For those making MAF logs with older tdi's

[M1KEH]

After doing some logs on my ahu i was getting a bit worried that my MAF was very bad and not working well at all. But after a bit of research on tdiclub.com and other places i have found out that anyone with the old style pierburg TDi MAF like this one pictured here. Part number 974906461

These tdi's will only ever get an actual maf reading of 847.9 mg/stroke. This reading should be held until about 3500rpm and then will start to drop off a little as the boost also drops as shown in this graph below. I had to buy a new MAF as mine was giving bad readings but not as bad as first expected when i thought i was meant to be getting valus similar to those with the Bosch or new syle pierburg mafs. Here is what my old one logged like

as can be seen it tails off very quickly after peaking not whats meant to happen.

And heres what my brand new good maf logged like very big difference between the two. MAP shown here just to show that as boost tails off so does the MAF.

Can a mod add this to the faqs as i think it's quite a valuable piece of information so people don't get confused.

 

[sssstew]

interesting. You dont see many of the really older gen 90 TDIs so hadnt seen this before.

 

[M1KEH]

Yeah i had to search pretty hard to make sure this info is right. Most of the problems with cars this old weren't written about on the internet and even then there weren't many people with vag-com to log things like this.