My Marquis was sitting for roughly two weeks, and I decided to take it out this afternoon to stretch its muscles.
As I was approaching my destination, I had an opportunity to do an Italian tuneup and as soon as I got in the parking lot and put it in reverse, it stalled. Started it back up, and it stalled once I put it in reverse again. Put it in drive, same thing. No CEL/MIL and my ScanGauge-II had no codes for me. First thing that came to mind was the IAC valve, but the one I have is only six months old.
Finished what I was doing and headed home, making sure I had it in neutral as I approached every light. When I was able to take a look at it, it wouldn't stall in gear anymore! I unplugged and plugged the IAC valve back in, the RPM dropped, but went back up as soon as I reconnected it.
Then I borrowed a friend's professional scan tool, and it went bananas. Each time I'd hit "Pending Codes" it would show me P1504 and two other codes. First it was:
1. P1504
2. P2000
3. P1008
Then when I checked pending codes again without clearing, and these came up:
1. P1504
2. P1514
3. P0004
When I checked again, there was another two codes other than P1504. This was when I decided to clear the codes, go for a drive and check again. No codes whatsoever, even after a 100 mile drive.
Worth noting, I threw in a bottle of Chevron Techron in the last tank. Not sure if that had anything to do with it. And here's the other thing, being a pre-'03 export model, the EGR system is disabled. The hardware is physically there, but there's no reference to it in the PCM. Also worth noting, due to leaded fuel capability, there are no oxygen sensors or catalytic converters.
As I was approaching my destination, I had an opportunity to do an Italian tuneup and as soon as I got in the parking lot and put it in reverse, it stalled. Started it back up, and it stalled once I put it in reverse again. Put it in drive, same thing. No CEL/MIL and my ScanGauge-II had no codes for me. First thing that came to mind was the IAC valve, but the one I have is only six months old.
Finished what I was doing and headed home, making sure I had it in neutral as I approached every light. When I was able to take a look at it, it wouldn't stall in gear anymore! I unplugged and plugged the IAC valve back in, the RPM dropped, but went back up as soon as I reconnected it.
Then I borrowed a friend's professional scan tool, and it went bananas. Each time I'd hit "Pending Codes" it would show me P1504 and two other codes. First it was:
1. P1504
2. P2000
3. P1008
Then when I checked pending codes again without clearing, and these came up:
1. P1504
2. P1514
3. P0004
When I checked again, there was another two codes other than P1504. This was when I decided to clear the codes, go for a drive and check again. No codes whatsoever, even after a 100 mile drive.
Worth noting, I threw in a bottle of Chevron Techron in the last tank. Not sure if that had anything to do with it. And here's the other thing, being a pre-'03 export model, the EGR system is disabled. The hardware is physically there, but there's no reference to it in the PCM. Also worth noting, due to leaded fuel capability, there are no oxygen sensors or catalytic converters.
