2001 Chevrolet Impala 3.8 L V-6 Automatic
Approximately 150,000 miles
Car consumes no fluids & all are up to full
MIL on with code PO 102 - MAF Circuit Low Input
Information that I read says that you will likely not notice any drivability problems except possibly a decrease in power or sluggishness.
However, this car is running very well at idle, under acceleration, and at cruise, but intermittently has a sudden, very short duration (less than a second), loss of power at cruise or accelerating, cold or warm. It sometimes doesn’t happen for extended periods of time and there doesn’t seem to be a pattern.
It’s almost as if you momentarily let your foot slip off the side of the gas pedal while cruising and then immediately got back on it. The car doesn’t stall or illuminate anything.
The Mass Air Flow Sensor was removed (wiring / connector looked good) and was cleaned with MAF spray cleaner and reinstalled. This did not change the problem.
Do you techs think that a MAF circuit or MAF sensor problem could cause these symptoms?
Can you suggest what I could try next ?
A new sensor is a $150 piece which is fine if it fixes it. I have one but hesitate to install it.
What should be the next move in getting this resolved? Do I need a shop or GM dealer with a certain capability to correctly diagnose this intermittent problem?
Thanks, CSA
Get a tech with a scanner that can perform a “wiggle test”. I suspect you’ve got some wiring problem that only manifests itself when you either hit a bump or some mechanical harmonic reaches some collision with others and breaches the connection.
I had this situation (not the same source) with my 86 Tempo. I finally took it to my mom’s mechanic and told him to keep it and drive it until he figured it out. He had a Sun Interrogator with the wiggle test capability (many lessor scanners have this feature). He man handled the harness and found the offending wire (in this case it was a connector).
It basically produced a random hiccup when you were in closed loop. You never noticed it on surface streets since you were rarely in closed loop. It drove us nuts.
Gary, Thanks For The advice. I Appreciate it.
CSA
You might find the problem by stirring the wiring, especially to the MAF, with the engine idling. It don’t cost nuttin’ to try.
Hello Kit, Thanks. I Had The Car Here, Yesterday. My Son Took His Chevy Back To College, But He’s Tuning Into This Discussion From 150 Miles Away When He’s Not In Class.
He e-mailed me and said he’s reading the responses.
CSA
Was the MAF sensor tested with an ohmmeter (or however the service manual says to test it)?
Also try to measure the voltage on the sensor in-circuit.
Good Suggestions, Circuitsmith. I Have The Factory Manual With Flow Chart, Voltage Specs, Etcetera and I have an ohmmeter.
I din’t get into it partly due to time constraints and also because the problem is so intermittent. The car works seemingly perfectly until it glitches, going down the road at a random time or speed. My thinking, although possibly flawed, is that it would test out O.K. in the driveway. You could stand a quarter on edge on the idling engine.
Also, I have yet to determine if this one code PO 102 can cause a noticed instantaneous abnormality or if it’s a “red herring”. Written information seems to suggest that code goes with poor performance (sluggishness) and reduced gas mileage.
If I can’t get it resolved by other means then I might just try getting a time to test the circuit and sensor.
CSA
Good Suggestions, Circuit Smith
It’s one word, like blacksmith.
Sorry, Circuitsmith. I Know Better.
What do you think of my theory that an intermittent fault might not be ferreted out while the car is performing normally?
CSA
I think a thorough wiggle test can track this down.
Have you checked the connectors to the engine computer?
If possible measure the sensor resistance at the computer connector (computer disconnected).
Shouldn’t be more than a couple ohms more than right at the sensor.
The P0102 code could be a red herring and the real problem is an intermittent power or ground connection near or inside the engine computer.
Thanks, Circuitsmith. I Haven’t Checked Connectors Other Than The One At The MAF.
I’ll do that when I get near the car, again. Another piece of this puzzle: After the short Sunday visit time was up and the MIL was turned off, the car was driven back to college in two legs. The first leg was a one-hour trip and the car had a couple of glitches. The MIL did not illuminate, however. The car stayed there overnight at a friend’s (my son’s, not the car’s). The second leg the next morning was a two-hour drive and there were no problems at all.
This is very intermittent and I tend to think Gary, Hello Kit, and you Circuitsmith are probably correct as to it being a connector type problem that could be found maybe by jiggling wires. I know that GM has as part of electrical diagnosis . . . unplugging and replugging any connectors pertinent to an electrical problem.
I’ll get an update soon as to the current status of the problem.
Thanks again,
CSA