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Dan, ASE Certified Technician
Category: Pontiac
Satisfied Customers: 2270
Experience:  20 + years working on cars 9 years GM Tech
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while driving along(any speed) my car will suddenly lose power.

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while driving along(any speed) my car will suddenly lose power. If I give it gas, it will die,then it will rev irratically on it's own. If it does stall, I can start it back up and it will be fine. It does this once or twice a week. Sometimes a code po102(mass air flow circuit low input) or po442(evap emission control system, small leak) comes on.Also my fuel gage is all messed up. 2001 Bonneville 3.8L
Hello <a href=""Customer

I replace the mass air flow sensors on these cars all the time for this problem. The MAF sensor is used by the computer to measure the air going into the engine so it can tell how much fuel to add. You need a scan tool that can read data to montior it to confirm that it is bad, Or sometimes you can drive with it unpluged and if it doesnt act up when it normally would have, the sensor is bad.
The P0442 code is caused by a leak in the emmission system and would need to be diagnosed with a smoke machine to pinpoint the leak.
The fuel guage problem could be caused by a faulty level sender in the fuel tank.
Customer: replied 8 years ago.

Dan,I have a scan tool and have used it while driving.The readings are in lbs/min,but I don't no how many lbs it should be.

Their should be MAF reading in hertz or grams. It should be low at idle and when you press on the gas, it should increase. Watch it when its running good and watch it when its acting up.
Customer: replied 8 years ago.
Dan, the problem is ,I never know when the car is going to act up and usually my wife drives it to work, so I can't test it. A few weeks ago, I did test it while my wife drove and I sat in the passenger seat, it worked as you said.(low readings at idle and increased readings during acceleration). Do these sensors work properly sometimes and malfunction other times or do they just stop working completely? I don't want to replace the part unless I know for sure this is what's wrong, they are expensive.
They will work correctly but only once in a while it will drop way down to around 400 hetrz when it should be way up there. That when its acting up. What I tell people is drive with it unpluged for a week or 2 and if it doesnt act up when it normally would have, replace the sensor.
Customer: replied 8 years ago.
Dan, tonight I unpluged the sensor and it idled fine until I gave it some gas, it almost stalled and would barely run,then it started reving high on it's own. It would'nt idle down until I turned off the car and started it again.I tried this a few times with the same results.It worked fine when I plugged the sensor back in. My scan tool reads lbs/min. I drove the car tonight with the scan tool hooked up and it read 0.6lbs/min at idle all the way up to 20lbs/min when I floored it.The last time the car acted up was last Friday but no code showed up until 2 days later and that was code po442. I erased the code and have not had one since. What do you think?
It go into a default stage and set a code when you unpluged the MAF sensor. Just to be sure, the MAF sensor is on the drivers side of the engine by the air intake tube. the MAP (manifold air pressure sensor is on the passenger side of the engine. I had people get the 2 mixed up before.
Is this a super charged engine?
Customer: replied 8 years ago.
This is not a supercharged engine and yes, the MAF sensor is on the drivers side.No code was set when I unplugged the sensor.
Customer: replied 8 years ago.
Tonight my car started acting up again,first time in about a week.It almost quit while driving and just chugged along,then took off without giving it gas.It seemed ok with the odd chugg until I got home.When I stopped and put it in park it idled at 1500 rpm so I turned off the car and restarted it, it still idled high.I hooked up my scan tool and it was reading 1.6lbs/min and increased as I gave it fuel.Shut the car off again and restarted it and it idled normal.Unplugged the MAF sensor and took it for a drive and it worked normal except for a high idle,1200 rpm. Plugged the sensor back in and it drives and idles normal again. Does this sound like a malfunctioning MAF sensor for sure or somthing else.
Customer: replied 8 years ago.
Also no codes are presently in the system
Customer: replied 8 years ago.
I'm going away for the weekend and won't be back until Tuesday 8, so I'll check in then.
Sorry for the long delay,

It does sound like a MAF sensor. They are hard to diagnose and be for sure. The thing that worries me is there should be a code set after 2 key cycles with that MAF sensor unpluged. Check the wiring and wiggle on the wires before you replace that MAF. The service engine light should come on after 2 key cycles with that sensor un pluged.
Customer: replied 8 years ago.
Do you mean wiggle the wires to the MAF while it's unplugged and are 2 key cycles two start ups?
wiggle the wires while its pluged up and running and see if it changes.
2 key cycles is two start up and shutdowns.
Customer: replied 8 years ago.
Dan ,the car acted up again today so I wiggled the wires and it stubled. I wiggled the wire connector because it seemed to be the connection, and it continued to stumble. I then tapped the sensor with a screwdriver and then wiggled the connector again and it would not stumble anymore.This must mean the MAF ,right?
Sounds like the MAF sensor.
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