer wouldn't need to be used, unless gm changed the connector from the harness's to the ecm, I haven't looked that far into it?

Is this a "no deal" swap or should I try a eprom burned for my mods, that is faster instead? thanks guys.

 

They both use the same ecm, just different computer code.

There are some things to change in the code but you can run the 89 code in the 87 ecm.

 

Pull the connector that goes to your cold start injector, take the 89 chip and disable vats. Then run the 89 chip in your 87

 

what he said. the 89 code is much better.

 

Just what you are telling will works with any problems.
Remove the ECM from the 89 put in the 87 remove the 89 EPROM and put the 87 EPROM and every thing will works like before because you haven't change nothing.
Both ECM's are the same.
Why all that work?
If you want to check the ECM OK! the latter one (89) will have new electronics components but will work in the same way.
I hope that this will help you.
Regards,
Cobra289

PS
If you want to change the other way around, let say put in an 87 car the EPROM of an 89 than is the situation different.
Let us know.

 

thanks guys, I appreciate it. The whole reason I asked, was because my 89 formula 350, would respond to tuning and any modifications very well, it was like the ecm was happier than before, I never even got an ses light, or any codes.

However my 87's computer gives me these codes sometimes:

33 maf (gm/sec HI)
36 close throttle air flow HI
44 oxygen sensor lean

These codes are negligable, because all of the sudden they will come out of nowhere; my ses light stopped working for a few hundred miles, then this last week it decided to start working again. The bulb wasn't bad, the ecm just decided it didn't want to cooperate, lol.

Also the car will surge once and a while, nape has had the same problem in his car recently, and when I met him up at the track, and his is a 91 gta map censored; and he has had the same thing recently. All of my sensors are fine, IAC is good, clean passage way, cts is new, 02 is good, new one this week when I put my headers and custom exhaust on.

As for mods, I've already ported a 91 formulas tpi base, ported the plenum, cleaned up the entries and exits of the stock runners, converted from the 9th cold start injector to the 91's fuel rail, for no more 9th injector, put in a manual steering gear, removed all the a/c, and the motor looks more like an old school one, my maf has the screens removed, and my intake tract has been modified, for more airflow, and k&n's are in there too. I get rubber in 2nd and third shifts, with nittos out back, on the original tranny and motor. The car runs rock solid and blows no oil. Thanks alot guys any other info, would be great, i'll be getting back to ya soon, peace.

 

Sounds like a bad ECM, common for the '165s. Do a tap test on it: with the engine running at idle tap on the ECM. If the engine stumbles or otherwise misbehaves the ECM is bad.

RBob.

 

A lot of those codes also get flagged on MAF car(in my experience) if they are any grd related issues, most common culprit i find is the pass head grd (back of the cyl head along with the dipstick tube etc)

That will kill the 02 real fast and make the MAF go nuts, will show up predominantly when the car is warm and/or hot, will be fine at first.. If thats ok and it flakes out of no where then most likely the ecm is bad as mentioned

later
Jeremy

 

That implies a mechanical problem… what's different about them that goes bad? Has anyone tried to just run all the solder joints on a bad one to see if it might just be a loose joint. Huh, I might have a dead one floating around, but when it was dead, it was dead…

 

haha thats funny. The has surged when its warm, and cold, and nape's 91 gta, has just begun to recently do the same thing, and its a map car, with a custom eprom, from the board. usually what happens to the computers, if they aren't usually touched, but someone that works on it like a nutbar, or shorts out one of the sensor wires, that shorts it out, and affects its tuning, such as the car always trying to rev high.

But all comments are welcome, if anyone has done a swap like this, tell me about it, this is still something I might want to do. I have a buddy that has a 87 iroc-z like myne, I'm thinking I should get the computer out of it, and the tpi intake. we'll see, ttyl guys

 

I figured out why my car was surging, I had my ALDL cable plugged in wrong because I just threw it on real quick. That's why it was throwing a SES light too.

If you need a custom chip for that '87 ECM let me know. You'll probably have to pick up an adapter from Criag Moates or pitch me a couple of bucks so I can buy his adapter to do it off the stock memcal.

You should come over and check out that '90 Formula I picked up. I've made quite a bit of progress on it. The PO probably won't recognize it in a week, I have a feeling that I won't either! It probably would've been easier to find a cleaner car, but so far I've picked up a clean hatch, clean doors, semi-clean hood, driver's side headlight motor, headlight relay, door panels, stock speakers, hatch struts, a hood strut, and a few other things for $160 + the stock formula hood. The hood and hatch are already on, but the doors are the project for the next couple of days

 

sweet dude, i wound up doing alot of **** over the weekend, I just finished installing my tes nickel chrome coated headers, painting the y with vht 1500* paint, and putting my longer 3" bullet muffler on the car, it sounds bad as ****, I'm going to try to take it over to this shop to get welded up today, out in joliet, the craig guy told me no more than 73$, maybe cheaper if it doesn't take too long, so I'll have the y dumping into no cat, then into my bullet muffler, and dumping before the rear axle, it sounds mean as hell, a video would really do it some justice, I'll be running it next tuesday too so. I'll give you a hollar nape, lata.

 

Yeah, that dollar amount sounds right. Labor runs around $60/hr + gaskets if you need them for the collectors.

I'm not sure if I'll be at 66 next tuesday. I'm going to GLD in WI tonight for Real Street Drags. Give me a call if you end up there though, maybe I'll drive up there and watch. I've been there half a dozen times but never watched anyone make a pass. LOL