QuestionTom- I cleaned the MAT Sensor, no luck then replaced it. Still no luck. I cleared the codes, and tried starting the car after replacing the cap, rotor, coil and module. Every once in a while the car would spit a bit. I tried spraying carb cleaner in to see if it would fire and no luck. The new codes are E21, E31, E38, and E74. What would cause all the sensors to to act up?
Thanks,
Jerry
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Followup To
Question -
I have a 1990 Deville with the 4.5 and 225,000 miles. The car was running ok, and I added a product called Seafoam to the fuel tank to clean the system. I also cleaned the throttle body with a spray cleaner. Soon afterwards, I was driving at 40 mph and the car began sputter and loose power, and smoked, too. The check engine light and the service vehicle soon light would alternately flash. I pulled off and the car died, and it took several tries to get it restarted and stay running. I checked the codes, and I had E16, E31, E38, E74. I let the car sit while I thought it over a day or 2, and then I did check the throttle body, finding the tubes down the center were filled with gunk. After I cleaned that, I drove around and the car was awesome, then it happened again. I replaced the MAP sensor and the IAT Sensor, now it cranks-fuel pump works, I checked, and won't start. Any ideas?
Answer -
Leave that SEA FOAM where it belongs, In the SEA.
Are you getting ignition to the spark plugs ?.
Test the MAT (manifold air temp sensor) as it may be covered with crud also.
tom
AnswerE21 = shorted TPS circuit.
E31 = Shorted MAP sensor circuit.
E38 = Open MAT sensor circuit.
E74 = Intermittent MAT.
I can e-mail you thr picture directives to diagnose and fix these codes, But you will need to contact me at: onlineautohelp@msn.com
