Quick question 1999 B5 S4 : peak MAF reading?

[Tom-S4]

Hi,

I've scoured best I can in the last hour over the internet and forum but i can't seem to find out the peak MAF reading for a stock '99 B5 S4 should be.

I've seen numbers as low as 215 g/sec
(mikey's post) http://www.rs246.com/index.php?name=PNp ... ic&t=69159

to the S4 wiki's suggestion of 260 g/sec
http://s4wiki.com/wiki/MAF#Effect_on_Velocity

I'm having issues with my car running lean and flat between 5-6k and my mechanic has suggested it could be the MAF (i assume its running the standard VAG/Bosch part at the moment) but he doesn't know what the true reading should be at WOT, only at idle.

Thanks in advance for your help.

[Philws4]

For a stock car then 215/220 is about right given that they came out the factory with approx 265 BHP.
The test is best carried out in 3rd gear 2400rpm> redline.

The rule of thumb is to divide the max air flow by 0.8

[Stigter]

Have a look here: Spen and flashyg are ledgends for this one. http://rs246.com/index.php?name=PNphpBB ... light=logs

[Tom-S4]

Thanks for the replies, 220 it is.

Sadly my mechanic informs me mine is running around 100(!?) but i will clarify this tomorrow when he gets back to me with prices on a new MAF.

[S4]

A lot of people make a big mistake and think.... oh 100 its the maf. they forget that another code can put it into limp mode, and it will only run wastegate boost. 7 ish psi, and what reading do you think you will get on that.

check that there are no other codes before you purchase.


Darren

[tartan_rob]

A simple test for MAF is to unplug it. If the car runs better or the same as before, it is shot and needs changing. If not, it is something else.

Rob

[Tom-S4]

A lot of people make a big mistake and think.... oh 100 its the maf. they forget that another code can put it into limp mode, and it will only run wastegate boost. 7 ish psi, and what reading do you think you will get on that.

Hi, can you shed some more light on this.

I ran a VAGCOM before handing it over to the mechanic and it came up with a 'bank running lean' error message but nothing else. If i had a boost leak or it was in limp-home mode would I not get some other code from the ECU?

He ran some tests with his equipment and found it ran lean at the top end and was affecting the power up here. Some investigation later and he found the lambda probes have been replaced reasonably recently and suggested that the car may have had running problems before.

[S4]

yes.... If it thinks its running lean, it will wack it down to just basic, waste gate boost... the NT75 is used to bleed the boost, like a bleed valve... when it get a fault, it will knock it down for safety, and just run low boost.. yes it could be your MAF, but like I said above.

Maybe clear the codes and do the maf reading test. if it thinks its lean it will go down to low boost. you only get 1 code sometimes to do this.

you say it was only on 1 bank? well the MAF would really do both.

does this help.


Darren