symptoms of bad ESC module?

symptoms of bad ESC module?

Postby eriemc [OP] » August 13th 2019, 3:05am

what are symtoms ESC module going bad? (external ESC module)

what are symptoms of EGR valve needs cleanout or replacement?

my ride: 91 RWD TBI shorty
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eriemc
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Re: symptoms of bad ESC module?

Postby paulo57509 » August 13th 2019, 12:34pm

eriemc wrote:what are symtoms ESC module going bad? (external ESC module)

:think: Intermittent no-start would probably be at the top of the list.

eriemc wrote:what are symptoms of EGR valve needs cleanout or replacement?

:think: High NOx level, pinging (light throttle), engine dies after sustained high speed running (freeway off ramp) followed by hard or no start condition, rough idle, etc.

A punctured valve diaphram is more of a cause for replacement than a symptom. Most symptoms can also be traced to plugged EGR passages.

There are probably other symptoms for both the ESC and EGR going bad. These are just the ones I can think of off the top of my head or have happened to me.
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Re: symptoms of bad ESC module?

Postby eriemc [OP] » August 15th 2019, 1:12am

it just wont idle right. either idles rough and nearly stalls out, or the ECM goes into panic mode and it idles too high. has stalled out a few times. Hard to start whether warm or cold theres a trick to it and I can get it to start on the 2nd or 3rd try will some playing with the gas pedal. warm or cold, no difference. will start instantly with squirt of quickstart. a little bit of misfiring and rough running. Smooth on the highway (so far) accelerates and goes up hills, but its around town traffic stop n go that make it unsafe.

I replaced ALL of the ignition components from the distributor on out. Slight improvement with installation of Pertronix module and coil; and an old set of Accel 8.8 wires.

it acts like it has intermittent timing issues. the timing is set and it runs OK at idle with the tan/black wire unplugged. so I am guessing the ESC has a short in it and is making the ECM do weird things.

recently swapped out the ECM and PROM. no improvement, but now the check engine light goes on occasionaly but then goes off. I have not road tested yet. this is all parking and idling. also the ECM gets warm to the touch. the old one did this too. I dont think this is right. it leads me to believe my shorted ESC theory.

Also done: checked all the vacuum lines and brought them back to factory specs
changed MAP sensor, O2 sensor, checked intake vacuum (good) IAC valve, rebuilt throttle body, 2 new AC delco injectors, temp sensor ( the one that talks to the ECM)

I have a replacement throttle position sensor but I don't know if it needs it.

I ordered a knock sensor and a ESC from rockauto. will try it and see what happens

the only thing I can think of that I did not check is the EGR

thanks again for reading my sob story
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eriemc
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Re: symptoms of bad ESC module?

Postby eriemc [OP] » August 18th 2019, 12:29am

replaces ESC no change
still waiting for knock sensor to come in the mail
replaced EGR solenoid - noticeable change, easier to start, seems to start normally now with no gas pedal
replaced EGR - slight improvement
still vacillates between stumbling at idle and high idle panic mode.
next thing to try is replace TPS.
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Extra Info: rwd 4.3 tbi z

Re: symptoms of bad ESC module?

Postby paulo57509 » August 19th 2019, 10:20am

Crazy, insane question but I have to ask:

Have you had the battery disconnected recently? Recently meaning the problem you're having with a hunting, erratic idle started after the battery was dis/re-connected?

I ask this because I have a similar vintage '92 Lumina (3.1L passenger car) that needs to have an "idle learn" procedure performed anytime the battery is dis/re-connected. I'm wondering if GM requires this same crazy re-learn process done with your Astro?

Upon re-connecting the battery, it will idle OK (so you'd think!) but once it gets into closed loop, it will hunt at a stop light, stall when closing the throttle at freeway speeds, etc.
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