VR6 MAF cleaning

[Rpmayne 0]

Have put up with the VR idling iratically and randomly stalling for some time, have just be greatful that it does generally work (don't expect too much). It's getting alot worse now, no power until I reach 1500rpm and idle can hunt from 500-1000rpm continuously.

 

Parts already changed for a variety of reasons.. Lambda, coilpack, HT leads, spark plugs, plastic box with foam in it (old one blew up due to dodgy ECU timing :roll: ).

 

Has got progressively worse so wondering whether the MAF is playing about.. Can it be cleaned with something, throttle body cleaner or similar?

 

Cheers.

[Taggart 0]

Tried cleaning the ISV?

[Toad 0]

The MAF (as far as I know, I don't have one) is essentially a coaxail type wire that runs accross the airflow, the outside of the wire is heated, and the inside has it's resistance measured, in order to measure the temperature.

 

Basically as the air flows over the wire, it is cooled. The more air, the colder it becomes. hence giving a reading for the mass of the air flowing through. The wire degrades and corrodes over time.

 

In fact I have heard that the company (South east asian, can't remember where exactly) went under because of the huge number of warranty recalls, and Bosch have had to buy the factory as there is no other facility for producing these.

[Toad 0]

Sorry, meant to say, it probably can't be cleaned.

[Rpmayne 0]

Cheers Toad, good info. Does it sound like that could be causing the problems?

 

Toad, did clean the ISV about 20k. Will have another go.

 

Any ideas where to get a MAF from other than £300 stealer.

[Guest]

I read on here last week that someone cleaned their MAF, and it helped loads, but can't remember the thread :-/

 

I'll have a hunt.

 

have you tried GSF and Eurocar for a price?

 

best bet would be to find a fellow VR6er locally, and see if you can drive round and try their MAF on your engine, then at least you'll know

[Roger Blassberg 0]

The hot wire goes through a self-cleaning process whereby it is heated to a very high temperature for a few seconds, either after the ignition is switched off or immediately after ir is switched on, (I can't remember which). It is a very fine wire indeed, (have a look, you came barely see it with the naked eye) and I can't imagine that you could clean it without damage.

 

As I understand it, in normal operation, the wire is kept at a constant temperature by passing an electric current through it; the current required to do so is a function of the cooling effect of the mass of air passing over it and the electronics work out that mass air flow by measuring the current. The ECU meters the fuel accordingly.

 

Best wishes

 

RB

[Rpmayne 0]

Cheers, just tried GSF and they don't stock them, and Eurocar want £284.00. Need to be dam sure its the problem. Does a mk3 golf VR6 use the same think, a mate has one of them I may be able to borrow the MAF off?

[antonio_b12 0]

this may help...

 

http://www.vwhowto.com/vwhowto/guide-view.cfm/id/83/

[Roger Blassberg 0]

I think that earlier ones do, but the later ones use a hot film MAF which is different. There is a part number moulded into the casing so you should be able to make sure that you are using the right one. Incidentally, VAG are knocking them out at about £180 at the moment. Not cheap, but a lot less than ECP. The sickening thing is that a lot of MAFs for other more recent cars are being sold for about £75, but we have to pay the Corrado tax.

 

Have you tried disconnecting it altogether to see if that has any effect? If it does not, it is almost certainly completely knackered.

Best wishes

 

RB

[Roger Blassberg 0]

Well you live and learn !! Real dedicated MAF cleaner. Thanks Antonio b12.

 

Best wishes

 

RB

[Rpmayne 0]

Haven't tried unplugging it, will do that later. Phoned GSF and they said they don't stock them, will try again if it turns out to be knackard.

 

Think I have some contact cleaner somewhere so will try that if disconnecting it makes no odds.

 

Dam Corrado tax, only thing keeps me going is knowing that older Audis are usually alot worse.

[Roger Blassberg 0]

Tried to order some MAF cleaner from Amazon.com but they won't send it out of US, and Amazon.co.uk doesn't list it. Anyone else know of a supplier accessible to UK?

 

Best wishes

 

RB

 

(incidentally, apologies for hijacking/monopolising this thread....)

[antonio_b12 0]

@Roger Blassberg - yea i notice that too mate...

 

my matey used brake cleaner?

 

said it worked well, i havent done mine yet will do soon...

[STORM 2 0]

Cant you get the MAF from Ford for their Galaxy VR6?

[steve @ 0]

:wink:

http://www.maplin.co.uk/free_uk_delivery/Contact_Cleaner_4153/Contact_Cleaner_4153.htm

[dr_mat 0]

Ford Galaxy has a later OBD2-style MAF I think.

If you have timing issues too, maybe you should consider swapping the ECU? It's not unheard of.

[vwgti 0]

the MAF from a Golf VR6 will work fine its the same so no Corrado Tax...

[Stan 24v 0]

Dude I have a MAF in the garage doing nothing. It works fine, well did when it was still on the car anyway. £70 posted if you want it ;)

[Kevin Bacon 5]

OBD1 wire MAF is the same price across Golf and Corrado. £350 last time I looked.

 

OBD2 film MAF is cheap as chips (Golf/Sharan/Galaxy etc etc), about £60 from GSF.

[Storm_VR6 0]

Rpmayne - If you haven't cleaned the ISV for 20K, there is a good possibility that you'll sort the problem by cleaning it again....

 

I had similiar problems and RW1 advised as follows:

 

It looks like a sticking ISV and it needs a good cleaning with carburettor cleaner on the moving metal shutter inside to remove the black deposits. Usually this will only last a few thousand miles before the symptoms gradually return. The good thing is that if it does start to return you at least know it’s the ISV before you outlay on an expensive part. That should sort the idle issues. If the engine is higher mileage, it may be that oil vapours are carbonising in the ISV so even with a new one, it will gradually return.

 

 

Hope this help.....

[Rpmayne 0]

Thanks for all the info. As long as the rain holds off tonight I'll try the ISV again, didn't get a chance to do anything with the monsoon last night round here. Funnily enough it didn't cut out once, although the complete lack of power under 1500rpm still remains.

 

Engine's on about 25k after rebuild so should be pretty tight but won't harm. Will let you know.

[DierWolf 0]

Thats your idle control valve doing that, mine was hunting like that and it was the valve.... still have another problem as well which i thought the icv would have solved but at least its not hunting anymore.

[Rpmayne 0]

I cleaned the ISV, did look slightly sooty but seemed to operate quick enough. Idle doesn't hunt so much now but the pull away is still well flat, and most importantly the intermittent stalling remains.

 

Tried disconnecting the MAF completely and the engine stalled immediately so its doing something. May bite the bullet and go for the VAG one, confirmed as £212.69 including the VAT (#021 906 462 which is the later type on some '94 and all '95 VR6's). Takes the piss that Eurocar are charging £284.00.

[Roger Blassberg 0]

Despite my previous misgivings, I cleaned my MAF with Halfords Brake Cleaner (predominantly isopropanol, so should evaporate without leaving a residue), and subjectively at least it feels to run more smoothly, particularly at low end of rev range.

 

Best wishes

 

RB