Club 80-90 Forums

Did you also check the temperature sensor in the AFM? This one controls which fuel map is chosen in the ECU

Hi, Yes I checked the temperature gauge and it was within spec at two temperatures.
I've ordered a new Brake Vacuum Hose from Brickworks, just to eliminate it if nothing else.
Also ordered new injector seals in case the garage reused the old seals when putting the engine back together after the rebuild.
I'll keep you posted.

OK. Another update.
Just to recap the symptoms, there is a slight lumpiness at mid revs (i.e. 30-40mph in 3rd; 40-50mph in 4th), like a misfire.
Fuel injection specialist has checked timing, AFM and adjusted the mixture. The mixture is fine at idle but runs weak at higher revs.
Engine rebuild 3 months ago.

Things which I have tried: -
Checked manifolds for leaks and sealed gaskets.
Replaced Brake Vacuum Hose, and vacuum pipes to dizzy and fuel pressure regulator.
Cleaned earths.
Checked Temp I & II sensors.
Checked timing.
Checked fuel pump delivery rate.
Checked injector spray pattern and delivery rate.
Problem still exists.
My next thought is to check the fuel pressure regulator, for which I will need a pressure gauge.
Any suggestions would be welcome.

Hi,

Okay you speak of lumpiness and before about running lean. As I'm Dutch hope I understood your English and problem correctly.
I drive a 1.9 DH petrol injection and had a severe hesitation around 80km/h (50mph) and for me it was the AFM that was causing these
symptoms.

Your AFM has been checked do you know how it has been checked ? The AFM is basically a a vane that moves a arm
across a resistor board that will wear down. Especially on spots that related to the most used speeds. Using a scope and
providing the correct voltage you could see dips in the signal when moving the vane or with an analog resistor meter (digital is probably to slow).
Those dips will result in incorrect injection amounts and that the engine holds in and when arm moves to a new spot in the AFM and the ECU
gets a value again it will inject the correct amount.

When this happens and you change speed (accelerate/decelerate) the engine should go back to normal running.

Cleaning the resistor board can help, also bending the arm slight to create a new path can help.
If you google vanagon AFM cleaning you will find a lot of information.

I cleaned my AFM resistors paths, added a wire to the arm for a better connection and bend the arm slightly to create a new path which helped greatly.
I sourced an other AFM as backup and now trying an alternative using a resisterboard from a Chinese webshop or a contact less solution

Contact less solution:
https://www.vwt3.at/index.php?/topic/45 ... nkelgeber/

Cleaning and measuring links:
https://www.thesamba.com/vw/forum/viewt ... hlight=afm

https://www.ericthecarguy.com/kunena/co ... ean-fiddle

https://www.bimmerforums.com/forum/show ... ng-idle%29

https://www.youtube.com/watch?v=7s985zg3s48

https://itinerant-air-cooled.com//viewtopic.php?t=7761

Chinese resister board:
https://nl.aliexpress.com/item/32974486 ... 4c4dhS12B6

Hi Jacobh
Thank you for your advice, in your excellent English.
I have cleaned the AFM track previously, but I will test it using an analogue multimeter as per your suggestion.
The links you provided are fascinating and informative. I was interested to see in the link for a Contactless meter the graph of resistance vs angle. It clearly shows that the resistance increases in a linear way (i.e. straight line graph). Is this correct in your opinion? Does anyone know for sure if this is the case?

I am genuinely very excited about the contactless repair. Brilliant work by our Austrian friends.

Sent from my S60 using Tapatalk

Excellent retainable information.
Thanks