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Discussion Starter · #1 ·
Hello,

I've got 92 240 wagon LH2.4 running rich. Problem is the worst on warmer muggy days and not so apparent on cold days. At times, and this is only on the initial startup I'ts hard to start, Once started it will drive fine until say I come to a stop light, it starts chugging and misfiring and If I don't keep my foot on the pedal it will shut off. If it does shut off, it's extremely hard to start and once started, black smoke is evident out of the tailpipe. After I get to work, the problem never shows back up. On cooler days it's not noticeable, but my fuel economy kinda sucks.

I got a check engine light with a 123 code a while back and put a new ect sensor on it. Well the light went off but the problem was still evident. Check engine light came back on a couple weeks later, and just for grins I put another sensor on it but to no avail. So I pulled the intake off, checked connector, and short of stripping the wiring harness back I don't see any issues. With the ECU disconnected, I do not have continuity to ground on either terminal, so I'm thinking I don't have a short to ground. However, this is kind of interesting, I decided to run a continuity test from the connector at the block to the Computer connection inside the vehicle - On pin 13 to one of the terminals I have continuity, but on pin 5 - I've got continuity but also .6volts. This is the part I'm kinda racking my brain on. ECM is disconnected and so is the sensor...Any suggestions as to why I'm seeing this?
 

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Discussion Starter · #2 ·
Ok just an update as the car is fixed.

Maybe it was just coincidence I was getting a faulty cylinder head temp sensor code, I dunno. But come to find out I had an intermittent failure of the Ignition power amplifier, over time I guess it coated the 02 sensor with black soot. Replaced power amplifier and 02 sensor. Last few days it's ran 100% better under the same conditions. Sooooo, I figure she's fixed.

On a side note, I did not pursue the temp sensor voltage at the computer.
 
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