Im working on a 1990 Iroc 305 tpi. the car starts fine when cool and under 180degrees. After runnign a while and hitting 200 but staying in normal operating temps 180-200, It will hesitate often and die at times and has a lack of power. Fuel Pressure is OK at idle and with key on, i tested the coil and the ohms readings were good(cold), had ign module tested-ok(cold) and it will turn over fine it will not fire and run when hot.

Can the coil and module be tested in a "hot" state? I have spark during all this testing but spark color is yellowish at the spark plug end.

Im thinking about cleaning the TB and IAC passeages too, look kinda gunked up.

any help is appreciated!!

thansk,
Nick

 

Your idea is a good one. It's always advisable to start with a good set of plugs, reliable wires, cap, rotor, pickup, connections, etc. before diagnosing a random problem. That removes as many variables as possible. The parts don't necessarily all have to be new, just tested/verified as good. Don't overlook filters and normal adjustments, like TSP, idle air, and timing.

 

yes, all ignition components have checked out okay in a cold state, plug wires are even a new GM packard set. brass cap and rotor are good. I know its going to end up being something simple, but at the same time i know im overlooking something. but so far the above mentioed has been checked and i will look in the artilce for the other tests.

One thing i cannot do on this car vs/ my other stock SD cars. you can attempt to do a powerbrake(yeah its a 305) and it will stall, and moreso when its in operating temp. my 92 and my other 90 have never stalled. So thats why i was thinking IAC was sticky, would that be a possible cause? I still dont like the yellow spark either. I'll keep you informed.

thanks,
Nick

 

Alrighty, i have an update.. everyhting checked out fine and within operating scpecification when it was running. So again, i shut it iff when it was warm abotu 200deg. let it sit for about 5 minutes, then it fired back up and ran - jsut a little rougher. SO i let it sit for 30-45 mins and attempt to restart - no such luck, crank crank crank.

Turns out my one last hurrah was its checking the injectors after heat soaking - Verdict says Toast. readings in the single digits on 5 of the 8. When they were overnight cold they all read above 11ohms so they were still able to fire i guess.


Just remember - check out EVERYTHING before you start replacing parts. I have seen a lot of people jsut start swapping things and blowing money they dont need to. Troubleshooting 101

thanks