bad pcm?

[SammY "Yo"]

what are signs of a bad PCM? i have a 99 GP sedan with a NA 3.8 that i just finish doing the lower intake gaskets and replaced upper intake, now it wont start, seems like its jus dumping crazy amounts of fuel in the motor cuz it keeps fouling out the plugs. i read on here of a few ppl burning the PCMs out by jumping their cars, and i jump started my car the nite int broke down and have been jumping ever since , tryin to get it running. i replaced the ign. module and all 3 coils also. dont know what i can have done or forgort to do while i was replacing the gaskets and upper intake . thanx



sammy

[CrazyHorst]

IMHO, if you are still fueling, your PCM is still working to drive the injectors.

In response to your other post I suggested very carefully re-checking the spark plug wire locations and cylinder numbering. The rear of the engine is trickier than it seems. Also, I'd put back all of your original ignition hardware as that was presumably running before you tore down the intake.

[tblake]

Injectors get constant B+ and the PCM controlls the ground circuit in order to inject fuel. Go back and double check all the injector wire plugs and harness. Look for anything like pinched wires or flaking insulation on wires.

[SammY "Yo"]

Originally Posted by CrazyHorst

IMHO, if you are still fueling, your PCM is still working to drive the injectors.

In response to your other post I suggested very carefully re-checking the spark plug wire locations and cylinder numbering. The rear of the engine is trickier than it seems. Also, I'd put back all of your original ignition hardware as that was presumably running before you tore down the intake.

actually the reason i changed the ignition parts was cuz it wouldnt start. after i did replace the ignition parts, purged the motor, and cleaned the plugs(which i replaced coupled days ago) it ran for a second and jus stalled out, crank it over a few times and nuttin, remove plugs to find them load wit fuel again, never saw an EFI motor drench plugs wit fuel like this b4, i even handle the pedal to the floor to see if the pcm would cut the fuel to the injectors and nuttin. i did check over the plug wire but i will do it again carefully. thanx for the info

sammy

[CrazyHorst]

Originally Posted by SammY "Yo"

never saw an EFI motor drench plugs wit fuel like this b4, i even handle the pedal to the floor to see if the pcm would cut the fuel to the injectors and nuttin

Not sure where this clear-flood info came from (Ford maybe?), I've heard several times of people trying it on GM vehicles and they all went WOT when it started up...

[DieselHilux]

My windstar will do "clear flood" lol, funny if you tell someone with a carb to clear there flood that way lmao!!

[BNaylor]

Originally Posted by CrazyHorst

Not sure where this clear-flood info came from (Ford maybe?), I've heard several times of people trying it on GM vehicles and they all went WOT when it started up...

From Ford?

Actually if you carefully check the PCM programming in detail there is a "clear flood mode" in addition to other modes like starting mode, running mode, acceleration mode, deceleration mode, battery voltage correction mode, fuel cutoff mode, power enrichment mode, closed loop mode and open loop mode, etc. just to name a few. In the engine off starting mode, open loop mode it will go into a "clear flood mode" when the PCM sees the throttle at 80% or better (WOT) at which point the PCM reduces fuel injector pulse width to in order to increase the air to fuel ratio. Typically, A/F ratio 20:1 or leaner. The PCM will hold this injector rate as long as the throttle stays wide open and the engine speed is below a predetermined rpm. The PCM returns to the starting mode if the throttle is not held wide open. Also, clear flood mode is then automatically disabled when engine RPM is greater than approximately 300 RPM. As for other safety features once engine starts as long as the car is in park/neutral not moving then the rpm limiter/fuel cutoff could take over which kicks in at approximately 4000 rpms.