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Model specific boards => Golf mk4 => Topic started by: Mr_Orange on 05 February 2010, 18:29

Title: Rough idle
Post by: Mr_Orange on 05 February 2010, 18:29
Right, still got a rough idle.  No fault codes other than an intermittent 17705.  Also noticing the revs drop down, with lights dimming etc like its gunna stall when coming to a stop (indicates a vacuum leak perhaps?) and a flat spot sometimes when pulling away from a junction etc.

After changing out most of the ignition side of things:
sparks
coil packs
coil pack wiring
MAF
N75
N249

I've decided tomorrow to:
clean and re-adapt the throttle body (again)
fit a new temp sender
look for a possible vacuum leak under the manifold (PCV etc did have crap all over it before I wiped it off recently)

Any handy pointers on the last item on my list?  ie spray some carb cleaner around a bit etc... ?  :grin:
Title: Re: Rough idle
Post by: dubcruiser on 05 February 2010, 18:47
I got my thermostat changed at Christmas time and mine runs a lot smoother afterwards. Are you having trouble with the temp guage at all? If your thermostat is faulty then the ECU will cause the fueling to be wrong due to the wrong temp signals. Just a thought and it's not too expensive to change  :wink:
Title: Re: Rough idle
Post by: T_J_G on 05 February 2010, 18:51
Already done it!
Title: Re: Rough idle
Post by: dubcruiser on 05 February 2010, 18:51
Already done it!

Ah, must of missed that Tim!  :wink:
Title: Re: Rough idle
Post by: Mr_Orange on 05 February 2010, 20:24
Having made myself dizzy researching this I can't help now but think its possibly a vacuum leak issue. 

Can I remove all the crap pipework and perform the PCV/vac pump mod without installing a catch can?.......  :undecided:
Title: Re: Rough idle
Post by: T_J_G on 05 February 2010, 21:58
Catch can is only about £70...
Title: Re: Rough idle
Post by: Mr_Orange on 06 February 2010, 14:44
Coil pack #4 fitted and no different.  Maybe pulls a bit better now though!

At idle briefly disconnected the MAF and it seemed to idle a bit better.

Will carry on tinkering in the morning again.
Title: Re: Rough idle
Post by: Mr_Orange on 07 February 2010, 14:23
Right-ho:

Coolant temp sensor, done.
Cleaned and re-aligned throttle body.
Cleaned IAT sensor.
Couldn't detect a vac leak under intake manifold, pipes all look a bit manky under there though  :undecided:
While doing all this I found one of the SAI pipes was no connected properly at the air box.  Must have been like that since I got the clutch done!

Fired it up and it seems to idle a bit better from cold, didn't run it up to temp to see if its better that end yet.  Still seems like its occasionally missing a beat at idle.  Will wait and see what its like warmed up after my drive to work tomorrow.


Title: Re: Rough idle
Post by: Mr_Orange on 12 February 2010, 18:33
Can someone please confirm the part numbers for suction jet pump and crankcase breather valve (puck) on a 2000 AUM?

Thanks  :cool:
Title: Re: Rough idle
Post by: radz on 12 February 2010, 18:39
Hi Orange mate

I had the exact same problem if you remember! Have changed my coil as well as you and pretty much done exactly the same as you.

Coil definately improved the driving side and the rough idle but it was still there - turns out my front lambda sensor was completely dead, no voltage coming out at all.

Got that replaced today and oh my what a difference, car seems to be running perfectly!

Title: Re: Rough idle
Post by: Mr_Orange on 12 February 2010, 18:45
- turns out my front lambda sensor was completely dead, no voltage coming out at all.

Got that replaced today and oh my what a difference, car seems to be running perfectly!

What was the pain $$$$$ ?
Title: Re: Rough idle
Post by: radz on 12 February 2010, 18:55
Part itself cost around £60 for a bosch, but I didnt have time to do it myself >.<

So overall cost me £120 which still isnt too bad if it fixes the problem.
Title: Re: Rough idle
Post by: Mr_Orange on 13 February 2010, 16:11
Just stripped off and cleaned out the vacuum systems under the inlet manifold. 

It was full of gunge!  The suction jet pump, most of the pipework and the crankcase breather valve (puck thing) were thick with it.  No obvious pipe splits but some of the hoses had deteriorated quite badly inside.

With it all apart I noted down some useful numbers for the AUM:
Crankcase valve (puck)  034129101B
Suction Jet Pump  058133753B
PCV valve  035103245A
The "soft" pipes that have gone bad: 06A103247, 06A133784P, 06A133783AS, 06A133783H

Didn't sort the idle.....  I admit defeat and will be seeking further help.
Title: Re: Rough idle
Post by: johnson6672 on 13 February 2010, 16:16
Can you post some pics of what you cleaned?
Title: Re: Rough idle
Post by: Mr_Orange on 13 February 2010, 16:29
Removed and cleaned out this little lot:
(http://i713.photobucket.com/albums/ww140/najmeade/DSC00194.jpg)

This creamy gunge is what spilt out when I removed the pipework:
(http://i713.photobucket.com/albums/ww140/najmeade/DSC00193.jpg)
Title: Re: Rough idle
Post by: T_J_G on 13 February 2010, 16:40
You need a catch can mate! :afro: Sod paying VW prices for all those pipes when they can be replaced with a fresh looking catch can install:

(http://img.photobucket.com/albums/v215/T_J_G/photo-54.jpg)

EDIT: What ones you got to replace mate?
Title: Re: Rough idle
Post by: Mr_Orange on 13 February 2010, 16:43
The 3 soft (not solid plastic) ones will be coming back out.
Title: Re: Rough idle
Post by: johnson6672 on 13 February 2010, 16:47
Think i might have a look at that lot when i do my service.
Title: Re: Rough idle
Post by: Mr_Orange on 13 February 2010, 16:52
Think i might have a look at that lot when i do my service.

Its rather fiddly and depending on age/mileage they will likely be very manky.  I spent 3 hours doing this today.  Cutting off the original hose clips, it took about 12 jubilee clips to put it all back together.  Would have been nice to find a great big split in something, but hey-ho....