Help! Need Advice Interpreting VAG-COM Data

[Alchemy]

Wow, after being absent from the forums for over a year, I find myself coming back seeking advice. Here is the situation. I own a 2000 Jetta TDI and over the last few months I have noticed a cyclic surging during acceleration, especially at WOT, and the cruise control cannot keep up at highway speeds. So, being a geek engineer I decided to buy the VAG-COM software and OBD connector. After performing a scan, the data came back looking like the following...

http://home.wi.rr.com/stevemetz/Jetta.jpg

What do you think? Wastegate controller? MAP sensor? My original thought was the MAF sensor, but I don't see that as being the case because the boost is so erratic.

Other info... 72k miles, 5 speed, Delvac-1 every 5k miles.

Thanks!

Steve Metz (alchemy)

 

[lstm]

That URL is asking for
username
password
domain name

 

[Alchemy]

The link above has been repaired. Sorry for the error.

 

[jaydhall]

Looks like the MAF to me. To make sure, unplug the MAF and then look at the same graph (with new data of course). I bet the MAP smoothes out. If not, I will have to rethink!

 

[Alchemy]

Here are the results with the MAF disconnected. Certainly looks like that is the problem, but would like your opinions.

http://home.wi.rr.com/stevemetz/Jetta2.jpg

My bigger gripe is that VW wants $350 for a new one!!!

Any other sources out there??

Thanks,

Steve

 

[VelvetFoot]

How does it run with the maf sensor disconnected? Better? Almost as good as new without that pulsing? If so, I would say maf.

If not, here is another idea:
Did you make sure your intake is clean, like esp. the snow screen? Perhaps the snow screen is so clogged that the oscillations are caused by the bypass door opening. The air flow levels, even with pulsing, is definately lower than requested.

Aren't you getting any fault codes?
A dying maf, USUALLY I THINK, just sort of fades away, along with the power, rather than this pulsing thing.

 

[jaydhall]

Yes, it is your MAF. No question. Look up Danix in the for sale section. He sells them cheaper. (I have bought two from him and he is a good person to deal with!)

Other than that, www.vwparts.com.

 

[weedeater]

2.0l MAF will work.

Have you checked you intake lately?

 

[Alchemy]

The acceleration smoothed out, but was not nearly as strong. This is due to the injection quantity backing way off with the MAF disconnected. Snow screen cleaned completely and bypass door checked for function with no issues. Have not yet dropped the intercooler lines to see how dirty they are.

 

[VelvetFoot]

You looked in the egr valve for deposits, right?

 

[Alchemy]

My brother-in-law stopped over with his 2000 NB TDI and we did a quick 5 minute swap of the MAF's. Definitely the MAF and have placed an order with Danix. Please may he have one in stock!

Thanks for all of your advice and help!

Steve

 

[danix]

In stock