How do you fit a MFTS?

[ian_jemo]

Hi all

Some of you are probably aware that my S2 is for sale. At the moment it is having a problem with a no boost issue so I have decided to try and fix it. Parts I have brought are a MAF Sensor, WGFV, & MFTS. I have practically changed everything else so Im hoping one of these will cure the 5PSI max problem.

My question is how do I fit a MFTS, is it just screwed into the water rail?

I presume as it is screwed into the water rail I'm going to have water coming out when I remove this part?

I brought a MFTS as I heard this can effect boost as well.

If I do fix it the car might not be up for sale anymore, cause I can just see it being way to fun

Thanks All

Ian

[S2central.net]

Yes - you are going to lose water out the hole where the MFTS lives - its a bit of a ****** to get at actually and the last thing you want is water pouring out in the middle of things. IIWUIW drain the coolant out at the bottom radiator hose to do the job - there might still be water left in the housing so dont be alarmed if you still get wet !

You might (not) like to know that only the ABY/ADU engine makes use of the high temp alarm from the MFTS to reduce boost levels. I'll have to double check that with the books at home but I'm 99% sure that is the case.

Have you checked your air temp sensor, coolant temp sensor (rear of head) ? What about the throttle pot ? How about the integrity of the WG itself - could it be jammed open ? Is the timing OK ? Have you thoroughly checked for air leaks ?

[ian_jemo]

Thanks for the info, you always the fountain of knowledge

Definately no boost leaks, checked and double checked holds pressure well. I'm sure the timing is ok.

Haven't even thought about these other sensors! Not even sure where any of them are.

Where is the air temp sensor? How much is this part?
Where is the coolant temp sensor? How much is this part?
Is there a way to test the wastegate being jammed opened???
Throttle pot, how do I go about checking this.

I'm looking to try and get the problem fixed this weekend, the more info I can get the better. Just causious about prices as if it is cheap I might as well get the parts you mentioned as they have probably never been changed.

Thank you

Ian

[audiman]

Fault codes?? Might save you loads of money, as buying loads of parts is a very expensive way to fix a problem. Unplug the MFTS and that should make car boost if the sensor is faulty, if you have the same prob, the sensor is not causing it and as they are £100 not worth fitting

[UrS4boy]

Yes - you are going to lose water out the hole where the MFTS lives -

You might (not) like to know that only the ABY/ADU engine makes use of the high temp alarm from the MFTS to reduce boost levels. I'll have to double check that with the books at home but I'm 99% sure that is the case.

Well I am not sure which engine you are talking about but AFAIK, the 3B ECU does make use of the Electronic Thermal Switch aka Multifunction Temperature Switch to limit boost but the AAN and ABY, etc. ECU do not. At least for an AAN, the MFTS is only really used to drive the coolant temperature gauge. The G62 coolant temperature sender provides the AAN (and ABY?) ECU with the temp info. See my AudiWorld post below for details (including part location diagrams - including the 3B intake air temp (IAT) sender):

http://forums.audiworld.com/s4s6/msgs/148742.phtml

If you are not happy with my explanation about the MFTS and the G62 sender, go to SJM Autotechnik's temp gauge page at:

http://www.sjmautotechnik.com/trouble_shooting/cooling.html#gauge

BTW, on an AAN, you can change the MFTS with a deep 29 mm socket and a stubby rachet in about 5 minutes (on a cold engine) without draining the rad (you lose about 200 mL). First remove the harness connection (boot may be stuck to the switch). Have the new switch handy. Using the deep 29 mm socket (you need the deep part to clear the electronic connectins), loosen the MFTS until you can turn it by hand. Continue turning it out until it is just about ready to come out, then quickly remove it but at the same time, plug the hole with one of your fingers. Swap the MTFS from that hand to your other hand and then swap the new switch back to Dutch boy finger in the dike hand. Quickly start threading the new switch in (DO NOT cross thread) by hand. Once its spinning in the minor leakage will stop and you can finish the job with the deep 29 mm socket and stubby rachet. Reconnect the harness connection and Bob's your uncle. I did this in my best Sunday clothes waiting for my wife to go out for Sunday brunch. (I had to wash my hands but no biggy).

HTH

Dave F.

[S2central.net]

Like I said - I was going on memory wrt the MFTS and whether the high temp alarm is used by 3B ECU to reduce boost. If only I can find my damn books !

UrS4boy could be right here (with his finger in the dike - heheh - lucky not to spurt G12 on his sunday best or what) on the 3B thing.

Paul

[S2central.net]

Bump - I stand corrected - just found 'the book' for the 3B and sure enough if the MFTS detects temp higher than 119celsius if throws a signal to ECU so that boost can be reduced.

[audiman]

LOL, i said that!

[S2central.net]

You did - I'm just old - I forget things

[ian_jemo]

cheers, I'll have a look this weekend and see if I can fix the problem, I have brought a MTFS already it cost about £50 from vagparts.

I might try and disconnect it, see if that brings back the boost. Hopefully parts will arrive tomorrow.

I'll keep you updated.

Ian

[Donker]

I changed mine without draining coolant. I thought a whole lot more coolant would come out of the rail but it was only about 10 ml or so. Just be careful not to get any into the plug for the MFTS, I taped mine up and afterwards I sprayed electronic cleaner into it. Too bad for me my 0,5 bar boost problem is caused by something else.

[ian_jemo]

This low boost problem seems to be a problem for quite a few of us.

And the main problem is it can be a few things that can cause it.

Would be a good idea for someone to start a thread regarding all things that effect boost. Probably be quite a long list tho

[S2central.net]

I have posted such a list in the past here - finding its the ****** - hence why I want to update s2central.net with such a faultfinding FAQ that links to the various procedures for testing things and providing component specifications.

Paul