302 running rich
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From: Illinois
302 running rich
The 91 XLT 302 has been running rich, getting around 8-10 mpg. I can see soot at the tailpipe, seems like I can smell some unburned gas at the tailpipe. Pulled a plug and it was sooty too. Right at 100k on the engine. I finally got an Equus code reader, and it showed code 552 on KOEO. Book says Thermactor air bypass solenoid circuit fault and also lists Air management circuit 1 failure for that code number too.
I have no idea what part this means I have to replace.
Also on the continuous test, it read code 118, which is ECT sensor circuit above maximum voltage/0 to -40 indicated. Does this mean the temp sensor to the computer need replacing and it doesn't mean temp guage sensor/sending unit?
Thanks, Bill
I have no idea what part this means I have to replace.
Also on the continuous test, it read code 118, which is ECT sensor circuit above maximum voltage/0 to -40 indicated. Does this mean the temp sensor to the computer need replacing and it doesn't mean temp guage sensor/sending unit?
Thanks, Bill
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From: Near Wamego KS
"which is ECT sensor circuit above maximum voltage/0 to -40 indicated. Does this mean the temp sensor to the computer need replacing"
Sensor to computer needs replacing. When it goes bad it starts reading -40C (?) and the engine thinks its very cold and never leans out the fuel mixture. Runs extremely rich and even after driving a few miles ( or a couple hundred my case) the car (or pickup) continues to blow white smoke like it did at start up. Running that rich screws up the EGR and can clog the cats.
Sensor to computer needs replacing. When it goes bad it starts reading -40C (?) and the engine thinks its very cold and never leans out the fuel mixture. Runs extremely rich and even after driving a few miles ( or a couple hundred my case) the car (or pickup) continues to blow white smoke like it did at start up. Running that rich screws up the EGR and can clog the cats.
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Put in the ECT first, and it might fix your thermactor code. I just got a new ECT from Ford and it was $47. Had a cheaper after market one in there and I didn't think it was as good as the Motorcraft, which is calibrated to your computer. It's right where your thermastat is located. If your computer thinks your motor is cold all the time, you are gonna be running rich and the thermactor divertor will never turn off. Diverter is on at cold start up and then goes off to divert the air from the air pump down steam more into your exhaust to help heat the CATs.
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Ok, a couple things I forgot to mention were that after the engine was warmed up, most of the time I could only get it to fire by holding the gas pedal all the way to the floor. Also, I never got a check engine light in all the time it was running rich except a couple times in the last week, then it went out after a minute.
Yesterday I put in a new ECT sensor. Now after the engine is hot, it will fire right up without the pedal to the metal. I ran the codes again and still get the same KOEO code 552 and on continuos test same code 118, plus now code 173: HEGO sensor fault/rich. I guess that's the O2 sensor.
I didn't clear the codes before I ran the test again, but I did disconnect the battery for 1/2 hour just now, and I'll run it around some and run the codes again. I don't know if the O2 sensor is original or not, but I imagine it's so carboned up now that it needs to be cleaned or replaced.
Any other suggestions would be appreciated.
Thanks, Bill
Yesterday I put in a new ECT sensor. Now after the engine is hot, it will fire right up without the pedal to the metal. I ran the codes again and still get the same KOEO code 552 and on continuos test same code 118, plus now code 173: HEGO sensor fault/rich. I guess that's the O2 sensor.
I didn't clear the codes before I ran the test again, but I did disconnect the battery for 1/2 hour just now, and I'll run it around some and run the codes again. I don't know if the O2 sensor is original or not, but I imagine it's so carboned up now that it needs to be cleaned or replaced.
Any other suggestions would be appreciated.
Thanks, Bill
Last edited by suthrnslew; Mar 21, 2004 at 11:40 AM.
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