Audi A4 2.0 TDI Rough idle

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nelnun
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Re: Audi A4 2.0 TDI Rough idle

Post by nelnun » Mon Feb 26, 2018 9:29 am

Shooter wrote:Can we see a Crank Sensor waveform, with at least 4 or 5 revolutions across one screen, when it is running bad ?
Hi shooter, thanks for your reply! I don't have it, it is really hard to access the sensor! But why would that be a problem if when I simulate a coolant temp below 40ºC or above 50ºC it idles perfectly? :roll:
Thanks

nelnun
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Re: Audi A4 2.0 TDI Rough idle

Post by nelnun » Tue Feb 27, 2018 10:22 am

On the 1st and 2nd red box, coolant temp was set to ~33ºC and it was idling perfecly, as you can see on the RPM flat line.
Then, the 3rd red box, I've increased coolant temp to 120ºC (fans stared spinning, message in the MFD and red temp light on) and it was idling perfect as well, but the reason here was probably due to the opened EGR.
In this coolant emulation temp test, even above 50ºC, it still failing, but rough idle will happened always when I start engine with a coolant temp between 40-50ºC, according to all of my tests! What an odd thing!
Software issue? I'm tempted to do the dieselgate fix to check if the problem goes away, but I don't want the fix... perhaps, it be mandatory next year...
Coolant_Emulated.jpg
CoolantTemp

Shooter
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Re: Audi A4 2.0 TDI Rough idle

Post by Shooter » Fri Mar 02, 2018 1:04 pm

Hi shooter, thanks for your reply! I don't have it, it is really hard to access the sensor!


I agree that it is not easy to access the CKP on this engine but "No Pain - No Gain" You should be able to get a reading somewhere in the loom or at the ECU itself
But why would that be a problem if when I simulate a coolant temp below 40ºC or above 50ºC it idles perfectly? :roll:
Thanks
What I am experiencing with these VAG CR Diesels of this era is that they do suffer from Injector faults with various symptoms. For example:
1. Misfire, shuddering only for a few seconds, only when cold.
2. Fuel pressure loss at heavy load only
3. Straightforward, constant misfire
4. Incomplete combustion smell
.... .......... ................

The odd thing is that it always (in my cases) just one injector, more surprising is that it always Injector 2 or 3 and none of these vehicles ever come back with another injector failed. It is as though some one is fitting one sub standard injector to each engine ??? :shock:

I note that you can manipulate Coolant Temp and promote change in that engine. The reason behind asking for the CKP signal is to establish what contribution each cylinder is contributing to engine rotation.

Also the fact that you have had this issue since you purchased the vehicle, in my head, raises alarm bells about software / bad mapping. My advice is that you get the "NOx Fix" Update done at the dealer. As part of the update you will get an additional 2 year warranty on all related parts ie. EGR, Injectors ..... ..... ...... ......

This could be your trump card

nelnun
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Re: Audi A4 2.0 TDI Rough idle

Post by nelnun » Sat Mar 03, 2018 2:53 pm

At the moment, I can discard the injectors, once they were already replaced (refurbish by bosch)! Reading the injection deviation oh the 4 injectors, when it is failing with rough idle, there are always one cylinder that increases deviation above 1mg/str, but it a kind of random thing, as sometimes is #1, other times #3, #2, 4#.... It seems to be trying the warm up phase (injection quantity increases quite a lot, from 5mg/str to 8/9/10, always oscillating around these values) for a regeneration before coolant temp reaches 80/90ºC?!

My problem is if I do the FixUpdate and the problem still persists, I'm back to "ground 0", but, I have to give it a try...

nelnun
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Re: Audi A4 2.0 TDI Rough idle

Post by nelnun » Wed Jul 25, 2018 7:55 am

Hi all!
Just a quick update!
I've bought ODIS to upgrade/downgrade the ECU software.
I changed it from version 6190 to 5597 and nothing has changed! Then, I changed it from 5597 to 9980 (fix file) and the rough idle problem has just disappeared!
Maybe, the issue is still there, but as the injection process is now different, the issue doesn't came up, who knows...

Anyway, I would prefer the sporadic rough idle then the fix file, but I will test it for a while!

nelnun
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Re: Audi A4 2.0 TDI Rough idle

Post by nelnun » Wed Aug 22, 2018 3:03 pm

Hi all,

I've been doing a lot of logs to try to understand what is going on!

After rollback to v.6190, the problem came back!
I've made some tests to the PRV and IMV with a PWM emulator, as following:
- PWM emulator on the IMV: PRV is able to maintain rail pressure stable from 0% dutycicle until IMV fuel "cut off", around around 80%(?).
- PWM emulator on the PRV: IMV is able to maintain rail pressure stable in a very short dutycicle interval, when compared to PRV, between around 15% and 20%. Below 15%, pressure starts to drop, above 20% pressure "jumps" to 320bar.

I would say that this is expected, IMV is a "gross pressure regulator" and PRV is a "fine pressure regulator"!

During this tests, at idle, I was able to see the ºBTDC started at -0.6 (coolant 23,3ºC), then -0.9 (coolant 27,0ºC), -1.2 (coolant 34.2ºC) and when it reaches 39.6ºC, the BTDC jumps from -1.2 to -2.5 with no apparently reason and is when the rough idle starts and #1 Injection Deviations starts to increase above 1mg/str (the max loged is 2.8mg) and now (after 4 x injectors replacement) it only happens on cylinder 1!
The funny thing is when I "kick" the accelerator pedal all the way down, even just for a fraction of a second, the idle is back to normal!
This does not happen with the Fix Nox software (9980)! I think that it only fails when the injection map switchs to "low emissions map", because the injection timing goes from -1.2 to -2.5 and I've found out that one way to reduce Nox is increasing the injection timing! When I kick down the accelerator pedal, I think, it switchs back to the normal injection map!

Must be there an hardware issue anyway, as this does not happen in all the engines like mine!

I've found in VW erWin a TPI from 02/09/2010 (2023897/1), talking about a know issue about roller rocker arm incorrectly mounted at factory the would cause erratic idle and could make some noise from engine head below 2000rpm, no fault codes showed!
chnical product information
Transaction No.: 2023897/1

Engine: erratic idle speed, rattling noises from engine
Release date: 18-Aug-2010

Customer statement / workshop findings
• The engine runs erratically at idle speed and up to 2000 rpm. There may also be noises in the cylinder head area.
No entry is logged in the engine control unit.

Technical background
• The roller valve lever is not in the correct position. As a result it can jam or jump out.

Production change
• Optimised production

Measure
• Check the idle speed rest control of cylinder 1-4 via the guided functions. With deviations of +2mg/h per cylinder, remove the cylinder head cover. Check whether the roller valve levers of the affected cylinder are in the correct position.
• With fallen-out or broken levers check the complete valve drive for consequential damage.

...
Could this roller issue be checked/confirmed with a compression test? Without removing the head cover?

Thanks and sorry for the long post :)
Last edited by nelnun on Thu Aug 23, 2018 8:15 am, edited 1 time in total.

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RYM6746
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Re: Audi A4 2.0 TDI Rough idle

Post by RYM6746 » Wed Aug 22, 2018 5:54 pm

With the WPS 500 you can definitely check valve opening time in relation to crankshaft degrees. You can compare this to every other cylinder if you dont have a spec to go buy. This will tell you if any of the components that operate the valve are worn/defective

fenwick458
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Re: Audi A4 2.0 TDI Rough idle

Post by fenwick458 » Wed Nov 21, 2018 9:55 pm

Hi Guys,
I have a rough idle problem with my 2.0 TDI, it's in a VW T5.1 van. 2012 140 DSG model to be precise. any help would be great!

noticed on Tuesday morning when i pulled up at the first set of lights that it would not idle smoothly, but would drive fine. that day I had a load of short trips and getting it started and maneuvered out of car parks was a nightmare because it would hesitate and stutter very abruptly and cut out, reversing from cold was just out of the question I had to reverse park everywhere.
Wednesday same problems but manageable once i got it going (only ever doing short trips by the way so it never had a chance to warm up), and tonight I have just been out for a short drive to get it fully warmed up to see if it would idle smoothly once it was at temperature, but it didn't. would drive fine and pull smoothly to the speed limit from 2000rpm onwards, yet come to a standstill and let it idle and it was all over the place. It actually cut out mid reverse park when i was parking just then
I did a log with VCDS, not sure what i was looking for I but I did find fuel high pressure actual and specified, and logged those. when Idling the specified was about 30 and actual was jumping around all over the place, and when driving the numbers were way higher and they were very closely matched, so it seems to be only at idle or below 1500rpm ish that theres a problem. but it also won't run smooth if i rev it to 3000 when stationary.
log below (if it works)
https://photos.app.goo.gl/DaxuXGTpWnEb51VeA

aswe
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Re: Audi A4 2.0 TDI Rough idle

Post by aswe » Mon Nov 26, 2018 8:39 pm

Hi guys,
I have similar issue with skoda superb 2.0 cr fuel pressure is very unstable at some time and specially when engine is cold. When I worm the engine fully its some times start jumping from 6 bar to max what I seen 53 bar. Other garage already have replaced all injectors (ok they net coded them in I did) I just now changed the fuel Injection pump ( bosch recondition ) still same if its possible fuel rail pressure valve (drv) can make so big fluctuation?

Regards

fenwick458
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Re: Audi A4 2.0 TDI Rough idle

Post by fenwick458 » Thu Nov 29, 2018 6:46 pm

STC wrote:
Thu Mar 23, 2017 8:41 pm
Not wishing to rain on your parade but please bear in mind that the new regulator should be adapted/calibrated to your vehicle with a diagnostic tool for it to function absolutely correctly in the long term.
can you elaborate on this please, how do you calibrate it. I have VCDS can do it with that?
since I fitted a new DRV on Monday it now idles fine but it goes into limp mode when overtaking (100% throttle for 5 seconds usually does it)

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