FAQ: Mass Air Flow (MAF) Sensor Issues?

1998 Riv wrote:

Well I'm not pulling off the old line just yet. Not until I can physically locate the MAP nipple. My fingers just don't seem to be able to follow the line far enough to reach the end. May not be necessary anyway. And my engine bay is not exactly grease and grime free, so won't be pulling any lines off any nipples without doing some cleaning first. Don't really want to have to mess with that in our current cold weather.

I spoke too soon earlier today when I stated that it seemed I had solved the problem with a MAF cleaning and rechecking vac lines. Set the code again at noon. Tonight I stopped by NAPA and picked up an AC Delco reman MAF sensor and swapped. It SEEMED to make a noticeable difference in the general idle quality, and no codes or engine surging after 15min driving around town. Will see if that holds true tomorrow.

IF your fingers are large, reaching the nipple could be interesting. If not, then all you have to do to find the nipple is follow the old line. I imagine you could dismount the MAP when replacing the line but I've not done that, did not have to once feeling it. On a cold engine it's pretty easy, you don't really need an inspection mirror unless you just have to see the thing... .when I did mine it was by feel at the MAP.

In your area it should be less damp this weekend, not actually warmer but it will feel warmer, maybe this would be a Saturday afternoon project.

I have a project out of town on Saturday, but might get at it after work hours during the week, if the need is still there. This morning, no codes and smooth idle. The original MAF sensor may have been the problem.

Yes I do have large hands, and long fingers. Just couldn't seem to find quite the right angle of attack to get a finger to where the nipple should be. I'm sure it can be accomplished, as I can get at all the rear plugs without too much trouble.

By the way, the reman sensor at NAPA was $129 with AAA discount, plus $78 core charge.

1998 Riv wrote:

I have a project out of town on Saturday, but might get at it after work hours during the week, if the need is still there. This morning, no codes and smooth idle. The original MAF sensor may have been the problem.

Yes I do have large hands, and long fingers. Just couldn't seem to find quite the right angle of attack to get a finger to where the nipple should be. I'm sure it can be accomplished, as I can get at all the rear plugs without too much trouble.

Long fingers not a problem. Fat fingers big problem.

you can get at it - as you face the engine (steering wheel will be to your *right*) you can reach under the mounted MAF by following the vacuum line with your fingers. use one finger (index) at first to figure out where things are. The point where the rubber fitting is on the line is what you want to remember. Once locating it you should be able to figure out how to get a few fingers in to remove the old fitting and pop on the new one, just be aware that there arr a few bolts under there that will feel kinda like the vac nipple so mind where the line runs and you'll be all set.

Thanks Albert, maybe I'll try that approach tonight if time presents itself. I think basketball and punkin' carving are on the agenda though.

2 full days with the new sensor, I believe that confirms I have resolved the problem. Perfect idle, no codes.

Well, looks like I blew up my MAF and it wasnt my tune afterall.

I tried starting it and it bogged and then stalled.
I unplugged the MAF and bingo, she went VE and is idling and running 'fine'.

Im not keen on getting a new L67 MAF because i plan on upgrading TB soon.

Dang..

http://www.datafilehost.com/get.php?file=62254e72

Just happy to know it was the MAF afterall. I mean, look at the scan above. Insane.

Now you can do some VE tuning!!!

deekster_caddy wrote:

Now you can do some VE tuning!!!

LOL my thoughts exactly. Already reset the fuel trims this morning and started to get them locked in with the VE table.

I did about 1.5 hours of driving with 4 engines starts. I will be ready for a nice 30+ min scan this evening and hopefully start with a new VE tune tomorrow morning.


My MAF tune was nearly perfect! :(my LTFT was like 0 to -3%

The question now is, get a new L67 MAF sensor (getting reman quotes for ~$115, have yet to check bone yards) or hold out with the VE and disabled MAF until the LQ4 MAF and northstar go on.

That's odd your MAF just 'blew up'. Is it dirty? Any damage? I know these things can fail, just seems strange. Mine's got 280k on the clock, and it's one of the last things I'd think would fail on this car. Check connectors and wiring, too.

If you're going to do N* TB just upgrade the MAF at the same time. More reason to do the N* ASAP.

AA wrote:

That's odd your MAF just 'blew up'. Is it dirty? Any damage? I know these things can fail, just seems strange. Mine's got 280k on the clock, and it's one of the last things I'd think would fail on this car. Check connectors and wiring, too.

If you're going to do N* TB just upgrade the MAF at the same time. More reason to do the N* ASAP.

I didnt take the throttle body off to check and I dont have a set of torx with a drilled out center to take the maf sensor off.

Alls I know is that on the highway last night it started feeling real weird and next thing I know my fuel trims went SUPER rich.

Everything I've read points at a MAF failure. I unplugged the MAF and bingo, my riv is running fine.

I might add, the stock VE tune i'm running right now feels MUCH better than the stock MAF tune I was running before I started tweaking it.

As soon as the gen V is mirror polished it will be time for all the upgrades.

Still trying to get to the hardware store to get that flap wheel...

I would look closely at the connectors. You said you were doing stuff under there - plugging in and unplugging things, right?

I would fix/whatever your existing MAF. You aren't going to outflow the stock MAF for a while yet. See if Morads has a cheap used one.

deekster_caddy wrote:

I would fix/whatever your existing MAF. You aren't going to outflow the stock MAF for a while yet. See if Morads has a cheap used one.

I think he already has all the stuff to do the N* conversion, so dropping money into something he isn't going to use doesn't really make sense. It's not my money or my choice, just my thoughts.

matt270avian wrote:

deekster_caddy wrote:

I would fix/whatever your existing MAF. You aren't going to outflow the stock MAF for a while yet. See if Morads has a cheap used one.

I think he already has all the stuff to do the N* conversion, so dropping money into something he isn't going to use doesn't really make sense. It's not my money or my choice, just my thoughts.

Oh that changes things then. I thought he was thinking about buying the stuff. Different if he already has it.

Yeah, just need to get the gen V polished so I can put it all together. Running on the VE table until then.

I didnt mess with anything under the hood and the wires to the MAF sensor look fine.

I havent taken the TB apart to see if its dirty or what but the scan says it all. MAF went CRAZY!

Any chance you recently cleaned/oiled your air filter?

deekster_caddy wrote:

Any chance you recently cleaned/oiled your air filter?

like 2 weeks ago.....maybe I should take the TB off and check the MAF?

Since we've ended up back to the air filter over-oiling topic, here's K&N's view on the subject: Mass Air Flow Sensor Urban Myths

http://www.knfilters.com/news/news.aspx?id=422

K&N has researched, tested and devoted many hours to confirm the use of K&N Air Filters, including over oiled air filters, will not cause a Mass Air Flow sensor failure under any remotely normal driving conditions.

Oil does not come off K&N Filters. If a mechanic or dealership claims K&N is the problem there has to be proof. K&N will often work with consumers to recover money for repairs which legitimately should have been covered under the vehicle’s warranty where warranty coverage would otherwise have been available.

“We’ve tested Mass Air Flow sensors and discovered these parts are being replaced when they don’t need to be,” said K&N Senior Lab Manager Rich Dwyer. “Consumers are sometimes told readings from the Mass Air Flow sensor show it is saturated with oil from a K&N Filter. This is not true. Consumers should ask to see the Mass Air Sensor codes and/or get a second opinion.”

Of all the years I've been using K&N filters, I'm yet to have an issue with an oily MAF. Just sayin.
Now, we HAVE had issues here at the dealer with people just absolutely soaking their filters and screwing up MAF sensors. That isn't K&N's fault though. They provide clear instructions on how to clean and re-oil their filters. Do it right, and you will never have a problem.

I've never had an issue, either. One thing I found interesting in the K&N research:

There were traces of silicone potting compound which is used in the manufacturing process of MAF sensors, meaning the MAF sensor contaminated itself. There was also evidence of motor oil contamination from blow-by; a condition where oil vapor from combustion is re-circulated into the vehicle’s intake tract...

...there is no silicone in K&N oil and testing has shown that MAF sensors will operate normally after being immersed in K&N Filter oil.

So according to K&N, even if there is over oiling, it wouldn't matter. I know K&N is trying to protect their brand, but it's reasonable that they published these facts based on controlled research. It's believable, imo.

I didnt use oil. Just air blasted it. This was like 2+ weeks ago. I doubt its what caused the failure

You air blasted the filter, not the MAF sensor, I hope.  

It's worth a try to clean it. Buy a can of MAF cleaner and remove the sensor to clean it. Don't spray it inside the throttle body, there is too much stuff in the way. (follow the instructions on the can - last one I used said to let it dry for something like 2 hours before putting it back in the car - may have been overkill since it evaporates pretty quick)

I've read K&N's statement on oil and MAF sensors too. I really want to believe them. But I have helped several over-oilers and talked to others on forums with MAF problems that occurred almost immediately after installing the over-oiled filter, and cleaning the MAF was the solution. It's happened too often to be a coincidence. Maybe they weren't using K&N oil, but K&N is the only cleaning/oiling kit I know.

K&N states it as fact, I've posted that statement from them elsewhere too, but there is too much coincidental occurrence of dirty MAFs for me to believe it. Maybe people are careless with the oil in the real world in a way they aren't duplicating in the lab tests?

Almost makes me want to put a drop of K&N filter oil on my MAF sensor element and see what happens...

Almost.

I don't think it's a matter of the oil itself causing the MAF to freak out. I think that it's the dirt that gets by the filter and sticks to the oily MAF that causes the problem. It doesn't matter how small the dirt particles either. Eventually, it will build up and cause problems.