2012 CAAB Limp Mode [Resolved]

[mmi]

I took pictures with my phone of the options in "Output test" and Basic Settings" because the drop down menu closed on me when trying to sceenshot it.

Thanks - the available functions are (obviously) specific to engine type -
There is a test "Auxiliary Fuel Pump (FP) Relay". Also in Basic settings there is "Test of auxiliary fuel pump"

Unfortunately I don't know what to expect about these tests - and how to measure their output by VCDS. I'd guess it's worth trying what those tests tell?

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Anyways, the data capture from working van below. Everything seems to be as expected - no fuel pressure build up.



However, an interesting dip at 50.84 seconds in camshaft RPM. Otherwise follows engine RPM (divided by 2). Possibly because of "forced" shutdown just causing data loss.




Then I'm afraid fuel pump tests didn't produce anything useful - no real change detected in fuel high pressure sensor data. Just flat curves. Also the grey one "Reducing agent tank" shouldn't be relevant to your van.

 

[Limpy]

The fuel pump relay is working, csv file attached.
The test of the auxiliary fuel pump on the other hand did not work.
"Not running malfunction" and then "aborted safety reasons malfunction".
I felt this was it and ran over to the working van to do the same test, but exactly the same error message. damn it.

Tomorrow I will take the pump off and test it just to be sure.

Yes the 50.84 dip in the working van must be the ignition off.

Too bad the fuel pump tests didn`t provide any information.
I can hear the pump going for a few seconds after ignition on.

I cleaned the camshaft sensor and did 3 runs up to when the engine cuts, this time it didn`t die but went down to idle having gas pedal all the way in.
I don`t know if this is a coincidence or something to do with the cleaning.

So as it stands, the problem may be the fuel pumps or the camshaft sensor right?
I have been thinking of a clogged fuel rail, I may take that off too and make sure it is in working condition.

 

[mmi]

The fuel pump relay is working, csv file attached.

Ok. Also here the log file is somehow mysterious = plenty of empty rows in the beginning and unfortunately the data is similar to earlier ones - just steady but a noisy line.

The test of the auxiliary fuel pump on the other hand did not work.
"Not running malfunction" and then "aborted safety reasons malfunction".
I felt this was it and ran over to the working van to do the same test, but exactly the same error message. damn it.

Thanks for trying and letting us know... unfortunately the error messages are a bit cryptic... did you try both engine not running and engine running?

I cleaned the camshaft sensor and did 3 runs up to when the engine cuts, this time it didn`t die but went down to idle having gas pedal all the way in.
I don`t know if this is a coincidence or something to do with the cleaning.

That's interesting - of course could be just a coincidence.
Below the plot - fuel pressure gradually climb up on all three attemps. Actually at the end much higher than on your working van earlier (the bottom plot.. Post#20...)



Also engine RPM and camshaft RPM "stick together" - the latter here multiplied by 2 to align the curves on the graph
Also plotted is their difference - seems plausible. As they are sampled slightly at different times the jitter is acceptable on the graph.

So as it stands, the problem may be the fuel pumps or the camshaft sensor right?

Possibly/hopefully - at least need to eliminate those as causes. The high fuel pressure a kind of suggests overfueling but for a diesel I would expect it to "run-away" instead of dying.
Have you tried running the engine having the camshaft sensor unplugged?

 

[Limpy]

Really bad weather in Norway today so I didn`t get to all the things I wanted to BUT I had the camshaft sensor connector off and did a stress test,
csv file attached.

I plugged it back in and did a hefty stress test revving engine up to max
several times in a row to try to force a fault code to show itself but
to no luck. Csv of that is also attached.

I also did a test with as high rpm as possible as long as possible.

I tried the auxiliary fuel pump with engine running but got a error message
on both vans.

I have ordered a new camshaft sensor, just to eliminate it as a potential
cause.

It`s strange that the fuel pressure gradually climbs up when engine is about
to stall.
The fuel pressure regulator is new, but not from a well known brand.
I will try the one from the working van and take a new test.

 

[mmi]

BUT I had the camshaft sensor connector off and did a stress test,
csv file attached.

So apparently the fuel pressure went high up and engine died?



May I suggest to record only few (max 3) items at a time - for the set of 5 it takes full second to sweep all of them. It's getting difficult to see relations between the data items when things happen quickly. Also it's not necessary to record both IDE00021 Engine_RPM and IDE00405 Crankshaft speed as their data comes from the same sensor.

 

[Limpy]

Ai ai Captain!
New tests, with only rpm, fuel pressure and camshaft values.
And a new stress test, all tests with turbo mode.

 

[mmi]

Interestingly the disconnected cam sensor reports steady 429.8 rpm full time. I guess having open circuit can do strange things

all tests with turbo mode.

The last one - no, I'm afraid not The samples are spaced by 0.6 seconds in this one.
In the 1 & 2 samples have 0.4 second spacing.

Anyways - still the same - fuel pressure climbs up and engine stalls or dies?

Have you had a chance to verify delivery rates of supplementary fuel pump and fuel system pressurisation pump (lift pump)?
As per workshop manuals

https://cardiagn.com/vw-transporter-2010-15-4-cyl-diesel-engine-2-0l-enginecr-caaa-caab-caac-caae-ccha-cchb-cfca-caad/

https://cardiagn.com/vw-transporter-2010-15-fuel-supply-system-diesel-engines/

New injectors coded with VCDS
New fuel rail pressure sensor
New egr & egr cooler
New turbo & actuator
New throttle body
New intercooler
New diesel & diesel filter
New MAF & rear Lambda Sensor

The fuel pressure regulator is new, but not from a well known brand.

Hmmm...

I guess there should be a couple of measuring values available - something like these

Fuel pressure regulator valve actual value​

Fuel pressure regulator valve activation​

Fuel metering valve actual value/feedback​

Fuel metering valve activation​

 

[Limpy]

The steady 429.8rpm cam sensor reporting must be because I unplugged it whilst engine was running.
I was sure I did turbo mode on all but I guess not, my bad.

I will take a look at that link and come back with an update after the cam sensor has been changed, looks like quite the job, seems like the timing belt must come off because the cable goes behind the support pulley.
Oh well, that way I can check the timing once again (3rd time) I have also ordered timing tool set so I can put that to rest.

Again, thank you for taking the time to analyse and replying back so quickly.
I appreciate it!

By the way, what software do you use to convert the csv files into graphs?

 

[mmi]

The steady 429.8rpm cam sensor reporting must be because I unplugged it whilst engine was running.

Thanks - that explains it.

By the way, what software do you use to convert the csv files into graphs?

Microsoft Excel. Attached an example if you want have a play.

 

[Limpy]

Thank you!
I'll be back when cam sensor and timing belt has been done. Should be end of the week or early next week.

 

[Limpy]

I did fuel, air and crank/cam tests on both my van and the working van at idle and then 2500 rpm while waiting for the parts to arrive.
Here are the results.

 

[mmi]

I did fuel, air and crank/cam tests on both my van and the working van at idle and then 2500 rpm while waiting for the parts to arrive.
Here are the results.

Thanks for sharing the data. Some intriguing details in there...

Fuel Pressure​

In both vans the actual fuel pressure is higher than specified.
"My van" +16% higher (average of all data)
"Working van" +12% higher (average of all data)

Charge air pressure​

Intake air mass​

The confusing part is air mass flow (lower pair of the curves)
In "My Van" actual air mass flow is +16% higher than specified.
In "Working Van" they are very close to each other.

Done DPF & EGR delete & removed particle filter & blanked off EGR on the exhaust side.

Is the "EGR delete" a ECU software to accommodate blanked off EGR (see specified vs. actual airflow above).
Does "Working Van" have EGR?

 

[Limpy]

Regarding the high percentage of the air mass flow, can that indicate a leak?

So the lack of the air mass specified value mg/stroke spike-up on my van is
because of the blocked off egr?


I took my van to a DPF & EGR Specialist to delete the dpf and egr from the ECU, the dpf filter is also removed and the egr is blocked from exhaust side, hoping to solve the stall problem but it didn`t help.

I haven`t done that to the working van.

 

[mmi]

Regarding the high percentage of the air mass flow, can that indicate a leak?

Well, anything is possible but for the mapped engine perhaps just the way it was implemented?? Anyways, difficult to imagine this would cause the engine stall.

So the lack of the air mass specified value mg/stroke spike-up on my van is
because of the blocked off egr?

Again, very difficult to say anything definite. Also, because of fairly slow sampling rate it could be just a "missed" value. On the other graphs it is just a one sample - so the "thing" didn't last very long - possibly captured there just by chance.

I took my van to a DPF & EGR Specialist to delete the dpf and egr from the ECU, the dpf filter is also removed and the egr is blocked from exhaust side, hoping to solve the stall problem but it didn`t help.

Ok, so the stalling did happen also before the DPF&EGR delete.

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EDIT:

Spoiler: A similar case - CAAC engine

VW 2012 Transporter engine CAAC loosing power above 2k rpm

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forums.ross-tech.com

 

[Limpy]

Ok I understand.
Yes, I did the DPF&EGR delete hoping that would solve it.

 

[Limpy]

The Auto Parts Store sent me the wrong sensor, so it took much longer time than planned.
That said, the stalling persists after I have changed the cam sensor and re-done timing belt.
I noticed something, my engine has alot of blow-by air when I take of the oil filler cap, the working van has almost nothing.
I guess that can be worn out piston rings, but the compression test showed around 300/min on all four cylinders.
What a strange problem this van is.

 

[Limpy]

I stand corrected, both of the vans have similar amount of blow-by.

 

[Limpy]

I managed to fix the van yesterday!

The culprit was the diesel return hoses, they had become clogged due to crumbling from the inside.
So the reason fuel pressure went up was because of the return flow was partial blocked and insufficient.

Just a heads up to other owners.

I want to thank mmi for all the help and all the graphs, much appreciated!