I've been trying to figure out my idle surge on my 90 for a while. It's running a 91+ TB/ISC.
Started out replacing possible issues, has a good 90 ECU, new black top ISC and it still surged with no vacuum leaks. In fact all of my 90's surge with the 91+ TB on it.
I found a post that it was possible the 90 wiring was different from the 91+ as far as the ISC went, but no evidence of it. Well I started digging through wiring diagrams and found some interesting information, two coils of the ISC are in fact swapped between the years. My one running 90 is currently missing it's injectors, so testing will occur once I get a new set to put in, but here's the diagrams.
Anyone's opinion? First picture is a 90 Diagram, second is a 91 GVR4 which is the same as a 91 DSM.
Started out replacing possible issues, has a good 90 ECU, new black top ISC and it still surged with no vacuum leaks. In fact all of my 90's surge with the 91+ TB on it.
I found a post that it was possible the 90 wiring was different from the 91+ as far as the ISC went, but no evidence of it. Well I started digging through wiring diagrams and found some interesting information, two coils of the ISC are in fact swapped between the years. My one running 90 is currently missing it's injectors, so testing will occur once I get a new set to put in, but here's the diagrams.
Anyone's opinion? First picture is a 90 Diagram, second is a 91 GVR4 which is the same as a 91 DSM.
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