I just bouht a TPI unit complete off ebay. it's in good shape but the guy said it was an '89 MAF system. I know it's not cause it's got the cold start injector. I would like to know what year I've got. I'm assuming either an 87 or 88. Can anyone tell by the computer? The pt# on the puter is 16198259. I also noticedit doesn't have the firewall connector for my electric gauges in my 90. Is there any way to convert this wiring harness to work in my 90 or am I screwed into finding a SD harness and runners? If I do need the SD stuff I'm going to be forced to waiting to do my TPI swap. Maybe I'm better off getting SD, but I don't want to spend major cash for a chip (cheapest $350, ed wright). If anyone has some ideas for me to save some cash and get this car F.I. in he next month or so it would be greatly apreciated. BTW i know it's at least an 87 as it'll fit centerbolt heads. And I'm trying my damndest to keep this under $1K as I'm not made of money. Sorry bought the long post but I'm frustrated.

Chris

 

I understand your frustration. I'm in the middle of that expensive learning curve with my '91 RS 3.1 to 305 TPI conversion. I'm using a '86 engine. So I thought I needed a 85-86 TPI setup. WRONG! After much research....I decided to keep things simple, and sell the '85 harness and computer(ebay). Your car has VATS which can be deprogrammed, but I suggest locating a 90-92 harness and computer, and you'll have a plug-n-play setup. The computer is the easy part(1227730). They were used on many GM applications, but use different chips(eproms). Your cold start injector is easily eliminated in 10 minutes with a kit available on ebay for $25. Other details like MAP sensor, and the like are available at your local auto parts store or salvage yard. You can PM me if you need all the details.

 

I know about the computer it was used in celebrity's, sunbirds, and many more. I've got a map sensor so that's no issue. I'm still trying to figure out exactly what year this stuff is out of so I know if and when I get rid of it. That and I'd really just like to know. I'm also trying to figure out if there's a way I can take the harness that's in my car (TBI chopped for a carb) and the one that's in my bedroom and combine them to mimic a 90-92 SD harness. If anyone knows for sure or has done it for that matter please clue me in. Thanks for the quick response.

Chris

 

Chris,
What your asking is definitly doable. Check out the Tech Articles on this site. Specifically, under Electrical there is subheading for converting 86-89 TPI to 90-92 TPI ecm(MAF to MAP). There is also some info under the Misc. Modification section that shows how to convert 90-92 TBI to TPI setup. I did try to identify your ECM. I could only conclude that it is p/n designated for rebuilt ecm. Unfortunately, I don't have a crossreference for rebuilt ecm's. The 86-88 are basically identical TPI setups with a cold start injector. The '85 also uses a cold start injector, but uses a harness unique unto itself. The '85 MAF is controlled seperatly, and literally mounts on top(piggybacks) of the ecm. More than likely you have a 86-88 setup. You might want to check out chevythunder.com. It has lots of useful information.

 

If you want to know what year the parts are from, check the underside of the plenum. The year is usually one year after that as it was casted in that year. Sometimes it's same year. Post some P/N of the injectors and we can find out what engine it was and so fourth.

 

your TBI harness will run a speed density tuned port system with minor modifications and a chip burned for it. the only changes to the harnes involve splicing into you original injector wires and adding a cut off section of tpi injector wires & lengthening the tps wires possibly and the idle air control wires, your original harness also has a MAP, intake temp, and all other sensors required to run tpi, thats your easiest route

 

Well the only issue is that the original TBI harness has been cut severly. I cut it to make for a cleaner install of the carb motor. It is efectively 1/4 of the amount of wires in it. The volatge, oil pressure, tach, speedo and gas guages all still work though. I think the easiest I'll be it still tough would just be to get a 90-92 SD harness. The fuel rails and runners are no big deal as I can modify those if I don't find suitable replacements. I'm not sure I want to take on the task of repinning the harness since it doesn't plug in to my harness as it is. I'd still have to wire in the bulkhead connector on the drivers side firewall that runs to the fuse block. Because as it stands the harness doesn't have this connector. I guess I'll just have to find a new harness. The other big issue involved is I have to be able to get this thing in and running from Sat afternoon to Mon morning at 9:00 am. While I know it's a lot of time I also have to change the timing chain cover, add my cam thrust plate, and pull and replace all the wiring harness. Not to mention if I run into issues with the sensors then I'm really screwed. I guess if anyone has a stock SD harness and computer they want to get rid of let me know.

Chris

 

The '259 ECM is a GM reman of a '165 ECM. (86-89 MAF, only the memcals were different over the years, I have one of these in my car now)

HTH!

 

fakez

I have a painless harness, bad part is its for mass airflow

 

Since nobody else spoke up (i read this fast so forgive me if i missed something).... All the MAF had a cold start injector, and the SD did not. I am 100% positive of this so maybe you want to double check everything.

 

89 was a MAF sensor and did not include the cold start injector.

 

Ummm.... no

89 TPI's do not have the CSI.

 

See the fact that this harness has MAF and the CSI doesn't bug me as much as the fact that it doesn't have the bulkhead connector on he drivers side firewall. I know a few of the sensors run straight to the gauges and from there to the puter. So I guess I actually need a 90-92 harness since they have those and the gauges will work then. Oh well I guess the search coninues.

Chris

 

fakeZ

when your talking about the ecm harness going through the drivers side, you lost me, and the ecm harness is entirely seperate from the cars main electrical harness, no gauge wiring runs to the ecm or the ecm harness, the cars main electrical harness and headlight harness run to the bulkhead connector by the power brake booster, and the ecm harness runs inside the passenger side front fenderand the under the dash to the ecm, Ive used a painless harness on my 84 trans am and all my instruments worked fine.

 

That I don't disagree with. On the 90-92 cars with the electric gauges and and electric instead of cable speedo there is a bulkhead connector on the drivers side under the fuel pump relay that connects the harness to the fuse block/gauges. Unfortunately I need a 90-92 harness as the previous year harnesses don't have the elec. speedo so they don't have this connector. I guess I could in theory run my cut-for-carb harness in conjunction with the earlier year harness. I'm dreamin' or does anyone else think this is possible???

Chris