MK4 golf rough idle and sucking in gunk

B

Baileymk3golf

Wrench Pro
Points
21
Location
Leeds
Car
VW Mk3 Golf 1.4
Hey people,


Just as soon as I've got rid of one car and got another, I've got a problem with it again!


It's a mk4 Golf, 2001 1.6L 16v. 110K on the clock


I bought it from a dealer just over a week ago and it was taken in part exchange so I got a fairly good deal on it.


It looked in decent nick and drove quite nicely on the test drive, it has got all matching Firestone tyres throughout too, even the spare so I thought this was a good inclination that the previous two keeper had looked after it, along with all the service history.


Anyway, when I got the car I gave it a bit of a service like I always do when I get a new motor, the oil had just been changed on so I put a new air filter in, replaced the spark plugs, put some oil additive in along with some fuel additive to help clean the old girl out.


I also took the throttle body off to give it a good clean because the revs were jumping up and down a touch when idling. done this in my old mk3 Golf and it sorted it out.

The underneath of the throttle body was absolutely caked in *#*#*#*#, a black greasy soot, I've never actually seen anything like it and took a good while to clean it out. inside the intake manifold looked like it had a lot of crud in there too.


Anyway, I cleaned the throttle body and what I could of the intake (without stripping it down) and put it all back together.


The revs are still bouncing up and down on idle and it seems to me like it doesn't have as much power as it should, it also seems like the speedo is out. I've tested it against a satnav and two phones which were all reading the same speed. so when I was doing 90 in my car (which really didn't feel like 90) it was actually 70mph. quite a difference!


I took the engine cover off of the top of the engine which houses the airfilter and has a breather pipe thing going into the box too.


The breather pipe was/is covered in gooey mayo grease. not a good sign anywhere if you ask me.


The came with a 30 day warrenty so I took it back to the garage where I bought it from, they said I would have to leave it with them. later that day, the sales man/receptionist (nob head) told me that the engineer couldn't find anything wrong with it, had plugged it into diagnostics and found no faults but did admit that it didn't seem right.


I'm thinking that they either couldn't actually be bothered to look at it properly or they found a big fault and didn't want to fix it because it would have to be done for free. Maybe not, I just got that sort of vibe from them...


Soooo...

Does anyone out there know what could be wrong with it?

I've got a feeling that it's sucking in a load of *#*#*#*# and cant sustain combustion properly so injects a bit more fuel in to compensate, hence the bouncy rev counter at idle...


The car is alos fine once started up but gets worse at running temp. I've also driven it without the airbox on for a short distance and the idle seemed to handle it a bit better..


Thanks!
 

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If the wheels are non standard that could account for the speedo inaccuracy. I don't like the look of that gunk, it reminds me of the water/oil mayonnaise you get when a head gasket goes.

I get a bad vibe from this and I would recommend you reject the car under their warranty. Asking for a repair implies acceptance of the goods IIRC so careful how you go. The car clearly has issues.
 
Being drive by wire;) you will need to reset the throttle body after cleaning this is either done by vagcom or disconnecting the battery for 30-60 minutes.(make sure you have your radio code) This is an easy free step and may resolve your issue. Also does the 1.6 have an idle control valve?
Baileymk3golf said:
It's not a cable no. if dbw mean electronic then it's that
Click to expand...
 
I've reset the system by disconecting the battery and I've got a little cheap diagnostics reader too where I removed any codes. the trouble is, the reader is for older vw's and the codes didn't tally up with any which are in the booklet.

I think I've found the problem for the gunk though...
I found a couple of forums where people have had similar problems. It's a build up of oil from the crankcase breather where oil vapour gets caught and should go back into the system but gets clogged up after time. Bearing in mind the car is 13 years old and has done 111K there will would probably be a fair build up of crap in there...

http://uk-mkivs.net/topic/18400-impossable-oil-leak/

http://vagdrivers.net/forums/lofiversion/index.php?t47519.html

There's a couple of links to the forums, if anyone has time to have a quick look and share their opinion that would be great.
Thanks!
 
Cleaned out the crankcase breather pipe but not had the crankcase breather box off to clean it. anyway. I've just done a 130 mile round trip and there's now no gunk coming from the breather pipe (for now anyway) but the cars idle is still jumping from about 600 to 800 rpm continuously.
I plugged my little diagnostics reader in and it's giving me a code of 17962 which translates to - Idle Speed Contr.Throttle Pos. Basic Setting Conditions not met

Any ideas on what that actually means?
 
Not getting enough air, air sensor needs cleaning replacing perhaps?

Run it for 15 minutes and see if the idle settles down a bit. Remove the air filter and see if this flows better and report back.
 
Took the air filter off once the car was up to temp and the revs were jumping around. thought it made a difference because the revs calmed down but later on, once the engine had cooled down I took the air filter off and drove the 3 or 4 miles home and the rev counter was still jumping up and down on idle so no difference there...

Any other suggestions? Thinking it's gotta be a sensor somewhere that's gone tit's up.
I'm kinda new to all this sensor business because my old mk3 golf had what seems like none compared to this motor!
 
Cleaned the MAF and EGR valves and gave the throttle body another clean.
Both the MAF and EGR were filthy!
It is definitely better but still not 100%.
I think the engine may just be a bit gunked up and need a bit of a thrashing. I've put some fuel additive into a full tank of petrol and am doing a 130mile trip later so sure that will help clean her out.
 
Ok, so here's the update...

I cleaned out the MAP sensor and EGR sensor along with the throttle body again. Put it all back together and it was driving nice and the revs weren't bouncing around at idle (or at least that I could notice)

I done a 300 mile round trip over xmas and now the rev counter was back to normal bouncing from 600 to 800rpm over and over at idle. But my little diagnostics reader isn't reading any faults.

I've just taken the throttle body off and it's caked in black soot again, which I think is coming from the Exhaust Gas Recirculation. I've cleaned the throttle body right up again, checked the MAP sensor and it's all clean.

The breather pipe is now not an issue. no gunk in there whatsoever, so that is good news at least. Think it just needed a clean out and a couple of long journeys.

I'm going to re-assemble the throttle body and leave the EGR unplugged for a few days and see how it gets on.

Just a bit concerned that my engine could be burning a lot of oil, but then if the intake manifold is dirty it will burn the crap that's in the manifold and then re-circulate some of that crap back into the manifold....

Cheers
 
Hey sorry sorry the lack of updates,

Basically, I think that the EGR valve has gone, I've done several miles with it unplugged and the idle seems to be fine, once it's plugged back in and after a good little while, probably 50 - 100 miles the idle starts to roughen up.

I think this is partly due to the engine burning a lot of oil, so the oily exhaust fumes are getting re-circulated back into the intake and is clogging up the throttle body. I think that the throttle body is getting clogged and the ecu can't judge the mixture that needs to be going through to keep the running smooth.

It's as though it starts to stall (revs drop to about 600rpm) and then the ECU goes 'Oh *#*#*#*#!' and shoves some more fuel in to keep it alive.

That may not be the case but seems to me at least to be logical...

I think the car's a bit knackered to be honest, not done a compression test yet but I've got a feeling the piston rings may be going, a general loss of power and burning a fair amount of oil?...

I think it's had a wrong gear box fitted to it too by one of the 2 previous owners, which I think is why the speedo is out, seems like it's probably got a lower ratio box on? Just a guess at the mo.

No more problems with gunky mayo oil in the breather pipe now though which I guess is at least one good thing,

Cheers
 
Well with regards to the incorrect speedo reading, are your wheels and tyre sizes still OEM? On my Saab as I graduated up in sizes from the factory 17" and through to my aftermarket 19". A Tech II diagnostic and programming tool had to be used to tell the car what wheel size was fitted now, this then altered the speedo accordingly. Just a suggestion as to what your issue might be....
 
Na, the tyres are the right size.
Pretty sure it's the wrong gear box. for example -

The speed that the speedo says is definitely wrong, but the revs match the speed. so at 70mph on the clock I'm at around 3k rpm. but 70mph on my clock is more like 58mph.

Also, my mileage is clocking up too high. I drove from Leeds to Whitby last Sunday with the girlfriend and the satnav said 73 mile but the clock in my car said 88! thats a fair few mile more. And no I didn't get lost or go a different route. just checked on Google too, 73 miles.

Not checked the Gear box code thoroughly yet but when I had a quick look I couldn't find one.
 
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