Got a strange one for you TPI guys?
 

Ok here goes. My friend is switching from TBI to TPI Speed Density. He got a TPIS wiring harness for speed density and still has the stock wiring harness running through the car. The new wiring harness is a generic for any street rod application. Well we were going to try and rig it up but it is just flat out confusing. Well the thing that we were told to try was to keep the stock TBI computer in the car and to put the new speed density computer in the car as well.

The SD wiring harness is only to make the engine run. It has the Knock Sensor, TPS, IAC, CTS, O2, Dist, you know the basic stuff and the injector. Well in order to intrigrate the new wiring harness with the old one you need to be a wiring genius and that I am not.

So my question is would we be able to run 2 computers one for the engine itself and the other computer to run all of the other things like smog and everything else.

There is a custom prom in the new computer to run all of the vitale things but what about the other computer would you need a custom prom to turn off the injectors and knock sensor, the other vital ones? Well, what do you guys think tell me our insite. Thanks!

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"I'm not dumb, I just have an amazing command of thoroughly useless
information."
Bill Waterson creator of Calvin & Hobbes.

My guess would if you can figure out how to split time between two ECM's...you'd be a better genius than anyone on this board https://www.thirdgen.org/messgboard/wink.gif

I'd sell the TPIS harness and get SD harness from painless that utilizes everything you have to have to keep the car emissions friendly (I'm assuming that you need to).

What ECM did you get with it? a 730? If so, then using it and a painless kit and a SD Eprom shoudl get you started...you may have issues with the VSS that you'll need to work around, but not much else I can think of off the top of my head.

You sure the TPIS harness is an offroad/non-emissions harness?

I had that feeling about the 2 ECM's having a problem running correctly. As far as emissions no there are no emissions here at all I am just not completely sure he wants to completely lose the emissions but I am sure I can talk him into it no problems. So you think there is really no way that you can run 2 computers on a car. Also I have no idea which one it is he got it out of a Chevy Corsica V6 thats all I know.

That would be a 730.

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1987 GTA L98 MD8 GH3
355 '97 Vortec 4-bolt block, TRW(suck) forged pistons 10:1 CR, TFS 23*, LT4 Hot Cam, Ported plenum and intake, SLP Siam Runners, BBK 52mm TB, Edelbrock TES, gutted Cat, Flowmaster, CAI w/K+N cone, AFPR, TB bypass, !AIR, !A/C, !EVAP, ARAP, 2300 stall, Alum. Driveshaft, Hotchkis STB, '99 Camaro seats.

Coming Soon!!: Fourth gen 3.42:1 rear, Spohn LCAs and Panhard.

This is my car that we are trying to figure out what to do. The computer that I got is 1227730, if i remember the numbers correctly. I will talk to TPIS tomorrow and try to figure this out. I have all my emission stuff out of the car, so that isn't a problem. On my invoice from TPIS it says, Street Rod Harness Speed Density.

You will need to run one ECM system or the other. In which case you have no choice but to use the TPIS harness and the 730 ECM since the TBI system is virtually completely non-compatible with a TPI system.

Without seeing what you are talking about, my advice would be to remove all of the stock wiring and ECM and install the 730 ECM and TPIS harness in its place. There really isn't anything else in the car that you will need an ECM for that the TPIS one does not have provisions for, I would think. Does the TPIS one have a VSS and a TCC system? Those are the only other things that the ECM would need besides the regular engine systems. A quick call to TPIS should clear up any questions on how they think the harness should be used on the car.

Matt that is the thing the TPIS wiring harness has nothing but the vitale sensors. It doesnt have anything else. Ok I will try and remember all of the sensors...TPS, IAC, O2, Knock, Injectors, Dist, Fuel Pump Power, 12V supply, ALDL, Umm I think that is about all so it has nothing to do with the VSS or TCC oh well we are trying to figure out what the story is.

I ran into the same problem with a painless harness, only engine related wiring, it does not include things like the wiper motor or headlight wiring, and half a dozen other things that are all part of the stock harness.
I ended up not using the painless harness, I bought a stock harness from someone parting out a wrecked Formula.
Probably not what you wanted to hear, but I hope it helps.

John

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89 Formula, Maui Blue,355 TPI(used to be TBI) Auto, TES, 3" dynomax Hi-Flow cat, 3"Flowmaster single in, single out cat back. B&M shift kit, afpr.
89 Formula, Black, with really bad paint, 305 TPI Auto, t-tops bone stock (so far)

For the price of those aftermarket harnesses and all of the headaches involved why don't everyone just go to howell engine developments for the wiring?
The guy used to work for G.M. on the TPI stuff from my understanding.

I could be way off base, but here is my personal experience. I put a 350 TPI in a silverado equiped with the 350 TBI. I then proceeded to splice the TPI injector harness to the TBI harnes by doing the following. You take the right side injector plug off of the TBI Harness and wire the right side bank of injector plugs from the TPI were the connector was. Do the same for the left side. I ordered a chip from jet with recalibrated curves for the fuel, lock up converter, map, and TPS. The truck runs well.
I may be wrong, but I am under the impression that four injectors are fired at a time. What I am not sure of is if they are all on the same side or not. The thing is if four injectors are fire at the same time then it would make sense that a person would only need two power leads for the injectors like those found on a TBI.

I'm doing something similar in a couple projects. It's not a small task to deal with the wiring, but the best method I've found so far is to first start w/ the vehicle schematics. I've learned that the Helms manuals offer the easiest schematics to read. Also, you catch a small breask from GM, in that the harnesses are actually not really one massive octopus, they are basically split into two harnesses, with some crossover. The EFI harness wraps from the ECM(computer) and over to the engine, and has some engine wiring included, such as oil pressure, water temp, and the starting and charging system. The TPIS sounds like a stand alone system, so I would guess that you only need a +12v and Ignition wire to get it to function. If that is the case, and you don't need the emissions equipment, just remove as much of the harness as you can, and leave those few things behind, they easily pop out of the loom, (starting, charging ckts, gauge wires, heater control power,etc) which route over to the firewall bulkead on the drivers side. Incidentally, you shouldn't need to mess with that bulkhead a great deal, as well, it's split in two, and the headlights and such are on thier own section of that bulkhead. Hope this helps, but the schematic is the key. You can trace wires out pretty easily with it.