wishuwerehere82
Well-known member
- Joined
- Sep 6, 2003
- Messages
- 2,316
- Location
- Rochester, NY
- Corvette
- Red '82 Coupe,Sebring Silver '98 Coupe
'82 Cross-fire running open loop
I went to the Chevy dealer to get a new ignition module in a last-ditch attempt to fix a problem that I seem to continue to have. He said they were discontinued, but pointed me to Meizensahl's auto parts that had them in stock. While talking to Charlie at the parts desk, I told him of my problems and he offered to put a diagnostic scanner on my '82 after work on his own time.
He advised me not to put in the new module until we had a chance to check it out first.
We met at a diner parking lot and he plugged it in and guess what? There are no codes stored! Nothing!:confused
We put it in active mode and monitored the ECM and it is running open loop for most of the time. It went into closed loop once and smoothed right out, but a few seconds later it went back into open loop again and stayed there.
The readings we were getting were:
Prom # 9531
Temp= 195 degrees.
O2 went from .53V in closed loop to 0 Volts when in open loop.
O2 cross count=none 00V
IAC motors went from .17V in closed loop to .007V in open loop.
Map sensor= 10" HG at 1.44V in open loop.
Knock sensor= 0V in open loop.
TPS sensor= .56V in open loop.
Timing= 9.5 degrees in open loop.
The mixture alternated between rich and lean while we were monitoring it in open loop and most of the usual stumbling and oscillations were observed.
Needless to say, this was a real eye opening experience.
To sum it up, all of the active feedback and control outputs to the fuel/air management system are off or at least at default values.
It seems to me that I have an intermittant open circuit on my O2 sensor somewhere or a bad new O2 sensor.
Or does a 0 Volt reading on the O2 sense mean a short to ground?
Or a bad connection inside the ECM somewhere. Maybe the active memory is fried in the ECM?
Any ideas? My brain hurts!
Pete.
I went to the Chevy dealer to get a new ignition module in a last-ditch attempt to fix a problem that I seem to continue to have. He said they were discontinued, but pointed me to Meizensahl's auto parts that had them in stock. While talking to Charlie at the parts desk, I told him of my problems and he offered to put a diagnostic scanner on my '82 after work on his own time.
He advised me not to put in the new module until we had a chance to check it out first.
We met at a diner parking lot and he plugged it in and guess what? There are no codes stored! Nothing!:confused
We put it in active mode and monitored the ECM and it is running open loop for most of the time. It went into closed loop once and smoothed right out, but a few seconds later it went back into open loop again and stayed there.
The readings we were getting were:
Prom # 9531
Temp= 195 degrees.
O2 went from .53V in closed loop to 0 Volts when in open loop.
O2 cross count=none 00V
IAC motors went from .17V in closed loop to .007V in open loop.
Map sensor= 10" HG at 1.44V in open loop.
Knock sensor= 0V in open loop.
TPS sensor= .56V in open loop.
Timing= 9.5 degrees in open loop.
The mixture alternated between rich and lean while we were monitoring it in open loop and most of the usual stumbling and oscillations were observed.
Needless to say, this was a real eye opening experience.
To sum it up, all of the active feedback and control outputs to the fuel/air management system are off or at least at default values.
It seems to me that I have an intermittant open circuit on my O2 sensor somewhere or a bad new O2 sensor.
Or does a 0 Volt reading on the O2 sense mean a short to ground?
Or a bad connection inside the ECM somewhere. Maybe the active memory is fried in the ECM?
Any ideas? My brain hurts!
Pete.