I currently am running the 1228746 ECM (the 91 RS ECM) and am having troubles. The Car was originally a 89 v6 Multi and I dropped a 350 out of a suburban into it. I stole all the wiring out of a 91 RS (305 TBI) and have been fighting with it ever since.
I found an aftermarket wiring harness on ebay and they said it was set up for the 1228747 ECM. I plan to send witch ever ECM I go with to Dynamic EFI.
I was wondering does anyone know enough about either ECMs to give me some Pros and Cons. The 91 RS ECM has the Pass key system but I already bypassed it.
Any thoughts or advice would be helpful.
-Rob
I found an aftermarket wiring harness on ebay and they said it was set up for the 1228747 ECM. I plan to send witch ever ECM I go with to Dynamic EFI.
I was wondering does anyone know enough about either ECMs to give me some Pros and Cons. The 91 RS ECM has the Pass key system but I already bypassed it.
Any thoughts or advice would be helpful.
-Rob
Moderator
It doesn't matter which ECM gets converted via the EBL Flash system. Once converted they are all identical.
For the wiring harness, if the one you have ('91 RS harness) is OK, I'd stay with it. If some of the connectors are bad, can replace those.
The '8747 ECM was used in full size vans. Which means that the harness for it will not even be close to fitting your RS. It is so long that you could put the ECM under the rear seat.
Not sure, but even if the '8747 ECM was used in pickups, it won't be a drop in in the Camaro. Just too many differences.
RBob.
For the wiring harness, if the one you have ('91 RS harness) is OK, I'd stay with it. If some of the connectors are bad, can replace those.
The '8747 ECM was used in full size vans. Which means that the harness for it will not even be close to fitting your RS. It is so long that you could put the ECM under the rear seat.
Not sure, but even if the '8747 ECM was used in pickups, it won't be a drop in in the Camaro. Just too many differences.
RBob.
Supreme Member
8747 was used in HD trucks and does not have KS input circuit.
//RF
//RF
Quote:
//RF
KS input?Originally Posted by RFmaster
8747 was used in HD trucks and does not have KS input circuit. //RF
Quote:
For the wiring harness, if the one you have ('91 RS harness) is OK, I'd stay with it. If some of the connectors are bad, can replace those.
The '8747 ECM was used in full size vans. Which means that the harness for it will not even be close to fitting your RS. It is so long that you could put the ECM under the rear seat.
Not sure, but even if the '8747 ECM was used in pickups, it won't be a drop in in the Camaro. Just too many differences.
RBob.
Sounds good, Thanks for the advice, I'll stick with the 91 RS wiring.Originally Posted by RBob
It doesn't matter which ECM gets converted via the EBL Flash system. Once converted they are all identical. For the wiring harness, if the one you have ('91 RS harness) is OK, I'd stay with it. If some of the connectors are bad, can replace those.
The '8747 ECM was used in full size vans. Which means that the harness for it will not even be close to fitting your RS. It is so long that you could put the ECM under the rear seat.
Not sure, but even if the '8747 ECM was used in pickups, it won't be a drop in in the Camaro. Just too many differences.
RBob.
Supreme Member
Like Rbob said there are just too many differences between 8747 and 91 TBI system (harness). The 91 should be based on 1228746 or later version service replacement which has IAT and KS inputs. Oh yea - IAT inlet air temperature & KS knock sensor. EBL conversion will further enhance this ECM capability.
HD trucks did not use IAT and KS - spark curve in 8747 is very conservative and GM deemed unnecessary to provide HD applications with these sensors. My guess they figured that there is little value since HD engines were meant to be abused and withstand this abuse.
The last 8747 that I have pulled came out of the '90 3500 that had well 450k on the clock and was wrecked (hit in the rear). The 454 mill backed by a manual gear box was still running although oil leaks made a mess out of engine bay.
//RF
HD trucks did not use IAT and KS - spark curve in 8747 is very conservative and GM deemed unnecessary to provide HD applications with these sensors. My guess they figured that there is little value since HD engines were meant to be abused and withstand this abuse.
The last 8747 that I have pulled came out of the '90 3500 that had well 450k on the clock and was wrecked (hit in the rear). The 454 mill backed by a manual gear box was still running although oil leaks made a mess out of engine bay.
//RF