Lumpy idle and cutting out

[nudgermanning]

Seems my mk3 vrs tdi has developed a little problem after ive been on a little run. If i start the engine a little while later with the engine still warm the idle is really lumpy, in fact its more like a pulsing. Itll do this quite violently then eventually the engine will/may cut out. Any ideas as to what this could be as any help is greatfully received.

[Stuart-h]

Checked the air filter?

[donny1972]

How many miles? If no fault on dash i would change the fuel filter and see if it makes a difference. 

[VAGGAZ]

Possible injector fault maybe?

[Gabbo]

It would be better to find someone to read the fault codes or take it to a garage for a diagnostic especially if it does it easily.

No point wasting money changing oil or fuel filters without having at least an idea what the problem is.

[donny1972]

Just now, Gabbo said:

It would be better to find someone to read the fault codes or take it to a garage for a diagnostic especially if it does it easily.

No point wasting money changing oil or fuel filters without having at least an idea what the problem is.

Very hard to diagnose without a light on.

[nudgermanning]

Theres no light on the dash. Ive used the OBD11 and all that is showing relates to my bluespark tuning box. I have recently put in a pipercross air filter, could this be the issue maybe? Shes done just under 45,000 miles if that helps 

Edited 20 March, 2019 by nudgermanning

[MarkyG82]

Something that people keep doing on diesels is putting 'performance' air filters in.  I'm not say you shouldn't as they often make them sound nicer.  But from a purely functional point of view they can damage the engine.  A diesel engine is controlled by the amount of fuel that is provided and the standard air systems can provide far in excess of what is required even in a tuned engine.  One way a performance filter achieves its increase flow is by having bigger holes.  This has the potential for bigger particles to enter and the first dynamic part they come accross is the turbo.

Additionally, if you have a tuning box fitted it will make the related systems work that much harder showing any week spots sooner.

 

This may be what is happening with your car.  First thing I would do it out an OEM air filter in and turn the bluespark to '0' to disable it (or fit the blanking plug).  If the faults persist then investigate the fuel filter and other things people have suggested.  What setting do you have the Bluespark on?  Mine is currently on C7 with no issues so far (only 2 weeks).

[Stuart-h]

I'm running a k&n air filter on mine with out any problems!  

[nudgermanning]

Also running mine on the c7 setting although i have flicked through others to see if it improves anything. I did fit the blanking plug and the problem remained so maybe ill revert to the oem air filter and see if that solves it. I got the pipercross filter as i had one on my previous octy and it did seem to make a difference all be it a small one so didnt see the harm in it. Could bite me on the arse now though 

[nudgermanning]

Turns out the problem was the connection between the tuning box and the engine. Having now removed the box everything is behaving as it should all be it, more sluggish than id like. Thanks for the advice everyone

[MarkyG82]

13 minutes ago, nudgermanning said:

Turns out the problem was the connection between the tuning box and the engine. Having now removed the box everything is behaving as it should all be it, more sluggish than id like. Thanks for the advice everyone

 

Glad you got it working well again.

Are you going to revisit tuning?  I.e get the bluspark checked out or go for full remap?  Mine has been fine in the short time having the box fitted.  Still planning on a full remap down the line though.

[nudgermanning]

Not quite sure yet. The bluespark box worked really well up until this point however i might just go with a full remap thats customised for the car. Had one previously on the mk2 octy and it made a world of difference but do you then notify the insurers or not ??? So much to think about 

[MarkyG82]

I'd notify them definitely. Many insurers don't charge or only charge a processing fee to add a remap. I'm waiting till renewal time to remap.

[Superiluminal]

9 hours ago, nudgermanning said:

Turns out the problem was the connection between the tuning box and the engine. Having now removed the box everything is behaving as it should all be it, more sluggish than id like. Thanks for the advice everyone

Which one of the connectors was it?

I’ve had mine fitted for 18 months or so and something has happened to the protrusion on the rail plug where it doesn’t always stay in position and has slipped a couple of times causing the same thing. 

Zip tie to the rescue. 

[nudgermanning]

Unsure where the connection error is however the same thing happened with my rail connector although it was more my fault when trying to remove it innitially. Right bitch to get apart. I used the tactic of a couple of small bits of card between the rail sensor and the connector to hold it and it seemed to do a good job although zip tie might have been easier