I am installing a tpi into my vehicle and struggling to find a good SD harness without spending a lot of money. Since the 3.1 Cavalier uses a SD ECM (730 I believe), it seems natural that this harness could be converted to a V8.

Has anyone done this???

I have searched the board but so far have not found any info.

Mark

 

Well, for one, you'd need to add two extra injector connectors... if you had the GM shop manual, you might go through it, and compare V6 MPFI wiring to V8 TPI wiring.

 

Thanks for the reply Tom.

I realize two more injector connections would need to be added.

My point was simply that the V6 harness should be a natural compliment to the SD harness. They use the same computer, and as such most of the sensors would likely connect to the same pin locations. I would think adding two injectors would simply be a matter of splicing them into the harness somewhere (this is where my theory gets a little shaky). Since the computer "batch fires" I thought it would not be too difficult.

Anyway - I am giving this some serious thought because it might be a chaeper and "cleaner" alternative to repinning a MAF harness.

Anyone have info please post..

 

it wont work, the two systems are completly different, im pretty sure that tpi is batch fire and the other is sequential, most of the sensors take different connectors anyways. just get the harness with the new motor.

 

interesting.....

Does that mean a 730 ecm can be programmed for sequential fire??

 

now that im thinking about it, i thinkk they might both be batch fire, i thinkk only the fwd 2.8 was sequencial but im not sure, i do have the schematics for both if u want to see them.

 

that would be great!!

If things look good I may try and convert a 3.1 harness to V8 SD.

Since my last thread I received a reply to the same question, from the guy at Chevythunder.com, and he says it will work. He has done a couple of them and it takes about 6 - 8 hours for the entire conversion.

This sounds promising!!!

Send the schematics if you have them..

thanks

Mark

 

A guy by the name of Daniel Burk that frequents this board bought a 3.1L Beretta harness from me, for the purpose of converting it to a V8 SD harness. Hopefully he'll see this thread and tell us how it worked.

I would've directed you to his web page, but I notice that its down.. The thirdgen technical articles page has links to his website, which I notice aren't working either.

BTW.. I'm pretty sure that the 3.1 V6 is batch-fired, just like a V8. Stands to reason that most of the wires SHOULD go to the same terminals on the ECM!

 

I don't know how much would be involved in getting all the other sensors and stuff set up properly, but im pretty sure you can easily add 2 more injectors to the harness.... provided its a batch fired system that only has two banks to fire (left or right).

There are only two wires to each injector, (ecm + and a ground)and if you follow them down the harness all the ground wires should connect to a common point. You would need to get two more injector fittings (from the parts store, ask to see the service pigtails) and some good quality wire.

Splice (solder, don't crimp) one wire each from the existing positive lead for each injector bank to each connector.
Then solder in two more wires for the grounds, preferably to the same point as the original injector ground wires.

Tip - use extra long lengths of wire so you wont come up short when you go to reassemble things! =)

 

sorry, misread the orignal post

 

Gravitar - thats what I was hoping for. Since the ECM is the same I would assume all of the terminals will connect to the same pin locations on the connector.

Later today I will go to the library and look up the schematics.

If everything looks good I will keep everyone posted.

 

The pin locations won't be the same, they will be different. Atleast half I would imagine, but with both schematics you should be all set. The program inside of the memcal ditates what engine your running.

Brendan

 

thanks for the info Leirch.

Any idea why the pinouts would be different?? I thought the ecm pinouts would have to be very similar, otherwise GM would have to completely reprogram the function of the ecm. Maybe I'm trying to over simplify everything, but wouldn't the same ecm (regardless of vehicle it came from) require the sensor pins to connect to the same location on the ecm??

This stuff is sooo confusing.

anyway - I will see if I can get the schematics because that will surely answer all my questions.

 

I was pretty sure the pinouts for the ECMs were similar, also. In '86, there was a jumper wire present on one of the connectors; the presence of the wire told the computer whether the engine was I4/V6 or V8. Maybe the same held true for later model SD computers...?

 

You would think so any most will be in the same location(sensor inputs), but its the program that looks at certain pins for the input so it the pinouts could be totally different or somewhat different.

Brendan