I have an Autel scan tool. It was throwing a code for rear o2 sensor heater circuit malfunction (po141). When I got it on the rack, discovered the rear o2 broken off... yep that'll throw a code every time! 
Replaced rear o2 & now it's not throwing any codes. Had to swap dash bulbs as the SES light was burned out... guessing PO drove it with that broken o2 sensor till the bulb blew, yikes. I did run it at idle with the EGR connector off with no change, though that only shows it's not an EGR electrical malfunction. It could be stuck partly open but if so I would think it would bog constantly not randomly.
I will pull the ISC valve & clean/inspect it & see if there's a problem there.
Are there any tests I can do on the ISC circuit itself to see if the ECU is sending proper signal? How do I check if the TPS is calibrated right so the ECU knows "I'm at idle"?
It's at 95k miles & I'll probably replace the front o2 sensor just as maintenance & to eliminate it as the culprit.
When looking at the scan tool while at idle, it shows no fluctuation on the front o2 & the AF ratio is constant. I can stop the drop out with slight throttle.
It has had both manifolds off the head at some point... I can see non OEM sealer/gaskets on both. I'm not even sure if it's the factory engine or a replacement.
On that subject: what numbers on the block (if any) should match the VIN? Or how can I tell if it has the original engine in it?
I'll be checking the COP's for good contact & check the plugs (which the dealer replaced but I have no idea if they gapped them properly. What is the proper gap for the 1.8l? I know it's .028 for the 1.6l... it the 1.8l the same?
Thanks for replies so far!
Replaced rear o2 & now it's not throwing any codes. Had to swap dash bulbs as the SES light was burned out... guessing PO drove it with that broken o2 sensor till the bulb blew, yikes. I did run it at idle with the EGR connector off with no change, though that only shows it's not an EGR electrical malfunction. It could be stuck partly open but if so I would think it would bog constantly not randomly.I will pull the ISC valve & clean/inspect it & see if there's a problem there.
Are there any tests I can do on the ISC circuit itself to see if the ECU is sending proper signal? How do I check if the TPS is calibrated right so the ECU knows "I'm at idle"?
It's at 95k miles & I'll probably replace the front o2 sensor just as maintenance & to eliminate it as the culprit.
When looking at the scan tool while at idle, it shows no fluctuation on the front o2 & the AF ratio is constant. I can stop the drop out with slight throttle.
It has had both manifolds off the head at some point... I can see non OEM sealer/gaskets on both. I'm not even sure if it's the factory engine or a replacement.
On that subject: what numbers on the block (if any) should match the VIN? Or how can I tell if it has the original engine in it?
I'll be checking the COP's for good contact & check the plugs (which the dealer replaced but I have no idea if they gapped them properly. What is the proper gap for the 1.8l? I know it's .028 for the 1.6l... it the 1.8l the same?
Thanks for replies so far!