bigal04

I recently purchased a 86 z28 that has no motor or trans. I wanted to buid a 350 and use tpi. My buddy gave me a tpi intake/runners/plenum that came of a 92 model. Can i use my harness and ecm from my 86 or do i need a harness and ecm from a 91-92? I did use the search and read the facts but i think im getting a little confused. Want to do it right the first time. Thanks in advance.

ternandes

iTrader: (7)

There were two different systems: One that used a MAF sensor and one that used "Speed Density". Parts like runners and the intake might be interchangeable between the two, but the electronics definitely are not. So you need to make sure that your sensors all match the system that you are using.

vetteoz

iTrader: (13)

Can use all your '86 wiring.
Will need TB with early type TPS and IAC ( IIRC ;connectors changed around 92 )
Need early model 350 TPI knock sensor and VSS to work with 86 computer.
Just plug the hole in plenum where MAP sensor was or leave it in place ( unused )
There will be nothing to hook the '86 cold start injector wiring up to and you may need a '89 tune ( has cold start built in ) if you are in a colder place because you will have no extra fuel on a cold start.
Many run without it ; no probs

bigal04

So it would be easier if I used the 91-92 harness and ecm. If so is the bulkhead the same?

ASE doc

Not sure if I understand the question but what I think you mean is will the harness from the 91-92 install correctly in the body. Yes it will. The fuel injection/ECM harness is seperate from the main electrical harness. In fact there are maybe two places where they even intersect and thats under the dash where the ECM gets power from the fuse panel. The ECM harness passes through to the engine compartment just in front of the passenger door.

Chevy86 IROC-Z

iTrader: (17)

Wow. This is a tough one. IIRC, the wire connectors are different from the 89 and up. The 3 relay connectors (FP, MAF Pwer, and MAF Burn-off) are different compared to a 86. Also the wiring harness for the 91-92 have provisions for the small cap dizzy. The 86 IROC ( I drive one) uses the large in cap dizzy with large 4 prong weather pack connectors. If you decide to use the 91-92 wiring harness you will need to use a small cap dizzy, not the large cap.

Chevy86 IROC-Z

iTrader: (17)

the ECM that is used in our 86's is 1227165 which will work for non VATS systems aswell as MAF, not speed density.

Chevy86 IROC-Z

iTrader: (17)

Also the 87 and below use a ninth injector (cold start) as for the 89 and above, there is none (9th injector goes into the intake manifold).

Chevy86 IROC-Z

iTrader: (17)

Runners are interchangeable but im not to sure about the plenum. My 86 has one sensor on the bottom and I think its a temperature sensor of some sort. The intake manifold is different than earlier models because of the 9th injector.

bigal04

I was going with a edelbrock tpi intake because i have a vortec engine that i will be using. @asedoc- Cool, i will just find a harness and ecm for a 91-92 model car. Is that going to be the easiest route?

Chevy86 IROC-Z

iTrader: (17)

Yes it would. You could get lucky and find a IROC of the year you need but that harness could have a lot of splicing and jerry rigging. Your best bet is to get a new wiring harness. There are 2 types, one is the regular length and the other which is 8 ft.

1. http://www.summitracing.com/parts/PRF-60103 Regular length = $387.95

2. http://www.summitracing.com/parts/PRF-60203 Exta long (8 ft) = $414.95

These are the cheapest ones I can find for you.

bigal04

thanks

Chevy86 IROC-Z

iTrader: (17)

ASE doc

Sounds good. Let us know how it goes, and 86 Iroc, good call on the connector changes. I completely spaced that. One thing though, all TPI's to my knowledge use the small body, external coil HEI dist. I dont believe that the large body, Internal coil HEI will clear the TPI plenum. Also, the runners are different from the earlier to later cars. I think this split was 89-90. The earlier cars have a extra small runner I believe for the EGR. The plenum and manifold base have ports to match this extra runner. The manifold base and plenum from one type will not properly fit the runners from the other type.

Chevy86 IROC-Z

iTrader: (17)

ASE doc, your correct on the EGR small tubes. As for the large cap HEI Dizzy, yes it does fit with the plenum dizzy cover. There is just enough space to screw down the dizzy plate. You may need to rearrange the plug wires so that they are as flat as possible or else the plate wont screw down. The large HEI dizzy was used on 1986 and down to where as the small dizzy with remote coil was introduced in the 1987 and up.

ASE doc

Thanks 86 IROC Z. Its good to know about the 86 using the large body HEI. I cant remember seeing one but thats just me. I wonder if the later TPIs would accept that dizzy. It makes for a simple ign sys.

Chevy86 IROC-Z

iTrader: (17)

the large computer controlled dizzy cap wont hook up into a 87 and up soley because of the wire harness connector. My 86 IROC uses the large 4 pin weather pack connector and the 87 and up uses 2 smaller connectors. I believe you can make your own connectors but Ive never seen it done. Look below.

Here are the size diffences of the computer contolled harness that connects into the dizzy. The first one on left is 87 and up and the 2 right ones are 86 and below. Notice the notchs on the tube on both the middle and right, Im not sure with applies but one is to a caddy and the other to a IROC. To read more on the connectors follow this link,,, http://chevythunder.com/fuel%20injec....%20pg%20A.htm

ASE doc

Thank you 86 IROC Z for the info on HEI options. I am familiar with the large body HEI dists with the large 4 pin connector. Ive seen these on many vehicles. I do not remember seeing one on a TPI but now I know about the 86.

John 89 Formula

the pinouts on the bulkhead connector were different between 86 and 91-92 there is a nother thread here dealing with it. You would need to repin the 91 harness to match the 86 bulkhead conn.

Chevy86 IROC-Z

iTrader: (17)