86 IROC 350 TPI swap

I have an 86 IROC and bought it off of someone that installed a 350 in place of the 305 TPI. I don't know what cam he used, but as I started to replace the TPS, IAC, and MAFS the car actually ran worse than it did before. I hooked up an AutoXray this weekend and it came up with a trouble code 33, which stands for too much air entering the MAF. I understand the computer is configured for a 305, but was wondering if I could get an 87 and up computer or chip out of a 350 car, or would the dealer be able to help me? I'm new to the site and think it's awesome, plus I would like to say thanks ahead of time.

The problem does sound like programming issues, however I think that 85-86 computers were totally different than 87-90 as far as the harness plug-ins and sensors. I don't think you can swap ECM's without a complete harness swap and the PROM is different too.

Go to www.thirdgen.org (http://www.thirdgen.org) in the message boards and check out the ECM board. I'm sure those guys can guide you a little better.

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Mike L.

1987 IROC Z 5.7 TPI A4 3.27 Borg-Warner four wheel disc
Mods: 2300-2500 Stall Converter, Shift Kit(GM parts), TPI Specialties Stage 3 PROM, Modified airbox w/ K&N's, Relocated MAT sensor, Gutted MAF, 160* thermostat, MSD 6A, Accel 8mm Wires, bypassed TB coolant, 3" Flowmaster 3 chamber single outlet, custom adjustable cutout, 3" MAC mandrel intermediate, airfoil, ported plenum. !smog, Crane AFPR, Accel rail mounted FP gauge, Harlan shiftlite, 24lb. injectors, Hedman headers, a few others I forgot...??? FINALLY GOT PAINT!!

Check out my IROC webpage! (http://iroc5.7tpi.home.att.net/wsb/html/view.cgi-home.html-.html)

I checked out www.thirdgen.org (http://www.thirdgen.org) and they told me that 1986 to 89 Camaro ECM's are the same, the only thing I have to change is the PROM. If I get a PROM from a 350 TPI car I should be OK. They also said I could get one from a dealer for about $40, I called the dealer and they have them, but I have to get them the part number. Sounds like BS about the part number, but I'll find it on my own. Just thought I would pass the info along for people having the same problem. If anyone has some real tech questions,

www.thirdgen.org (http://www.thirdgen.org)

is the place to go!

I could pull the Part number off my 350 TPI EPROM for you. My car is an 89 so I have the MAF setup with the 165 computer like you do. Just gimme the word and I'll grab it and post it.

That would be mighty nice of you if you could, thank you.

You can't use an 89 chip. The 89s have VATS. If you use that chip, your car won't start.

But... your car should run just fine with the 305 chip. Maybe not optimally, but well enough to run and drive well, and certainly not throw codes. If you're throwing a code 33, then it's possible that either your MAF or your MAF relay is shot. Both are very common problems with these cars.

You said that you replaced the TPS. Did you adjust it properly when you installed it? You should show .5 volts with the throttle blades closed, and 4.5 volts at WOT. If that's adjusted wrong, it could be getting more air than it thinks it should, which might throw a 33.

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The IROC Homepage (http://iroc.fbody.com)
View the Restoration of an 85 IROC (http://www.rit.edu/~jli4307/camaro)
Weekend projects aren't.

[This message has been edited by Jim85IROC (edited June 11, 2002).]

Yes I adjusted the TPS the right way, I even drove the car with an AutoXray hooked up and noticed the MAF was reading too much air flow coming in, but the TPS was reading the right voltage, so the ECM started to lean the engine out and it overheats everytime I drive it. Actually to the point where I have to shut the car down. The stock 305 injector is 19 lbs. per hour, the 350 size is 24 lbs. per hour, that's what I have in there now along with a new MAF. Even with the different injectors, that will cause a problem, plus I already changed the MAF relay and still no change. It runs good for about 10 to 15 minutes, then the computer goes haywire because it's trying to learn whats going on. The AutoXray showed that also, it bounces in and out of open and closed loop constantly, it just doesn't comprehend. If this still sounds like I could use the stock 305 chip let me know, I don't want to come off as a smarta**, it's just been so frustrating because the car is nickel and diming me to death.

Yes I adjusted the TPS the right way, I even drove the car with an AutoXray hooked up and noticed the MAF was reading too much air flow coming in, but the TPS was reading the right voltage, so the ECM started to lean the engine out and it overheats everytime I drive it. Actually to the point where I have to shut the car down. The stock 305 injector is 19 lbs. per hour, the 350 size is 24 lbs. per hour, that's what I have in there now along with a new MAF. Even with the different injectors, that will cause a problem, plus I already changed the MAF relay and still no change. It runs good for about 10 to 15 minutes, then the computer goes haywire because it's trying to learn whats going on. The AutoXray showed that also, it bounces in and out of open and closed loop constantly, it just doesn't comprehend. If this still sounds like I could use the stock 305 chip let me know, I don't want to come off as a smarta**, it's just been so frustrating because the car is nickel and diming me to death.

Stock 350s use 22lb/hr injectors.

But anyway... my IROC had the stock 305 chip in it and I've got a 350 with 24lb injectors, so I know a little bit about your specific situation. My car runs pig rich, but it runs. I drove it for 3 summers like that. I had the 85 ECM too, which is way more primative than the 165 that you're running. The 165 has bigger tables and is much more capable of dealing with the swap. The injectors shouldn't cause the 33 problem, and sure as hell shouldn't cause you to run lean. I think your MAF is shot. If you're running lean with those oversized injectors, then the MAF is totally out of whack. What's your MAF g/s count at idle with the auto x-ray? Over 47 if you're throwing a code I'd imagine.

Just for sh!ts and grins, as long as you replaced the MAF relay and got no improvement, use the old relay to replace the burnoff relay. When my GTA was throwing a 33, I replaced one of the 2 relays (I couldn't remember which was which) and got no improvement, so I replaced the other one and after a few days the code disappeared. I suppose if the burnoff circuit isn't working, the wire could be boogered up and metering incorrectly.

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The IROC Homepage (http://iroc.fbody.com)
View the Restoration of an 85 IROC (http://www.rit.edu/~jli4307/camaro)
Weekend projects aren't.

I understand the injectors wouldn't cause the code 33, and this is the second brand new MAF that I've put on the car. I've also tried the relay switch and still no change. I'm sorry but I can't remember the exact number the AutoXray was reading. When I bought the car it ran ok, but I wanted it to run better, the MAF didn't work, the wire was broke. So I changed it and all my problems began. It started overheating (260 degree overheating, and no I didn't blow the head gasket), then it started to hesitate and run choppy. I've actually considered disconnecting the MAF, but I want it to run right because I would like to sell it. This is what I've done/fixed in order:

* Replace and adjust the TPS and IAC
* Replace the MAF
* changed the t-stat
* broke a bolt in the t-stat housing, then broke an easy out in that, had to take intake off, get the bolt and easy out out, weld up hole, drill and tap hole, reinstall intake
* Replaced the radiator cap
* flushed the system
* Replace the MAF for the second time (the wire wasn't broke, I just thought I had gotten a bad unit)
* replaced fan switch relay
* Replace MAF burn-off relay, can't find the part number for the other MAF relay, nobody here at Summit nor any of the parts stores or even the dealer could help
* Started to blow the instrument cluster fuse, still researching it
* Replaced temperature sensor for the ECM
* Car still overheats after 10 to 15 minutes of driving, not siting at idle
* Car still hesitates and falls flat after 10 to 15 minutes

That's been my nightmare for the past 2 months, I've learned one hell of a lesson, not to buy a car that is already modified. Sorry this is a book, but I wanted to give you all the information so you knew where I was coming from. Please let me know what you think.

That's a goddamned mess. http://web.camaross.com/bb/frown.gif

I still don't think the MAF is causing your overheating problems though. You didn't mention it, but I assume you adequately repaired the broken wire?

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The IROC Homepage (http://iroc.fbody.com)
View the Restoration of an 85 IROC (http://www.rit.edu/~jli4307/camaro)
Weekend projects aren't.

I don't know what to think anymore, but I still think by purchasing a memcal chip from a dealer for about $40 and replacing it for the 305 chip, I hope it will help cure some of my problems. If not, I'll piece the damn thing out. I'll be sure to let you know what happens, thanks...

Oh, I forgot to mention the broken wire, it's the wire inside the MAF that measures the air flow, that's how I knew it was bad.