MAF sensor on a 2001 Impala 3.8l

I have been having an issue with the car surging at 55-60 MPH when I would let off the Gas. Yesterday it started doing it at any speed and the check engine light finally came on so I could test out the Codes. The code came up as P0102. But when the guy was testing it he said it sounds like a vacuum leak. Last night we took apart the Air Filter box, and the boot that connects the filter box to the Throttle body. The Sounds sounds like it is coming from the Throttle body itself. I have checked all the air lines and cannot find anything wrong with any of them. Does anyone know what this noise could be caused by? Maybe one hose is clogged?
Also have 2 other questions regarding Sensors. there are 2 sensors I'm not sure of... 1 is on the boot that connects the Air filter to the throttle body. And 1 on the throttle body.. What are these 2 sensors called. one I'm guessing is the MAF but not really sure.

Any Suggestion would be appreciated
Lonnie

One in the duct is the int. air temp sensor and the other is the maf. You may have a bad throttle body gasket for the vacuum leak, also anyone replace pcv recently?

I was also told by a friend a little bit ago that it could have something to due with the throttle sticking? One of the problems I noticed last night explains why when I step on the gas that it sticks (in the morning, or after the car has sat for a while.) When we had the Car apart last night we noticed that the throttle is gummed up inside the throttle body, causing the throttle to stick.

My buddy said the MAF should be the last thing to replace because it is probably a problem before the MAF, but the MAF is catching the problem and sending a signal to the Engine light not necessarily it being the MAF itself even though it is what is throwing the code.

Before I spend 150. on a sensor (the size of a soda cap) I'm going to clean the Throttle body with some throttle body cleaner, then put everything back together and test it again. He also said to take the Throttle body cleaner and spray it around the air lines if the engines idol increases you can find the leak vacuum leak if there is one.

Where is the Throttle Gasket located?

Yes I just replaced the PVC valve last weekend. Before the problem got to where it is today.

1st do not use TB cleaner on the maf, use specific maf cleaner made by CRC. Second, make sure both o rings are in place in the pcv, there is one just under the map and a smaller one the pcv goes into. TB seal/gasket is where the TB mounts to the intake.

I took off the Throttle body (which was loose), and replaced the Throttle Body gasket, cleaned out out the throttle body with Throttle body cleaner, and a tooth brush.. Looked like new when I put it back together. So far it sounds and seems to be running smooth.

thanks for the help.

I have the same problem with my 2000 impala 3.8l. I replaced the connector to the maf sensor at first because it was only sending a reading occasionally to the computer. Check engine light was off for a month. Came back on, the new connector wansn't making contact with the 3 pins inside the sensor itself. So i bought a remaufactured sensor. This fixed the problem for another month. light comes back on. figured because i cheaped out and bought the remanufactured sensor it went bad. So i went to the junk yard and bought one off a junker. Same problem. New connector again-same problem. I thought it may have been a vacum leak as well. Replaced the plenum with a new one because i had coolant leaking out from around the sides and had a whistling sound coming from somewhere. New plenum and intake gasket (while i was at it) and same problemo. The po102 code.:banghead:

Well, just like others I have read.. Works great for a couple of days and then right back at it. I don't get it. I just got some MAF cleaner and seems to be running good again. But I don't feel comfortable about it at all.

Just curious could a plug be fouled and just throwing the car off? I bought new plugs, and wires but have not had a chance to change them out.

I'm getting really close to take it to the dealer, but god knows they are going to change everything like I'm doing now till they find a problem.

Once again I have no clue :(

Sit on it and see if the code comes back if it does the maf just may be bad a full scan would show that and again was the pcv replaced? Remember the 2 o rings that are sealing the pcv, if one is left out you can set that code. I asked you that, no answer?

The PCV had both Seals when I put it on. It has a spring that sits below the PCV and the top fit on pretty snug, was king of hard to put everything back together. I have only gotten P0102 code one time, that is what has me so focused on these type of problems.. I'm wondering now if there is a different problem in general.

Yesterday, my belt started squealing, and caused the car to die, 2 different times? The car has never died on me, till then. The belt was replaced Oct 06, and still looks New.

Is there anything else that could cause the Car to surge, with out sending a code to the check engine light? Plugs? Fuel Filter?

I'm changing out the plugs this weekend. The car has 111,xxx miles on it and the Plugs/Wires have never be replaced.. We have never had a major problems with the car till a month ago.

Seems like the cat has failed/is failing -- An exhaust back pressure test will tell you for sure -- this an extended emissions warranty repair at the dealer.

I have also thought about something else.

About a month ago before this problem started, I forgot my wallet at home when my fuel light came on. I had to drive all the way back home from work about 60 miles after the light came on. I wonder if the fuel filter could be clogged a little, causing not enough fuel, and then with to much air, if that could have set off the MAF sensor a week ago?

Any thoughts?

replaced the MAF and everything is running fine. No codes :D

Thanks for everyones help!

and again was the pcv replaced? Remember the 2 o rings that are sealing the pcv, if one is left out you can set that code. I asked you that, no answer?

Thought my belt or something was giving off this ear piercing squeal. I wish I would have paid more attn to this comment. Took out the PCV last night no O-ring.. Put in a new O-ring, Vacuum sound gone, squealing sound gone, and the Car runs much better. $500 later for a .39 cent O-ring. But hey... Got some new parts :D

After replacing this sensor twice with no luck I am wondering if the sensors are manufactured for specific vin#'s. I've tried the re-manufactured ones and also one off a junker.

@mattridessleds:

Maybe the MAF is not the source of your problem. Many "symptoms" as described will often have more than one solution/cause.

That's why we share our experiences here.

After replacing this sensor twice with no luck I am wondering if the sensors are manufactured for specific vin#'s. I've tried the re-manufactured ones and also one off a junker.

Try replacing the PCV, and MAKE SURE you replace the O-ring on it too.. That fixed all my problems.. Wasn't the MAF after all.

Does the O-ring typically get wasted when you try to replace the PCV? do you typically get new O-rings with a new PCV?

I know a lot of parts on the Imp are meant to be replaced when they are serviced... are the o-rings one of them?

* I hate the torque-to-yield bolts (ie: head bolts) that once they are torqued once (read that, stretched) they are history.

Does the O-ring typically get wasted when you try to replace the PCV? do you typically get new O-rings with a new PCV
No the O-ring did not come with it. Nor did I see it when I took the old PCV off. But it really makes the car run like crap with out it.

That makes this a good tip :)

There are 2 o-rings in the PCV housing on the 3.8. The big orange one at the top of the housing, and a smaller black one that goes on the PCV valve itself. The black one is the one most people miss and causes the whistling/squealing noise and odd codes to pop up. The most common code caused by this missing o-ring is a p0401 (EGR insufficient flow detected), as the PCM uses the MAP sensor vacuum signal to determine EGR efficiency. Since the MAP is mounted in the top of the PCV housing, a vacuum leak will cause a low vacuum reading, tripping the P0401 code. Other air flow related codes can pop up also due to the vacuum leak, so theoretically this could be the cause of your MAF code. Normally a p0102 (mass airflow low input circuit) is caused by a bad MAF or the wiring between it and the PCM, but it's not impossible that it could be caused by a vacuum leak.

2002 impala 3.8l 9c1, my car had a rough idle, and would die after warm up, things that were changed were all 3 coils, spark plugs and wires, map sensor, idle air control valve, cat convertor, fuel pump, fuel filter, throttle body was cleaned, maf sensor was cleaned. all these parts and no effect on the running of the car. took it to a trusted mechanic, and he did multiple test on all the sensors, and had good readings. he checked the fuel pressure regulator on the fuel rail it was ok. he did a pressure test on the fuel supply it was ok, he removed the fuel line from the back fuel rail and shot 200 psi air through it make sure there wasn't a restriction ,with the fuel cap removed of course. hooked everything back up, still there was no difference in idle or running, we did a road test, and car ran horrible with hesitation and misfire , pulled over disconnected the maf sensor got back in and took off, and the car ran like it was brand new, plugged back in the maf, and all the symptoms were back, we put in a new maf sensor and the car runs great. I've spent over $1500 in new parts before the maf sensor/ it seems just cleaning my maf sensor didn't help it at all, so if you have problems like mine, unplug the maf take it for a short road test, if it runs great than get a new one, hope this helps some else with the same problems before they spend that kind of money:smile:

To jleer.
I had the same problem as you and unpluged the maf sensor and it runs great. Bought a new one and im happy again. Very helpful story thanks.
Also my car is a 2002 impala 3.8, 9c1 police package.

Well, just like others I have read.. Works great for a couple of days and then right back at it. I don't get it. I just got some MAF cleaner and seems to be running good again. But I don't feel comfortable about it at all.

Just curious could a plug be fouled and just throwing the car off? I bought new plugs, and wires but have not had a chance to change them out.

I'm getting really close to take it to the dealer, but god knows they are going to change everything like I'm doing now till they find a problem.

Once again I have no clue :(
I have replaced brand new mass airflow sensor, and seemed to solve problem for a couple months.... then 2002 Impala would hesitate in starting, idle uneasy when giving gas and at its worst - Driving at highway speed stall or stutter out. I cannot give it gas, and only option is to have it die out, no air, no gas, then no power. Start it again until it happens again. Mass Air flow is not the solution, but works well when you replace with new one. I went through two new ones, and now its starting again!!!

If these are reman units from Cardone they are unreliable from my experience.

There are "new" ones and there are "new" ones....

Had one 3.8 where reman one failed right out of the box.....got another, it lasted one day and failed(easy to check with a scan tool by looking at MAF data)......customer wanted the el cheapos, until he got stuck a second time....bought the more expensive GM reman, and had no problem after that....a brand new GM one is out of sight....

I would like to add that a lot of 3.8L Impala issues can also be with the intake manifold. They are plastic and can warp, especially at the throttle body and also the mating surface. There is also an issue with I believe where the EGR comes up through the manifold. This is just info I have heard, I have a 3.4L that has the metal intake manifold, even with that I recently replaced the upper intake manifold gaskets and it made a considerable difference in the running of the car.

Although this thread is pretty old, it appears to have some really good information regarding the same issue that i was experiencing.

Symptoms
Hesitation/stubbling at low RPMs
Periodic surging/bucking at all speeds
Stalling at low speeds/idling
Symptoms would disappear for several days and then reappear at different times.
Initially, no check engine code

None of my symptoms prevented me from safely driving, but they were annoying and sporadic.

finally, after a couple months the check engine light came on. It was a P0102.
This finally gave me some direction and i ended up in this forum. I removed and cleaned the MAF with CRC MAF cleaner and cleared the codes. So far my car is running better than when i purchased it in January.

If any symptoms reappear after time, i will also remove and clean the throttle body. I tried to clean it without full removal, but did not do a very good job. It is pretty dirty.

I would like to note for the less informed, that the MAF is very easy to remove and clean, but mine (and i assume most) have security screws holding it in. I had star bits, but no security star bits. I went to Harbor freight and bought a security bit set for $10. After that, it too less than 5 minutes to removed, clean and replace.