Mfts -how much does it affect boost ?

[andyg plym]

So I've read a few posts regarding the mfts but just want to clarify.

As well as the temp gauge it sends signals to the ecu and can cut/reduce boost ?

I've got a lovely misfire still after switching to the 1.8t coil packs but my mfts plug is fooked and disconnected hence it running rich.

How does it affect boost ? I'm down to 1.6 bar from 1.8, also had a lambda fault code.......I'm thinking it all goes hand in hand

[andyg plym]

http://forums.quattroworld.com/s4s6/msgs/22584.phtml

[newsh]

The ECU does not use the MFTS for temperature info, it uses the white temp sensor on the back of the head, if the MFTS is disconnected it will not reduce boost.
Are you sure you don't have a boost leak? Maybe a leak in the PCV system?

[UrS4boy]

http://forums.quattroworld.com/s4s6/msgs/22584.phtml

Key part of that post of mine is: (hyperlinks disabled):

"The F76 Multifunction temperature sender has different functions in the ABY and ADU than the AAN. For all three, the MFTS is the sender for the temperature gauge in the instrument cluster. On the ABY/ADU, the MFTS is also connected to the ECU via pin 46 of the T55 ECU connector. Using this pin as a high temp alarm (> 119 C) - the ECU cuts off active boost control as a safety measure. However, for the AAN, pin 46 is not used, as indicated in this Motronic 20VT AAN pin-out. On the AAN, the MFTS F76/R pin connects to is the HVAC/climate system to shut off the compressor during such high temperatures. In addition, the MFTS is connected to the coolant temperature gauge. Reference for the ABY/ADU info HERE"

[220bhp]

MFTS will cut boost on a 3b. BTDT.

[Rusty]

MFTS does cut boos on ABY but the amount depends on the map and is a one-time hit, rather than a gradual reduction, like some of the other safety features.

Andy, I'd be surprised if it was responsible for your issues. IIRC, it pulls an ECU pin to ground as an over-temp alarm for coolant temps of 120degC or more and that kills boost.

Have you done any running with someone monitoring a laptop? Might be worth getting a £5 lead, as that's all I use and it's just fine.

[bilko0795]

Just changed mine as Mrc advised along with a lamba and finally after 3 yrs of ownership the car is running spot on and since i had a pro-speed turbo back system fitted it's even better

[newsh]

Guys, lets look at Andy's post..

So I've read a few posts regarding the mfts but just want to clarify.

As well as the temp gauge it sends signals to the ecu and can cut/reduce boost ?

Yes it can cut boost but it has to be plugged in to do so! The only signal it sends to the ECU is an over temp switch, no temperature info for calculating mixture.

I've got a lovely misfire still after switching to the 1.8t coil packs but my mfts plug is fooked and disconnected hence it running rich.

So Andy's MFTS is unplugged and cannot cut boost!

And since the ECU does not use the MFTS for calculating mixture this has nothing to do with the car running rich. If you're running rich on boost then you almost certainly have a boost leak.

How does it affect boost ? I'm down to 1.6 bar from 1.8, also had a lambda fault code.......I'm thinking it all goes hand in hand

AFAIK When the MFTS cuts boost you only get spring boost, ie a lot less than 1 Bar.

[martinws]

Newsh seems to have answered the original question well.

URs4Boy might be the man for this related question: Is the difference between ABY/ADU and AAN with regards to pin 46 a wire in the loom being different or is the pin in the AAN ECU not present? I have an ADU loom in my typ85 and im fairly certain I have an AAN ECU. so not sure if the MFTS will flag a high temp on my setup.

[S2central.net]

The AAN loom doesn't carry the signal from MFTS-R pin to the ECU... The AAN software running in your ECU should not be interested in this pin, but if that same ECU runs ABY or ADU software then the R-pin comes into play (as long as you have ABY/ADU loom).

[UrS4boy]

AAN Motronic ECU pin-out info

URs4Boy might be the man for this related question: Is the difference between ABY/ADU and AAN with regards to pin 46 a wire in the loom being different or is the pin in the AAN ECU not present? I have an ADU loom in my typ85 and im fairly certain I have an AAN ECU. so not sure if the MFTS will flag a high temp on my setup.

Paul's answered your question already. I would have said that "as far as I know, the AAN loom does not have a wire going to pin T55/46 on the ECU connector or if it does, the AAN ECU (with AAN-based chips) ignores the signal".

AAN Motronic ECU pin-out info WITH hyperlinks to each of the devices connected to the ECU: http://forums.quattroworld.com/s4s6/msgs/21009.phtml

[andyg plym]

so just put the blink code reader on and got 2111 and 4444- looked them up and apparently there are no faults..........

[UrS4boy]

so just put the blink code reader on and got 2111 and 4444- looked them up and apparently there are no faults..........

4444 = everything's good.

•2111 (Blink Fault Code), 00513 VAG1551/2 Fault Code Number
RPM sensor (G28) (ALWAYS PRESENT IF YOU PULL THE CODES WITH THE ENGINE OFF)
Open or short circuit, sensor malfunction
Defective sensor & cables, metal fragments on flywheel teeth
Symptom: Engine will not start, misfires, may stop running

[andyg plym]

I'm going to do another boost leak test tomorrow to rule it out....

Damn you misfire !

[newsh]

Do a low pressure leak test with the PCV system still connected, no more than 1 Bar.

Disconnect PCV and test to 1.5Bar, should hold up fairly well.

Check the DV as well by disconnecting the small vac pipe at the IM and sucking on it. It does not get tested when it's fully connected as you're pressurising both sides of the diaphragm.