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1991 Camaro intermittent misfire & stalling
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92-RS-V6
User
May 29, 2010, 12:05 PM
Post #1 of 9
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1991 Camaro intermittent misfire & stalling
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Hello guys / girls. First time post, hope someone can give me a solution as I am banging my head against a wall with this one... 
Year: 1991
Make: Chevrolet
Model: Camaro RS
Engine size: 3.1 liter v6
Mileage: 125,000.
Symptoms: Sudden bad misfire at random intervals, large amount of unburnt fuel from exhaust under misfire, sudden stalling on some occasions.
Checked so far:
Fault codes - different fault code every time PCM memory cleared
Compression - all within spec
Injector operation
Timing
Fuel supply
Spark
Replaced:
PCM - swapped for new unit and problem persists
Spark plugs
Plug leads
Distributor cap & rotor
Coolant temp. sensor
MAP sensor
Ignition coil
Any suggestions would be really appreciated
Regards, Matthew
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nickwarner
Veteran
/ Moderator
May 29, 2010, 1:56 PM
Post #2 of 9
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Re: 1991 Camaro intermittent misfire & stalling
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Check for vacuum leaks. Also, what are these ever-changing codes that are coming up?
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92-RS-V6
User
May 30, 2010, 9:02 AM
Post #3 of 9
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Re: 1991 Camaro intermittent misfire & stalling
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Hi,
Sorry I forgot to mention there were no vacuum leaks I checked with a can of carb cleaner on the vac lines.
The fault codes that I personally got were:
53 - System over-voltage (over 17.1v for one second). I checked the charging voltage at the battery, it was 14 volts.
then after reset
14 - Coolant sensor low temp indication
But I'm unsure of the codes the mechanic got aside from it was a different one each time.
Hope this helps, Matthew
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nickwarner
Veteran
/ Moderator
May 30, 2010, 6:48 PM
Post #4 of 9
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Re: 1991 Camaro intermittent misfire & stalling
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Well a coolant temp sensor will make it run rich or lean depending on which end of the scale its not working right in. I would look in that direction and see what you find
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92-RS-V6
User
May 31, 2010, 1:09 PM
Post #5 of 9
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Re: 1991 Camaro intermittent misfire & stalling
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Hi
I took out the coolant sensor and measured it's resistance value, and when I heated it gently the value changed steadily. I then fitted a Delco one just to make sure I had eliminated that problem.
OK... what's next? Lol
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Sidom
Veteran
/ Moderator
May 31, 2010, 2:30 PM
Post #6 of 9
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Re: 1991 Camaro intermittent misfire & stalling
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If just curious about the statement "different codes keep coming up each time" . Exactly what codes are coming up? Is the ECT code coming up consistantly?
If you then you are going to have to check the circuit. Could be a bad connector or wire.... It would help to be able to hook a scanner up & moniter the ECT PID to see if the temp is jumping around or fixed..........
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92-RS-V6
User
Jun 4, 2010, 9:50 AM
Post #7 of 9
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Re: 1991 Camaro intermittent misfire & stalling
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Hi
The car went off to the mechanics so I don't know the specifics other than the PCM was generating a whole lot of different fault codes every reset. There is a diagnostics expert coming to examine it on Monday so we shall see....
Matthew
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92-RS-V6
User
Jun 7, 2010, 9:17 AM
Post #8 of 9
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Re: 1991 Camaro intermittent misfire & stalling
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Just been in to see the Camaro at the garage. They hired in a local diagnostics specialist. Looks like he tracked it down to a bad connector on the PCM! Car wouldn't start at all until he gripped the wiring on the connector, then he could pretty much make it stall on demand by releasing it. He was halfway through re-crimping all the connectors when I arrived.
As for the rogue trouble codes, they've cleared up with the new PCM.
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nickwarner
Veteran
/ Moderator
Jun 7, 2010, 9:27 AM
Post #9 of 9
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Re: 1991 Camaro intermittent misfire & stalling
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Thanks for posting the fix and glad you will be able to enjoy your car
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