G40 rough on start up...

[supercharged spaniel]

yeah it is a chug, and mine does have a decat yes!

if i rev the chug just ups its speed, until after a few minutes, it goes away

i will be swapping the decat for a cat soon so i will see how it goes!

good input from all here, i hope we sort it

yep! exactly the same!  try it and see..shame i weighed my cat pipe in ha ha

[G40DAS]

I've been running a VAG decat pipe on mine for about 3 years now and mine doesn't chug, either with standard ECU or a Jabba chipped, cup spec ECU. I do get a petrol smell on start-up sometimes though, but I think that comes from the rubber tube between the valve on the water cross-pipe up to the manifold, it's getting little cracks in it with age. Anyone know how much these are ?

[hayesey]

what is a "cup spec" ecu? 

The aux air valve is quite expensive, VW only and I think they are over £60.

[G-spot]

My first input on this one, I'd check that the throttle shut off valve switch is set-up probably(its the little microswitch on throttle body), it should be switched(pushed) when the throttle is closed, quite often a sticky accelerator cable or poorly adjusted idle screw can stop it closing probably.  This is more noticable if the butterfly has been de-wegded.

[supercharged spaniel]

My first input on this one, I'd check that the throttle shut off valve switch is set-up probably(its the little microswitch on throttle body), it should be switched(pushed) when the throttle is closed, quite often a sticky accelerator cable or poorly adjusted idle screw can stop it closing probably.  This is more noticable if the butterfly has been de-wegded.

im interested in what your saying but im not 100% what to do to check this or cure it?  my throttle butterfly is dewedged actually. cheers

[supercharged spaniel]

ermmm i darent believe this but i went out side to try what you said G-spot and it didnt do it at all? 
what i did:  unclipped the throttle cable rubber support from the bracket on the manifold (not removing the little metal clip that keeps the cable under tension) so the accelrated cable was hanging untensioned and started the car...then i revved the car manually from in the bay...no chugging whatsoever?!  Now the car has been sitting since i got in from work at about 5:45 so at the point i started the car is about 4 hours and its freezing outside which always makes it worse.  I'll try it in the morning when it always does it and if it doesnt do it  will be overjoyed!  im not sure why it would do it and how the cable would effect it to be honest and why the cold would make it worse other than the cold makes the cable tighter and pulls more making something not close??

plus it always does it after sitting for a while 3+ hours as if something is slowly changing (previous thoughts were fuel flooding a cylinder from a leaking injector but swapping them proved otherwise)...cable tensing as time ticks by?

anyways fingers crossed!

[PeteG40]

its the idle switch in throttle - ther eis a like 2 switches, on and off if you like - one for idle and the other for full throttle. If the cable is too tight then it wont switch the 'off' switch

pete

[supercharged spaniel]

so maybe its choking it with too much air?  and fuel?  thinking ite open than it is?  make sense?

[supercharged spaniel]

someone else noted havi the same problem a while back but i cant remember his name on the forums.  had a red G which he sold to luke.  sure it was him...said he had one in his garage which was doing the same.

[G-spot]

sound like we fixed that one then, reason I suggested looking there is that I had similar issues after my last rebuild, even though everything went back the same, the switch wasn't quite closing out, it also meant that it was running rich on the overrun as the ECU didn't see the throttle as being fully closed.

[supercharged spaniel]

well im otimistic but tomorrow morning will tell for sure then i can see as well and adjust cable accordingly.... fingers crossed.  cheers for the help...dn knight said it didnt make a difference for him so im a little gutted about that...see how it goes though..

[supercharged spaniel]

still no change this morning...gutted lol

[G-spot]

 

[PeteG40]

tried another throttle? you sure switches are working?

[supercharged spaniel]

no not yet but im gonna wait for dan knight to change his as its one of his plans.  if all is well after then ill source one.