Air Mass Meter

[Rockhopper66]

Please could somebody help. I have a Type 25 1990 Watercooled 2.1 litre petrol camper van and up until last Wednesday it was the most reliable van I had owned.javascript:emoticon(':lol:')
Laughing
On my way to work, in traffic the van stalled. It would start but there is no power and the engine would just about idle. After about 5 minutes, and the traffic building up, the van started again and continued as if nothing was wrong. However, when I tried the van later and it would only idle (poorly) on start up.javascript:emoticon(':roll:')
Rolling Eyes
I got it to a garage and they have changed the plugs, rotor arm, distributor cap and the ignition module. They have said that this has improved the spark but still the van fails to rev. They have now said they think it is the Air Mass meter, but cannot get hold of one from GSF or Europarts. The cost is also ridiculous - £180 + £60 deposit + VAT.javascript:emoticon(':x')
Mad
Does anyone know if the part is interchangeable with any other models or where I might get a secondhand one.javascript:emoticon(':D')
Very Happy
Thanks
Steve

[Bosun20]

I have the same sort of problem but not as bad on a 2.1 MV engine.
I`m just working my way through the advise on this web site www.vanagonauts.com.
There is a lot of things that might cure the problem first.
If it turns out to be your air mass,try some sites in America first.

[syncrosimon]

As it takes about 3 minutes to change one of these afm's I would find someone willing to swap out theirs with yours, and see if it is the problem. With an electrical meter it is straight forward to test the operation, haynes and bentley manuals have details.
Also I have tried to start my engine , and have forgotten to plug the afm in, she would tick over, just, but fail to rev up, sounds like yours. Best to check the wiring.
There are a few simple checks you can do to sort out these injection systems, a simple meter check on the wiring would be the first place to go, looking for broken wires, fault finding is time consuming, rather than particularly difficult. Also try by-passing the idle control module, take out the two little round black plugs (near the coil ) and connect them together, this unit can cause allsorts of problems.

The early 1980 Mazda's used an identical system, and the afm is similar to the contemporary vw systems, but the casings are different.

Has the garage confirmed that it is ignition, or are they guessing.?

See Here. for american advice as stated above.
http://www.vanagonauts.com/files/FIxSys ... xxxfix.rtf

[Grun]

Rockhopper66, Steve,

Here is the procedure for checking the AFM from the cheaper of the two publications that syncrosimon mentioned.

1.Unplug the wiring connector and disconnect the air inlet hose from the AFM.
2. Connect an ohmeter to the following terminals and observe readings.

3. Between terminals 3 and 4 resistance should be between 500 and 1000 ohms.

4. Between terminals 2 and 3 the resistance should vary as the AFM flap is moved back and forth.

5. Between terminals 1 and 4 the resistance should be........
At 0 Celsius 5500 ohms (approximately)
At 20 Celsius 2500 ohms (approx)
At 45 Celsius 1000 ohms (approx)

If resistances are not as specified renewal of the AFM is required. They suggest that the temerature sensor may be available separately.

Might give you something to work on

Mike

[bigherb]

Rockhopper66, Steve,


4. Between terminals 2 and 3 the resistance should vary as the AFM flap is moved back and forth.



Mike

That correct but what you are looking for is a smooth increase and decrease in resistance over the full travel of the flap whitout any dips indicating a worn, broken or dirty track.
Mike

[Simon Baxter]

not wanting to split hairs but..

AFM = Air Flow meter, i.e, it mechancially measures the FLOW of air and turns it into a electrical signal.

MAF = Mass Air Flow Sensor, measures the mass of the injested air by measuring the cooling effect on a "Hot Wire" or metal foil.

AFM's are fitted to T3's, MAF's arent.

AFM are fairly troublesum, most problems being the fact that it has a mechanical track inside, very similar to that of a scalextric controller.
The tracks wear, or get dirty and give false readings.
First job to do is remove the black plastic cover and carefully clean the track.

[Rockhopper66]

Thanks for all of your advice. The garage owner is a mate of mine so I'm going to go down with him and pull the unit off and have a look. If it is broken, I just hope I can get a replacement as they seem as rare as rocking horse poo!!!
Thanks again
Steve

[wasserleaker]

got my original one refurbed/recalibrated recently by ATP Electronic developments in staffs. as i have been running on one from a 1.8 golf/jetta for about a year, since the original suffered damage from a big backfire on LPG and jammed solid, it cost 140 quid to get it done, but it runs brilliantly
[IMG:640:480]http://i210.photobucket.com/albums/bb19 ... er/afm.jpg[/img]

[andysimpson]

got my original one refurbed/recalibrated recently by ATP Electronic developments in staffs. as i have been running on one from a 1.8 golf/jetta for about a year, since the original suffered damage from a big backfire on LPG and jammed solid, it cost 140 quid to get it done, but it runs brilliantly
[IMG:640:480]http://i210.photobucket.com/albums/bb19 ... er/afm.jpg[/img]

LPG good at doing stuff like that

[Ye Olde Syncrospares]

got loads of 2.1 air flow metres here for sale,cj.

[Simon Baxter]

LPG, yeah the destroyer of AFMs!

I have done quite a few too.

[grenjs]

Get a new set of leads.

Our Vanagon broke down in France (Paris) last year with the exact same symtoms. Turned out to be a bad HT lead.

[wasserleaker]

must admit, the van was running well rough at the time of the backfire that bust the AFM. due to various ign system probs, and it was stupid of me to try it on gas until it was tuned up properly, as you'll know, gas won't stand for duff ign components, it'll let you know it's not happy!