Temperamental Engine Prob

[PDvRS]

So,

Every other journey or so my car has the following issue:

Driving along normally then the car feels like it drops a cylinder whilst cruising along, being hesitant when trying to accelerate, to say overtake someone. Sometimes it clears, sometimes not. I've found that if i switch the ignition off and back on it clears up. Also the idle rpm sits at a constant 1,000 on some occasions also.

I figured it might just be caused by my daily commute which is only 15 miles each way at an average of about 40mph, so i've just been out round the back roads to clear it out.

Stopped at the garage for derv on the way home and after setting off the car wouldn't rev above 3,000!!! Carried on driving and a few minutes later all was back to normal.

Anyone any idea wtf is going on???? (I had the new injectors fitted early Jan 2012)

[cheshire_cat]

fuel filter? sticky egr? really need vag com first

[PDvRS]

Was thinking fuel filter maybe. How do you clean the EGR??

[Jane_i10]

My car feels like this sometimes, it backs off when cruising, feels jerky to drive and theres a major lack of power when you need it most.

Iv cornered the problem to the DPF, mines booked in to be removed on the 30th as its on its last legs (light coming up at least 3 times a week)

[Notorious_g]

is it jerking up the rev range when you try to give it some beans?

could be fuel filter or maybe the maf

[PDvRS]

is it jerking up the rev range when you try to give it some beans?

could be fuel filter or maybe the maf

no, just if you gently touch the pedal. Change down and give it beans and it's ok, just sounds 'off'.

[Stormchaser]

Also read on here the injector looms are a problem too on those.Maybe worth checking?

Or as Ema said a DPF issue.

Good luck hope you sort it out.

[Wardy]

Injector or DPF I'd say, based on what you've described.

Either way, that should have logged an error code - if you can get it checked by a garage, or someone nearby with VCDS.

[mattcut]

Sounds like mine when its going through a regen of the DPF.

Will run a bit rough and idle at 1000rpm and not the best when feathering the throttle. All back to normal after regen.

Try doing a normal regen and see what its like

[Davidsr20]

Yes ur prob right maybe it's doing a regen cause iv felt it once or twice too. Makes sense.

[PDvRS]

Had the car plugged in today, no fault codes registered.

Will clean the EGR and replace fuel filter this weekend and see what happens

[Jane_i10]

What mileage is your car on? Mine was on 53k when bought and 55k when i realised it was on the original fuel filter! So definitely needed changing but it didt stop the jerky feeling. Personally id say it was your DPF.

What kind of driving do you do most of? If you car very rarely see's 60mph+ the DPF's fill up rather quickly and regen alot more frequently but if your doing alot of motorway/60mph road driving you will hardly ever notice it doing a regeneration and it will cleaning itself.

My new job requires me to do alot of town driving and the DPF light can flag up about 3 times a week so i can wait to get the sodding thing off

[Howardian1]

I'd agree it sounds like DPF - I get the same every so often, sometimes with a DPF warning light at around the same time (give or take a couple of days!)

One thing I've always wondered - as the car doesn't know when you're going to stop driving and turn the engine off, what happens if it's part way through the regen sequence?

[silver1011]

One thing I've always wondered - as the car doesn't know when you're going to stop driving and turn the engine off, what happens if it's part way through the regen sequence?

The regen stops. You then need to meet all of the requirements to start another regen.

However if the regen was half way through then some of the ash will have been burnt off so it will be bellow the trigger point and so it may then be a little while longer before it attempts to regen again.

[Davidsr20]

The regen stops. You then need to meet all of the requirements to start another regen.

However if the regen was half way through then some of the ash will have been burnt off so it will be bellow the trigger point and so it may then be a little while longer before it attempts to regen again.

Silver have u ever got this slight hessitation while accelerating during a regen or not?

[PDvRS]

Just turned over 40k. Daily commute is 15 miles each way with 60mph for about 3 mins of that lol.

Car has been good last 2 days since i went to and drove the arse off it the other night. Maybe i should just make this a weekly thing to stop it getting clogged up.

Fuel filter going in after work tonight just to eliminate that and then i'll do the EGR tomorrow.

Edited 20 April, 2012 by PDvRS

[Jane_i10]

Yeah this is what i do, that if im not already going over the moors to boyfriends ill take it out for a good blast to clear it out for the next couple of days of driving around town. Over time it does start to cost you a fair bit in fuel doing this once maybe twice a week hence why im taking mine off.

If your light does ever come up, when you manually clear it till the light goes off keep the revs high for a few more miles just to clear it out completely. When the DPF light comes up that means it 25% full so when that light goes out there still could be a little left in, not really a problem it just means its going to fill up quicker.

[cheezemonkhai]

Fuel Filter or an injector, although I'd think the latter would get a light.

Other things to look at are cleaning out the EGR and intake system and also checking the timing of the engine.

[Jane_i10]

See i think if it was a fuel starvation issue, (fuel filter blocked ect) this would flag up some form of emissions reading? as it will be running lean?

Have you had the injector recall?

[PDvRS]

Yeah injectors and loom where done 1st week of January 2012.

Never had the DPF light come on either.

[Davidsr20]

Yeah injectors and loom where done 1st week of January 2012.

Never had the DPF light come on either.

I'd say it was just doing a regen! How is it since?

[Howardian1]

It would have helped us all, and saved a hell of a lot of internet time, if the handbook actually said that the car will run slightly rough while it's doing a DPF regen...

[silver1011]

Silver have u ever got this slight hessitation while accelerating during a regen or not?

I wouldn't describe it as a hesitation, more like my turbo kicks in later than normal...

[silver1011]

Taking the car for a 'blast' isn't really going to help clear the DPF as all you'll be doing is producing more smoke and soot.

The ECU waits until a certain criteria is met before it'll start a regen. The DPF works by heating itself up through the use of additional fuel to burn off the soot turning it into ash which is caught and stored within the DPF.

What you need to do is generate enough heat in the exhaust to allow the DPF to start a regen and lower the level of soot, this is the only way you'll 'clear it out'.

Whilst driving hard will create additional heat the higher speeds will also be cooling down the exhaust and DPF.

A steady and prolonged high RPM (4th gear) 50-60mph drive will be better than a red line, rev limiter bouncing 70-80mph blast.

[Howardian1]

When the DPF light comes up that means it 25% full so when that light goes out there still could be a little left in, not really a problem it just means its going to fill up quicker.

That's handy to know and probably explains why mine keeps coming on occasionally - with my pattern of driving it's probably hovering around the 25% mark most of the time.

Notwithstanding Silver's comment about a good blast not necessarily doing the trick, the moor road between Pickering and Sleights has to be one of the best places to have a blast, if only for the hell of it!

What Silver said would tie-in with what the dealer told me when they replaced faulty sensor and did a manual regen - drive the car harder in general, so that you produce less soot in the first place. As the DPF is supposed to be an environmental piece of kit, to reduce particulates emissions, having to drive a DPF car harder so that it doesn't clog up (thus using more fuel) seems a bit counter-productive.