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View Full Version : Low MAF Readings (Lean Codes)



Nebone
04-29-2008, 04:30 PM
I got some CELs recently on a Knock Sensor and Lean Condition. Took some readings on the MAF and got low data. Swapped the MAF with one from a 2001 1.8T MK4 (same part #) with ~90k miles and got much better readings but not quite what they should be. I am about to get a remanufactured MAF from the dealer since thats all they sell (i get it at cost ~$150).

So from the graph below I am beting its a faulty maf. I havent cleaned it. Car has 125k on it. AWM motor.

1st, 2nd and 3rd gears shown (Car has APR Chip and was boosting ~15 psi)

http://memimage.cardomain.net/member_images/4/web/436000-436999/436359_176_full.jpg

Nebone
04-29-2008, 07:31 PM
Bump

317ssayzarc
04-29-2008, 08:06 PM
Try my MAF man... sorry i didnt call you after i got outta school, i was on the phone all the way home [down]

biketsai
04-29-2008, 08:14 PM
your air mass should peak at a number that is .8 your horsepower

MikeWasHere05
04-30-2008, 06:50 AM
your air mass should peak at a number that is .8 your horsepower

Not true for all engines. A chipped nDBW peaks at 158g/s.

Nebone
04-30-2008, 10:57 AM
You can clearly see the the difference after I swapped the MAFs; same part numbers on both. I don't think cleaning it will restore it to new quality so its not even worth trying. I'm staying out of boost as I drive now besides when I log.

Gotta blow $150 on a remanufactured one I guess. Thats all that dealers sell and warranty it.

Mawhitey
04-30-2008, 11:15 AM
The reman ones work well,it what i had to do as i tried 2 of the Ebay specials i wish i hadnt wasted the time and money

Nebone
04-30-2008, 02:02 PM
That 0.8*hp=gal/s is a load of crap. Every engine is different. Hp does go up linearly just like the gal/s but it can't be assumed that the ratio works.

I hope this new MAF cures the issues and I'll be able to use the element on a bigger housing down the line.

Nebone
05-04-2008, 05:04 PM
Update.

Put the new MAF in and added some data to the graph.

There are 4 runs with different setups.

Original problematic MAF
Original problematic MAF Cleaned
Working MAF from another car
New $MAF$

http://memimage.cardomain.com/member_images/4/web/436000-436999/436359_177_full.jpg

The results speak for themselves but I haven't driven around enough to get a CEL yet. Knocks on wood.

Nebone
05-15-2008, 02:21 PM
The new MAF has fixed the lean problem and MPG have gone up.