General: V50/S40 DPF or FAP filter removal

[daniel4894]

Originally Posted by Stew

Hello,
Not sure if this subject has already been covered but I thought I would post it in case it is of some use to people.
I have recently been having problems with my 2.0 TDI 2005 Volvo V50 going into limp mode. I did a diagnostic check and found it was showing a blocked DPF filter. I tried cleaning the filter with jet wash, detergent etc which worked for a while but it soon started to clog again as I use the car mainly around town. Decided that instead of replacing the filter I would try to remove it all together. Now I must point out before I go on that I am not some sort of electrical/electronic wizard, I just did a bit of reading and came up with a solution.

As you will probably be aware, you can’t just remove the DPF and begin driving again as the pressure sensor for the DPF will show a fault. To prevent this from happening you need to fool the ECU into thinking that the DPF is working fine. This was not as hard as I first thought. The sensor for the DPF (attached to the battery housing) is fairly simple. It has two pressure pipes which are feed from either side of the filter, an electrical socket with a 5 volt live, an earth and an output wire which sends a voltage to the ecu. I worked out that if the ECU receives a voltage of approximately 0.35 volts it believes that the filter is working fine. I therefore cut the three wires feeding the sensor and fitted a 5k Cermet potentiometer (see below). These can be found at Maplin or eBay for under £1.50p

http://www.maplin.co.uk/Module.aspx?ModuleNo=2202

These simply allow you to adjust the output voltage from 5volts down to zero in very fine increments. I then soldered the earth wire to the earth connection of the potentiometer, the 5v cable and output cable to the remaining connections on the potentiometer. Once that was done it was just a simple case of setting the output voltage to the desired reading which is approximately .35 of a volt and clearing any fault codes from the ECU. I also took the DPF filter off the car and removed the carbon insert with a large drill.

The engine has run for a few weeks now with no pending or current faults on the ECU.

Like I said at the start, I am no technical guru but I would say that anyone who can use a soldering iron, multimeter and a large drill could do this and save a fortune on replacing DPF’s or having your ECU remapped.

Hope this is of help to someone.

Cheers,

Stew

Do you have any pics that you can upload or a diagram with this fitted
I will be attempted the bypass procedure today at some point
many thanks

[dounroid]

Hi Getsome,

thanks for posting the circuit for the DPF. Is the LMM the air mass flow meter? Did you tie into the output from the line i.e. a parallel circuit in the ECU? Also what value did you set the pot to? What voltage outputs were you sending to the ECU?

thanks,
Chris

[getsome]

The LMM is just as you point out the air mass meter on the intake pipe. The circuit runs in parallel from the Air mass meter but the signal from DPF sensor is cut and a diode soldered inbetween , I set the pot to 0.48 V (as the DPF sensor itself has a voltage of 0.44 V with engine not running and 0.46 in idle with a clean filter). I have also done a little more experimenting and replaced this whole circuit with a 10 K pot soldered paralell over the DPF sensor and the strange thing with this is when the pot is just in the middle the value should read approx 2.5 V and approx 500 hPa in Vida (filter blocked beyond repair) on output but it doesn´t , instedad the volatge is 0.5-0.55 V and show as 4-5 hPa in Vida, I think something sinks the weak signal from the pot but this is only good news as this gives a nice variations on the signal when you drive and fools the ecu 100% , I can take a measurement of my values later this week if you want to skip the pot and just go for fixed resistors. But the downside is that my car still regenerates after about 600-1000 km of driving and will probably do until I get a proper DPF delete remap done.

[dounroid]

Done a quick measurement. When the engine's running or NOT running I'm getting the same readings.

+5V to SIG -> 4.7V dc

SIG to GND -> 0.3V dc

Maybe this would explain why, after I've driven for say 10 miles, I can turn my engine off and then re-start and it gets full power.

Am I right in assuming that when the ignition is on, but engine is off then the SIG to GND should be around 5V dc? I read somewhere that the sensors have a 0.45V off-set voltage. Maybe mine is faulty as it's reading low and reading the same value all the time.

[getsome]

Maybe your pipes are blocked with soot , try to disconnect the high side of sensor (marked with High or H) , connect a bit of hose and suck and have someone to read the voltage sig->gnd (with ignition on but car not runnning) , if you see a variation then the sensor is OK and you have sh*t in the pipes if not the sensor is faulty.

[scooby]

strange no one makes a dpf delete pipe out of stainless for the v50 you can get them for vw ets rather cheap of ebay

[dounroid]

5K resistor in parallel between +5V & SIG to give a higher resistance on the SIG to GND has done the trick. I haven't cleared the fault yet but I don't go into limp mode anymore. Cheers Getsome. For reference, I now measure 0.375V from SIG to GND. Time to get the drill out and rid myself of that DPF. I'll never buy another car with that installed and I think I'll never buy another volvo.

[getsome]

Little update
I have now sucessfully reflashed my ECU with a hand tailored DPF free MPC555 file . So no more DPF and good bye all regens forever.

[Like its stolen]

Thanks to this forum, i cut open the dpf, removed the internals, welded back together and modified the wiring by putting the 5k resistor in parallel between +5 and Sig. To my delight, it all worked perfectly! Had to clear the errors after starting but that was it. It had been blocked due to the turbo having blown and oil entering the dpf (i suspect). After replacing turbo, car was in limp mode and was giving dpf blocked error. Is now running fine. I only have about 200 miles done since removing it but so far so good. Im now just wondering if the car is likely to try and regenerate at some stage? If so, will this really matter, or will i even notice? Any thoughts would be appreciated.

Thanks for all the info, has saved me a lot of $$$$!

[getsome]

The car WILL regenerate since the function is still in ECM , you will notice it and people behind you will definitly notice it (smoke) ´, I had this mod on my car until I got fed up with regenerations happening every 600 km so I decided to do some digging and managed to disable the darn thing in ECM alltogether. If someone is interested I can supply file but not for free since I have put a LOT of work into finding the right bits and testing. I only have a file for the 2.0D Siemens SID803 (not 803A) ECU. My file makes the car like a stock Euro 3 V50/S40N from factory with ALL references of the DPF system deactivated.