R50V10 light throttle miss

Ecca · Feb 25, 2019

Hi Guys
I have an issue with a very slight misfire / rough running of my 2008 R50 V10. Problem is worst at very light throttle around 1300 RPM in 6th gear. Not easy to achieve this combination. Also occurs with light throttle in 5th gear 1500 RPM. Just feels like a shudder. Drop a gear and all is OK. Engine performance with throttle on is perfect. ( love a V10 twin turbo):smile2:
Checked system with VAG-Com. no errors. Drove the car with data feed from VAG-com running and the engine is very lean on both banks when the problem occurs. I immediately changed the fuel filter. Same problem.
I am thinking the fuel pressure from the mechanical pumps is too low at these very low RPMS causing a lean miss?
Any thoughts, advise, experience would be appreciated.

Just some car info. Camshafts changed about 15000KM ago to colt. No cats or DPFs. ECU's re-flashed to suit. Custom tail shaft. Car is used mainly for towing and the problem less obvious as I normally run the trans in manual 5th. Normally have more throttle on while towing also.

4ePikanini · Feb 25, 2019

I reckon the reflash needs a tweak.

seafarer28 · Feb 25, 2019

As was reading your post I thought could be tailshaft related but then I read further so........ please tell us more about your custom tail shaft.

TonyB

Ecca · Feb 25, 2019

I am sure a tweak on the tune would address the problem. I would like to fix the problem. Car was tuned 15000km ago and was running fine until very recently. Something is wrong/broken. Thanks for your thought anyway.

Ecca · Feb 25, 2019

Hi Tony. Cannot tell you much as the tailshaft was in the car when I purchased it. Has a huge plunging center CV with the center bearing. Guessing the previous owner had problems and did not want any more so he went away from the VW carrier.

Bubbadust · Feb 25, 2019

Hi there,

I have 2010 R50 with about 160.000 km's. Have owned the car for about 3 years and got light shudders in similar gear/rpm conditions. I have considered it to be "normal" and just kick down the right pedal or change to sport mode.

I have been driving it regularly on german autobahns and its clear the german engineers have designed/optimized the car to be driven hard around 160-200 km/h for extended periods =) The shudder does not occur then.

Interested to find out if this is not normal and if there is a fix. I reset the gear box every once in a while.

Best regards,
Bubbadust

Ecca · Mar 6, 2019

Hi guys
Still chasing the problem. I measured the fuel pressure after the fuel filter , before the mechanical pumps. Pressure was 6 psi when I first started the engine cold and about 8psi after 45 minutes of running. Not sure why it changed cold to hot. Warm fuel? This pressure is normal from what I understand. The fuel pressure is very erratic above 1500RPM. I am using a manual gauge and the needle pulses 5 or more psi each side the 8psi where the RPM is increase above 1500. Is this normal ?

R50 V10

GTekW8 · Mar 6, 2019

I have had a US model 2006 V10 for about 2 years and have noticed this exact problem/condition since I bought it. Mine is all stock and I noticed that it is worse when its about to initiate a re-gen. I'm curious if others have experienced it and what was done to resolve it.

Ecca · Mar 29, 2019

Hi Guys
I have found my light throttle misfire. Injector is cracked. see picture. This would have allowed fuel to leak out the body and not inject into the cylinder. Found the problem with a high injector correction on cylinder 2 with vag com. Made me look at this injector and found the crack. Has anyone see this before? Like to know why it cracked.

dragline1570 · Mar 29, 2019

Ecca said:
Hi Guys
I have found my light throttle misfire. Injector is cracked. see picture. This would have allowed fuel to leak out the body and not inject into the cylinder. Found the problem with a high injector correction on cylinder 2 with vag com. Made me look at this injector and found the crack. Has anyone see this before? Like to know why it cracked.

Wow Eric
That is a nasty crack in the injector the photo says it all :shock:

Not sure about anyone else but i personally have never seen or heard of that.

Comments from anyone who has ?? :idea:

Keep us up to date on the replacement injector fixing the issue

Regards
Drag

R50V10 light throttle miss

Ecca

4ePikanini

seafarer28

Ecca

Ecca

Bubbadust

Ecca

GTekW8

Ecca

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