i have a 91 short bed chevy with a 90 model 350 tpi when i plug in the est wire it starts missing and running hot have replaced knock,fuel pump,tps,regulator,cap,plugs,ecm,icm,o2,please any help would be very much appreciated

 

Pulling up and checking out any and all codes would definitely help before throwing money at something without knowing what's wrong exactly.

 

only code i get is code 42

 

and it runs great for first 15 min

 

Did you recently have the distributor out?

 

code 42 is ignition system, where is your timing at now?

 

Shld set the timing at 6 degrees but I run my 305 tpi at 8 and its fine. Maybe the coil bad when they get hot they start acting up.

 

Its unlikely, but i do know that when an ignition control module is bad they act up when they get warm or engine warms up.

 

Let me ask you this: Are all your plug wires good? Start it up at night and look to see if you have any blue sparks on the outside of your wires (arching). This would act like a miss.

 

I have seen coils do this if they r bad an start getting hot they will arc jus like a plug wire does. Best to have a few spare parts laying around for trial and error.

 

Thats true too. Mine had a blue spark going across it once. Coulnd't see it until it was dark outside tho. Thats how i found my bad plug wires too.

 

Check the spark timing once the EST/BYPASS is re-connected and the engine is restarted. If it retards (likely) the pickup coil wires to the ICM are reversed. Note that you will need to key-off for at least ten seconds after re-connecting the EST/BYPASS connector, then restart the engine.

RBob.

 

it does retard so what do i need to do

 

they are all good no spark and they are all knew

 

no sparks at coil

 

thank you i know me not knowing that makes me stupid for over looking it i checked it prob a dozen times never thought to look at the colors you made my day alot easier