Golf Mk4 1.6 Revs Fluctuate / stalls / temp up & down!!

[randall977]

I've just aquired a 1998 Mk4 Golf 1.6SE off some friends who are clueless about cars. It drives well and has done 103K - but it needs work. The main problem is that the revs fluctuate badly (500 - 1000rpm) when idling and it oftern stalls (when idling). I watched the temperature guage go upto near 90 after a few minutes , then it dropped to 70, then went up again... Are the two problems relatated? Is the temp really going up and down?

Any help really greatfully recieved - then I can move onto the dodgy door locks, rear wiper and front suspension!

[randall977]

Ok well I'm guessing it's the temperature sensor so I'm going to put a new one in this evening.

[Anzee]

Im sorry i gotta break it 2 u like this but mate its sounds bad i had a 1.6S MK 4 golf and it had the same problem....

Basically the idling and when u come to a halt at a light it stalls is what i incured alot and i got so fed up i ended up changing the car... The part that needs replacing is a THROTTLE BODY best place 2 do that from is VW becuz u will gt guarntee but be warned does cost a bit... the second option u have with that is what i used to do was get the actually Throttle Body Cleaned out becuz muck gets stuck in it and if u use Nail Varnish and clean it out properly u should be able to clock up on average 5000/6000 miles before it goes again..

The temperature Needle i had that problem on mine as well that is just a sensor fault not actually linked to the Idling problem.

Hope this helps

[randall977]

Hi, thanks for the reply. I think you are right - I replaced the temp sensor and now it reads the correct temperature...but still stalls! My first stop is to clean the throttle body - then a £300 replacement if all else fails! Bummer.

[amz]

If only I had found this forum 2years ago.... I had exactly the same situation as yourselves, and ended up doing what Anzee did... sold my 1.6 SE Golf. I had looked after it extremely well, and got fed up having it checked over by many garages who tried and tested different things, but to no avail. The main VW dealers said its not something they've heard off, and would cost £65 per hour to diagnose the problem, and then depending on the fault, cost accordingly to fix. I wouldn't have mind paying £300 for a replacement, as I ended up selling the car for more than £1500 less than its actual value.

The guy who bought it knew its a bargain!

[Eshrules]

Hi, thanks for the reply. I think you are right - I replaced the temp sensor and now it reads the correct temperature...but still stalls! My first stop is to clean the throttle body - then a £300 replacement if all else fails! Bummer.

i had a similar fault on my last car (fiat) , with the throttle body, i can't see how replacing it would do more than a good clean is capable of doing... its basically just a cylinder with a butterfly valve in the middle of it, give it a good clean and it should be good as new :)

[randall977]

Cleaning the throttle body did cure the problem, though I'm not sure using WD40 as the cleaning agent was a good idea? I'm also not sure if I need to reset the fault code??? I disconnected the battery for 10 miutes. The revs are a bit high when idling (1500rpm), why is this?

[Huweth]

Could be residual WD40 getting into the cylinders and burning, or the WD40 has lubed the throttle body too much meaning it's holding itself slightly too open, or the previous owners had the throttle adjusted to 'fix' the problems they may have been experiencing before it really buggered up. I'd just drive it around for a bit and see what happens.

[guyg]

I don't know about this particular engine, so I'm not sure how relavent this will be but...

I had an ABK engine on an A6, there was an adjustable grub screw and locknut that prevented the butterfly from closing completely. As Huweth suggests, someone may have buggered with the setting. It only needs to be open a fraction, as the ICV should control the air bypass needed for idle. I would also check the ICV itself [unplug it, the engine should die immediately], it's hose and any other hoses on the vacuum side for leaks.

Cheers

Guy

[Anzee]

Guys i dont know wheter u will take this seriously but the person that cleaned mine was a specilist in German cars i.e. VW, AUDI, BMW, Merc and he said to me once on my 4th visit (Over Exagurating) in a year and a half whilst getting the throttle body cleaned, he stated that Nail Varnish Remover is the best thing to use after u have clened the muck out all the big bits get some cotton buds and use them to clean wat evers left.... Dont know if this is true though

[guyg]

Nail varnish remover is largely [if not completely] made up from acetone, which will also dissolve super glue, most plastics and some types of rubber. It's good for cleaning lots of things as long as they don't contain any of the above!

Cheers

Guy

[Huweth]

Nail varnish remover is largely [if not completely] made up from acetone, which will also dissolve super glue, most plastics and some types of rubber. It's good for cleaning lots of things as long as they don't contain any of the above!

Cheers

Guy

It's not completely acetone. There is a small percentage of colouring, and a flavour to make it taste foul (so you don't drink it). I suspect that the small amounts of 'contaminant' would have no real effect on the throttle body, but it would be best to try and get hold of some 100% acetone from a chemist.