Does anyone know what the normal "idle" reading should be from the MAF on a 110TDi? On the labels showing on vag-com, most of mine fall within the the range, but my MAF has always been miles off. I am working at home today, so I'll pop down to the car in a bit and get some readings and post them on there.

I changed my MAF a good few years ago, and certainly don't have the normal general dog like performance when th MAF has failed big time. Still I am wondering if mine is just on the edge.... Some days the car pulls like a rocket (rare), and sometimes it is really limp (normally after an overboost). Generally it does not feel as perky as I think it should. I would expect either perky or limp-home mode.....

Thanks :-)

Matt

Take a look here

http://www.myturbodiesel.com/1000q_how_to/a4/maf.htm

You really need to be comparing measured against requested at WOT. At WOT the EGR valve remains closed so you can compare the two values accurately.

What is WOT?

I grabbed a few figures before I saw your post, so maybe irrelevant, but here they are (fortuantely taken from group 003)

Test 1 (engine off)

Engine speed: 0 rpm

MAF (specified): 850.0 mg/R

MAF (actual): 1275.0 mg/R

EGR duty cycle: 4.8%

Test 2 (engine running)

Engine speed: 882 rpm

MAF (specified): 305.0 mg/R

MAF (actual): 325.0 mg/R

EGR duty cycle: 64.9%

Test 3 (engine running)

Engine speed: 2898 rpm

MAF (specified): 390.0 mg/R

MAF (actual): 395.0 mg/R

EGR duty cycle: 54.2%

It would appear from that (with no load on the engine, sat in the garage) that my specified and actual values are not far apart, and I can probably ignore the MAF from any future investigations?

What is WOT?

WOT = Wide Open Throttle

= flat out....

(feel sorry for any vehicles behind me )

= flat out....

(feel sorry for any vehicles behind me )

You will notice that the EGR duty cycle drops to its minimum value at WOT. IIRC this is 4.8%.

You should see a series a plateau between 800 and 850 for each gear.

Remember...

"Air through MAF" = " 'air' entering the engine" - "crap through EGR"

I would check the EGR to see if it is sticking.

Edited 30 March, 201016 yr by rwbaldwin

You will notice that the EGR duty cycle drops to its minimum value at WOT. IIRC this is 4.8%.

You should see a series a plateau between 800 and 850 for each gear.

I'll try and get someone to come out in the car and control the laptop for me and log some stuff.

Remember...

"Air through MAF" = " 'air' entering the engine" - "crap through EGR"

I would check the EGR to see if it is sticking.

Had the EGR assembly off the other weekend and gave it a good clean up (http://www.matthewames.co.uk/briskoda/index.php?loc=./20100314_egr_cleaning)