Hunting! - Vacuum Pipes!

[Len]

Well I replaced the vac pipe up from manifold to ECU and a secondary one from MAF vac up to god knows where! That seems to disappear behind the washer bottle then up into wing!

Any way I now have very bad "hunting" at idle in fact it wont idle any lower than 1200 revs!
So I tried swapping on the K&N again and changed over the throttle body! And combinations!

I think there was some threads about this before or similar traits but cant find em! 

So where to look? I'm thinking it must be a sensor? But which one? MAF?

[Khare]

only way to know for sure is vagcom. Is the throttle body nice and clean?

[Len]

Yep both are! One being more polished than the other!

Yes I need Vagcom!

[spunkymonkey]

If its hunting around 1200rpm sounds like a vac leak.

When you say it goes god knows where, is it connected to something at both ends? If not block it off and try it.

[Len]

Yes I agree! But where? Cant see any other hoses and no spare places to connect one!
Checked with another 16v and have same hoses!
Now all hoses are new!

This one from the T piece of the MAF hose goes to another T then by white plastic pipe behind the washer bottle then in under the wing and I cant see where it goes!
Yes I took the battery and washer bottle out!

[davero]

Have you changed the one under your inlet manifold.? The maf is the one from the t.b. to the ecu. Have you a pic of the other one?

[Paul86S2]

Confused on this - you haven't got a MAF so what part are you referring to as the maf?

On my 16v throttle body I have a vacuum pipe going to the airbox for the cold start air diverter valve (if you've got a induction kit this will need to be blocked off. A second larger one going to the valve on the charcoal canister. From the manifold above the VW sign I have a vacuum pipe going to the ecu under the passenger side scuttle panel. And below the throttle body from the manifold I have a short vacuum pipe that goes to the fuel pressure damper on the fuel rail. A large vacuum pipe goes from the back of the manifold to the brake booster.

Not sure what vacuum pipe goes under the water bottle and battery, have you got cruise control?

Paul

[davero]

Confused on this - you haven't got a MAF so what part are you referring to as the maf?

On my 16v throttle body I have a vacuum pipe going to the airbox for the cold start air diverter valve (if you've got a induction kit this will need to be blocked off. A second larger one going to the valve on the charcoal canister. From the manifold above the VW sign I have a vacuum pipe going to the ecu under the passenger side scuttle panel. And below the throttle body from the manifold I have a short vacuum pipe that goes to the fuel pressure damper on the fuel rail. A large vacuum pipe goes from the back of the manifold to the brake booster.

Not sure what vacuum pipe goes under the water bottle and battery, have you got cruise control?

Paul

This is the map sensor hose, the equivalent to the maf on a 16v.

[AudiA8Quattro]

Len, did you replace the throttle body gasket when you removed it?

[Diamond Hell]

There is clearly only one solution to this problem.

A Golf3 with a fault is like a horse with a broken leg.  There's only one option open to you.