Classic Audi - View Single Post - Cold Start problems

TheTwelveQuidKid · 26-02-09, 01:56 AM

They have water heated auto choke don't they ?
And an electric manifold pre heater ?

I had one with that carb set up about 7 years ago and the symptoms on mine were:-

Poor cold starts
Stalling
Flooding.
Flat spots.

It would initially start from cold, after a blip of the throttle prior to turning the key. It would fire up, then stall, and after that, it was flooded. Killed the battery a few times on cold morinings.

In hindsight, if I had one like that again, I think I'd make, obtain or buy a manual choke conversion kit for it.

Did this model of Audi have the thing that stopped the vacuum advance retard mechanism in the distributor from working when the engine was cold ? If so, it's fitted in one of the heater hoses and has a couple of vacuum pipes connected to it.

Looking at the diagram in the Haynes book, in addition to the water temp controlled auto choke thing, there's an electrical one as well, with a wire going into it. I don't know where this wire connects to, but it might be worth checking if there's power going to it.

Just looking at the diagrams for this carb remind me what a complete nightmare they can be. Convert it to manual choke. At least that way, you can get it to idle at a speed that's acceptable until it warms up. Talking of warming up, is the thermostat ok ? If not (or if it's missing), it'll be sluggish for ages, and use more fuel as well.

Have you got a Haynes book with this carb in it ? On page 346 of the Audi 80, 90 and Coupe book, there's mention of thermo switches for auto choke and manifold pre heater. If either of these aren't working, the warm up process isn't going to be what it should be.
If you haven't got the book or if you need any more info, let me know and I'll find it for you.

26-02-09, 01:56 AM	#4
TheTwelveQuidKid Grown up member Join Date: Dec 2007 Posts: 422	They have water heated auto choke don't they ? And an electric manifold pre heater ? I had one with that carb set up about 7 years ago and the symptoms on mine were:- Poor cold starts Stalling Flooding. Flat spots. It would initially start from cold, after a blip of the throttle prior to turning the key. It would fire up, then stall, and after that, it was flooded. Killed the battery a few times on cold morinings. In hindsight, if I had one like that again, I think I'd make, obtain or buy a manual choke conversion kit for it. Did this model of Audi have the thing that stopped the vacuum advance retard mechanism in the distributor from working when the engine was cold ? If so, it's fitted in one of the heater hoses and has a couple of vacuum pipes connected to it. Looking at the diagram in the Haynes book, in addition to the water temp controlled auto choke thing, there's an electrical one as well, with a wire going into it. I don't know where this wire connects to, but it might be worth checking if there's power going to it. Just looking at the diagrams for this carb remind me what a complete nightmare they can be. Convert it to manual choke. At least that way, you can get it to idle at a speed that's acceptable until it warms up. Talking of warming up, is the thermostat ok ? If not (or if it's missing), it'll be sluggish for ages, and use more fuel as well. Have you got a Haynes book with this carb in it ? On page 346 of the Audi 80, 90 and Coupe book, there's mention of thermo switches for auto choke and manifold pre heater. If either of these aren't working, the warm up process isn't going to be what it should be. If you haven't got the book or if you need any more info, let me know and I'll find it for you.