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M.A.F sensor issue... Please help


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dannynvpro
Novice

Feb 20, 2014, 3:41 PM

Post #1 of 17 (1331 views)
M.A.F sensor issue... Please help Sign In

I have a 2002 buick rendevues with 130 miles (3.4L 2x4). It started Reving up really high (past 4000 rpms) and stalling sometimes. I pulled the code and it stated p0101 mass or volume airflow malfunction. I checked the vacuum line on the tube that connects between the throttle body and the airbox, it has good vacume. The air filter is also clean. I cleaned the maf sensor with no success. I unplugged it and it still ran like crap. I then bought a cheaper maf sensor at pep boys and replaced it, still didn't help after diving for a day. I bought a better more expensive maf sensor and that didn't help either. What I found very odd is after replacing it 12 new codes popped up. When I clear the codes with the scanner the car runs perfect with the new maf sensor. 10 minutes later the check engine light will pop back on, then the car will stall and run like crap again. It's not drivable at this point. I can, but it puts a lot of stress on the car and revs very high.


Hammer Time
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Feb 20, 2014, 4:35 PM

Post #2 of 17 (1323 views)
Re: M.A.F sensor issue... Please help Sign In

You are getting unmetered air in there from somewhere. The first sting to check is the intake snorkel for any tears or leaks of any kind between the MAF and the throttle body.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



dannynvpro
Novice

Feb 20, 2014, 4:41 PM

Post #3 of 17 (1319 views)
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In Reply To
You are getting unmetered air in there from somewhere. The first sting to check is the intake snorkel for any tears or leaks of any kind between the MAF and the throttle body.


I checked and it is secure and tight with no possible passage for air to bypass the maf sensor. After replacing the maf I am getting p0101 and p0102, before it was just the p0101. Thanks for taking the time to help me.


GC
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Feb 20, 2014, 5:55 PM

Post #4 of 17 (1309 views)
Re: M.A.F sensor issue... Please help Sign In

Closely look at the connector for the maf and make sure that its in good shape. Check ALL vacuum lines. Ive had the one on the top of the throttle body give me problems, as its hard to see it under a bracket. Do you have a digital multimeter? Does your scanner show live data?


____________________________________________________
Willing to help, willing to learn... Rob


dannynvpro
Novice

Feb 20, 2014, 6:22 PM

Post #5 of 17 (1307 views)
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The connections look good it almost seems like something is giving it a false reading. I checked with the multi that has a hertz setting and it is stable at idle and increases as I jump the rpms up, seems to be doing what it should. Could the pcm throw a maf code? Any other sensors? I'm at a loss.


Hammer Time
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Feb 20, 2014, 6:44 PM

Post #6 of 17 (1302 views)
Re: M.A.F sensor issue... Please help Sign In

There may be a problem elsewhere in the circuit.

Make sure you have "key on" power on the pink wire and ground on the blk/wht wire.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



dannynvpro
Novice

Feb 20, 2014, 6:46 PM

Post #7 of 17 (1298 views)
Re: M.A.F sensor issue... Please help Sign In

I did, I followed a detailed step by step on it...


Hammer Time
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Feb 20, 2014, 6:48 PM

Post #8 of 17 (1297 views)
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You might want to check your exhaust for restriction and excessive backpressure. Air won't come in if it can't get out.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



dannynvpro
Novice

Feb 20, 2014, 6:55 PM

Post #9 of 17 (1293 views)
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A day prior to the problem I had my car on a lift and had to cut the tail pipe off because it was pinched almost shut after the muffler. The rest of my exhaust was good. Strange that it happened a day after that though. It was literally only the last 5 inches of my tail pipe.


Hammer Time
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Feb 20, 2014, 7:01 PM

Post #10 of 17 (1290 views)
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You don't know that. You have no idea if your converter is restricted unless you took a pressure test.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



dannynvpro
Novice

Feb 20, 2014, 11:20 PM

Post #11 of 17 (1273 views)
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I really doubt it's my cat I replaced them about 8 months ago with brand new ones because they were throwing codes and I couldn't pass emissions. That problem has been fixed and it has been less then a week since this problem has happened. I didn't replace them with cheap ones either. All the advice you have given has been great but I've tried all that, I am pretty knowledgeable on fixing cars and have done all repairs on my vehicles any time a problem has risen, I must say this time I am stumped though. I really appreciate your on going help. Thanks again.


Tom Greenleaf
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Feb 21, 2014, 12:52 AM

Post #12 of 17 (1269 views)
Re: M.A.F sensor issue... Please help Sign In

Don't guess, test for back pressure. That bent tail pipe may not have been the only problem and may have caused another,


T



dannynvpro
Novice

Feb 21, 2014, 1:04 AM

Post #13 of 17 (1263 views)
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I will update you when I do, hopefully tomorrow. I have access to a garage where I can do it for free with the proper equipment. Thanks.


GC
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Feb 21, 2014, 7:11 AM

Post #14 of 17 (1252 views)
Re: M.A.F sensor issue... Please help Sign In

Does this garage have a smoke machine? If so smoke that thing for leaks.


____________________________________________________
Willing to help, willing to learn... Rob


Hammer Time
Ultimate Carjunky / Moderator
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Feb 21, 2014, 7:16 AM

Post #15 of 17 (1251 views)
Re: M.A.F sensor issue... Please help Sign In

You can also check for backpressure using a vacuum gauge

Measure direct port vacuum and you should have something around 18-20". Slowly bring the throttle up to around 2500RPMs and see if the vacuum drops off substantially.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



dannynvpro
Novice

Feb 23, 2014, 10:29 AM

Post #16 of 17 (1206 views)
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Vacume pressure was good today and we thoroughly checked for vacuume leaks. I read that my car has a map sensor too. I thought it had either a maf or map not both. I'm going to pick up a new map sensor and give it a try. What do you think?


Discretesignals
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Feb 23, 2014, 10:32 AM

Post #17 of 17 (1205 views)
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The MAP sensor on that engine is used to measure barometric pressure and to act as a back up when the MAF sensor signal is lost. Don't think I have ever seen a MAP sensor go bad on those.

Have you cleaned the throttle body? I don't see how an exhaust restriction or vacuum leak would make the engine idle up to 4 K. You may need to bring it to a shop and have them connect a scan tool up to monitor datastream information. Maybe they can pick out something to get direction in determining the culprit.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Feb 23, 2014, 10:35 AM)






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