2005 Silverado Mass Air Flow and Evap Cannister

[lawdog]

YIKES! Got the ol check engine light and have it in to the dealership. They called and say I need to replace the Mass Air Flow Sensor and the Evap Cannister system in the fuel tank. $366.11 and $572.21 respectively. OUCH!!! Are these common problems? What else should I expect soon?

Truck has about 56,000 miles on it. Guy said the K&N filter might be to blame for the Mass Air Flow. 5.3 motor, auto tranny. Already put a new torque converter in that about 15,000 miles ago too.

THOUGHTS?

[Scott K]

K&n filters are killers for MAF's, because they allow dirt in, and if you think about that, it is allowing dirt in the engine as well!

[Hafnutz]

I'd get a second opinion. I believe you can clean a MAF. I too would chuck the worthless K&N air filter

[Jeremy airjer W]

I'd try cleaning it first as well. Ditch the K&N as well.

Has the light been on for a while? Seems odd that a maf and charcoal canister would fail at the same time.

[deadeye]

Before you throw out a 50$ K+N try a 5$ can of Mass Airflow Sensor cleaner. It does make a huge difference even in cars that don't have a K+N in it. Besides, those trucks (and for that matter just about all gm vehicles) have problems with the MAF anyway. We stock a whole shelf of those sensors at my store just for GM vehicles. I'm pretty sure that 99% of the vehicles I sell the sensors for don't have a K+N in them.

I have yet to see any real problems with a oiled gauze filter that wasn't part of a pre-existing problem or error in part of maintnence (i.e. over oiling the filter after cleaning).

As far as the evap canister, maybe a line got cracked, kinked or busted in the removal and replacement of the tranny. I remember that those lines are kinda fragile and would be easily messed up in the heat of battle when pulling or installing the transmission. I have also seen a bad/loose fuel cap throw a evap code too, you might want to get the specific code from them to see what your up against...

[Jeremy airjer W]

We stock a whole shelf of those sensors at my store just for GM vehicles. I'm pretty sure that 99% of the vehicles I sell the sensors for don't have a K+N in them.

I would bet that 75% of those didn't really need a MAF sensor to begin with!

[Scott K]

Originally Posted By: deadeye

We stock a whole shelf of those sensors at my store just for GM vehicles. I'm pretty sure that 99% of the vehicles I sell the sensors for don't have a K+N in them.

I would bet that 75% of those didn't really need a MAF sensor to begin with!

Agreed!

[Macgyver55]

I also agree, I was going to say something but I held my tongue. Over 30 years as a mechanic, (mostly GM) and in those years I can count on 1 hand the number of MAF sensors that I have found to actually be bad. There are way too many techs that will throw one on just because there is a MAF code.

[Jeremy airjer W]

Those where the ones about 5 or 6 years ago that would fall on there face at about 2 grand as you where trying to get on the freeway. After that episode you'll get the occasional 3.8 and 4.3 with a bad one but not very often anymore!

[lawdog]

How do I clean a MAF??? I don't even know where it is... Is this a feasible do it yourself project?

Thanks for the replies guys!

[Scott K]

Its the piece that goes into the airbox, from the airtube coming from the throttle body. Remove it, locate the little coiled wire spray brake clean on it, or lightly rub it with a q-tip that is wet with brake/carb spray, then reassemble.

[Jeff D]

Not to steal your thread, but i have a 1999 silverado with the 5.3 that falls flat on its face when getting on the freeway sometimes. i do have the k&n filter and intake kit. would that be a MAF problem for me?

[Scott K]

I would try cleaning that MAF and see if it improved, or got better, then install a regular airfilter.

[Macgyver55]

There is also a flash update on that vehicle if I recall for that very problem.

[Jeff D]

how would i go about doing this flash update you speak of?

[Macgyver55]

You would need to bring it in to a dealer to be flashed if it indeed needs it. I'm not sure but possibly if you bring in the VIN number they could look it up and see if it has already been done. Not sure about that part though.....I would first clean the MAF as was suggested before doing a flash update anyway.

[putter]

call the dealer have them punch in your vin# and they will tell you if there is any updates

[deadeye]

A flash update will change how the vehicle performs dramatically. My own truck had a flash done and it fixed problems with the abs brakes, transmission shifting and overall performance. It is something that should be checked into once in a while, its amazing how many updates were done to my truck when I had it flashed. I bet there were about 8 problems that were corrected when I did that.

As said above, you will need all the vehicle info, VIN and what the problem is specifically.

[Jeff D]

there are no codes that pop up and th echeck engine light isn't on. so how would the dealer know what the heck is going on whern theres no codes?

[Jeremy airjer W]

They would first try and duplicate the problem. Once they get an idea of what the problem is experience takes over. Monitoring scan tool data while the problem occurs will give more clues. Further monitoring of specific components will help narrowdown the possibilities even more.

The "magic computer" still does not exist. Although a code will give clues it still will not pinpoint the source of a problem. There are many times I'll have a check engine light on with a misfire (for example) where I wont even look at the scan tool until I physically find out what is causing the missfire. Then I'll check the codes and investigate further if need be.

I had a car that would not crank over. No codes, no power to the starter "s" terminal. Traced it back to the pcm not grounding the starter relay. The customer wanted a printout from the computer I used to figure this out. He was absolutely convinced that there was supposed to be a printout no matter how many times I explained that there was no computer and I had to use a multimeter and wiring diagrams to figure it out.

[Scott K]

Airjer you mean your shop didnt buy one of those scan tools that tell you what part to replace? Those have been an available option since obd2. LOL

[Jeff D]

the problem is that it happens intermittently. i never know when its gonna "fall on its face", there are no warning signs. and i hate taking stuff in because i can usually figure it out myself, but this time i can't. I'm gonna take the k&n system off tonight and clean the MAF and see if that will eliminate the problem.

[Jeremy airjer W]

Airjer you mean your shop didnt buy one of those scan tools that tell you what part to replace? Those have been an available option since obd2. LOL

I'm getting closer! I'm thinking about getting the new Snap on Verus.

[lawdog]

well, thanks for the replies guys, a $7 can of MAF sensor cleaner and a little of my time on Saturday seems to have cured that problem, no more engine lights. I did have the evap cannister fixed as I don't want my gas tank collapsing but I think I saved or at least held off the need for a $350 MAF sensor that doesn't seem broken in the first place...

[deadeye]

Its amazing that 7 bucks would save so much more money. Glad too see that it worked. You kinda wonder if they would even replace that part or just clean it out.

Cleaning that sensor should probably be done every time the air filter is changed/cleaned. My talon gets it done once every six months or so just to keep the problem from happening.