Pierburg Automatic Choke

[AngeloEvs]

I have no ptoblems with modern Auto chokes that interface with modern Engine management systems but the Pierburg Auto choke is, for me and a lot of others, its achilles heel. Covkid metioned on a thread that he uses his van as a daily driver all year round with no choke fitted. I disconnected mine and strapped the choke flap fully open then started the van from cold - it started and ran far better without the choke. There is nowt wrong with my choke, it functions perfectly well but my argument is that it is also functioning when not actually needed and relies on temperature to open the flap . This initial period is just washing the bores with unecessary fuel and effects the economy. The counter argument may be that the fuel/air mixture is lean and the combustion temperature high but I have to disagree with that given that the test runs today showed none of the typical signs of a weak mixture.

I'm convinced a manual choke is the answer, better for the engine, improved economy and probably only needed during the winter to kick start the engine. Anyway, I have just ordered some components and will be converting mine so that the choke is controlled manually from the dash but not via a cable but electrically.

If there is anything I may have overlooked then let me know as the the 'pull down' unit and the choke heater element would appear to be no longer required if the choke flap is manually controlled.

[kevtherev]

I for one, shall be interested in your results.

[ghost123uk]

If you are happy with the results of your experiment, you can take off the choke pull-down unit and flog it.
I am told they are very hard to come by and folks pay good money for them

[AngeloEvs]

If you are happy with the results of your experiment, you can take off the choke pull-down unit and flog it.
I am told they are very hard to come by and folks pay good money for them

Reasonably optomistic that I will come up with a reliable solution but as for selling the 'pull down' unit I just wonder if ever I sold the van whether a buyer would prefer the standard set-up. I guess the proceeds would probably cover the cost of the conversion so worth considering. At the end of the day all you have to solve is obtaining approx. 40 degrees of movement from the dash without using the tradditional cable linkage. There are some cutting edge materials and components available today that just didn't exist a few years ago.

[ghost123uk]

A switch and a servo perhaps ?
R.S. components would have a suitable servo me thinks.

[AngeloEvs]

Yes, one idea is to use a stepper motor but link it using a new 'smart' ploymer which transmits rotational forces no matter how you bend it. Stepper motor can be anywhere in the engine bay and the polymer can follow any path to the choke spindle. My favoured idea is simpler and cheaper using Mechtech solenoids specifically designed for automotive applications such as this one. Stepper motor would give a multi-position solution and the Mechtech solenoid a 3-position choke via simple linkage, i.e, open, part cholke and full choke (not completely closed otherwise you would never start it!). There are also precision rotary solenoids now but at £100-00+ don't think I will be going that route!

[matty o]

keep us updated on how it goes

[ricicles]

do you need it at all? i can start mine with no choke. 5 presses on the pedel (accelerator jets) starts first time, use small throttle movments until warm. schimples

[AngeloEvs]

do you need it at all? i can start mine with no choke. 5 presses on the pedel (accelerator jets) starts first time, use small throttle movments until warm. schimples

Glad you posted that, that's exactly what I have found, no choke and still starts (and runs sweeter!) after a few depressions on the pedal. Just out of interest, how do you get on in the winter?

[Bowton Lad]

do you need it at all? i can start mine with no choke. 5 presses on the pedel (accelerator jets) starts first time, use small throttle movments until warm. schimples

Glad you posted that, that's exactly what I have found, no choke and still starts (and runs sweeter!) after a few depressions on the pedal. Just out of interest, how do you get on in the winter?

If you're depressing the accelerator & relasing it, then you are setting the automatic choke.

[CovKid]

Wasn't me running around without a choke, but have done this on bugs. The drawbacks with autochokes include being out of sync with engine demand and consuming more fuel (in theory) than a manual choke although what tends to happen with a manual choke is folk forget to turn them off. If you can nurse the engine along from cold without one then great but theres probably not a great deal of saving to be made here and in my view better to tweak an autochoke to work correctly. This time of year you probably don't need much if any choke on - maybe a good opportunity to set one up right

Mind you, come a morning when the world is frozen up, you might feel differently about having no choke.

[Gadders]

do you need it at all? i can start mine with no choke. 5 presses on the pedel (accelerator jets) starts first time, use small throttle movments until warm. schimples

Glad you posted that, that's exactly what I have found, no choke and still starts (and runs sweeter!) after a few depressions on the pedal. Just out of interest, how do you get on in the winter?

Been running without choke for about a year now.Couple of taps on the peddle to start with and just keep it ticking over while i roll a fag and away we go,no probs.(was even ok during winter months)

[ricicles]

had these on for two winters now, no probs .

[AngeloEvs]

Sorry Covkid, thought It was you who had no choke but seems others have removed the auto-choke completely and still find that they can start their vans. Bowton Lad - the Autochoke has been removed on mine so that I can trial fit the new mechanism that bolts in its place. The heater coil coil seems to opens the choke flap after a bout 5 minutes irrespective of coolant temperature and, as Covkid says, you could adjust the choke body by rotating it forward to a summer setting so that it opens earlier using the element alone. However, now that I have a prototype mechanism that can be linked to a cable or a stepper motor I might as well go ahead and trial it - I still prefer a manual choke - about the only thing I can pull these days.........


E D I T: Ricicles, What are those then, looks as though they are on the head.

[ricicles]

pair of dellorto 40,s on type 3 manifolds