Automatic Choke

[M17 KVN]

I was wondering how difficult it is to change my automatic choke as it doesnt seem to be working whent he car is cold?

[rubjonny]

A bit fiddly but not too bad.  First check some other stuff:

Does the autochoke get 12v with the ignition on when cold, & switch off when warm? If not the red temperature sensor at the front of the block may be faulty.
Does the autochoke pass current (1 pin of multimeter on plug, the other on autochoke housing)
Does the autochoke get enough coolant, the o'ring in the inlet manifold can degrade and block the channel, very common problem!

If all of those check out:
Take 3 screws off autochoke housing & remove 2 coolant channels, remove autochoke.  Refitting is reverse of removal, but remember to line the notch up on the housing with the mark on the carb, and make sure you locate the choke flap pin in the spring properly.

P.S. This is for a 1.6/1.8 Carb engine, 1.3 will be similar.

[M17 KVN]

All i can tell you is when it is cold it sits at 800rpm but when it heats up it sits at 1300rpm?? Not any use when you need to get away quick and it is too cold for it to run. Stutters a lot, and i guess that is becuase of the choke, its a 1800 GTI MK1.

[rubjonny]

Yup defo an autochoke problem as you say, try those 3 suggestions before you take the autochoke off though, I would say you have the last and most difficult of the 3 problems, you'll have to take the inlet manifold off!!

I had a knackered red coolant sensor and the o'ring problem too, replacing the red sensor helped a bit but it still ran like crap just not for as long ? As soon as I replaced the o'ring my car ran like a dream!

I put together a FAQ on the 'other' forum, am I allowed to post it here?? If not I could copy & paste my info into a post
http://www.clubgti.co.uk/forum/forum_posts.asp?TID=46724&PN=1

[mk1]

Hi BlackMk1Cab, you say your engine is a 1800 gti mk1. This engine is fuel injected so doesn't have a auto choke as such. The engine cold idle speed is controlled by a air bypass valve and enrichment is regulated by the warm up regulator. When the engine is hot pinch closed one of the rubber pipes on the air bypass valve and the engine speed should stay the same (but may need adjusting if it's to fast as someone may have adjusted the hot idle speed to stop it from stalling when cold), if it drops the valve is not closing. Check the two pin plug for earth on one side and battery voltage on the other when the engine is running, same for the warm up reg. If voltage is OK, the bypass valve is gubbed. The warm up reg is a bit more involved to check as you will need fuel pressure test equipment.
Steve.

[rubjonny]

Damn missed that, ignore everything I just said then 

[M17 KVN]

Ok no problem will do.

Thanks for you're help guys.

Kev