Jetronic gurus please
10-26-2015, 08:22 PM
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E34
Jetronic gurus please
Hello all. Asking for some advice and direction with a persisting problem. I will try to be as concise as possible... But positive I'll forget something.
Background: 1988 560 sec with 169,xxx miles. The car was purchased after sitting for several years non-running because of a "fuel problem" according to the previous owner. The rest of the vehicle is in great shape and the obvious problem was that the fuel pumps/accumulator was missing.
Here's the current "issue":
Duty cycle reads 83% with the ignition on and motor off. This is close enough to the California controller numbers that it's not a concern. However when the sensor plate is deflected the duty cycle does not drop OR drops to 0% and stays there (2 different ecus). Also, the LED on the x92 connector is on all the time with the car off, and duty cycle measurements are constant between the X11 and x92 connectors. Throttle position sensor (throttle valve) was tested and failed. So a brand new one was calibrated and installed. The air flow potentiometer was tested and failed... And replaced with a known working (and tested) unit... No change. I have plugged in a new 02 sensor to see if there is a short... No change.
Possibly of no relation... But also of note:
New plugs
New wires
New dist cap/rotor
Tested jy coil
Rebuilt and tested fuel dist
Multiple ezl's
Tested used eha.
Jy crank sensor (no change)
Multiple jy ecus (pre 87 also)
The motor compression tests just fine 4.5% between all 8
New injectors
Fuel pressure while cranking/running on feed line is 95ish psi
OVP relay tested and functioning
Fuel pump relay tested and functioning.
Now... A Wideband a/f gauge/sensor is installed and while idling smoothly the a/f at idle can be adjusted to ANY stable a/f. However when the "misfire " occurs the a/f reads full lean (which could be unburnt fuel = SUPER rich) and then recovers. The "misfire" at operating temperature occurs every 6 seconds or so with a duration of 2 seconds or so. Every time an issue is found (eg TPS the motor requires a completely different amount of fuel to idle, but the "misfire" persists.
This not being a W124 it would be very difficult to blame the harness, but I'm starting to lean that way... Partially because I don't have much anywhere else to go that makes sense. I know it must be something simple... Any constructive input is appreciated.
Thank you in advance.
Background: 1988 560 sec with 169,xxx miles. The car was purchased after sitting for several years non-running because of a "fuel problem" according to the previous owner. The rest of the vehicle is in great shape and the obvious problem was that the fuel pumps/accumulator was missing.
Here's the current "issue":
Duty cycle reads 83% with the ignition on and motor off. This is close enough to the California controller numbers that it's not a concern. However when the sensor plate is deflected the duty cycle does not drop OR drops to 0% and stays there (2 different ecus). Also, the LED on the x92 connector is on all the time with the car off, and duty cycle measurements are constant between the X11 and x92 connectors. Throttle position sensor (throttle valve) was tested and failed. So a brand new one was calibrated and installed. The air flow potentiometer was tested and failed... And replaced with a known working (and tested) unit... No change. I have plugged in a new 02 sensor to see if there is a short... No change.
Possibly of no relation... But also of note:
New plugs
New wires
New dist cap/rotor
Tested jy coil
Rebuilt and tested fuel dist
Multiple ezl's
Tested used eha.
Jy crank sensor (no change)
Multiple jy ecus (pre 87 also)
The motor compression tests just fine 4.5% between all 8
New injectors
Fuel pressure while cranking/running on feed line is 95ish psi
OVP relay tested and functioning
Fuel pump relay tested and functioning.
Now... A Wideband a/f gauge/sensor is installed and while idling smoothly the a/f at idle can be adjusted to ANY stable a/f. However when the "misfire " occurs the a/f reads full lean (which could be unburnt fuel = SUPER rich) and then recovers. The "misfire" at operating temperature occurs every 6 seconds or so with a duration of 2 seconds or so. Every time an issue is found (eg TPS the motor requires a completely different amount of fuel to idle, but the "misfire" persists.
This not being a W124 it would be very difficult to blame the harness, but I'm starting to lean that way... Partially because I don't have much anywhere else to go that makes sense. I know it must be something simple... Any constructive input is appreciated.
Thank you in advance.
