SClark08
Newbie
I am working on a 1989 350-TBI. The previous owner installed a TB spacer and headers and tampered with the TB set screw.
In my efforts to achieve a stable idle I have replaced the following: idle air control valve (IACV; Delphi brand), EGR, PCV + grommet (ACDelco), Breather + grommet (K&N), valve cover gaskets, vacuum lines (EGR, PCV, both MAP, and charcoal), plugs/wires, cap & rotor.
I rebuilt and cleaned the TB, replaced the injectors (CS Performance, flow matched) and replaced the TB base gaskets.
I set mechanical timing to 0* with the EST disconnected. Then reconnected the EST.
I then jumped the ALDL A&B with key ON to fully extend the IACV, then disconnected its harness. I removed the ALDL jumper and turned the key to RUN and set the transmission to Drive. I adjusted the TB set screw until my RPM was 500-550 (in Drive) and confirmed Park/Neutral to be 750RPM.
Satisfied, I turned the key off and reconnected the IACV. Running the truck I have 750RPM in P/N but now around 400RPM in Drive.
I have no idea what would cause this or what to check next.
I also had a heck of a time establishing 0* timing. Every time I got it just right with the timing light, it would advance 2 to 3* once I had the distributor tightened back down. I even tried adjusting it to a few degrees retarded then tightening to try and counteract it. But every time it would lock in retarded. So the compromise was to set it to 1/2 to 1* retarded and live with it.
In my efforts to achieve a stable idle I have replaced the following: idle air control valve (IACV; Delphi brand), EGR, PCV + grommet (ACDelco), Breather + grommet (K&N), valve cover gaskets, vacuum lines (EGR, PCV, both MAP, and charcoal), plugs/wires, cap & rotor.
I rebuilt and cleaned the TB, replaced the injectors (CS Performance, flow matched) and replaced the TB base gaskets.
I set mechanical timing to 0* with the EST disconnected. Then reconnected the EST.
I then jumped the ALDL A&B with key ON to fully extend the IACV, then disconnected its harness. I removed the ALDL jumper and turned the key to RUN and set the transmission to Drive. I adjusted the TB set screw until my RPM was 500-550 (in Drive) and confirmed Park/Neutral to be 750RPM.
Satisfied, I turned the key off and reconnected the IACV. Running the truck I have 750RPM in P/N but now around 400RPM in Drive.
I have no idea what would cause this or what to check next.
I also had a heck of a time establishing 0* timing. Every time I got it just right with the timing light, it would advance 2 to 3* once I had the distributor tightened back down. I even tried adjusting it to a few degrees retarded then tightening to try and counteract it. But every time it would lock in retarded. So the compromise was to set it to 1/2 to 1* retarded and live with it.
