Kirk

I met up with Eric (pikejerky) and we swapped his dirty old MAF into my car, I reset the ECU, set the readiness codes, went out for a drive and no fault codes were thrown. Logged some data which we will get to later.

Eric then cleaned his maf and we put it back into his car... reset his ecu and reset the readiness code and went out for a drive and logged some more data which we will get to later. Interesting, looking at Eric's air/fuel numbers at idle and part throttle, his numbers would indicate a boost leak of some sort at part throttle. I gave Eric my DIY leak tester to try out.

I met up with Steve (not on AW) and adjusted his short shifter to 35%. We then looked at his air/fuel numbers and his were worse off than Eric's. Interesting Steve had a code thrown earlier this week and MM (local dealer) diagnosed the problem as a leak somewhere. Steve logged some more data on a short drive which we will get to later.

So here are three 2000 A4s with poor MAF or air/fuel numbers. The two chipped cars are throwing codes as a result.

<a href="http://www3.sympatico.ca/kirkgj/images/maf_compero.pdf">link to maf comparison</a>

Here is the maf comparison data. I tried to compare a single data point that would be consistent on all three cars. 5600 rpm in 3rd gear. Steve's run was today, the other three were last night. From this little comparison, we can see that my new maf is flowing more air and Eric's cleaned maf in stock form is flowing more air than Steve's dirty maf in chipped form (Sorry Steve, but I'm sure MM will get you sorted out). Eric's dirty maf in my car allowed me to get up to 6300rpm without issue. No error code.

Here is a data plot of Eric's maf in my car:
<a href="http://www3.sympatico.ca/kirkgj/images/maf_data_chipped_ericmaf.gif">link to swaped maf data</a>

While I had my maf out, I took a good look at it and made sure everything was seated just right, put it all back together and logged some more data. Here is a data plot after I put my maf back together:
<a href="http://www3.sympatico.ca/kirkgj/images/maf_data_chipped2.gif">link to my maf data</a>

This data plot looks similar to my previous plots of my maf except that my code didn't get thrown until 5700rpms instead of the 5400rpms like it did before.

Some how, the car is pulling more air through my new maf or the new maf is measuring this air incorrectly. I can't get my car to throw a code in stock mode with the new maf and until I get a code, MM is not able to do much. I'm going to take the car by MM tomorrow for them to "take a look at" so that I have a record of such a problem. MM can't schedule me in for a couple weeks. If my problem is maf related, and I think it is, I just need to convince MM to replace the new maf.

The last thing I'm going to try is to put in another by-pass valve (where is Henry (AUDIOHS) when you need him) and see if I get the same sort of data plot. I want to believe that my bpv is letting go at the higher air flow rate that the maf is measuring.

Kirk

Brent V

Of the requested/actual boost readings for all three cars overlayed on the same graph?

I see on the chart all three cars have N75 at 95% (max) so I'm curious to see how their respective boost curves relate. Might point you to something, never know.

-Brent

Brent V

The new MAF i bought was bad too, had to take it back and get a new one

Kirk

... there is no nice curve from 3000 to 6000 rpms as the other drivers lifted off the throttle part way through or something. Thats why I picked the one data point to compare across all three cars.

I'm going to see about getting a new new MAF today.

Also, I tried out a hyperboost valve last night and I still got the code so my new new 710n valve is holding. I'll post some more data on this later.

Thanks,
Kirk

Brent V

rad...looking forward to future posts