Fuel Pumps
Re: Fuel Pumps
Or maybe they reset to zero every time the ignition is turned off and the previous stored values are for the current “session”. This would be worth checking.
Next time it happens, plug the Vagcom in and check the measuring block before you turn the ignition off.
Next time it happens, plug the Vagcom in and check the measuring block before you turn the ignition off.
Last edited by Shoppinit on Fri Apr 19, 2019 10:47 pm, edited 1 time in total.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
Re: Fuel Pumps
Yes I did clear the codes last time I checked, to be sure I wasn't worrying about old faults. I'll make a small trip tomorrow and try to replicate the issue. Mind giving me a few hints about how to interpret those numbers? 

RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
Compressor Shut-Off Criteria
0 = Compressor ON
1 = Compressor OFF: Refrigerant Pressure too High
2 = Compressor ON: Reduced Performance Requested by Engine Control Unit (ECU)
3 = Compressor OFF: Refrigerant Pressure too Low
4 = Compressor OFF: Fault Code stored
5 = Compressor OFF: Engine not running or less than 300 RPM
6 = Compressor OFF: ECON Mode active OR Basic Setting not performed
7 = Compressor OFF: System deactivated (by Driver)
8 = Compressor OFF: Ambient Temperature too Low
10 = Compressor OFF: Supply Voltage too Low
11 = Compressor OFF: Engine Temperature too High
12 = Compressor OFF: Requested by Engine Control Unit (ECU)
14 = Compressor OFF: High Pressure Sensor (G65) faulty
15 = Compressor OFF: Evaporator Temperature too Low
No number 13. Superstitious Quattro engineers?
0 = Compressor ON
1 = Compressor OFF: Refrigerant Pressure too High
2 = Compressor ON: Reduced Performance Requested by Engine Control Unit (ECU)
3 = Compressor OFF: Refrigerant Pressure too Low
4 = Compressor OFF: Fault Code stored
5 = Compressor OFF: Engine not running or less than 300 RPM
6 = Compressor OFF: ECON Mode active OR Basic Setting not performed
7 = Compressor OFF: System deactivated (by Driver)
8 = Compressor OFF: Ambient Temperature too Low
10 = Compressor OFF: Supply Voltage too Low
11 = Compressor OFF: Engine Temperature too High
12 = Compressor OFF: Requested by Engine Control Unit (ECU)
14 = Compressor OFF: High Pressure Sensor (G65) faulty
15 = Compressor OFF: Evaporator Temperature too Low
No number 13. Superstitious Quattro engineers?
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
Re: Fuel Pumps
wow, many thanks! So I'll have a look if number 11 appears at some point..
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
So did you risk the RS6 or did you self-flagelate in the 208?
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
Re: Fuel Pumps
Ha, short story is that it's gonna be the 208
But things are progressing, here's the full story :
HVAC: definetely a faulty G65, you were totally correct in your assumptions as I've got now a nice series of shut-off criteria #14. At least this should be an easy fix, but I can't have the family suffer from heat during 600kms or so awaiting for a repair. So in all cases I'll be driving a Peugeot tomorrow..
Radiator cleaning: with the help of a local garage, I've done it the long way:
- One full dose of cleaning fluid in the coolant - wait 10 min engine idle then flush completely (with a gentle little help of an air compressor through the tank)
- Complete fill with demineralized water with another full dose of cleaning fluid - wait 10 min engine idle then flush completely (+ air compressor through the tank)
- Complete fill with demineralized water to rinse the circuit completely - wait 10 min engine idle then flush completely (+ air compressor through the tank)
- Add 5 liters of coolant whilst engine idle, then flush (+air compressor)
- Finally fill completely the coolant circuit
Good news is that we've seen quite a few black aggregates of dirt coming out of the circuit, so it was a well deserved maintenance for the car and I'm glad I've done it. Bad news is that it didn't change anything for the engine temperature, except if everyone now agrees that the BCY nominal temperature is around 98°C!
Oh and by the way, the coolant radiator cap is indeed on the right side of the car (when you look at the front), but the main bottom hose is definetely on the left side on my model. There could be some variants depending on the countries I suppose. We all know you guys have the driving wheel on the wrong side, so they had to adapt to it.. (don't shoot!)
Sooo in summary, and supposing the last point (engine temp at 98°C) is solved, I only have the MAFs discrepancies to fix. Wiring issues? Bad hoses below the air inlet? Faulty clamps? Broken turbo on the 'cold' side (bank 1)? Can't tell so far but it is narrowing down, isn't it?
BTW I've started a thread on the Rosstech forum to check if they have any bright idea regarding ECU that could have been tricked for some reasons regarding those MAFs readings, maybe something related to the programming could come off. I'll report here accordingly if there's something interesting to share.

But things are progressing, here's the full story :
HVAC: definetely a faulty G65, you were totally correct in your assumptions as I've got now a nice series of shut-off criteria #14. At least this should be an easy fix, but I can't have the family suffer from heat during 600kms or so awaiting for a repair. So in all cases I'll be driving a Peugeot tomorrow..

Radiator cleaning: with the help of a local garage, I've done it the long way:
- One full dose of cleaning fluid in the coolant - wait 10 min engine idle then flush completely (with a gentle little help of an air compressor through the tank)
- Complete fill with demineralized water with another full dose of cleaning fluid - wait 10 min engine idle then flush completely (+ air compressor through the tank)
- Complete fill with demineralized water to rinse the circuit completely - wait 10 min engine idle then flush completely (+ air compressor through the tank)
- Add 5 liters of coolant whilst engine idle, then flush (+air compressor)
- Finally fill completely the coolant circuit
Good news is that we've seen quite a few black aggregates of dirt coming out of the circuit, so it was a well deserved maintenance for the car and I'm glad I've done it. Bad news is that it didn't change anything for the engine temperature, except if everyone now agrees that the BCY nominal temperature is around 98°C!

Oh and by the way, the coolant radiator cap is indeed on the right side of the car (when you look at the front), but the main bottom hose is definetely on the left side on my model. There could be some variants depending on the countries I suppose. We all know you guys have the driving wheel on the wrong side, so they had to adapt to it.. (don't shoot!)

Sooo in summary, and supposing the last point (engine temp at 98°C) is solved, I only have the MAFs discrepancies to fix. Wiring issues? Bad hoses below the air inlet? Faulty clamps? Broken turbo on the 'cold' side (bank 1)? Can't tell so far but it is narrowing down, isn't it?
BTW I've started a thread on the Rosstech forum to check if they have any bright idea regarding ECU that could have been tricked for some reasons regarding those MAFs readings, maybe something related to the programming could come off. I'll report here accordingly if there's something interesting to share.
Last edited by Classik on Sun Apr 21, 2019 5:06 pm, edited 2 times in total.
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
Definitely feels like progress. The AC issue was a red herring.
At least the G65 is an easy fix.
How sure are you that the MAF seal is good? It still seems like a good candidate for the air leak. Can you test the pressure with the MAF in-situ? Maybe block off the top?
At least the G65 is an easy fix.
How sure are you that the MAF seal is good? It still seems like a good candidate for the air leak. Can you test the pressure with the MAF in-situ? Maybe block off the top?
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
Re: Fuel Pumps
Sure I will, although it's gonna be in aweek or so by now.. It's just that I have already unmounted and reglued it since we started the discussion, and it's the exact same behaviour. But I will try for sure.
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
A reminder for myself to address this MAF problem for good :
- check wiring, impedances, grounding
- find or build MAF wiring extensions to exchange left & right connectors
- leak test with higher pressure / vacuum
- leak test as described just above
- ignition retardant
- oem map checksum compared to a trusted oem map source (just added this one following discussions with Rosstech)
- check wiring, impedances, grounding
- find or build MAF wiring extensions to exchange left & right connectors
- leak test with higher pressure / vacuum
- leak test as described just above
- ignition retardant
- oem map checksum compared to a trusted oem map source (just added this one following discussions with Rosstech)
Last edited by Classik on Wed Apr 24, 2019 9:13 pm, edited 1 time in total.
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
For what it's worth, one S6 c5 (ANK engine) and one rs6 c5 owners confirmed the same figures : those V8 engines run hot, and to our surprise the consensus is indeed around 98-99°C nominal (as measured with VCDS) with new thermostats / coolant pumps.
And please don't ask about the 600km trip with the Peugeot, but at least we had aircon..
And please don't ask about the 600km trip with the Peugeot, but at least we had aircon..

RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
Good to know. 

Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
Re: Fuel Pumps
After leaving the car for a week, I can now come back to my MAF problem with a fresh mind. So I reopened the #@*! air box for the 100th time, and upon inspecting those MAF connectors again, I just noticed something wrong: when I look at the female connector with the square side on the right (round side on the left), the first pin on the left -say pin 1- is disconnected on both connectors (bank 1&2). By 'disconnected' I mean no wire is attached behind pin 1.
Is that normal? Please tell me it's not, could well be the reason for my headaches..
BTW, a diagram showing the correct pinout of the harness on both sides (big engine ECU connectors ===== MAF connectors) could really help to check continuity / impedances.
Thanks in advance for any help and the good vibes!

Is that normal? Please tell me it's not, could well be the reason for my headaches..
BTW, a diagram showing the correct pinout of the harness on both sides (big engine ECU connectors ===== MAF connectors) could really help to check continuity / impedances.
Thanks in advance for any help and the good vibes!
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
Sorry, dude. Nothing connected to pin 1 in those connectors. PM’d you a diagram.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."
Re: Fuel Pumps
Many thanks Shopp, but arrgh, I was so much hoping I had finally something to chew on...

RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
Continuing my electrical journey, I decided to measure what goes into these MAFs connectors, so here's the catch of the day:
Measurements are made on each pin compared to a direct link to the minus point of my battery. Key on but engine not started
Pin 1 : N/A not connected
Pin 2 : +1.8V
Pin 3: 17mV - Impedance to ground = 30 Ohms moving (*) for the left side of the engine (as seen from the front - Bank 1), 40 Ohms moving (*) for the right side (Bank 2)
Pin 4: +5V
Pin 5: 17mV - Impedance to ground = 10 kOhms on both banks
(*) by moving I mean the resistance measurement is constantly moving, like a floating ground.
With the help of the PM'd diagram, I'd say Pin 5 is the MAF output signal sent to the ECU unit J220 (high impedance which is logical), Pin 4 is the +5V power feed for the MAFs, and Pin 3 should be the ground power feed. It's not clear to me what Pin 2 is really about (tagged as 103 & 108 in the diagram). Green/yellow color would point to some sort of ground, but the constant 1.8V voltage makes me wonder..
So, except if there is a floating ground system to feed the MAFs, the moving 30 Ohms figures would point to the ECU ground not properly attached to the chassis ground. Where is the ECU ground supposed to be attached to the chassis ground?
Oh and on a different suject, when I key on without starting the engine, for like 10sec I can hear a whining and a not so nice crackling electrical noise coming from my throttle body adaptor. I'll try to clean the contacts, but I don't like the crackling noise (like those old 56k modems). Something to worry about?
Some days I hate this car, today is one like these...
Measurements are made on each pin compared to a direct link to the minus point of my battery. Key on but engine not started
Pin 1 : N/A not connected
Pin 2 : +1.8V
Pin 3: 17mV - Impedance to ground = 30 Ohms moving (*) for the left side of the engine (as seen from the front - Bank 1), 40 Ohms moving (*) for the right side (Bank 2)
Pin 4: +5V
Pin 5: 17mV - Impedance to ground = 10 kOhms on both banks
(*) by moving I mean the resistance measurement is constantly moving, like a floating ground.
With the help of the PM'd diagram, I'd say Pin 5 is the MAF output signal sent to the ECU unit J220 (high impedance which is logical), Pin 4 is the +5V power feed for the MAFs, and Pin 3 should be the ground power feed. It's not clear to me what Pin 2 is really about (tagged as 103 & 108 in the diagram). Green/yellow color would point to some sort of ground, but the constant 1.8V voltage makes me wonder..
So, except if there is a floating ground system to feed the MAFs, the moving 30 Ohms figures would point to the ECU ground not properly attached to the chassis ground. Where is the ECU ground supposed to be attached to the chassis ground?
Oh and on a different suject, when I key on without starting the engine, for like 10sec I can hear a whining and a not so nice crackling electrical noise coming from my throttle body adaptor. I'll try to clean the contacts, but I don't like the crackling noise (like those old 56k modems). Something to worry about?
Some days I hate this car, today is one like these...
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
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