What would cause the mass air flow sensor constantly put out low input

210

Asked by May 22, 2013 at 10:27 PM about the 2001 Pontiac Grand Am GT

Question type: Maintenance & Repair

Ok so just put in a brand new mass air
flow sensor and it still coding out
po102 which is low mass air flow
current.what could it be? Dash lights
stay on. Car idles erratically and
doesnt go passed 2000 rpm

42 Answers

96,765

Plugged exhaust possible, if it can't get rid of exhaust it can't take in air. Have the exhaust back pressure tested.

3 of 3 people found this helpful.
210

Could the PCM be sending out a faulty code for the mass air flow sensor

7 of 7 people found this helpful.
96,765

The computer actually reads the input signal from the MAF to determine air/fuel mix. Try this: Disconnect the battery overnight, one cable will do it,this will reset the computer, reconnect battery, set parking brake, start engine and let idle for a minute, release park brake, then try to drive it, if it still won't go past 2 grand then I would still want to have the back pressure tested in the exhaust.

2 of 2 people found this helpful.
10,415

Check the wiring and plug for damage. If you have a voltmeter check the voltage on the plug. One lead will be your voltage supply, need 5 volts going to the sensor. There will also be the ground wire and the signal back to the PCM. Damaged wire? Loose wire? Dirt in the plug? I use dielectric grease on all my connections. If it's running that bad it's telling the truth the PCM is not seeing your map signal!

4 of 4 people found this helpful.
210

But the mass air flow sensor is brand new out the box. But still giving same code.

8 of 8 people found this helpful.
10,415

Exactly why I would check the wiring and or plug. Just takes a couple seconds on the exhaust to NFG the wiring. The pins on your wiring harness for the MAF plug could be corroded. 0-ring pick or small screw driver to clean the contacts. It could be the PCM failing but I would check the cheap components first.

2 of 2 people found this helpful.
Best Answer

there is no air flow...nothing to read...isn't connected in~

3 of 3 people found this helpful.

I think these things are on California smoggers only~ can't think of a non- California car that uses them~

1 of 1 people found this helpful.

they only work comparatively in conjunction with a MAP sensor, the EGR being the little devil in between~ just one piece of the puzzle is non- comparative~

4 of 4 people found this helpful.
10,415

What. A MAF. Most GM OBD 1.5 and 2 engines use the MAF with the MAP for EFI fuel tables.

3 of 3 people found this helpful.
210

Thank you we are going to try that stuff and see what happens lol

1 of 1 people found this helpful.

yes the reason it's not working as it compares levels of N2,C02 before and after the EGR, the MAP sensor doing the second reading...if there isn't a signal to compare we are only getting one half the puzzle (all assumptions are that you are a California smogger with the EPA endorsed smog equipment)---~assuming 2001 still has a map and an egr...really should familiarize myself with YOUR vehicle...you could check to see if these things exist on your car....thanks~

1 of 1 people found this helpful.

apparently the EGR has been Engineered out these days and combustion is so clean that they are not needed anymore....should know if yours is this way~

1 of 1 people found this helpful.
210

Ok i have no idea what your talking about but i dont live in California and im just trying to fix my car.lol

but your MAF sensor has NO output, you know this thing measures to the millionth degree of these elements...perhaps is working just fine, but our measurement tools are not able to go this precise...especially if a brand-new one yields the same result...these things are a platinum grid (kinda pricey) and found myself goin' to pickNpull to get a used one (well I did on the volvos I had with OBD)~ Is it your on-board diagnostics telling you low-output or your measurements?~

1 of 1 people found this helpful.
210

No my husband has a $300 machine thats a diagnostic machine or something. Its a innovia or something like that. And i kmow it cant be the maf sensor cuz i bought a new one from carquest

1 of 1 people found this helpful.

the thing ain't connected, or the connector is messed up.~

210

It came with a new one

96,765

OK your husband has a scan tool, is it capable of live data? If so access the menu and put it in live data mode with the engine running, scroll to MAF and watch the readout as you slowly increase the RPM, it should take very much of a RPM increase to notice a change in the MAF reading, if the numbers change with the throttle then the MAF is working even though it may have low values. Next open up the air box and run it again to see if the values are higher, if they are check the air filter, it maybe plugged, if the values don't change then reconnect the air box. Next disconnect the exhaust pipe from the exhaust manifold, start engine and see if it will rev past 2000 rpm if it will then you have a plugged exhaust, or you can take it to someone that has the equipment to do an exhaust system test. It really sounds like you engine can't breathe. Not a MAF problem.

1 of 1 people found this helpful.

"low input"...still having trouble wrapping my head around that one...does seem somehow NOT possible~

2 of 2 people found this helpful.
25

egr valve

2 of 2 people found this helpful.

not a California smogger Patrick.

1 of 1 people found this helpful.
10,415

Even if the egr valve was stuck wide open it would not cause this issue. The MAF reading would be slightly lower as the re-circulated exhaust would displace some of the incoming air. Long story short if it runs there will be air flow to intake and there should be a MAF signal. Even if the engine is off there will be a zero flow signal back to the PCM. Wires, plug, faulty new MAF and possibly but hope not NFG PCM.

34,275

Long story short every newer GM has a mass air flow sensor and the reason you can't go past 2000 rpm is because your catalytic converter is plugged and the computer is throwing a mass air flow sensor code because the computer is comparing the throttle position sensor to your mass air flow sensor and it knows that with the amount the gas pedal is being pressed there should be more air entering the engine so by default it is assuming the mass air flow sensor is bad. Remove your upstream oxygen sensor and you will notice about 500-1000 rpm increase... Roy every f***ing car built for the USA has an egr on it. My f***ing 86 Chevy from Alabama is carbureted and has a f***ing egr on it. My 92 regal had and I'm sure still has one my 1990 had one my dads 92 firebird 03 gmc Sierra 99 jimmy and 01 blazer have one on them. My fiancee 01 sunfire and 05 Saturn have one my sister's 06 hyundai azera has one my mom's 2001 grand am has one........... WE ALL LIVE IN INDIANA, you have no clue what you're talking about. tennis shoes had it right from the start.

1 of 1 people found this helpful.
10,415

This issue sounded like it happened suddenly never heard of a cat suddenly plugging. P0102 is a low voltage code which means the PCM is seeing a signal lower than the range on that channel. Since this code triggers well below the reading at no flow and that a typical MAF cannot read reverse flow the issue has to be within the MAF circuit. EGR valve. There is one earlier but modern EFI motor that doesn't have one, the POS Quad 4.

1 of 1 people found this helpful.
34,275

A catalytic converter can clog up on a trip down the highway, all it takes is a little too much extra raw gasoline dumping into it and it can turn cherry red and the honey comb will turn to a brick. Never have I heard someone say my car only hits 4k rpm what's wrong? It's always a sudden loss of power, won't go past 2000-3000 rpm. When the mass air flow sensor goes bad the computer ignores it and goes off of preset numbers in the ecm.

1 of 1 people found this helpful.
34,275

Quad four was ballsy you have to give it that

1 of 1 people found this helpful.
210

Thank u everyone but it is the exhaust or whatever yall said. He was runnin it in the garage and i saw something glowing and he said it was something with exhaust so now we gotta fix that. Its clogged up. Thats what he gets for lettin it sit up a year lol

4 of 4 people found this helpful.
140

Check Your Fuses. Seen this problem MANY times. Check each and every fuse. Pay attention to the ECM, PCM, Electric fuses under the hood. Check over wires. If its not reading the MAF its NOT reading it at all. as if its not there. as in NO CONNECTION. your MAF Has NOTHING to do with your EGR or any other sensor. Its not your CAT if that was clogged you would get other codes, and you would sure know it. Good luck!

34,275

Mass air flow and throttle position sensor are read and the readings are compared constantly inside the computer, if the throttle is opened then the computer has a pretty good idea of how much air should be entering the engine and it uses the mass air flow sensor to get the exact number to assist with the correct air fuel mixture. If the throttle is open and the mass air flow reading isn't within the predetermined limits or making it's way too those limits then the computer will assume the mass air flow sensor is bad and throw a code. Therefore a clogged cat limiting your engine from passing 2000 rpm at wide open throttle will restrict air flow keeping the mass air flow sensor from reading the way it should be at that throttle position making the ecm think there is a problem with it throwing a code for it. Jae you obviously have no idea what you're talking about.

1 of 1 people found this helpful.
140

John, if you knew your roots, you would know that a catalytic converter has an 02 sensor before AND AFTER to ensure the CAT is completely working. If you read correct, Nichole has a 2001 which means she is running OBD2 Complian PCM. NOW. Whenever your car DOES NOT read the Mass Air Flow Sensor, it goes into a backup Mode which in return uses the MAP ( Manifold Pressure ) sensor to gauge the pressure inside the manifold for how much gas to use, The o2 reading tells the PCM if the measurements are rich or lean if they need adjustments. And how do i now this, i custom tune 3100, 3400, and 3800 Power Control Modules on a daily bases for Digital Horse Power , and i now exactly what a pontiac v6 pcm does when it does not read a MAF. So john please take your stone age book and update it with todays standards in OBD 2 Compliant Vehicles. If she had a clogged CAT she would have 4 to 6 different engine codes, BARO, MAP, MAF, EGR, oxygen sensors, etc etc. This is one of those things they hard coded for dealers to figure the issue using there tech scan tool much easier. And your welcome.

4 of 4 people found this helpful.
140

Her issue, was coincidental to her CAT Glowing Red. She had multiple problems, and they just didn't run 3 cold start cycles to clear.

34,275

You told the woman to check her fuses because one code was thrown, yea masks sense.. Congrats you know how to flash an ecm, anyone with any knowledge on how to use a computer can flash an ecm. A mas air flow won't restrict an engine to 2000 rpm and the downstream O2 sensor will not read a fault if there isn't hardly any exhaust air passing over it. It measures the efficiency of the cat with the air that is passing over it and if the cat is clogged then air can't pass over it, so it won't read the cat being inefficient so it won't throw a code. Every sensor is reading in compliance with one another, more throttle means less vacuum and the map sensor is reading that so as far as the computer can tell the two are working properly, downstream O2 sensor is showing clean exhaust gas because there is no air flowing over it. very little air flow over the MAF sensor though must be a bad mass air flow. Stone age book that lesson into your computer. I'm 25 and had only just turned 7 when obd2 became a requirement. If you had any idea of how an engine worked you would probably be capable of comprehending what's going on but since you rely on your computer to do all your diagnosing for you, you're lost when a real issue arises. You're not a technician, you program control modules, that's about as difficult as opening a jar of peanuts.

2 of 2 people found this helpful.

I am having similar issues, but I know m catalyic converter has been removed already (prior to my ownership) is it possible that I may still have a clogged exhaust or should I look more into the MAF cleaning/replacement ? Also what does PCM mean ?

34,275

Pcm is powertrain control module, your cat was removed or replaced? Installing a universal cat on an obd 2 car will be lucky to make it much over a year. There is a special aerosol cleaner for mass air flow sensors.

Ok so i would like a serious thought. first off hears my back ground. I'm 27 and have worked on vehicles scene i was 5 so i have 20 plus years of experience and I'm not a back yard joe smo. My fathers a master tech who trained me. I started out on gm vehicles and when he told his boss of 10 plus years at Farnsworth to shove it up his ass he moved on to Toyotas at LeBrun across the street. He hates Chevy now but still works on them. when i say I've been working on vehicles i mean every aspect and we have full fledged shop at my parents house. With all the amenities. So i have experience including old school diagnosing and complete engine rebuilds. I'm big on 2.2 and 2.0, i loved the 3.1 in my 1990 z24 cavalier before i smashed it. But quads meaning 2.3, 2.4 and 3400 by chevy are pos that bend valves and i wouldn't own another after my Beretta but it was a fast 2.3 and i loved it but ny rotted it out, i drive toyota now though the 2.2, 2.0 are awesome and though i hate the mpg my 1993 3.0 pick up (Tacoma) gets i love the truck and want to put a 2.0 turbo or 2.2 in it but that aside. With that being said I'm not stupid by any means and know how to diagnose both with and with out snap on scan tools. Ok so now that that is outta the way. i bought a 3800 2002 impala to trade for a 3800 2007 grand prix. Well kid smashed the car before i could finish my impala for him. so i was stuck with it. I put new every thing on it and so i put it on the road and it sat for 3 months waiting for me to pay for the cat, and exhaust system. My wife's Camry transmission went and i decided to fix the impala for her then a good transmission came in to my buddies yard and being that the impala wasn't inspected or done i put the Camry transmission in and sent her on her way. So back to the impala as its almost winter and i need a beater to keep ny salt off my truck. I bought an aftermarket exhaust system and a new down stream o2 sensor because up stream was fine and down stream wouldn't come outta the factory cat even with head and decided not to break it because the factory cat still good but the flange was rotted and figured what the hell its only 150 at roc auto to get the cat and another 200 for the entire system 360 total. So i just put it on today and besides putting new struts, repairing the frame and new trailing arms, don't ask just know ny winter rot out cars bad and a few pot holes ripped the trailing arm off the frame but its a winter beater with 100k on it and i put way too much money into it. That aside i got it all back together today and it was dark by the time i got it down the road for a test drive to the shop to pick up scan tool. Here is were it gets interesting. I drove at 60mph maby three minutes tops and when i got to the shop smoke rolled outta the hood. I pop the hood to find a slightly glowing front header. So we threw it on the scan tool and four codes were on there from before i touched it. Among them was the MAF. I cleared the codes and brought the scanner with me ten minutes down the road to get gas because it was on E. I check it every couple of minutes and i was not hot and not glowing, i never shut the car off just park and poped the hood to check check it. So i put seven gallons of 93 octane in and turn around still no codes scene i cleared them. I drove another ten minutes back towards the shop and at the half way mark a total of 15 minutes if driving and shutting it off once to get gas the check engine light kicks on and it P0102 again. That is the only code and i drive it for 5 minutes to the shop were i pop the hood and there no smoke but the front manifold is cherry red and the rear is starting to have a amber spot. So what I'm figuring is the MAF told the motor to dump to much gas in and it sent unburnt fuel into the header and caused it to burn in the manifold or its burning to hot due to the air to fuel ratio. The car idles up and down slightly and hesitated when given gas. So my old man says he has never seen that before and so i clear the code he says why whats that going today and i simply told him what i just told you and low in behold that same trip back to were it started from to the shop it didn't turn the manifold red hot and the check engine light didn't come on. So my question is do you think its just the MAF sensor? I'm going to check all fuses because it says it has low voltage on the p0102 code. I'm going to get a bunch of MAF sensors from a junk yard as my buddy owns a yard before i buy a new one and might try cleaning it with spray if not buy a new one if that truly is the problem. I appreciate any opinions or advice but in my opinion if that is what happens from a MAF sensor being bad that might explains why these cars catch fire and the leaky valve seal gm is replacing is only half the problem because i could see a cherry red manifold bursting into flames with oil build up or leak. Also there is no plugged cat as its new and i have great power in the car so there is no plugged any thing just to add. Thank you all for the advice.

34,275

Running lean causes the combustion/exhaust temp to raise, running rich will cool the combustion/exhaust temp. doubt a vacuum leak would cause it to be this lean, more like a bad O2 sensor, bad mass air flow sensor, bad fuel pump not supplying quite enough fuel, vanished injectors. If it was running rich the catalytic converter would glow red not the manifolds. Converter generates extreme heat when it gets hit with excess raw fuel.

3 of 3 people found this helpful.

Could DAT make my car cut off

20

Hey guys,been having the same problem with my 97 eclips turbo. I just got a new air flow meter and installed it..still the same lake a power to the car I unplug it and the car does better I plug it and it starts shaking ,I don't know what else to do or chek ..eny advices or eny next step please ,thanks

2 of 2 people found this helpful.

Try a new battery, may not be getting enough voltage

10

I got a blazer that only goes up to 1000 rpm and it's reading the mas air flow to but I already put a new one in there.

1 of 1 people found this helpful.
10

Ok I'm having the same problem on my 04 silverado, but I'm also running straight exhaust and I can't give mine any gas without it misfiring like a mother f***** and then dying if I hold the gas. If I press the gas it just stutters and stalls. I'm getting the low voltage on my mass air flow and 02 sensors. Brand new stuff all the way around and still having the same problem. Unplugged my mass air flow and 02 sensors and truck still does same thing. It idles fine. I don't know how to check for vaccum leaks. A you help would be great

1 of 1 people found this helpful.

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