MAF Sensor Problems and Erratic Shifting

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BArkels Associate Join Date: Jul 2008 Location: New Albany, IN USA Posts: 34	MAF Sensor Problems and Erratic Shifting 08/18/2008 9:30 AM
	Hello All, I have a 2002 Grand Prix with a 3.8 V6. The car seems to stutter badly, intermittantly. It has 130K miles so first I changed the fuel filter (original) then the plugs and wires (also original) Along the way, my wife noticed that it seems to do a lot worse when you first fill it up, so I thought, water or sediment in the fuel tank getting stirred up. I started adding fuel treatment to deal with any water, but that has had no effect. Here's the rub... I drove the car this weekend and noticed that at least part of the time, the problem seems to be that the transmission is hunting. Watching the tach, it seems to be shifting erratically through the gears, like driving a steady 45 mph, not accelerating, it will shift several times in a couple of seconds, all over the place. I pulled a MAF sensor code last week, but haven't replaced it yet, because it seems to be pristine and the cost is crazy. Here's the question... Could a faulty MAF sensor be responsible for the erratic shifting? Not to confuse the issue... When I changed the fuel filter, I expected to see significant pressure as I bled the fuel rail. There was only a quick spurt, just a couple drops. I was surprised by this. Any suggestions would be greatly appreciated. BA
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bob c Guru Join Date: Jul 2007 Location: Fort Lauderdale Florida Posts: 5708 Good Answers: 123	#1 Re: MAF Sensor Problems and Erratic Shifting 08/18/2008 9:35 PM
	I do not have enough experience with bad MAF sensor to answer your question. But I will look into it for you. If your transmission is shifting erratically you have to be concerned that it is not failing. If a transmission clutch pack is not able to transmit the torque being applied by the engine, it will slip, just like a standard transmission. When this happens usually the transmission will down shift to the next lower gear. If this is the problem you are having, the transmission fluid will be dark. The darkness in transmission fluid is almost always the scrapped away clutch dust from a slipping transmission. The other thing that can darken the transmission fluid is severe overheating of the transmission. Ether of these conditions are going to make changing the MAF sensor look cheap. Check your transmission fluid. If it is low, that could be the problem. If not you should decide how much you want to put into this car. There are some transmission fluid additives that might buy some time. Check the transmission fluid and let us know. Good luck. __________________ Bob
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BArkels Associate Join Date: Jul 2008 Location: New Albany, IN USA Posts: 34	#2 Re: MAF Sensor Problems and Erratic Shifting 08/18/2008 9:51 PM
	Well, After posting this question I googled it and found many sources that confirm MAF sensor causing erratic and hard shifting. I replaced it tonight and a couple of months worth of problems disappeared! All seems to be fine now. Thanks for your response. B
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Shawn33 Power-User Join Date: Sep 2006 Location: New Jersey, USA Posts: 178 Good Answers: 8	#3 In reply to #2 Re: MAF Sensor Problems and Erratic Shifting 08/19/2008 5:55 AM
	Sorry I didn't read the thread sooner but quite a few people have had pretty good look cleaning the sensor with alcohol and q-tips. Although you have to be very careful as it is a delicate piece. No sayinng it would have helped on yours but just an FYI. Shawn
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BArkels Associate Join Date: Jul 2008 Location: New Albany, IN USA Posts: 34	#4 In reply to #3 Re: MAF Sensor Problems and Erratic Shifting 08/19/2008 8:12 AM
	Yes, I read yesterday that spraying them down carefilly with fuel injector cleaner to clean them helped sometimes. This one looked so delicate, i'd have been afraid to actually touch it with anything. The price is high to replace them, but if it does the trick then it's not so bad. One less thing (forrest gump)
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EnviroMan Guru Join Date: Nov 2007 Location: Gone to Alabama with my banjo on my knee... Posts: 5595 Good Answers: 20	#5 In reply to #2 Re: MAF Sensor Problems and Erratic Shifting 08/19/2008 9:25 AM
	Hey, great it's fixed. I voted you a GA here because you actually had the courtesy to come back and tell "the rest of the story"! __________________ Veni, vidi, video - I came, I saw, I got it on film.
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BArkels Associate Join Date: Jul 2008 Location: New Albany, IN USA Posts: 34	#6 In reply to #5 Re: MAF Sensor Problems and Erratic Shifting 08/19/2008 9:39 AM
	Thanks EnviroMan. It's interesting what the ECU will do to foul things up on the output side when the input side is a bit disturbed! I guess it makes sense. I suppose that the automotive industry is about like any other in terms of technology. Who'd a thunk it? I'm just glad I didn't go to Billy Bob's transmission/ bait shop over $139 worth of doubt concerning the MAF sensor! BA
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BArkels (3); bob c (1); EnviroMan (1); Shawn33 (1)

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