Motor shuts down whenever it wants
11-28-2008, 02:59 PM
#1
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Motor shuts down whenever it wants
I am moving this problem over here from the Computer and Tuning forums since I got the computer software issue worked out. Here's the original thread. https://www.camaroz28.com/forums/sho...d.php?t=647996
Readers Digest condensed version: 93 LT1 w/93 PCM in an 85 Camaro. Was running fine then started shutting down. Sometimes it would restart, sometimes it wouldn't. Hot or cold, doesn't matter. Throws a code 36, nothing else. Fuel pressure is good. Scan is here:
http://www.mediafire.com/?sharekey=2...db6fb9a8902bda
Do I need to start yanking stuff off to get to the opti? Thanks.
Readers Digest condensed version: 93 LT1 w/93 PCM in an 85 Camaro. Was running fine then started shutting down. Sometimes it would restart, sometimes it wouldn't. Hot or cold, doesn't matter. Throws a code 36, nothing else. Fuel pressure is good. Scan is here:
http://www.mediafire.com/?sharekey=2...db6fb9a8902bda
Do I need to start yanking stuff off to get to the opti? Thanks.
Last edited by Savannah Dan; 11-28-2008 at 10:31 PM. Reason: Fixed link.
11-28-2008, 10:33 PM
#3
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11-29-2008, 08:02 AM
#4
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My 96 used to do that as well as my 94. With the 96, the MAF connector would get fouled. Usually at a stop light (it seemed) with lunch traffic honking behind me. I'd have to pop the hood, jump out, disconnect/reconnect the connector about four times to scuff off the crud, it would start right up, close the hood, and be ready to go by the time the light turned red again. I know 93's are Speed Density so the MAF is not your issue but it might be a similar dirty connector somewhere, perhaps at the coil or ICM. The 94 was something else. Everytime I turned right at any kind of speed, the engine would stumble, then die. In my typical style, I suspected every connector, wire, sensor but nothing fixed it. I had to have to towed once because it refused to start. I started thinking, "Why only on the turns? What moves around that could swing like a pendulum and kill the engine?"..... aha.. the battery! I felt the connectors and they felt tight. I tried to shift the battery around and it would shift around in the battery tray. I started the car and then got out and attempted to move the battery around. When I did, it made the engine stumble then die. I then took off the connectors. The facing plates on the connector looked fine but under the positives protective red cowl was an immense amount of that green crud. I took off that cowl and scraped it out, reattached the cables and I never had that problem again. I think the connection with the crud was 'just' enough to start/run the car but when I made right hand turns, the battery shifting broke the connection long enough for the computer to go dumb and it let the motor die.
11-29-2008, 03:07 PM
#5
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Thanks Dave. I've looked and did the 'shakedown' test on every connector I could find. I found some nicked and cut wires going to the IAC and fixed those. Only wiring I haven't checked is the connectors on the PCM and the PCM grounds. I also need to give it a run at night to see if there is any arching going on. After that I guess it will be time to pull the opti. I may try noids in the injector connectors first.
11-30-2008, 07:16 AM
#6
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Why do you keep going back to the opti?????
Is it because it's the only consistent code you keep getting?????
Fred told you a while ago, if all it gets is a 36 but shuts down, it's something else causing the shut down. Like a 16 but you said there was no 16 code either active or in memory.!!!!!
Remember, if the low voltage side of the opti is the problem, it will set one or both of the 2 codes. ONLY the 16 will shut the fuel system off (as Fred mentioned before).
The high voltage side of the opti is like any other distributor. Albeit with a some what weird cap. So if it's a distribution problem, you will see it on the spark plugs with fooling. Have you even looked at the condition of the plugs?????
So if your engine is shutting down BUT the fuel pressure is fine when it does, it's not the opti.
First point is, how confident are you that the fuel pressure is not the actual problem?????
Second point, was common items checked during the no start problem? Such as, spark and fuel?
An inline spark tester on all plugs will not take much time. OR, take the intake off and squirt fuel into the TB directly while someone cranks it over.
If you squirt fuel into the intake and nothing happens guess what you should be looking for ?
Fred told you a while ago, if all it gets is a 36 but shuts down, it's something else causing the shut down. Like a 16 but you said there was no 16 code either active or in memory.!!!!!
Remember, if the low voltage side of the opti is the problem, it will set one or both of the 2 codes. ONLY the 16 will shut the fuel system off (as Fred mentioned before).
The high voltage side of the opti is like any other distributor. Albeit with a some what weird cap. So if it's a distribution problem, you will see it on the spark plugs with fooling. Have you even looked at the condition of the plugs?????
So if your engine is shutting down BUT the fuel pressure is fine when it does, it's not the opti.
First point is, how confident are you that the fuel pressure is not the actual problem?????
Second point, was common items checked during the no start problem? Such as, spark and fuel?
An inline spark tester on all plugs will not take much time. OR, take the intake off and squirt fuel into the TB directly while someone cranks it over.
If you squirt fuel into the intake and nothing happens guess what you should be looking for ?
11-30-2008, 11:43 AM
#7
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Yes, I keep thinking opti because of the 36. Fred didn't say that if all it gets is a 36 and shuts down, something besides the opti is causing the shut down. Fred said, "An erratic high res signal could cause your problems, although is shouldn't cause a complete shutdown."
I have not pulled the plugs.
You got me on that one. 
Are you assuming the computer is commanding the shutdown? I don't know if that is the case or if the engine is just dieing on its own when it shuts down.
I had a FPG hooked to the valve between the FPR and the rail. It was rock solid, @40psi I think, before, during, and after the shutdown. So there is fuel at the rails. Whether or not the FIs are doing anything with it or not I don't know yet.
I have a bunch of spark testers around here somewhere. I'll have to install them and check it out.
When the car has crapped out it hasn't been at a time when I had time to look at it any longer. The car belongs to a friend and I only have about an hour a week to look at it.
I know a motor needs fuel, fire, and air to run. Take any one of them away and you have a very quiet car.
Sorry if I am frustrating anyone. I am asking questions because I don't know everything, and my time is very limited and I want to maximize my effort verses time. I'm not slow either. If I had a lot of LT1 knowledge I would be answering questions here instead of asking them, know what I mean? Thanks.
I have not pulled the plugs.
So if your engine is shutting down BUT the fuel pressure is fine when it does, it's not the opti.
Are you assuming the computer is commanding the shutdown? I don't know if that is the case or if the engine is just dieing on its own when it shuts down.I had a FPG hooked to the valve between the FPR and the rail. It was rock solid, @40psi I think, before, during, and after the shutdown. So there is fuel at the rails. Whether or not the FIs are doing anything with it or not I don't know yet.
I have a bunch of spark testers around here somewhere. I'll have to install them and check it out.
When the car has crapped out it hasn't been at a time when I had time to look at it any longer. The car belongs to a friend and I only have about an hour a week to look at it.
I know a motor needs fuel, fire, and air to run. Take any one of them away and you have a very quiet car.
Sorry if I am frustrating anyone. I am asking questions because I don't know everything, and my time is very limited and I want to maximize my effort verses time. I'm not slow either. If I had a lot of LT1 knowledge I would be answering questions here instead of asking them, know what I mean? Thanks.
Last edited by Savannah Dan; 02-16-2010 at 05:40 PM.
11-30-2008, 01:43 PM
#8
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What about the fuel pump relay? Have you checked that?
Yes, I keep thinking opti because of the 36. Fred didn't say that if all it gets is a 36 and shuts down, something besides the opti is causing the shut down. Fred said, "An erratic high res signal could cause your problems, although is shouldn't cause a complete shutdown."
I have not pulled the plugs.
You got me on that one. Are you assuming the computer is commanding the shutdown? I don't know if that is the case or if the engine is just dieing on its own when it shuts down.
I had a FPG hooked to the valve between the FPR and the rail. It was rock solid, @40psi I think, before, during, and after the shutdown. So there is fuel at the rails. Whether or not the FIs are doing anything with it or not I don't know yet.
I have a bunch of spark testers around here somewhere. I'll have to install them and check it out.
When the car has crapped out it hasn't been at a time when I had time to look at it any longer. The car belongs to a friend and I only have about an hour a week to look at it.
I know a motor needs fuel, fire, and air to run. Take any one of them away and you have a very quiet car.
Sorry if I am frustrating anyone. I am asking questions because I don't know everything, and my time is very limited and I want to maximize my effort verses time. I'm not slow either. If I had I had a lot of LT1 knowledge I would be answering questions here instead of asking them, know what I mean? Thanks.
I have not pulled the plugs.
You got me on that one.
Are you assuming the computer is commanding the shutdown? I don't know if that is the case or if the engine is just dieing on its own when it shuts down.I had a FPG hooked to the valve between the FPR and the rail. It was rock solid, @40psi I think, before, during, and after the shutdown. So there is fuel at the rails. Whether or not the FIs are doing anything with it or not I don't know yet.
I have a bunch of spark testers around here somewhere. I'll have to install them and check it out.
When the car has crapped out it hasn't been at a time when I had time to look at it any longer. The car belongs to a friend and I only have about an hour a week to look at it.
I know a motor needs fuel, fire, and air to run. Take any one of them away and you have a very quiet car.
Sorry if I am frustrating anyone. I am asking questions because I don't know everything, and my time is very limited and I want to maximize my effort verses time. I'm not slow either. If I had I had a lot of LT1 knowledge I would be answering questions here instead of asking them, know what I mean? Thanks.
11-30-2008, 03:11 PM
#10
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Location: Upstate New York,USA
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Here's the reason I asked...
https://www.camaroz28.com/forums/sho....php?p=5217829
Best of luck. I've had such mysterious and troublesome problems in the past. Spent days, weeks, months fighting them and, occasionally, hundreds of dollars in vain until the ultimate culprit was found.
examples:
Symptom: Drove fine to grocery store. Got out, went shopping, came back, no start. Not one hit or attempt. Towed home. Solution? Start switch on top of the steering mast under dash went bad.
Symptom: Intermittent dying, sometimes restart, sometimes not. Solution? Female pin hole on ICM connector not making good contact. Pried pin capture more tightly closed.
Symptom: Intermittent dying going down road or just not starting after turning off engine. Solution? Dirty MAF Connector. Scuffed off crud and sprayed pins with Radio Shack Electrical contact cleaner.
Symptom: Engine ran fine with ignition. Rebuilt motor. New motor installed and hooked up to prior ignition system. Ran horrible. Intermittent missing, running rich as hell. Solution? Spent about a month and $1,000 replacing sensors, wiring harness, coils, ICM, injectors, plug wires, rechecked Cam degree by tearing off the front of the motor before fixing it by Replacing Opti.
Symptom: Ran like crap/Rich. Blowing Sensor fuses. Solution? Wiring harness bundle touching SLP headers, shorting out sensor circuit. Replaced wires with 4' section to reroute them away from the headers.
Symptom: Drove car in evening just fine. Drove into the garage and shutoff normally. Next morning, no start. Solution? Two week old MSDAL went bad. Bypassed to use stock igntion. Fired right up. Returned MSD to vendor, got free replacement that lasted 2 years before it too failed in similar fashion.
Symptom: Aforementioned (in prior post) dying when turning right. Solution? Clean underside of Positive battery connector (not the side that faces the battery but rather the side where the bolt head is exposed)
https://www.camaroz28.com/forums/sho....php?p=5217829
Best of luck. I've had such mysterious and troublesome problems in the past. Spent days, weeks, months fighting them and, occasionally, hundreds of dollars in vain until the ultimate culprit was found.
examples:
Symptom: Drove fine to grocery store. Got out, went shopping, came back, no start. Not one hit or attempt. Towed home. Solution? Start switch on top of the steering mast under dash went bad.
Symptom: Intermittent dying, sometimes restart, sometimes not. Solution? Female pin hole on ICM connector not making good contact. Pried pin capture more tightly closed.
Symptom: Intermittent dying going down road or just not starting after turning off engine. Solution? Dirty MAF Connector. Scuffed off crud and sprayed pins with Radio Shack Electrical contact cleaner.
Symptom: Engine ran fine with ignition. Rebuilt motor. New motor installed and hooked up to prior ignition system. Ran horrible. Intermittent missing, running rich as hell. Solution? Spent about a month and $1,000 replacing sensors, wiring harness, coils, ICM, injectors, plug wires, rechecked Cam degree by tearing off the front of the motor before fixing it by Replacing Opti.
Symptom: Ran like crap/Rich. Blowing Sensor fuses. Solution? Wiring harness bundle touching SLP headers, shorting out sensor circuit. Replaced wires with 4' section to reroute them away from the headers.
Symptom: Drove car in evening just fine. Drove into the garage and shutoff normally. Next morning, no start. Solution? Two week old MSDAL went bad. Bypassed to use stock igntion. Fired right up. Returned MSD to vendor, got free replacement that lasted 2 years before it too failed in similar fashion.
Symptom: Aforementioned (in prior post) dying when turning right. Solution? Clean underside of Positive battery connector (not the side that faces the battery but rather the side where the bolt head is exposed)
Last edited by DirtyDaveW; 11-30-2008 at 03:28 PM.
12-03-2008, 04:56 PM
#11
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I made some time last night to look at the car. Before I did anything I popped the hood and put a spark tester in line between the coil and the opti. Car cranked right up but only ran for a few minutes before it died because the coil quit putting out. Now I have a direction to t/s.
12-04-2008, 06:48 PM
#13
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I had a few minutes this evening so I took a look at it. It cranked fine then shut off after a few minutes. I pulled the connector off the ICM. Ground was good. Getting 11.64vdc from the two wires from the coil, and 6vac from the signal from the PCM. The coil is new, so I tried another known good ICM. It cranked up and died after about 5 minutes. Thought I had the culprit for a few minutes. Oh well, I'll do some more looking this weekend.
While it was running I shook down all the wire harnesses with no results.
While it was running I shook down all the wire harnesses with no results.
12-04-2008, 08:12 PM
#14
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Is the engine running a length of time you could refer to as 'dependable'? Like 1 minute or 2 minutes , etc. consistently, before it dies? Does it stumble then die or does it just act like a light switch and shut off abruptly?
12-05-2008, 08:45 AM
#15
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When it starts it has always run at least a minute. Usually it is between 3-5 minutes. It has run for as long as 35 munites, but not in the last 8-10 times.
Sometimes it shuts right off, but I think that more times than not it stumbles a little before it dies. As a matter of fact when I had the spark tester hooked between the coil and the opti I remember the the spark in the tester faltering before it died. Fuel is always present.
Sometimes it shuts right off, but I think that more times than not it stumbles a little before it dies. As a matter of fact when I had the spark tester hooked between the coil and the opti I remember the the spark in the tester faltering before it died. Fuel is always present.