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Can't get to 3000rpm


Cloverdale
09-17-2010, 04:52 AM
My mother brought me her car because it was acting up.
The problem seemed that it was that under any kind of hard acceleration, the car would buck stall and die. Sometimes it could be restarted, others it would take a while.
The EGR had been disconnected by a previous mechanic. I figured this would cause these problems. It runs better, but hard acceleration the car just dies. I found a lot of info on here about the CPS going out and causing these problems. I replaced that and no help.
I am able to duplicate the problem while under the hood. So, I hooked up my timing light and a pulse light on the injectors. When I goose the throttle and it dies, I go right to start and it just cranks. My timing light shows spark pulses, but I get no injector pulse. If I go to off and back to start it tends to fire right up.
I checked fuel pressure and it is 40psi engine off and 35 running. It also holds the 40psi long after shutdown.
I have checked grounds and cleaned and applied dielectric to all. I also cleaned under the ICM. I am not able to find any wires rubbing or broken.
The computer just shuts off when the car dies. I have my Ethos up to it and it loses communication at the same time as the car dies. It reconnects within a couple seconds.
Would love suggestions. Planning on a trip to the yard for troubleshooting parts this weekend. Thinking of a PCM and ICM. Any thoughts?
Thanks
94 Park Avenue. 140k, auto, not ultra, electric everything...

maxwedge
09-17-2010, 08:48 AM
I would check all the connections to the pcm to start with maybe some corrosion issues.

HotZ28
09-17-2010, 10:42 AM
Without a scanner capable of viewing live data, all you can do is speculate & throw parts at it. If you are using JY parts, this process might not be too costly, but when you pick up several parts, replace only one at a time, otherwise you will never know what the problem was. Start with the easy things first, like the ICM, TPS & MAF. The PCM is more trouble to replace; however, the 94-95 units are prone to failure. Good Luck on your part replacement expedition!

AutoService101
09-17-2010, 11:51 AM
Check with your local parts store and see if they will scan it for you. That is always a good start, even if the light is not on it could have coded up. Wondering if your catalytic converter may be plugging up??? :runaround:

Cloverdale
09-17-2010, 04:45 PM
Check with your local parts store and see if they will scan it for you. That is always a good start, even if the light is not on it could have coded up. Wondering if your catalytic converter may be plugging up??? :runaround:

Well, my scanner does live feeds. I am able to watch every sensor as it is recorded by the ecm. Everything appears to be working. There is one item on the live feed that bothers me.
Crank/Cam faults = 1
As far as troublecodes, nothing. With it would throw a code.
I shook the harness as it runs through the firewall while running and nothing.
Does the ICM handle fuel injectors? I think it just drives the coils and the ECM drives the injectors. It really feels like it goes out of time when it stumbles.
No sulfur smell from the converter. The rich/lean signal seems fine.
I am leaning towards the ECM due to the computer shutting down when the car dies. Other cars have had similar problems but the computer doesn't shut off.:confused:
I appreciate your responses. I will certainly post whatever I find. It bothers me how many dead ends I have come to in this forum due to others not posting their fixes.:runaround:

AutoService101
09-17-2010, 05:16 PM
The ICM sends info to the PCM that it uses to control the fuel system and spark advance. So no it does not control injectors. Checking the ECM on that vehicle is pretty straight forward, tap on it an if the vehicle dies then you have a bad ECM. That is how we tested back in the day, pretty sophisticated stuff.
I would think that what you are seeing is more a problem with the crank or cam sesnor. I have not worked on GM for several years now but I do not recall much of a issue with either component. Please realize I stopped working for GM in 2000. Things have changed and that vehcile is now 16 years old. I would have to think that the crank sensor was your issue. I do not know how to test either sensor properly on that vehicle so I am not much help there. Obviously it is a pretty big job to replace either sensor so you need to find out how to test it properly. wish I could be of more help

HotZ28
09-17-2010, 10:51 PM
If your scanner is capable or recording live data, it should also be capable of recording freeze frame data when the engine dies. What is the freeze frame data results?

Cloverdale
09-18-2010, 11:23 AM
ECM
Grabbed one out of a 95. Plugged it in. Cleared codes. Turned it off. Turned it on. Started it. Runs ok, little shaky but smoothed out. Once idle calmed down, I did my test. It worked!! I have a knock sensor code, but the original problem/symptom is gone!
Also the crank/cam fault = 1 now says = 0. Took some snap shots but the home computer doesn't have the software to share them on here.
Everyone's ideas sounded plausible but the ECM cutting out when the car died is what was pushing me to it.
Thanks All!! Happy driving! Mom will be happy when she gets back from vacation. This and several other fixes will give her a virtually new car:smokin:

Blue Bowtie
09-18-2010, 11:27 AM
When you induce the failure mode and try to restart, and you are seeing ignition but no injector pulses, what does the MAF read?

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