Slight drop in revs? Any ideas?

[Craigh1983]

Since buying my car I've noticed when the car is idle I can feel the revs drop ever so slightly and I can feel the car shudder very very slightly too however it's not enough to make the revs needle drop but when the headlights are on I can see them also dim slightly when I feel the drop in revs.

I took the car in today to have the coil packs changed as there was a recall and I thought this would solve it however it's still doing it. Spark plugs have recently been changed. Any ideas what could be causing it?

Thanks

[56OctyVRS]

Check your PCV valve as that might be failing.  Pullout your oil level stick and see if the engine starts to hunt badly. If it does your PCV is working fine.  If it only slightly gets worse then Id suggest the PCV is bad.  What revision PCV is fitted to yours?

[Craigh1983]

What do I look out for when I pull out the stick?

I don't know what revision it is to be honest. Where will I find the revision?

[bacillus]

To see which version you have, take a small mirror, and stick it under the pcv valve. The last letter after the parts number identifies the revision.

[56OctyVRS]

[Craigh1983]

Ok well I took the oil stick out while the engine was on and it first started to shake and then the engine started racing quite alot!... so by the sounds of it the PCV is ok.

Any other suggestions?

[Craigh1983]

I should mention too that everytime I feel the slight drop in revs i can hear a slight blip from the exhaust roughly every couple of seconds too at the same time.

[Craigh1983]

Woke up this morning and the exhaust system
Light was lit up on the dash. Took it back to vw thinking it might be a fault with the coil packs. It turns out I have a faulty intake manifold flap and this is also causing the rough idle apparently. Does this sound right?

[Saintsteve]

Woke up this morning and the exhaust system
Light was lit up on the dash. Took it back to vw thinking it might be a fault with the coil packs. It turns out I have a faulty intake manifold flap and this is also causing the rough idle apparently. Does this sound right?

Sounds like they ran vag com, found that was the only error and are gambling that's the fault. I have my doubts that will be the problem, but see how you go...

Intake runner is an expensive unit so make sure they cover it if it's not the fault. Ive had an intake runner error code before, and what was causing it was a dirty air filter, since it was changed, the fault has disapeared.
Is your car totally stock?? Any mods? Worth checking the spark plugs are nice and tight, as these have been known to work loose and cause rough or a slight missfire as well.

[Craigh1983]

Yea car is totally stock.

Well I have got a friend of the family who is a mechanic to do it now. Quite a bit cheaper too. Problem is he has already ordered the part and I have paid him so I guess if it is a dirty air filter then i've just wasted money!! :(

I will get him to check air filter and spark plugs tho. VW quoted £270 inc labour and my mate can do it for £220. I know its only £50 difference but im a bit skint atm.

Quite weird tho cos when I took car into VW, they turned off the warning light on the dash. I thought they would have left this on?

[Saintsteve]

Yea car is totally stock.

Well I have got a friend of the family who is a mechanic to do it now. Quite a bit cheaper too. Problem is he has already ordered the part and I have paid him so I guess if it is a dirty air filter then i've just wasted money!! :(

I will get him to check air filter and spark plugs tho. VW quoted £270 inc labour and my mate can do it for £220. I know its only £50 difference but im a bit skint atm.

Quite weird tho cos when I took car into VW, they turned off the warning light on the dash. I thought they would have left this on?

All they have done is removed the fault in that will remove the light. usually, if the fault is a persistent fault, the light should be back on again almost straight away? I would be looking at the air filter, plugs.Have you ever had the Diverter valve inspected, I know the cars not mapped, but it's worth having a look at that as well.All these things can cause poor performance and worth looking at before going for something that may necessarily be causing the highlighted error in Vagcom.