N75/PCV - Lumpy Idle

[malaroo978]

Hi all,

I was hoping someone could help me out here. I've got the 1.4 TSI but in the MKV golf (pretty much the same as in the Roc though). Is the N75 valve the PCV? I havnt heard anyone actually link the two but im pretty sure the N75 is the PCV?

Reason being my lumpy idle is still around and seems to be getting worse, so I wanted to check the PCV as its a common fault and cause of lumpy idle. Spark plugs are new and gaps are set at 0.8mm. I'm not sure about the coil packs, one has been visually gauged on the plastic by a previous garage but besides that look ok. I havn't got a fault code reader so don't know if its misfire etc. (got one in the post - cant afford VCDS )

Any other suggestions for excessively lumpy idle?

[RW1]

N75 isn't the PCV valve.

N75 controls the boost.

The PCV is part of the oil breather system. In the first below, its part of the pipework assembly - item 8. Not listed as a separate item. For valve itself see second picture.

1-4TSI Oil Breather-PCV - 01.JPG

1-4TSI Oil Breather-PCV - 02.JPG

Some how I don't think its your problem. I would be looking more at the injectors/spark plugs.

C.

[malaroo978]

Thanks RW1, that picture is perfect!

I know its probably not the cause but worth ruling out. Its hard to get vw to take a rough idle seriously, but if it is injectors id like them to be paying for it!

Think I read somewhere you're up in/near cheshire? Or did I just imagine it?! I'm up that way in knutsford this weekend. Ive got a set of spare spark plugs ill try them this weekend but without a code reader its hard to pin point.

Thanks again for the picture and explanation

JC

[RW1]

I trust you have read this topic?
http://www.sciroccocentral.co.uk/forum/ ... park+plugs" onclick="window.open(this.href);return false;

East side of Stockport.

Saturday/Sunday both look like blue sky days.
Can dip the diagnostics as well as the right coil puller tool.

C.

[malaroo978]

Yer I've had a good read through and was really helpful when I checked the plugs before Christmas

Awesome, I'm picking up some parts from TPS in stockport on Saturday (full engine undertray and aerodynamic cover for underside) so will be over that way then. Do you think you could lend a hand/have a listen and see what you think? Would be much appreciated and beer tokens

Jc

[malaroo978]

Hi all, just to let everyone know I met up with Chris at the weekend and we changed the plugs for new ones regapped to 0.74mm (thanks Chris ) and scanned for codes but no improvement. Whilst the plugs were out we had a look into the cylinders with a torch, on cylinder 1 on inspection the old plug was scorched and all deposits had been burnt off. Obviously running hot. As well as this we could see light spots which looked like metal filings on top of the piston.

Very worried at this point!!

Took it to VW Bristol on tuesday morning (nice enough to fit me in with a call to them on the monday) and told them what I had seen and the lumpy idle. By the end of tuesday I got a call to say the master technician couldnt find what was causing the problem so they had emailed VW central a report for some help.

Wednesday morning they put a camera down into the cylinder to have a look, they found that the light spots wernt metal but they were patches where the fuel had been spraying and cleaning the cylinder. They told me they think its the injector on No.1 cylinder with an irregular spray pattern (faulty injector or clogged, not sure) so it wasnt firing properly causing the misfire (no fault codes at any point for this!) A new injector is being fitted today and should be ready for pick up this afternoon. I'm hoping this is the problem and will run much smoother after (maybe more power/mpg too )

Very impressed with the service from VW bristol, highly recommended!

Also just wanted to say a massive thanks to Chris, for the time on saturday and the knowledge! It meant I could steer VW in the right direction and all been sorted (fingers crossed!) quickly.

Hopefully this may benefit someone else, if you have an excessive lumpy idle check your spark plugs and in your cylinders!

[malaroo978]

Just an update guys, looks like I spoke to soon!

Basically it was the injector that caused the problem. But when they replaced it the lumpy idle wasnt completely fixed. So they looked deeper, took the head off to have a look inside the engine for any damage.

They said the injector has been spraying fuel incorrectly so that the piston had heated up too much and caused the valves to become burned and so much so that the bore of the engine has become out of shape. Therefore... NEW engine. New block, new pistons, new valves, new injectors new everything! Other than ancillaries (AC, power steering etc.). All the parts they need should be with them tomorrow/monday latest. And they reckon it should be done next week.

I'm glad they looked deeper into it and found the problems the injector had caused. And I'm happier that I'm getting all new components rather than half and half, with some old components left in I couldnt help but think something else might go wrong!

Just to re-iterate, look into you cylinders if you have any lumpiness or odd going's on with your engine! Insist VW check it out as it was only after Chris and I found the markings in Cylinder 1 that they looked into it (before this they gave the typical "no fault codes found")

Thanks Chris for helping me point them in the right direction. And thanks to VW Heritage Bristol, daily updates and timely work and a good resolution (not good, but got to the bottom of it!) Very impressed by the support I've received Now I get to run in the engine as if new...

[RW1]

No problemo J.. Glad to see they are tackling it properly.

Pity we didn't photograph the inside of the cylinder No.1 of those shiney bits on the piston crown and the effect the injector was having on the spark plug for others to see.

C.

[thewhiterider]

Well I'm glad I accidentally stumbled across this thread, Had my car to VW for a lumpy idle, they found no fault codes even though its been misfiring

How to get them to take me seriously though I'm not really confident to be taking the head off the engine to see if there is anything there, reckon they'd fobb me off again