MAF readings

[rage385]

All, I logged a run to see if my MAF was causing some issues (fuel consumption and some misfires). It turns out it is (or at least it is based on my research) btw, I have a 2000 1.8TQM ATW motor:

RPM GS
1560 21.92
1840 30.08
2240 37.19
2640 52.39
3080 91.39
3520 89.03
3960 99.61
4400 107.36
4880 110.5
5280 108.42
5600 104.28
5840 102.58
6040 97.75
6200 94.14
6320 91.28
6400 89.64
6480 85.11
6520 87.19
6560 87.47
6600 82.36
6640 83.92
6600 82.11

Anyway, before my new MAF comes in (authentic audi part), I wanted to verify that my harness is wired correctly. Below is a picture





Thank you

[walky_talky20]

Here is a MAF log of a perfectly healthy 2000 1.8T (ATW) for comparison.



and here is yours:



Your peak number is good, which is were they usually have trouble. But the curve looks kind of wacky. Was this an actual 3rd gear pull at WOT? Or were we messing about with the gas pedal during the log?

[Wraith600]

Why would you question the wiring? Is the connector not stock? The new MAF is a male end and your showing the female. As pointed out by Walky your log doesn't look to bad. I had a bad one and it's really noticeable in the log, which yours is not. Walky helped me figure that out last year.

http://www.audizine.com/forum/archiv.../t-527722.html

Log, 003, 032, and 115 and post all those values.

[rage385]

Here is a MAF log of a perfectly healthy 2000 1.8T (ATW) for comparison.



and here is yours:



Your peak number is good, which is were they usually have trouble. But the curve looks kind of wacky. Was this an actual 3rd gear pull at WOT? Or were we messing about with the gas pedal during the log?

Yes, it was a 3rd gear WOT run. I was not messing with the gas pedal. It was pinged to the floor. I do have a cone filter and not heat shield protecting it from the turbo. Could that be an issue?

[rage385]

Why would you question the wiring? Is the connector not stock? The new MAF is a male end and your showing the female. As pointed out by Walky your log doesn't look to bad. I had a bad one and it's really noticeable in the log, which yours is not. Walky helped me figure that out last year.

http://www.audizine.com/forum/archiv.../t-527722.html

Log, 003, 032, and 115 and post all those values.

It was more of a curiosity question than anything else.

Below is the groups I captured from the entire run. I do not have group 32, but I can get that later.




Can you guys make out the picture? So if my peak numbers are ok, what do you think is causing the erratic numbers down low?

[rage385]

One more thing. I am a full stage II (APR chip, diverter valve, test pipe, borla cat back).

[rage385]

Here are some runs. I did the runs per APRs website. The tech there stated that my MAF readings looked low based on post #5 (run 3). Not sure where to go from you, but anything you guys can provide would be greatly appreciated.

Run 1



Run 2



Run 4

[MetalMan]

A chipped stock-turbo B5 A4 should be seeing closer to 150 g/s peak. The graph Walky posted is for stock ECU (hence the ~7psi).

Do you have a stock air box you can throw in when you get the new MAF?

[rage385]

Thanks for the reply. I did throw a new MAF in there with no change. I will reinstall the stock box and see what happens. Since I do not have an air filter, should I just stick with a typical foam filter, or go with a drop in K&N?

[AudiB5owner]

Do not do the K&N oiled filters, my mech headed an Audi dealer shop and said he had tons of cases where the oiled filter destroyed the MAF. Paper filter or dry flow will be fine.

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[rage385]

Thanks for the insight. I will report back when this is complete.

Does anyone have any additional input? If re installing the box does not work, I am wondering what the next course of action will be.

[walky_talky20]

Couple things from me:

- Yeah, I'd put a stock airbox in. At the very least it eliminates that possiblity. MAF values look wacky, so I would not be surprised if turbulence from the filter is throwing it off.

- In the future, please post text of the logs (like you did in the first post) or Google Docs spreadsheets with public access. Pictures of log data doesn't allow me to graph it.

- In general, log 1 or 2 blocks at a time. 3 blocks at a time slows down the sample rate enough to be a problem. Not enough data.

- You didn't say the car was chipped. That's important and should be in the first post. We can see from your boost logs that it's hitting almost 1.2 bar, so definitely aftermarket software. As such, I retract my previous statement saying that your peak value was good. It's not. I see 120 g/s peak and should be 150+, as MetalMan pointed out.

[rage385]

Sorry about that man. First time I ever had to dig this deep into stuff like this. I'll make sure to post better data in the future.

Once I install the OEM box, I will log another run and report back. I'll make sure to concentrate on the three blocks stated in the previous post.

Thanks again guys.

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[AudiB5owner]

Are you also running rich? I'm hunting down a problem of my own with 15mpg fuel consumption and a P1137. Walky posted great stuff I'd follow his advice. What are you reading at idle? I have a cone filter and read 3.8 to 4.0 g/s. Curious to see if putting in the air box fixes your problems.

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[rage385]

Well, I am consuming more fuel than expected (18-21 highway).

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[rage385]

All,

I have installed the stock box and tried both MAFs (reman and new). The below graphs of the new MAF with the stock box. I saw no difference between the two MAF runs with the stock box, hence the reason why I am only posting the runs of the new MAF.









I know the MAF readings from my previous post was the main concern, but I figured it wouldnt hurt to post some of the other findings.

Now, I am seriously at a loss. There was no improvement between the two MAFs. I did see on another post that maybe the connections might be bad. Should my next step be to check each pin for the proper voltage?

Any idea on what the issue might be?

Thank you very much for the help.

John

[rage385]

Just to make sure I did not leave any information out, I want to make sure I disclosed all of my mods:

APR stage II
ATP test pipe
Borla Exhaust
Stock KO3
ER TIP
FSI coil packs
ngK BKR7 copper spark plugs gapped to .28 (changed 2K miles ago)

Now, the car does have an AWM head on it (from the previous owner). I can only assume that the previous owner let the timing belt go and replaced it with this head. I am hoping at this would not affect the readings from the MAF, but I honestly have no idea what to do at this point. All cylinders show a compression of 175-180 psi.

Anyway, thanks again.

John

[rage385]

Bump

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[walky_talky20]

MAF values don't look good for 1bar+ boost pressure. Do you have a stock program you can flip it to?

The way the MAF value goes down at the top end is not normal either. So either the MAF value is wrong, or there is something wrong with the actual airflow through it. For example, your TIP is collapsing. (Is the ER the metal one? I thought it was). Anyway, yeah.

[rage385]

Thanks Walky.

I did perform some runs with the stock TIP (which were the numbers in the original post) so there was no change between the TIPs. I also put the stock airbox back (original post had the cone filter).

You stated that, "So either the MAF value is wrong, or there is something wrong with the actual airflow through it" Lets assume the airflow is ok, what could cause the values to be wrong? Could it be a power issue? Should I try to pin out the individual pins? I was reading this post and it seemed promising.

http://www.audizine.com/forum/showth...ngs-on-the-MAF

[rage385]

UPDATE...kind of:

Well, I have not had an opportunity to pin out the MAF harness yet, but I did want to run something by you guys.

After doing so research and speaking with a rep from APR, I am begining to wonder if the source of my MAF numbering being low is my cylinder head (I have a AWM head). Hear me out.

Based on what I have read, when one does a head swap, you need to match particular parts to your block (and not the head). So things like the cam gear, intake cam, tensioner, and timing belt need to match your block (in my case a 058). So typically when someone does a AEB swap, they need to make the internals of the head match that of their block. This could be causing my issue of pulling timing. I just am not sure if it is a directly related to the fact that my MAF numbers are low.

What are you thoughts. Thanks again for your patience and understanding.