Intermittently dies, no start
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From: Aloha, Oregon
Car: '91 Camaro Z28, '85 Camaro Z28
Engine: LB9, LB9
Transmission: T5, 700r4
Axle/Gears: Eaton 3.73 Posi, 3.23 Posi
Intermittently dies, no start
So I'm working on a car with a speed density LB9 and and having an issue with a code 32 (EGR), 42 (ICM), and 43 (ESC). It's also having drivability issues. It will run fine when everything is cold, however in hot weather or when the car gets hot it will lose nearly all power for a second or two, then pick back up again. It's not a misfire but it completely loses power. If I push in the clutch while this happens the car will die. It will start back up the first 2 or 3 times but eventually it won't start and will just crank. I have to let it sit for 20 minutes or so until everything is cool for it to start again. And just the be clear it doesn't matter if it's it's open or closed loop, it will do it in either situation
Obviously this is not EGR related, so it has to do with code 42 and 43. It has a new knock sensor, yet the code still stays. I checked all the wiring and connectors for the ignition and everything looks ok, even has a brand new Ignition control module. I just put a new distributor in yet the problem persists. I also put in a new AC Delco ECU.
Checked TPS operation via DVOM, readings were steady and within spec for both idle and full throttle. Checked Fuel pump relay by swapping with the fan relay, no change there. I pulled a spark plug wire when I cant get it to start and it was getting spark. I also checked fuel pressure at the fuel rail and its getting a full 50psi during the crank/no start, straight to 50psi with key on and while cranking and the pressure does not drop when the car dies. I'm baffled, it's getting fuel and spark yet wont start.
I pulled the codes again after I put in the new ECU and the only code present is the 43 (Electronic Spark Control circuit), in other words, the knock sensor. I followed the diagnostics flow chart from ALLDATA and i get 4.88V at the ECU side of the circuit and 4.88V at the connector, so theres no wiring issue there. I then checked the ohm reading for the knock sensor by connecting the ohmmeter between the sensor terminal and the engine block and got .0003 ohms, which is definitely a far cry from the proper operating range of between 3300 and 4500 ohms. This leads me to believe that the knock sensor is bad. Can a faulty knock sensor cause a no start issue? I was under the impression that it only caused drivability problems.
Obviously this is not EGR related, so it has to do with code 42 and 43. It has a new knock sensor, yet the code still stays. I checked all the wiring and connectors for the ignition and everything looks ok, even has a brand new Ignition control module. I just put a new distributor in yet the problem persists. I also put in a new AC Delco ECU.
Checked TPS operation via DVOM, readings were steady and within spec for both idle and full throttle. Checked Fuel pump relay by swapping with the fan relay, no change there. I pulled a spark plug wire when I cant get it to start and it was getting spark. I also checked fuel pressure at the fuel rail and its getting a full 50psi during the crank/no start, straight to 50psi with key on and while cranking and the pressure does not drop when the car dies. I'm baffled, it's getting fuel and spark yet wont start.
I pulled the codes again after I put in the new ECU and the only code present is the 43 (Electronic Spark Control circuit), in other words, the knock sensor. I followed the diagnostics flow chart from ALLDATA and i get 4.88V at the ECU side of the circuit and 4.88V at the connector, so theres no wiring issue there. I then checked the ohm reading for the knock sensor by connecting the ohmmeter between the sensor terminal and the engine block and got .0003 ohms, which is definitely a far cry from the proper operating range of between 3300 and 4500 ohms. This leads me to believe that the knock sensor is bad. Can a faulty knock sensor cause a no start issue? I was under the impression that it only caused drivability problems.
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