Climbing idle

[stoo 0]

Hi all, I'm new to the forum and to VW ownership. I bought my C last week and I'm enjoying the car a lot, much better handling than my old Civic, but I'm having a few teething problems.

 

The most annoying of which is that my idle climbs and settles around 2800rpm when I stop. It will sit at 1000rpm for a few seconds then gradually climb, taking about 5 seconds. Also, if I blip the throttle the revs will go to 2800rpm and stay there.

 

I have done a search and found the ISV seems to cause similar problems, but would it really cause my idle to climb from a standstill? Not checked to see if the throttle plate is fully closing but the cable isn't sticking so don't think that's causing it.

 

Any help would be appreciated.

 

Thanks

[matthewb1985 0]

hi welcome

mine does a similar thing havent managed to solve it yet try cleaning the isv out.

[Blinky16v 0]

I had idling problem with my valver, was a small hole in a vaccum pipe attached to the ISV.

 

You might try getting some carb cleaner spray and carefully (it is flammable) spray around the vaccum pipes... Make sure the engine is running when you do this and if you have a leak you should hear the engine revs increase.

[matthewb1985 0]

i might try that thanks

[G60SC_Stoney 0]

you can disconnect the isv. thats whative done on my G60. temporary solution only tho i think.

[stoo 0]

I managed to solve the problem temporarily lastnight. I took apart the entire intake system, cleaned it out and reassembled it. I started the engine and let it idle for a few mins whilst playing with the throttle. It idled at 850 rpm for the entire time. However, I took it around the block and when I stopped it was up at 2800rpm again.

 

There is a pressure valve that comes out the back of the airbox and connects again upstream of the airfilter, but before the throttle butterfly. It has a vacuum hose connected too. This was full of oil (no idea how it got there)when I took the intake system apart so I cleaned it out thoroughly. I suspect that this might have solved it, and when driving again, cornering has surged oil back into it. I will clean it out again tonight to have a look, though I can't see any oil in it just now but there might be some at the bottom.

 

I also took the throttle body off and check it out. The smaller butterfly had a tiny gap around it, proably 0.5mm over about 30 degrees of its circumference. Would this leak enough air for the idle to climb to 2800?

 

I will also play around with the ISV tonight now that I know where it is - I'm so used to Honda's.

 

By the way, I have a 1.8 16v 1990. Thanks for your help guys.

[stoo 0]

Solved it!

 

Turns out the throttle cable was sticking just enough for it to open a tiny amount, there was a loose vacuum hose that connects to the pipe just in front of the throttle, and the ISV valve is sticking too. A good blast of WD40 has fixed it. Started the engine and idled at 850 (give or take) right away.