maf sensor probs

[cweant11]

so my 98 ex is throwing two codes for the maf sensor. i was wondering if i replace it myself can i reset the computer and erase the code by unplugging the battery or will it go away once the new sensor is on? thanks everyone!

 

[2000StreetRod]

KAM clearing

The PCM has nonvolatile memory referred to as Keep Alive Memory or KAM that stores diagnostic trouble codes (DTCs) and "learned" parameters such as fuel trims. Normally it is best to clear DTCs with a code reader so the learned parameters are not lost as they will be if you disconnect the battery. In your case clearing the DTCs will let you quickly determine if replacing the MAF sensor fixes the issue. Even if your replacement MAF sensor is OEM like your original one there will be differences in the outputs because of age and film deposits on the sensor. It might be good to force the PCM to quickly relearn the fuel trims by clearing the KAM. A fast way to clear KAM with no special tools is with the ignition off disconnect the battery negative cable and turn on the headlights for a minute.

 

[cweant11]

thanks, i went by the local auto parts store and they scanned it and it was throwing two codes the left and right banks are running rich, so as i believe the MAF sensor, thats what the guy also said he thought it was, so if i reset the KAM after installing the new MAF sensor will this clear the code? with the auto parts store not able to clear the code i just need another way to do so, if not find a friend that has a scanner? also if i reset the KAM before i replace will the MAF sensor will it change anything to help? the only result of the MAF sensor being bad is the check engine light and it has trouble starting sometimes. but if its dead cold it will start right up

 

[96eb96]

Well, changing the MAF sensor is an amateur guess, and if its not that the code will come right back. I would strongly suggest CLEANING the sensor first.


1)What codes did you get? P0171 and P0173? Usually a bad MAF runs lean not rich, but I would like to see the codes.

2) Also, some of those engines have issues with the intake manifold gaskets causing vac leaks and those same codes come up. That could cause starting issues too.

 

[2000StreetRod]

Which engine?

It might help if you identified your engine type: V8, OHV V6 or SOHC V6? Is the engine intake, exhaust and emission configuration stock?

Also, your first post stated you had MAF sensor codes but the next post stated that you have both banks rich which is not necessarily a MAF sensor problem. Have you checked to make sure there is no obstruction in the intake path such as a mouse nest or the air filter is caked with dirt? The MAF sensor is fairly reliable. Have you tried cleaning it with MAF sensor aerosol? Do you have black smoke exiting the tailpipe indicating a rich condition? Have you tried disconnecting the MAF sensor electrical connector to see if the engine runs better, worse or the same? Are your catalytic converters overheating (glowing or CEL flashing)? Have you checked for excessive fuel pressure? Are the spark plugs wet from excess fuel? Have you disconnected the vacuum hose to the fuel pressure regulator on the fuel rail and checked for fuel?

 

[fast_dave]

MAF Sensor Cleaner.
Any decent Auto Parts Store will have it for around $8 - $10 a can.

You will need "safety torx" bits to remove the MAF Sensor (the ones with the hole in the middle).

NOTE: Depending how dirty the two sensors within the MAF are, to get them totally clean, you MIGHT have to coat a q-tip in MAF Sensor Cleaner, and VERY CAREFULLY wipe off the sensors. And I mean VERY CAREFULLY as they are suspended with very thin wires...

 

[cweant11]

more info

alright everyone, sorry about the late response, been away from the computer for a couple days, its a 98 sohc 6 cylinder, not sure if they are inline 6 or v6. but anyways i checked the air box and air intake tube, nothing in the way, air filter kinda dirty, but the cat convertor doesn't seem to be overheating, i can't check the fuel pressure as i do not have the tools to do so, but the two codes that it is throwing are PO174 and PO171, also everything on the truck is stock. i hope this helps! thanks guys!

 

[2000StreetRod]

lean condition

P0171 System too Lean (Bank 1)
P0174 System too Lean (Bank 2)

It's very common for the intake manifold gaskets to dry out and shrink with age and leak resulting in a lean condition for both banks. The gaskets are fairly inexpensive but the upper intake manifold is a pain to remove. I suggest replacing both the upper and lower intake manifold gaskets since the lower is easy to remove once the upper is off. The following thread may help: Lean condition procedure