MFTS Do ABY/ADU use it ??

[alg]

Thanks Paul

[S2central.net]

For 3B - the 'R' pin of the MFTS (F76) does indeed connect to pin 36. When coolant temperature exceeds 119celsius this pin is activated on the MFTS and the ECU reduces boost pressure. The 3B gets actual water temperature from G62. This is the same behaviour as the MB, MC, 1B and 2B engines although a different ECU is used.

The self study manual for the Audi S4 (AAN engine) dated March 1992 clearly states on pp7 that MFTS input is no longer used. The schematics in that book reflect that.

The ABY Motronic manual dated 09.92 however clearly states (Page 24-79) that MFTS is used by the ECU at pin 46. If the voltage on the R pin is greater than 2V then everything is normal. If R pin voltage is below 2V then boost pressure is reduced. My ABY schematics agree with this, showing a blue/white wire from MFTS pin-R that connects to the ECU on #46 via one of the cylindrical connectors on the wiring loom in the engine bay - T8f pin #5.

I expect the RS2 will follow ABY logic.

Need to dig up a bit more info from Bentley manual to see if later AAN is any different to this.


Paul

[UrS4boy]

Hi Jas

My personal suspicion is the the ABY / ADU / ANN all just use the G62 for engine temp, and the MFTS for the dash temp gauge.

Is this why earlier MFTS have 4 teminals and the later ones have 3 terminals ???

ASPRO

I know on my AAN'd 93 S4, the MFTS is only involved with the dash water temperature gauge. When it fails, water temps are low and/or go up and down, fluctuating for no reason. With the Automatic climate control diagnostics, on Channel 51, you can check the coolant temp and figure out whether its a thermostat problem or the MFTS. BTDT both for the thermostat and the MFTS.

Dave F.

[S2central.net]

Guys - let me go away and look at this one... When I put that part of the site together it was a LONG time ago. There is some confusion on my description based on what I think I know now.

I have the schematics for 3B and ABY/ADU here - official ones from Erwin. I also have the various Group 24 & 28 manuals on both engines... Plus some other 20VT training books so I'll get a definitive answer - unless Audis own info is misleading (which it sometimes is).

Paul

[aspro]

Hi Jas

With the engine warm how about hooking VAG-COM up and uplugging the MFTS to see if it does do anything to the realtime readout in graph mode. if it does anything fuel related you should see the inj duty cycle change.

My personal suspision is the the ABY / ADU / ANN al just use the g62 for engine temp, and the MFTS for the dash temp gauge.

Is this why earlier MFTS have 4 teminals and the later ones have 3 terminals ???

ASPRO

[UrS4boy]

Don't know Alastair. Mike usually has his stuff straight.

Jas..

I am sure Mike is a great guy. However, if you go to his write up on the changes in the Motronic between the 3B and ABY:

http://s2central.net/motronic_03.html

You will find the following quotation in what Mike wrote:

"Also in deference to the 3B engine, the multifunction thermoswith (F76) is not used by the ABY Motronic ECU"

So he is not being consistent between this write-up and his pin-out. I think the write-up (and my AAN pin-out for example) is correct. (But I could be wrong). I am pretty sure the AAN does NOT use pin 46 or the MFTS for ECU input so I would think the ABY is the same.

Mike?

[alg]

It would be nice to have a definative answer Jas.. If there is no 'talk' to the ecu on ABY/ADU its one less thing to worry about unless coolant temp gauge goes haywire and/or false warning lights. If u see what I mean.

[Jas11n]

Hang on. We know Paul's source of info Audi service manual referenced on the site. What was Mike's source ?

Don't know Alastair. Mike usually has his stuff straight.
Do you want me to pop into my local specialists and have a look at their ABY and ADU Motronic schematics?? Its stuff supplied by Bosch themselves rather than erwin sourced info from Audi.
I suppose Bosch would have the correct diagrams.

Jas..

[alg]

Hang on. We know Paul's source of info Audi service manual referenced on the site. What was Mike's source ?

[UrS4boy]

Really sorry to do this, cos it'll cause confusion.

Mikes site has 3B and ABY pinout's side by side.
Guess what? no input from MFTS to pin 46.
So which is right?

LINKY

I'm off >>

Well, the ABY info is consistent with my AAN info for pin 46. The 3B info for pins 36 (MFTS) and 46 altitud sensor is the same as I have in the VAG111 Self Study guide for the 3B 200 20vt.

I don't see any confusion. The AAN and ABY ECUs do not use any signals from the MFTS.

[Jas11n]

Really sorry to do this, cos it'll cause confusion.

Mikes site has 3B and ABY pinout's side by side.
Guess what? no input from MFTS to pin 46.
So which is right?

LINKY

I'm off >>

[UrS4boy]

Hi all

I am pretty sure that on the AAN the G62 is the sensor that sends the coolant temprature signal to the ECU.

The MFTS may still do somthing boost related but G62 defo tells the ecu what temprature the coolant is.

I recently changed mine and gained 4MPG so the ecu must have been permenantly thinking it was cold and increasing the injector duty cycle.

ASPRO

I am not sure how this will translate to an ABY but there is no MFTS input to an AAN. Only two temps Pins 44 and 45. See below

Pin-Out for the T55 AAN ECU (or Engine Control Module (ECM)) connector

The AAN ECU connector has 55 pin positions. The pins are arranged in three rows. The longest row has 19 pins, Pins 1 through 19. Pin 1 is nearest the metal release lever on the harness connector. The middle row is Pins 20 through 37, with Pin 20 nearest the metal release lever. The last row is Pins 38 through 55 with Pin 38 nearest the metal release lever. Not all pins are used.
The following are the Pins and their assignment. The information is taken from the Robert Bentley manual with comments based on VAG service manual information and some experience. The Letter/Number, e.g. N71, are for the devices that are either being controlled or are sending a signal to the ECU. The Letter/Letter code is the wire colour code. Not all pins are used – especially on the standard transmission cars.
Pin – Assignment – Device Code – wire colour (Code at bottom) - Comment if any
1 - Output to Power Output Stage – N122- G/W- for Coil No. 1 (N122 Pin 4/4)
2 - Output to Power Output Stage – N122 – V/BK – for Coil No. 2 (N122 Pin 3/4)
3 - Output to Fuel Pump Relay – J17 – BR/Y - ECU triggers the relay after it gets the G40 cam position sensor signal
4 - Idle Air Control Valve (aka Idle Stabilization Valve (ISV)) - N71 – W/Y the ISV is used to control the idle, e.g. when the air compressor come on.
5 – Output (Fuel) Tank Breather valve N80 – W/R- Controls the evaporative emissions frequency valve - N80 – to cycle evaporated fuel vapours back in to the engine (NOTE: Bentley shows this as T55/3 on page X57 – presumably in error) VAG143 has it as N80.
6-Connection to A/C Control Head –E87- G/Y – likely related to shutting off A/C under wide open throttle (WOT) and/or when the engine is too hot and the extra load from the A/C compressor puts the engine in jeopardy.
7-Mass Air Flow (MAF) Sensor - G70 - G/W – the MAF allows the ECU to know how much air (by mass) is heading to the cylinders so it can adjust the fuel, boost and timing to suit the conditions
8- Input from Hall Sender - G40 – GY/R - signal wire
9 - Barometric sensor – G16 – GY/BK – provides a signal to the ECU to help control boost at higher altitudes – between 1000 and 4000 meters – prevents the turbo from spinning over 155000 rpm.
10- Ground for Lambda (Oxygen) Sensor – G39-BR/R
11-Input from Knock Sensor No. 1 - G61- G/G - for cylinders No. 1, 2 and 3
12- Power Supply (+5V) out to Hall sender – G40; Throttle Potentiomenter (G69) and Altitude Sensor (F96) - R/R –
13- Output to Data Link connector “L” for diagnostics - W/R
14-Ground for Fuel Injectors (N30-83)- BR/W - ground on intake manifold
15-Not Used
16. Output control signal to Fuel Injector No. 5 – N83 – W/BL
17. Output control signal to Fuel Injector No. 2 – N31 – W/BR
18- Constant power supply to ECU J220 – R/R- from power terminal 30 (+12V) Fuse S26 (5A) – passenger footwell
19- Ground from the ECU for various ECU controlled devices – BR/R – to intake manifold
20 - Output to Power Output Stage – N127 – BK/Y – for Coil No. 4 (Note – some early versions of the Bentley have this as Coil No. 5 – but this is wrong, it is 4 – check it yourself) - VAG143 has it correct.
21- Output to Power Output Stage – N127 – BK/W – for Coil No. 5 (Note – some early versions of the Bentley have this as Coil No. 4 – but this is wrong, it is 5 – check it yourself)- VAG143 has it correct
22 - Data Link Connector – W/BL – linked to Check engine light (Malfunction indicator lamp) – also used in the blink code check.
23 – Output to Power Output Stage – N122- BK/GY signal for Cyl #3 Ignition coil
24- Power Ground for “actuators” other than injectors – Not found in Bentley, presume BR/R, ground to intake manifold
25- Mass Air Flow (MAF) Sensor (aka - hot-wire air volume meter) - G70 – G/V- Burn off signal from ECU – every time the engine is switched off, the hot wire is heated to 1000 deg C for one second to keep it clean
26- MAF – G70 - R/BK- “Reference voltage, earth (ground) in”
27- Switched Power to ECU from power (+12V) – BK/G - from Terminal 15 under the knee bolster – 15A circuit breaker, BK in BK/G out – S64
28- Heated Oxygen (O2) Sensor - G39- G/G- input from sensor
29-Input from Knock Sensor No. 2 – G66 - W/W- for cylinders No. 4 and 5
30- Ground for ECU and ECU sensors - G/BK
31- Fuel consumption signal for trip computer – BL/BK – Note: only used in N.America on 92 spec cars
32-Output toTrip Computer Boost Pressure Gauge – Y/BL - Note: only used in N.America on 92 spec cars
33 - Waste Gate Frequency Valve – N75 – Y/R – also know as the charge pressure control actuating valve – lets the ECU control the boost – by dumping excess boost through the waste gate
34 – Output control signal to Fuel Injector No. 3 – N32 – Y/BL
35 - Output control signal to Fuel Injector No. 4 – N33 – Y/G
36 - Output control signal to Fuel Injector No. 1 – N30 – W/V
37-Switched +12V for all 5 Fuel injectors (N30-N83) and MAF (G70)- BK/R – 15A - Circuit Breaker S72
38-T6ag Coding plug -Pin 1-GY/W
39-T6ag Coding plug- Pin 2- GY/Y
40-Input from Engine Speed Sensor – G28 – V/BK – Also connected to Ch.28 in the A/C head (you can read out RPM in the A/C head)
41-Signal from A/C control module –W/W – signal used by ECU to increase idle speed through ISV control when A/C compressor is activated (actually just maintains the idle seed when the extra load from A/C compressor is added to the system during idle)
42 –Gear selection input – Automatic only
43 – Not used
44 - Intake Air Temperature (IAT) Sensor - G42 – BR/BL – the ECU uses this signal to dial back timing (and power) to prevent pinging if the intake air temp is too high
45 – Engine Coolant Temperature Sensor - G62 – GY/BR – the one at the back of the head that the AAN ECU uses to figure out if the A/F should be enriched because the engine is cold.
46. Not used
47- Input from Crankshaft Position Sensor – G4 - V/V – used by the ECU to control ignition and fuel injector timing
48- Combined ground through ECU for G4 crankshaft position sensor and the G28 engine speed sensor – R wire from G4 and BL wire from G28
49-Input from Engine Speed sensor – G28 – GY/GY
50- Road Speed signal output (input?) to Instrument Cluster-G21-W/BL–signal also goes to Automatic Climate Control Head Channel 17 – which you can read out speed as well.
51- Not used for standard transmission cars – relates to shift point for automatic
52 - Idle Switch – F60 V/V– a microswitch inside the G69 throttle potentiometer that tells the ECU that the throttle is closed
53 - Throttle valve potentiometer - G69 – GY/GY the potentiometer on the throttle body that tells the ECU the degree to which the throttle body is open
54- Not used for standard transmission cars – relates to automatics
55- Output to Data Link connector “K” for diagnostics - G/R

Wire Colour Codes:

BK = Black
BL = blue
BR = Brown
CL = Clear
G = green
GY = gray
LT G = Light green
OR = orange
R= red
V = Violet
W = white
Y = Yellow

Examples:
W/V = white with a violet stripe
R/BK = red with a black stripe

[alg]

Thanks missed that

[Jas11n]

It definitely has an input into the ECU on an ABY and ADU engine.
As Stu said above, pin 2 of the MFTS goes to pin 46 of the main ECU connector.
I guess only someone like Minhea etc (tuners) will know exactly what that input tells the ECU and then what the ECU does with it.

Link to ECU pinout for the ABY/ADU >>> here

Jas..

[alg]

This may or may not help but for an AAN, the ECU gets its coolant temp from the G62 sensor on the back of the head, not the MFTS, like the 3B uses. For more info, check out my post on my FAQ page in the UrS-car forum on AudiWorld:

http://forums.audiworld.com/s4s6/msgs/150040.phtml

HTH

Yes I had noted the AAN from 92-96 did not according to the sjm site