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1.9 TDi PD driveabliity problems

8581 Views 4 Replies 3 Participants Last post by  chittychittybangbang, 
E
Hi.

I'm a newbie here so please go easy on me. Vehicle in question is a 2008 VW Transporter T5 van with 84ps engine which has done 29,000mls. Please ignore the fact it's a van...it's the engine I need to sort out...hence the reason I'm posting on this generic Mk5 year appropriate forum.

This is a 1.9 TDi Pumpe Deuse engine rated at 62kw or if you like 84ps. In the main the engine "seems" to run well but there's a couple of problems.
Whilst moving through the gears I get a slight flat spot in 1st & 2nd.....I think it's probabaly there in 3rd/4th, but not so noticeable due to higher speed and momentum. In first the flat spot is more noticeable and happens about 1500rpm, and in 2nd the flat spot is slightly less noticeable and happens about 2500rpm. Also, and this is significant.........when driiving above 2,500 rpm in any gear I hear this sort of slight misfire.....like an old manifold gasket blowing slightly, if you know what I mean.

I booked the van into the dealer this week, and they thought the timing may have moved after 29K and would check this ! I've now collected the van and they tell me they have retimed the engine. The change is not significant, but I do feel/hear the engine running slightly better but the same underlying problem is there. I'm pretty handy with tools but don't have any specialised equipment. I've checked all the high pressure side of things for leaks........intake system, intercooler pipework, etc, and the vacuum side.....no obvious leaks on any of this stuff. I've also checked the diaphram/linkage for the variable turbo vanes.......and linkage moves relatively freely. However, can you confirm THIS about linkage rod for variable turbo. When engine is off, rod is at longest, extented state........when engine is idling, rods is at shortest.....and when engine revs are raised to say 2500/3000 rod length reduces.......is this correct I thought it might be the other way round.

I should add, when the engine is revved whilst parked there's no funny noises...it's only when under load these symptoms appear. Don't let me blur your thoughts but I'm steering towards lack of air/fuel under load.

Sorry this has been such a long first post but I'm really concerned about my engine. Hope someone can give me a steer on this.

Many Thanks

Eddie
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chittychittybangbang
The VNT actuator works off vacuum. This is the opposite of wastegate acuators which work off pressure. At rest there is no vacuum so the spring inside the can is the only force acting on it. Your understanding of it is correct. When it's at rest the vanes are wide open and the rod is longest, when the actuator gets full vacuum the vanes are closed and the rod is shortest. When it's running it's somewhere in between. The car modulates vacuum using the N75 solenoid.

http://www.myturbodiesel.com/1000q_how_to/a4/VNTadjust.htm see here for some videos

Have you checked for camshaft wear? There's an article in the mk5 FAQ for this linked below. It was a problem area on the US 1.9L pumpe duses. Worn camshaft lobes would create a lumpy idle or strange acceleration problems. The misfire symptom seems like it might be caused by this. There's a video of a car with a strongly worn camshaft idling too. See this: http://www.myturbodiesel.com/1000q_how_to/multi/camshaftInspection.htm
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E
Hi Chitty Chitty BB

Thanks for your response, but I'm still not sure where we are here.

I said..."when engine off rod is longest, but with engine idle, rod is shortest".
You said " when it's at rest.....rod is longest"...is this with engine off or at idle ?? Sorry to be so pedantic here but obvously there's a big difference here.

Many Thanks

Eddie
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If you have the same part as the US you're right. If I'm reading this right off=rest.
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chittychittybangbang
eargo said:
I said..."when engine off rod is longest, but with engine idle, rod is shortest".
You said " when it's at rest.....rod is longest"...is this with engine off or at idle ?? Sorry to be so pedantic here but obvously there's a big difference here.
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Sorry, when the engine is off the rod is longest because only the spring is acting on it. When you turn the engine on it cycles short/long. At a certain engine range the rod gradually gets shorter because vacuum is working against the spring and shortening it.
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