Volvo XC90 - D5244T4

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Re: Volvo XC90 - D5244T4

Postby volrem » Wed Nov 16, 2016 8:01 pm

P2002 is OBD code but Volvo uses different combination.

There are different conditions for limp mode. One being too high pressure, other too low pressure and so on.

You should have at least 5 mbar at idle. If there is no pressure then fault is logged. Cause could be hole in DPF.

But still need real DTC for more info.
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Re: Volvo XC90 - D5244T4

Postby Dave Hill » Wed Nov 16, 2016 8:10 pm

Hi STC

Have you provided the actual fault code yet? (sorry if I have missed it)

I am troubled by the 400 millibar (5.8 psi) at full load & zero at idle, something doesn't add up there, which possibly explains your problem.

When you say that this has had a new genuine sensor recently, can you be sure? You know how some folks will claim adamantly that it is a genuine product, until you finally prove that it is no good & then they reveal that they sourced if from Ebay :evil:

These sensors are incredibly cheap from Volvo & if, like me you are seeing a few, you probably keep them in stock?
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Re: Volvo XC90 - D5244T4

Postby STC » Wed Nov 16, 2016 8:39 pm

Dave
Most definitely a Genuine product from a Volvo Dealer. I have the Invoice and opened the box with my own fair hands. Google Diagnostics led the owner to purchase it and asked me to fit it.

Nope, I have not provided the actual fault codes or data (got lost somewhere) However the roads are quiet and I may go out for a drive tonight and get some graphed serial Data.

Watch this space.
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Re: Volvo XC90 - D5244T4

Postby STC » Wed Nov 16, 2016 11:11 pm

Here goes

The recurring fault code is,
2A20 Particulate trap. Faulty Signal - always the same
Volvo DPF.png



You can see from the Engine speed that at the first good attempt to raise engine speed rapidly the Pressure sensor registers at best 15 hpa which I believe is 15 millibar ?? -- Next to nothing ?

If you look at the Blue Line I have drawn then you can see RPM is falling at that point, DPF pressure hit Zero then defaults to 65535 (which is FFFF in Hexidecimal). That is the point at which the DTC & Limp home is set. Has always followed the same pattern.

I will provide Scoped Evidence, will have to collect it as the last lot disappeared, and I can assure you that the Voltage signal from the pressure sensor does not spike up to cause that 65535 hpa reading, it is in my view a Substituted value from the ECU. Ground & 5v Ref to the sensor does not flinch either.

The VIn is YV1CT714661297758

Volrem
You should have at least 5 mbar at idle. If there is no pressure then fault is logged. Cause could be hole in DPF.


I'm thinking the same as you, has someone removed the internals of the DPF and not mapped it out ?

I may at some point put a resistor between the 5v Ref and the signal wire to artificially hold it up at 6 millibar at idle. Alternatively, I wonder if I was to Adapt the pressure sensor with a 6mb vacuum applied to it, would it allow me ?

What DTC's then manifest at partial or full load (if any) will be an education and an insight into its strategy, and justify the expense of a replacement.
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Re: Volvo XC90 - D5244T4

Postby volrem » Thu Nov 17, 2016 2:08 pm

In first post you said that DTC is for DPF pressure sensor but now we know that it's for DPF itself (not pressure sensor). Very big difference.

Also you said pressure is 400 mbar but we can see that it's actually 15 hPa = 15 mbar. Also very big difference.

And still no actual glow plug DTC mentioned.

In short this car has DPF removed but not (correctly) programmed out.
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Re: Volvo XC90 - D5244T4

Postby Martinjensen » Fri Nov 18, 2016 9:49 am

Hi STC.

There are 2 different defenitions for DTC 2A20. Signal too high or too low.

From the data the signal is too low



Diagnostic trouble code (DTC) information ECM-2A20
Condition

Engine Control Module (ECM) compares pressure before and after particle trap.
If Engine Control Module (ECM) detects that the signal from the pressure sensor particle trap is too high or low, the diagnostic trouble code (DTC) is generated.
The diagnostic trouble code (DTC) can be diagnosed when the engine is running.
Substitute value
■ Limitation of engine output and speed.
Possible source
Signal too high
■ Contact resistance or oxidation in the terminals or connections.
■ Short-circuit to supply voltage in the signal cable.
■ Hoses/pipes for the pressure sensor particle trap has been changed.
■ Damaged differential pressure sensor.
Signal too low
■ Hoses/pipes for the pressure sensor particle trap has been changed.
■ The signal cable is short-circuited to ground.
Particle trap missing.
■ Damaged differential pressure sensor.
Fault symptom[s]
■ Poor performance
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Re: Volvo XC90 - D5244T4

Postby steevegt » Fri Nov 18, 2016 11:54 am

volrem wrote:
Permanent. Anything between few hundred and 20 000+ km. If ECM would stop regeneration then DPF would be clogged very soon. Definately in 20 000 km. I have validated by checking DPF pressure and accumulated soot quantity. Also by driving the car and checking exhaust temperature.

Software version may be different but I seriously doubt that this logic would be different. And there is no MIL for glow plug code.
...


I agree with you, in normal conditions the DPF should not last for a long time with active regeneration disabled...
But we may have a vehicle in "running" conditions for some time. I'm guessing 3000 km or more!? Don't know, may variate a lot from vehicle to vehicle, and other conditions.

It would not be wise for the software to disable the active regeneration without some type of warning to the driver, you're totally right...

With the new data that STC posted, the hypothesis of a clogged DPF being the cause of the DTC is 0 or very near that...

STC:
Can you endoscope the DPF and share some pictures? That will be nice...
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Re: Volvo XC90 - D5244T4

Postby STC » Fri Nov 18, 2016 7:50 pm

STC:
Can you endoscope the DPF and share some pictures? That will be nice...


Yes Steeve that would be a nice and a great idea but I wont be doing that anytime soon. This is a job I am doing in my spare time. It is more a project than a real job.

The Glow Plug Issue, the fault has not come back for a couple of days, anyway, as soon as it does I will deal with that even though it is not the cause of the Limp Home.

Next I want to experiment with resistors etc. in an attempt to make it believe (at Idle) a DPF is fitted. If I can achieve that then I want to see what DTC's I get, if any, above at idle right through to full load.

Once I have some additional evidence I will purchase and fit a new DPF. That is when I will take photos and come back with before and after waveforms. That may well be in the new year.

The retired owner left it with me in January, some 11 months ago, and is away in a sunny climate until at least March 2017. It must be fixed by that time.

Since then I have used it almost daily around town and the odd long journey (80 miles plus) - With the DTC cleared she pulls like a train !! and there is no evidence of The Particle Trap clogging or a Regeneration having taken place.
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