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revs dropping off - mainly when its cold...?

Posted: 07 May 2015, 15:22
by Jamesy
Hi we've noticed usually for the first mile or 2 of driving, when you put into neutral, 75% of the time the revs will just drop off and it will stall.

Usually once heated up its fine - did it once on the motorway after a long-ish drive when I put into neutral as I came off the slip road.

Any ideas what this can be?

Its due a service but will a servide likely clear this? or would it be plugs? or a split hose?

It drives lovey, no misfire or hesitation...

Any help welcomed :)

Re: revs dropping off - mainly when its cold...?

Posted: 07 May 2015, 18:05
by lefty67
what engine is it?

Re: revs dropping off - mainly when its cold...?

Posted: 07 May 2015, 19:21
by kevtherev
As you have said plugs in the service we can assume it's a petrol engine, with a carburettor.

So take a look at the autochoke and it's operation.
Look in the wiki for more information, under the title 'Pierburg choke' in 'water cooled engines'

Re: revs dropping off - mainly when its cold...?

Posted: 07 May 2015, 20:42
by Jamesy
Thanks. Yes 1.9 petrol water cooled.

Is that about turning the carb a bit to see if it helps? Im not doing the work myself but tips for the garage are greatly appreciated

Re: revs dropping off - mainly when its cold...?

Posted: 07 May 2015, 21:15
by kevtherev
Jamesy wrote: tips for the garage are greatly appreciated
I'm out.

Re: revs dropping off - mainly when its cold...?

Posted: 07 May 2015, 21:32
by Jamesy
?? Why's that

Re: revs dropping off - mainly when its cold...?

Posted: 08 May 2015, 06:04
by CovKid
Kev means theres not much point in advising the garage if they are indeed a garage (thats their job), besides which without seeing it, its impossible to speculate with any accuracy. It could be one or a number of things. A methodical approach needed.

Re: revs dropping off - mainly when its cold...?

Posted: 08 May 2015, 06:52
by kevtherev
CovKid wrote:Kev means theres not much point in advising the garage if they are indeed a garage (thats their job), besides which without seeing it, its impossible to speculate with any accuracy. It could be one or a number of things. A methodical approach needed.
Indeed..totally agree.
Perhaps the garage should register on the forum and learn something. :D

Re: revs dropping off - mainly when its cold...?

Posted: 08 May 2015, 07:27
by Jamesy
Ok fair enough... I was just hoping that on an enthusiast forum people will have encountered and overcome such issues and a few hints to help us out would have been great.

no worries....

Re: revs dropping off - mainly when its cold...?

Posted: 08 May 2015, 07:30
by silverbullet
Enthusiast forum yes, but we are a bit short on mechanical psychics.
It could be any number of things but asking for advice to pass on to your garage suggests that they are severely lacking in T3 or any old VW experience.

Re: revs dropping off - mainly when its cold...?

Posted: 08 May 2015, 07:48
by Jamesy
Good point, I wish there was a brilliant T25 specialist garage near me to take it to - but unfortunately haven't found one yet (Mid Sussex) ... so my next best option is a decent mechanic and forum advice.

thanks

Re: revs dropping off - mainly when its cold...?

Posted: 08 May 2015, 08:04
by CovKid
If its sat on your drive we can suggest this and that (and do) but certainly get your garage to do a compression check. This is an important starting point as it'll say much about the overall condition of the engine. Choke has already been suggested - that and air leaks are common areas to check when trying to pinpoint rev drops. You may just find a carb rebuild/overhaul makes all the difference. On the other hand you may not.

Re: revs dropping off - mainly when its cold...?

Posted: 08 May 2015, 08:05
by Jamesy
Ok cool thanks a lot, hopefully its something like a split vac pipe and we can get on with enjoying the summer trips

Re: revs dropping off - mainly when its cold...?

Posted: 08 May 2015, 15:17
by kevtherev
VW has been making it's owners into mechanics for 60 years, because their engineering is very simple and people friendly.
Your lack of any specialist garage near to you, would suggest a more hands on type of ownership might be rather beneficial.

If your willing to learn to do some basic stuff yourself, then this place can be VERY helpful.
You come across as an intelligent chap, I dare say you have some curiosity, so what do you think?

Re: revs dropping off - mainly when its cold...?

Posted: 08 May 2015, 21:48
by Jamesy
Thanks Kev. I have a highly modified Supra and my best friend is one ofnthe best supra mechanics and engine builders in the country, who happens to live 3 miles away!

I have been fortunate with that marque, but id love to really get into the vdub scene so perhaps will have to try something ive never done before and get hands on!!