Another idle issues thread.

[Waspy]

So, my car idles at about 1k, not solid as a rock, but not so problematic. But it does have the classic drop the revs when coming to a stop and sometimes dropping them so far it stalls.

I have read countless threads about this, and still havnt solved the issue.

So far I have:

Checked the ISV, including checking it vibrates when the electrics are on, and cleaned it thoroughly with carb cleaner.

I have checked for vacuum leaks and can find anything, although see the pic below, the pipe below the connector is supposed to be blanked, right? However it makes no difference to the issue when I block it.

Took the TB off today to check the idle switch with a multimeter. The switch clicks just as you open the throttle and the multimeter showed no issues. I also completely cleaned the TB since it was off.
After putting the TB back on and connecting everything. It idled solidly at 950, and didn't drop the revs at all! I was delighted, however 60 seconds later it was doing it again.

So, anything else I should be looking at?

[Sgt_Lemon]

Still sounds like vacuum. Did you change the to gasket?

[Waspy]

Still sounds like vacuum. Did you change the to gasket?

Ill ordrer some new lines then, not like they are expensive.

As for the gasket, it wasnt until after  had the TB off that it even crossed my mind. So I had to reuse the one that was already on. However looking online it is impossible to find! Does anyone know where I can get that gasket?

[Santiago]

VW dealers still sell the TB gasket, despite online rumours to the contrary. 037133073A


As for your idling problem; if you unplug the two-way connector from the throttle body while it's idling (fully warmed up) does anything change?

[Waspy]

VW dealers still sell the TB gasket, despite online rumours to the contrary. 037133073A


As for your idling problem; if you unplug the two-way connector from the throttle body while it's idling (fully warmed up) does anything change?

Brilliant, thanks for the info!

And I am not entirely sure which connector you mean? Do you mean the connector which connects to the idle switch?

[Santiago]

The one and only electrical connection to the throttle body. Goes to idle- and wide-open-throttle switches.

If unplugging it makes no difference, suspect a wire break somewhere between loom connector and ECU.

[Sgt_Lemon]

I would assume vacuum as it changes with engine load aka coming to a stop. Or does the idle continue to go loopy on any form of idle once warm?

[Waspy]

It messes the revs up when I dip the clutch from say 2000 it will drop them to 500 then recover. If the revs are climbing quickly, then clutch it, it will drop them so fast it stalls. If I come to a gradual stop and let the revs fall to 1.2k it will handle it fine. The idle is around 1k, but it does move about +/- 50 while idling, so it's not solid.

But the more I think, the more I see you are probably correct. Vacuum is likely. The hoses look tired, bound to be leaks. Buying new hoses now. Anyone know where you can get hose blanks from? I can't find any the right size (for 3mm) and I don't want to be doing the old screw in the end trick really...

[Waspy]

For the benefit of anyone hitting this page from searches for gasket 037133073A (I found lots, with conflicting info, as mentioned above)

I can confirm these ARE still available. Leeds had 16 in stock.

[Sgt_Lemon]

My vacuum blanks are pop rivets