1992 lt1 tech help
Thread Starter
3rd Gear
Joined: Aug 2009
Posts: 3
Likes: 0
1992 lt1 tech help
Hi everyone I have a stumper here and I hope one of you nice people can help. Ok here goes. The car quits while driving instantly. I pull over and the car starts right up usually. Here is the scan tool info.
I recorded these readings on our Tech II while the car was running and then quit.
Low res signal 19.7 ms
High res signal 67 ms
Now the readings when the car quit
Low res signal 1.0 ms
High res signal 0.0 ms
Desired idle 3187 rpm
Actual idle 15 rpm
qdm 2 Fault
qdm 3 Fault
I just don't want to change parts and put on another dist. I want to make sure this is it. The car has 42.000 miles on it and the previous owner put a new dist on it at 14.000 miles. I know the puke tube becomes plugged on these systems but this isn't the case on this car. Do these cars have a bad ignition switch problem? I'm thinking it's losing voltage somewhere because of the quad driver faults. Any help would be very grateful! Thank you!
I recorded these readings on our Tech II while the car was running and then quit.
Low res signal 19.7 ms
High res signal 67 ms
Now the readings when the car quit
Low res signal 1.0 ms
High res signal 0.0 ms
Desired idle 3187 rpm
Actual idle 15 rpm
qdm 2 Fault
qdm 3 Fault
I just don't want to change parts and put on another dist. I want to make sure this is it. The car has 42.000 miles on it and the previous owner put a new dist on it at 14.000 miles. I know the puke tube becomes plugged on these systems but this isn't the case on this car. Do these cars have a bad ignition switch problem? I'm thinking it's losing voltage somewhere because of the quad driver faults. Any help would be very grateful! Thank you!
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Start w/the basics. What goes away when it dies? Spark or fuel?
I don't know what the data is that you posted from your scan tool. I've never seen that before. What is "Low res signal 19.7 ms/High res signal 67 ms" -refering to?
I don't know what the data is that you posted from your scan tool. I've never seen that before. What is "Low res signal 19.7 ms/High res signal 67 ms" -refering to?
Melting Slicks
Joined: Feb 2005
Posts: 2,135
Likes: 0
From: Sebastian Florida
St. Jude Donor '06
Have you pulled codes yet?
QDM 2 is quad driver 2 fault and should turn on your engine light, QDM 3's won't do that/
QDM 3 faults are either a bad fan(s) relay, a/c relay or egr solenoid.
QDM 2 is most likely your evap solenoid.
Low res signal could be caused by a bad opti, coil or ICM, ICM's are almost impossible to test and coil testers are hit or miss, I have seen coils test good that were junk.
The High res going to 0 sounds to me like a bad coil or ICM.
Does the car die suddenly or does it sputter?
Have you checked the fuel pressure while the car is running?
For the best help give us all the info you can!!!
QDM 2 is quad driver 2 fault and should turn on your engine light, QDM 3's won't do that/
QDM 3 faults are either a bad fan(s) relay, a/c relay or egr solenoid.
QDM 2 is most likely your evap solenoid.
Low res signal could be caused by a bad opti, coil or ICM, ICM's are almost impossible to test and coil testers are hit or miss, I have seen coils test good that were junk.
The High res going to 0 sounds to me like a bad coil or ICM.
Does the car die suddenly or does it sputter?
Have you checked the fuel pressure while the car is running?
For the best help give us all the info you can!!!
Thread Starter
3rd Gear
Joined: Aug 2009
Posts: 3
Likes: 0
Sorry fellas, The res signals are in Milliseconds. Fuel pressure and spark are ok when I test it because it will be fine until the moment it quits. Then the car starts and runs fine. I have a 0016 code which is opti-spark ign system low resolution pulse. I have checked the red/blk wire with the key on and have .064 volts which in our mitchell manual is ok. Of course again everything is in working order when I am testing these things. I know it's an intermittent thing but I obvioulsly want it to stop stopping...lol. I just don't want to be a parts changer.. Thanks again!
Melting Slicks
Joined: Feb 2005
Posts: 2,135
Likes: 0
From: Sebastian Florida
St. Jude Donor '06
Code of 16 is usually a bad opti, but you could have a bad wire or a grounded wire.
The FSM says that .5 volts and below is a open or grounded wire and you are pretty close to that. Mine is almost exactly 1 volt, check for a broken wire, that is what happened to another forum member a few years back.
He would throw a 16 and replace the opti and car would run good for a while then throw a 16 again. His broken wire was right at the connector to the opti, also if there is a oil leak, then you might have oil seeping into the connection. Happened to me when I thought I had a bad opti, cleaned the connection and rapped it on electrical tape and never had a problem again.
Also, a 16 can be thrown by a bad ECM, according to the FSM.
If you give me your email, I will scan that section of the FSM for you and email to you.
The FSM says that .5 volts and below is a open or grounded wire and you are pretty close to that. Mine is almost exactly 1 volt, check for a broken wire, that is what happened to another forum member a few years back.
He would throw a 16 and replace the opti and car would run good for a while then throw a 16 again. His broken wire was right at the connector to the opti, also if there is a oil leak, then you might have oil seeping into the connection. Happened to me when I thought I had a bad opti, cleaned the connection and rapped it on electrical tape and never had a problem again.
Also, a 16 can be thrown by a bad ECM, according to the FSM.
If you give me your email, I will scan that section of the FSM for you and email to you.
Melting Slicks
Joined: Feb 2005
Posts: 2,135
Likes: 0
From: Sebastian Florida
St. Jude Donor '06
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