After months of no MAF on my LS3, the solution was...

[davepl]

...to install a honeycomb in front of the MAF.

I'd been fighting what I thought was an air/vacuum leak. The MAF wasn't seeing all of the air, the car would go lean, both banks of O2 would throw codes for being lean, and eventually a low air mass code for the MAF.

I tried everything, different pipes, different filters, straight pipes with no bends, all to no avail. I was by this time very certain that it wasn't actually related to the MAF. Had tried a different MAF too.

As a last resort I bought a section of 4" pipe with a MAF mount and a honeycomb from eBay, and it works nicely. It's a straight 6" pipe that I can't put a filter on, so some kind of intake tube will need to be constructed, but at least it runs happily now!

[chev3600]

Amazing that something so simple can be the fix. Glad it's running well for you. Any chance you could run a 6" inlet filter or just not enough room? http://www.spectreperformance.com/mo...x?prod=HPR9605

[davepl]

Right now I have it sticking straight out from the throttle body pointing at the radiator, so I need to fabricate a new intake tube that incorporates the air straightener.

As it sits, it runs well, but no filter at all!

[e015475]

How about a pic of your setup?

I've had problems with MAF errors before too - mostly shows up when the car went for a dyno tune.

Would be nice to see what setup worked for you.

[Andy4639]

Just throwing it out there. This is my cold air setup. It's been in the truck over 3 years now with no problems. The tuner did some fine tuning to get it right but in the end it's never thrown a bad code.

[davepl]

Andy, I think you've got the old style hot wire MAF there that reads a long cross section of the pipe. The "problem", or challenge, with the new MAF is that it sniffs a tiny section of the center of the airstream and deduces the rest. If the air has raced around a corner and is along the outside wall, it doesn't get seen and is not read by the computer.

Here's my current setup, that works well but clearly is temporary. Tilt your head, forum software is broken when it comes to rotated photos...

[Andy4639]

Originally Posted by davepl

Andy, I think you've got the old style hot wire MAF there that reads a long cross section of the pipe. The "problem", or challenge, with the new MAF is that it sniffs a tiny section of the center of the airstream and deduces the rest. If the air has raced around a corner and is along the outside wall, it doesn't get seen and is not read by the computer.

Here's my current setup, that works well but clearly is temporary. Tilt your head, forum software is broken when it comes to rotated photos...

That's messed up right there. You mean to tell me a new car want read right if the ninty is put on the throttle body! Dang.

[davepl]

I think I'm OK with a 90 (which I will definitely need) but it will need to be downstream of the MAF, so that there's nothing in front of the MAF except straight pipe, a honeycomb mesh, and a filter. After that it can bend.

I actually talked a guy up there in the crate engine dep't at GM and he led me to believe the instructions are insufficient - they say all is well as long as you've got 6" on either side of the MAF, but given the way air is sampled by this type of MAF, doesn't work so well in real life.

Dave

[Custom 68]

I think that is the case on all the MAF even the older ones. They work better and are more predictable with the straight pipe. Some will work with the bends but it changes the air velocity as it "bends".
It does sound like the older ones are a little more forgiving than the new styles.
I am glad it worked out.

[davepl]

Indeed.... the old style measure -across- the entire width of the tube pretty much, whereas the new ones sample just from the very middle. Of course even with the older one you could have it turned 90 degrees from where the air was "building up" and still miss it.

Ran pretty well with the MAF though. I did notice it sometimes way rich or lean (under 10.0 or over 17) but the car itself doesn't have a wide band so it doesn't know HOW far it's off, even though I do with my gauge. But it'd usually come back to center right away.

[First c10]

Davepl, I had the same problem with my sons truck. Even with a spectra truck intake for a 2011 which is what the motor came in. It was always lean. I ended up tuning out the MAF.
Did you have to calibrate the MAF after adding the eBay part?

[davepl]

No, it's 100% stock tune (except for the reluctor speedo VSS count for my Tremec). I can see it doing some block learns at the edges of the envelope but it seems to be pretty much spot on. The MAF screen should not interfere with or change the MAF calibration at all, I don't think... it just straightens the air, doesn't restrict it any real amount.

There are a lot of other things that will cause these symptoms, like an exhaust leak, vacuum leak, mis-routed PVC that ingests unmetered air, bad grounds, and so on...

[First c10]

Cool. Do you have a link to what you bought?

[davepl]

Yes, this was it here. It has the GM MAF mount. You can also just buy the honeycomb insert, apparently.

http://www.ebay.com/itm/252080319202...%3AMEBIDX%3AIT