Lumpy Low Revs, Cause And Cure?

Farnorthsurfer

Farnorthsurfer

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LWB EU5 180
On the way to work the last couple of days I have noticed that in slow traffic at low revs there is a rumble and vibration at small throttle openings.
In typical fashion I decided to warm it up and give it some red line beans, clean things out a bit.
Now runs much better without rumbling of vibrating.
Is this early indications of clogged EGR or maybe something else.
Warranty ends in May and it’s in for a cam belt and service on the 19th when I will raise the issue with the dealer.
Any advice gratefully received
 
Thanks @Loz I don’t think it’s a regen but guess it could be. If it was a twin Weber or Dellorto I would be balancing the carbs and happy in my work. The feeling was the same, a bit like labouring it but the revs were high enough.
Definitely not the DMF @Salty Spuds the clutch is fully engaged and foot off, smooth acceleration and changes without juddering.
Don’t believe in the fancy fuel argument but might fill up with a premium to see if it makes a difference.
After I blew the cobwebs out with some enthusiastic driving it was fine. Not so easy as it’s travelling pretty quickly for a bus:)
 
Update here. So after worrying about my lumpy rough running engine for a week or so I reported it when I handed the van over to VW Van centre Inverness for an inspection service and full monty cambelt change.
When I picked it up that evening I was told that the rough low revs was no fault found, no charge.
But weirdly driving home it was much better than it was!
It is still rough at 1500 revs in any gear and unfortunately that’s exactly the revs in 6th gear on our local A roads.
So I spend quite a bit of time in 5th avoiding 1500 revs. It’s got plenty of power and pulls no problem from there.
It’s just uncomfortable. I was wondering if a Revo map would help but am concerned that there might be an underlying problem to fix first. @BognorMotors seems to be the man with lots experience on remaps, hope he doesn’t mind me looping him in here :)
 
Think we have a Revo agent in Inverness ?
Duncan Sutherland ? Had a euro 5 remap ( Pendle ) on my 140 5.1 done by Russell's garage at inchmore on the beauty road and it was fantastic . Nicer to drive even than the 180 I tried.
 
I wouldn't recommend remapping an engine that has a fault. There must be an underlying issue that would need to be sorted first.
 
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MAF Sensor? Try some MAF Sensor cleaner, it won't cost a great deal and won't do any harm anyway. It's a 10 minute DIY job.
My last car, a Landrover, had similar symptoms, cleaned the MAF sensor, some improvement, got a new one, fully cured the problem and it ran much better throughout the whole rev range.
An out of spec or faulty MAF sensor will not trigger a fault code so won't show up on diagnostic check.
 
You're showing as a VCDS user - plug it in and start measuring some of the signals being fed to the ECU. If it's a regen, you'll see the temperature of the DPF, if it's the EGR starting to open, you'll be able to see that etc....

Slightly off topic - Have you got a Euro 5 van that was registered after September 2016?
 
Mooncat said:
You're showing as a VCDS user - plug it in and start measuring some of the signals being fed to the ECU. If it's a regen, you'll see the temperature of the DPF, if it's the EGR starting to open, you'll be able to see that etc....

Slightly off topic - Have you got a Euro 5 van that was registered after September 2016?
Click to expand...
Actually a pretty novice VCDS user but I will take a look thanks.
It’s an EU5 but a March 2016 registration I think as the MOT is end of March.
 
DaveD said:
MAF Sensor? Try some MAF Sensor cleaner, it won't cost a great deal and won't do any harm anyway. It's a 10 minute DIY job.
My last car, a Landrover, had similar symptoms, cleaned the MAF sensor, some improvement, got a new one, fully cured the problem and it ran much better throughout the whole rev range.
An out of spec or faulty MAF sensor will not trigger a fault code so won't show up on diagnostic check.
Click to expand...
Thanks for that. I will check it out.
The VW workshop said there was nothing wrong with it and there were no fault codes when I checked it last week.
Definitely comes and goes though, the engine pulls fine it just feels like a bag of nails at 1500revs. I thought maybe a clogging EGR but the symptoms don’t seem the same.
 
BognorMotors said:
I wouldn't recommend remapping an engine that has a fault. There must be an underlying issue that would need to be sorted first.
Click to expand...
Thanks, there may be a fault and I am still investigating despite being told it’s fine at the service. Assuming there is no fault would the Revo Stage 1 improve low revs throttle response and make it a bit smoother. Really doesn’t need more power but better economy would be nice.
 
Isn’t 1500 revs right around the point the first turbo kicks in ?
Past this and the second turbo will be boosting ?
 
It was just with you saying the warranty runs out in May - I was working back three years from that.

At small throttle openings the EGR should be feeding exhaust gases into the inlet manifold. If there is a restriction in this system or the valve is sticking slightly you can get a bit of what will feel like jerkiness when modulating the throttle. The fact that it goes away after an Italian tune up I think points more towards a regen. I have the E5 140 and during a regen at low rpm, you can hear a difference in combustion noise (it sounds like the injection timing has been advanced) and the van isn't quite as responsive - most people wouldn't notice it but if you're used to tuning a pair of DCOEs and adjusting ignition timing advance curves you will do.

With VCDS you can see exactly what is going on inside the engine - no more fitting pressure or vacuum gauges, EGT sensors etc they're all there waiting for you to read in VCDS. Most people that buy VCDS don't even scratch the surface of what it's capable of and just code in tow bar electrics or change the stereo output for some rear speakers. It's a really powerful tool that allows you to see exactly what the vehicle is doing and has lots of module and component test features to help you troubleshoot symptoms (not everything will throw up a fault code).
 
Thanks @Mooncat thats good advice. I shall do some reading on the VCDS features and see if I can work out what’s going on.
It might well be that lots of other people wouldn’t even notice the vibration.

The van was bought from VW van centre in Inverness with the Das Auto warranty. If there is a problem I would hope to get it sorted before it runs out in May. To be fair the dealer experience has been above my expectation. I won’t even go through the door of the adjacent VW car dealer who are actually the same group.
 
coupcoup said:
Did you ever get to the bottom of this?
Click to expand...
No not really. It still doesn’t like cruising along at low revs. I actually think I got used to driving round the lumpy rev range. Although the economy probably suffers a little.
I think it’s normal if not very refined.
 
I’ve the beginnings of the same problem but just a lumpy cold start issue just now. The advice ranges from £4000 rebuild Egr fuel rail to £20 bottle of diesel additive. Fingers crossed for the latter.
 
I do take care not to use the van on short journeys when it won’t warm up and walk or cycle instead. And when I get the chance on a run and the van is well warmed up I carefully explore the full rev range on easy accelerations. Sure this helps keeps the systems in good order. I have done the same with all my cars performance or slugs. Use it or lose it as they say.
As above, not much to lose on a bottle of injection cleaner.
 
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