Maf readings?

-Mike- · 15 Feb 2013 at 17:47

Hey,

Have logged my current cars MAF readings using vagcom and just wondering if anyone can tell me if my sensor is majorly out?

Code:

RPM       Spec      Actual
2184	430	382.2
2205	615	563.5
2331	850	1200.5
2520	850	901.6
2709	850	911.4
2919	850	931
3066	850	935.9
3213	850	950.6
3360	850	921.2
3507	850	891.8
3612	850	877.1

Another Section


2793	850	901.6
3339	850	916.3
3801	850	837.9
4221	850	837.9

I believe it could be deemed faulty but can anyone comment?

Brookert · 16 Feb 2013 at 00:50

Not sure what those readings are? What block did you log? normally you get one value in g/s. Mine peaks at 180g/s, multiply by 1.25 and you get a rough idea of the power its putting out (225 ps).

Dave L · 16 Feb 2013 at 08:50

Brookert said:
Mine peaks at 180g/s, multiply by 1.25 and you get a rough idea of the power its putting out (225 ps).

What?? You can get an idea of engine output by MAF readings?? :confused:

-Mike- · 16 Feb 2013 at 09:40

Block 3. This is a 1.9 Tdi btw! They are mg/stroke.

dalin80 · 16 Feb 2013 at 13:18

Dave L said:
What?? You can get an idea of engine output by MAF readings??

You can get a Very vague idea, a MAF is a primary load sensor and one of the most important in telling the ECU of the power that is being demanded, EGR's can make things more interesting though.

As a load sensor those numbers arent of much use iam afriad as engine speed is not represntative of load.

Are you having any running issues or warning lights?

Brookert · 16 Feb 2013 at 14:50

-Mike- said:
Block 3. This is a 1.9 Tdi btw! They are mg/stroke.

ah that would make sense, derv is not my territory on vcds

Matt82 · 16 Feb 2013 at 15:28

Dave L said:
What?? You can get an idea of engine output by MAF readings??

its a ball park thing. i could change ignition timing on mine, airflow would remain the same but id have more power

-Mike- · 16 Feb 2013 at 17:22

dalin80 said:
You can get a Very vague idea, a MAF is a primary load sensor and one of the most important in telling the ECU of the power that is being demanded, EGR's can make things more interesting though.

As a load sensor those numbers arent of much use iam afriad as engine speed is not represntative of load.

Are you having any running issues or warning lights?

Well foot was to the floor during acceleration and should have produced 100% load?

The car doesn't display eml as the mad doesn't throw up a fault when it's on the way out! Car feels down on power higher up the rev range is all

Gibbo · 16 Feb 2013 at 17:30

Just pull it out and give it a clean with some maf cleaner.

MatteH Oxford · 16 Feb 2013 at 22:26

You can't really go by OBD information. MAF sensors ideally need to be hooked up to a lab scope to check for a specific voltage or frequency, at certain RPM, for an accurate diagnosis.

-Mike- · 17 Feb 2013 at 00:07

Plenty if other people seem to be quite happy with vagcom readings!?

s0ck · 17 Feb 2013 at 01:15

Those readings are fine.

MatteH Oxford · 17 Feb 2013 at 07:49

If you solely rely on OBD info then you are potentially including wiring faults into your readings, because there are several metres of wiring and at least two connectors between the MAF & the ECU. If you scope at the MAF then you are getting data directly from the sensor itself.

Ideally you would want to look at both sets of information and compare to spec for proper diagnosis, this is the way I was taught at Ford technical in Daventry and it seems pretty logical to me?.