VAG-COM Logging and proper MAF airflows

[culaslucas]

Okay so I was reading from http://www.mjbmotorsport.com/datalog.html and decided to map my MAF flows. The site says:

Channel 2: Mass Air Flow Sensor (MAF)

This channel measures the grams per second or airflow taken into account by the MAF sensor. Input I have collected from tuners suggest that this is not a direct measure and depends on other sensors, so programming may be able to affect the g/s independent of changes to actual airflow. Nevertheless, while this may not be a reading that can completely state the airflow your car is taking in, it can provide a good estimate. This is a great log to look at if you suspect a common failure, the dying MAF sensor. On a chipped car one would expect MAF numbers to increase linearly as the car approaches redline. Your highest numbers will be seen at or near redline and are likely to be in the neighborhood of 160-180 g/s. Low numbers at redline such as 120 g/s are a good indicator your MAF is on the way out. Codes may not be thrown at this point. Terribly low or NO readings means she is dead.

I mapped my MAF flows and got the following result - Horizontal axis is RPM, Vertical axis is air mass flow in g/s.



My car is an '01 A4 1.8t - 125k miles - totally stock (for now)...at 6k RPM I'm maxing out around 137g/s. Does this seem normal or indicative of a MAF on it's way out?

[mike-2ptzero]

You should set the RPM range to only what the maf readings cover. Your numbers look pretty normal for a fully stock 2001, chip 2001 will see readings in the 170's. Another way to see if the MAF is good is to look at the engine load reading which is also on block 002. You should see a max of 191 load reading.

[culaslucas]

Here's the graph for my engine load for the same period.



I'm nowhere close to 191.

[mike-2ptzero]

Might want to see if anyone else can post up a log of block 002 of a 2001 running stock boost. Have you looked to see what your block 032 readings look like, you dont need to log it just look at the stored reading. This will also help you figure out if the MAF is on its way out since 032 is the fuel trim adjustment readings.

[culaslucas]

another thought - this was in 2nd gear from a 5mph roll. I was entering the interstate and had to back off on the throttle slightly toward redline. This afternoon I'll try to take a WOT run in 3rd and see what i can pull up - I'll try to post a copy of the speeding ticket I get as well ;)

I don't think I can look at 032 - I have the shareware version of Ross-Tech 409.1. I'll check it out later today.