Rough Idle

[Oddyse]

Hi guys, so I have just became the proud new owner of a VW golf Mk4 1.6. Its a beautiful car to drive and in the 300 miles I have owned her she has been great. I noticed the engine management light was on and the codes pointed to a faulty EGR. So I began to remove it to give it a clean, which is when I noticed the blanking plate. I removed it and fitted everything back together. Around 100 miles later I ran pretty low on fuel and noticed the idle running really rough. Jumping between around 700 and 1000 RPM. It has stalled twice in this time also. so now im worried the EGR is causing problems and I should have left the blanking plate in.

So my question is .... do you think the rough idle is linked to the fuel running low, or to the EGR valve?

Any help would be great.

[Eshrules]

When you say ran 'pretty low' - how low is that? Did you run out?

When was the vehicle last serviced and what service was completed?

[Oddyse]

Thanks for the reply matey. It hasn't been serviced in 5 years!! I'm doing a full oil, air and fuel filter change, an oil change, plug change and coolant change on Sunday. The fuel wasn't low enough to stop the car running but was well in the red. I plugged my diagnostic machine in and cleared some faults off, that is when the rough idle and stalling started. Even though these faults were present before, I'm confused?? It's really frustrating stopping at lights and losing all power :( another thing that might help you help me is that it runs perfect, the rough idle isn't there when the engine is cold, it only starts after the engine is warm. The guy before had a egr blanking plate in there and I have removed it, should I put it back in?? I'm really hoping I can solve this soon

[Oddyse]

So just a quick update. I have cleaned the throttle body and disconnected and reconnected the battery. Now when the engine is warm it seems to idle much better ( still not perfect though) . The only thing that remains is when I break harsh the revs drop and then shoot back up before they return stable again. Does this help with the diagnosis of my fault?

[SammoVWT]

It could be a vacuum leak, one of the hoses that connects into the inlet manifold where the throttle body sits. Usually includes a brake hose too to the brake servo, make sure the screw clamp is tight. Check for perishes etc.

Its not limited to only vacuum leaks with this sort of symptom - could be voltage related, alternator battery etc, ground connections also. Looks like it needs a good going over!

[Oddyse]

Thanks for the reply Sammo,
It's funny you should mention that as I ran a diagnostic on all other parts of my engine system and it has thrown up a 00532 fault which would suggest exactly what you are saying with a possible bad earth etc. Il go over everything on Sunday and give you guys an update. Thank you for helping this newbie out , not many forums are quick to help a newbie without a few insults first :) thanks again guys

[Eshrules]

My course of action would be to give the car a full and comprehensive service first, especially as it's not been done in 5 years (!) and then look to see if there's anything obvious causing you issues, per Sammo's post.

I suspect the car is just in need of a good service although I'm not qualified to offer insight on how much damage the engine may have suffered during those 5 years.

As for the insults to new members - we only tend to insult the idiots here on VWAF, if you're not an idiot, you don't get insulted :naughty:

(tongue in cheek, clearly)

(we don't insult many people)

[niall campbell]

The fault might be caused by idling not within range

Or a faulty battery / alternator ........................ so get a free check on a dud cell(s) at a garage & check alternator output. It has been cold at night with frosted screens in Glasgow at least, cold weather kills batterys and any dud cells pop up

So that's giving you a red herring, I would concentrate on fixing idling firstly.

If it starts ok, idles okay when cold , then possible coolant water temp faulty as the car may think its either warmer or indeed colder than it really is, the ECU getting fooled.

Could be the knock sensor as well, adjusting the timing all the time

Live data would be useful for water temp when car shows 90 degrees on dashboard

[Crasher]

owner of a VW golf Mk4 1.6

Which year and engine type code, what were the fault code numbers?

[Oddyse]

Hi guys, thanks all for the replies. So .... I have given her a full service :) changed air filter, oil filter, fuel filter, changed the oil too. Just changed the temp sensor and ran a flush as the guy before was just using water in the coolant :( I have cleaned the throttle body too. The idle is much better now but it still hates it under harsh breaking, the revs drop then either over rev or just completely stalls?? The fault code I had was 17848 and the engine code is ..... Where would I find that?? It's a 2002 mk4 1.6 if that's any good? I'm hoping the new sensor may help but if it doesn't what would be the next check? Battery/alternator as Niall said?

[Crasher]

Sounds like a BCB code engine so fit a new EGR valve. This MUST be adapted to the ECU and then checked using the Basic Settings functions 074 and 075, if you don't do this, the new valve WILL burn out.

[Oddyse]

The EGR has a blanking plate in it mate. Does this make a difference? I did get another code pop up, 00532, which would point towards alternator or battery etc. But where do you start?

[Oddyse]

Just had this code pop up too ... 16555? Don't know if this helps you guys out at all?

[Crasher]

16555 could be an air leak or a dirty/badly set throttle body. The BCB does not take kindly to having the EGR blocked and its also pointless and illegal. 00532 is low voltage so start with a multimeter and check the alternator output.

[Oddyse]

Thanks for the reply crashes. I only put the blanking plate back in there as when I took it out is when all the trouble started. Shall I remove and get it all set up on a vag com? Il have a look at testing the alternator too, no idea where to begin there but I'm sure Google can show me :) thanks again mate , all help is much appreciated

[Crasher]

If your EGR valve is the old type with a rusty steel parallel cylindrical body,
http://i222.photobucket.com/albums/dd20/Crasher1964/06A131501F-PEGRvalve.jpg (http://s222.photobucket.com/user/Crasher1964/media/06A131501F-PEGRvalve.jpg.html)
You will probably find it will not set up and this can cause code 16555. You may find you have to take a gamble and fit a new EGR valve but only fit the correct VW specification 036 131 503 T or Pierburg 7.28248.17.0.
http://i222.photobucket.com/albums/dd20/Crasher1964/036131503T%20EGR%20valve_zpswagubta6.jpg (http://s222.photobucket.com/user/Crasher1964/media/036131503T%20EGR%20valve_zpswagubta6.jpg.html)