luvmy64

Ok....i know this has probably been asked before, but i searched and couldnt find anything.
1992 RS 305tbi, swapping to 92 350tpi....will the harness under the hood from the tpi car plug in to the firewall of the tbi car, or do i need to get the WHOLE thing all the way back to the computer? Im also getting the computer, but its for an automatic and i have a stick.......will i need a new chip?
If theres already a thread on this, please point me in the right direction.......

camaronewbie

You need the whole thing, including the computer (not just he chip but entire ECM module).

luvmy64

Im getting the computer with it, but i was wondering if i needed the inside part of the harness, or if the tbi and tpi were the same.....by "inside", i mean the part from the inside of the firewall to the computer, etc.

ASE doc

You may be confusing the engine harness with the ECM harness. The engine harness breaks at the bulhead connector(C100). The ECM harness is one piece and passes through to the inside in front of the passenger door. Remove the pass side kick panel to expose the pass through. You have to remove the pass side front inner fender liner to perform the harness swap.

tonys91rs

iTrader: (17)

I also have the complete harness/ecm from a 92 tpi I am planning to swap into my 91 305. Will the engine harness bolt into the bulkhead without further repinning or modification? I also have a 5spd.

luvmy64

How is this going to affect the computer when it realizes i dont have an auto trans? Will it throw a code and run like crap, thus meaning that i have to burn a new chip and tell it that it has a manual trans?

ASE doc

tony, see my post #4. And I'll state this again so there's no confusion, the ECM harness is seperate from the engine harness. I know this may be confusing. The engine harness contains the instrument cluster, lighting, charging/starting, and ignition power circuits. It breaks at the bulkhead connector(C100). There are variations of the wiring/pin locations of this connector and you may need to repin it for different engine combos. You should really have a good service manual with good digrams and pinouts before undertaking any such project. The ECM harness is, again, completely seperate from the engine harness. It is one piece(no bulkhead connector). It does have a pass through fixture built onto it which seals to the body where passes through in front of the passenger door.

luvmy64, camaronewbie has said that for swapping from auto to manual, you will need the complete man trans ECM, not just the PROM. I do not remember what the difference is. I think it has something to do with the VSS circuit and the electronic trans controls for the 4L60E.

luvmy64

So, I will need to get an ecm for a tpi305 5 speed car and burn a chip to go in it that will be compatible with the 350, correct?
To be on the safe side, im going to pull the whole harness. I dont want to get halfway through and realize i dont have what I need.

So with it being a 92 model, it would be a 4l60e instead of a 700r4?

ASE doc

Teh 700R4 became the 4L60E about 92 with the addition of a fully electric valve body.

luvmy64

Ahh...i see....
I pulled up the ecm on autozone and advance auto parts and neither one seems to differentiate between automatic and manual, they just give the 7730 for both.....i also read a post on here that someone had done a few of these and the only side effect was that the car returns to idle slower after the conversion to 5 speed. Is camaronewbie sure that the difference cant be fixed with a PROM change?

99xtreme

I put a 1991 350 TPI in an 1992 RS, that came with a 305 tbi, but both cars where automatics.
The C100 terminal block(drivers side dash) plugs right in. Shown here https://www.thirdgen.org/forums/elec...ctor-info.html.

The C207 Connector required repinning.
https://www.thirdgen.org/forums/tpi/...e-tbi-tpi.html

That is all that I had to do wiring wise.

If you get the TPI exhaust manifolds, they will not work with you Y-pipe. You also have to change you fuel pump, to a high pressure pump.

I also remember reading of a few people burning their own 5 speed 350 TPI chips, starting with the 5 speed 305 TPI code, and changing the displacement, injector sizing, and volumetric efficiency maps. For stock engines just put those tables, and values in the 305 code. You will still need the 350 memcal, for the knock sensor to work correctly. This is what i plan to do when i find a T56.

tonys91rs

iTrader: (17)

[quote=ASE doc;4868215]tony, see my post #4. And I'll state this again so there's no confusion, the ECM harness is seperate from the engine harness. I know this may be confusing. The engine harness contains the instrument cluster, lighting, charging/starting, and ignition power circuits. It breaks at the bulkhead connector(C100). There are variations of the wiring/pin locations of this connector and you may need to repin it for different engine combos. You should really have a good service manual with good digrams and pinouts before undertaking any such project. The ECM harness is, again, completely seperate from the engine harness. It is one piece(no bulkhead connector). It does have a pass through fixture built onto it which seals to the body where passes through in front of the passenger door.


I understand that the ecm and engine harness is separate. thanks for the clarification. one less hurdle. i looked again at my harness and it is the ecm harness. im going to be using the same engine. therefore im not going to change the engine harness. the 92 305 tpi and ecm is replacing my 91 tbi and ecm harness. this is to include the ecm and chip. the 92 was from an auto. i have a 5spd. will this work?

86T/A_Ram_Air

94 in f bofies...93 had a 700R4....so 4L60E does not apply to thirdgens unless you swapped on in

ASE doc

Okay. Thanks for clarifying that. I'm not sure what the difference is between manual and automiatic as it pertains to the ECM. Obviously TCC control goes away. There may also be a difference in VSS rate. Camaronewbie seems to know something about this. Since he hasn't chimed in on this thread lately, you may want to PM him.

Pat Hall

iTrader: (31)

If you want to get downright technical about it, what the 92 and 93 cars had was a 4L60. Notice there's no E? Basically it's still a 700r4 with a TV cable controlling the shifts. GM just re-labled it a 4L60 instead of continuing to call it a 700r4. Stupid thing to do really because it just confuses a lot of people. The shifts weren't electronically controlled until 94, when they added the "E" suffix to 4L60, making it 4L60E. Regarding the OP's wiring questions, as long as the donor TPI harness you get is the same year as your original TBI harness, it'll hook right up and have all the proper pinouts at the firewall bulkhead connector. Don't need to change anything in the dash harness. In the engine compartment you only need the "engine" side of the harness. You can keep the original harness that goes to the headlights, horns, turn signals, etc. As for the speedo buffer mod mentioned above, that may indeed be required on a Firebird. Didn't have to make any changes like that on my 89 Camaro when I swapped from TBI to TPI. As far as ECM's are concerned, the actual ECM is identical whether it's an automatic or manual trans. The only thing that changes is the PROM or MEMCAL chip. In fact, you can snag a 730 ECM out of a V6 car and use it no problem as long as you put the right chip in there, which is nice to know since there's a ton of V6 cars in the junkyards that used the 730 ECM, like the Pontiac Sunbirds, as well as 89 and newer, 3.1 V6 f-bodies. There's a post here in the FAQ's that lists all the cars that use the 730 ECM.

86T/A_Ram_Air

it basically takes away any confusion if you just say 700r4....the 4L60E is just a electronically controlled 700R4. there is really no difference between the two other than electronics

Dyno Don

iTrader: (7)

Actually, it was 700R4 up to late '87, then they added the aux. valve body and changed the name to 4L60.
They changed the name to 4L60E when they added the electronics.

Dyno Don

iTrader: (7)

That's not true, after '87 it was all in one harness.

Part plugs into C100 the other side goes thru the fender well into the kick panel.
But C100 does have two parts, the other being the headlight circuit etc.

Pat Hall

iTrader: (31)

Believe me, I totally agree that it's less confusing to just call all the pre-94 automatics 700r4's. The point I was making though is since GM decided to change the name to 4L60, you have a lot of poor, uniformed souls that'll argue that their so-called 4L60 is a completely different trans than the 700r4. Also, there's more that's different than just electronics. Physically, on the case, the 4L60E doesn't have the hole or provisions to even put a TV cable on there. Like Dyno Don said, when the aux. valve body was added, that's when the name changed, but it does cause a lot of unnecessary confusion at times. In fact, my ATSG rebuild manual covers 1987-1993 and the title says 4L60/700r4. So even ATSG acknowledges the fact that it's best to use both names on the book so the purchaser of the manual knows they've got the right book no matter what name they call their trans.

bobbyk3lly

im curious to see how this swap goes, keep us updated