anyone come across this before

I was driving along the A55 at 4am this morning, Suddenly the engine starts to miss badly wouldn't rev at all then crawled to a halt.

Left it standing for 2 mins, it started again

Drove fine for 2 miles and it started to happen agin

and the third time, I gave up and rang breakdown.

He said the valve in the air intake wasn't working so it was sucking all the freezing air up and actually freezing the carb. So he placed a flexi pipe to the air intake and moved it closer to the engine.

Since then it's driven like a dream

If that makes no sense then forgive me lol

But my question is, what valve needs replacing

What carb do you have fitted? Original or aftermarket?

original

The phenomenon is a common one, and the breakdown man didn't quite expliain it properly. The engine sucks in air. Due to the venturi effect in the carburettor, it cools down. If it cools lower than 0 deg C (which is easily done during winter time) the moisture in the air freezes and gradually closes up the airflow path, leading to a 'choking' or 'throttling' effect. This is carb icing.

The way (one way) round it is to use a valve which chooses air fed from the normal place (front right of engine bay near the grille) or from near the exhaust manifold, ie hot air.

At this point, I don't know exactly what the valve looks like, cos I don't have a carb car any more (and the one I did have, was fitted with an aftermarket carb) but no doubt someone can point you in the right direction. It might be possible, if your valve is merely stuck, to manually alter it to feed hot air, that way at least your car will still run, albeit down on power a little.

The valve isnt a valve as such its a flap on the airbox that diverts from warm to cold depending on the temp of the Vacuums Air. Most cars have either had them removed or they don't work.

Some from what I can remember have two 'hose settings' in other words you move the air intake hose from the front to the back of the car.

Depending on your carb/model of car, you may have a hot water feed or heated manifold, also there might be a throttle body heater (pierburg 1B3,probably others)

Hope that helps

ok thanks for you help

would a aftermarket airfilter help??

if so any suggestions

llywelyn111 said

ok thanks for you help

would a aftermarket airfilter help??

if so any suggestions

If anything, it would make it worse.

Not really, problem is cold/wet air in the carb, not something you can do anything about this time of year, just leave the hose where it is and put it back when/if it gets warmer.

Possibly might be something else such as the airbox flap not working but the only way to tell if its that is to see a pic of the engine bay

ok many thanks

i'll get some pics uploaded tomorrow is there isn't a huge puddle (lake) outside the garage

there is no throttle body heater. there is no throttle body. there is a carburetor. there is an electrical intake heater which is controlled by water temperature. when the water reachs a desired temperature (35-50c) the intake heater is switched off.

to the right of the engine on the air intake pipe there is a vacuum controlled valve which switches between air from by the rad to air from above the exhaust manifold. this is controlled by a bi mettallic strip in the carb.

if this is faulty you will not get warmed air the result as paul says is carb icing.

this vavle can be stripped and serviced. if you are concerned about doing this go to a scrap yard and get a manual valve from a pug 205. you can then switch it for winter running.

Its called a throttle body heater, of course theres a throttle body, its the big chamber where the petrol gets squirted in…

Both my carb manual and haynes manual call it a throttle body heater, the Carb is the whole unit….

And its on the left on mine, it all depends on the car and the carb which is why I asked for a picture….  :roll:

I take it you have only cold air hose connected which is causing problems.
The flap madferret mentions as a purpose i.e open/close thus either cold or warm air getting to the carb.
So you have a big block carb, basically same air filter box regardless of engine size.
If yours is a 1.5, you will have a 1b3 solex and metal top part of air filter box, this is plastic on the 1.6 Post 1980 and 1.8 block thus the carb will be a pierburg 2e2 post 1980 or the pierburg 2b2 which is pre 1980.
You will have a long arm coming from the air filter box to the left, it will have two outlets, one facing the front near grill (Cold Air feed) and a smaller one underneath which faces towards the rear i.e for the (warm air feed)
In colder months moisture will create and travel up the cold air pipe i.e now water getting into carb, it mixes with the air/petrol supply thus your coughing issue, it should blow black smoke from exhaust when you try and ut foot down also and stutter and lose power.
If you have not fitted warm air feed pipe to connection of air filter box as mentioned and only have a cold feed this will happen.
When it does, pull over leave engine ticking over on idle for a few minutes for the droplets of water aka moisture to dry from engine heat and off you go, but it will happen again as mositure yet starts creeping back up air filter box.
But what you need to do is fit both cold and warm piping to the 2 outlets, on air filter box, you should have a heater plate bolted to the exhaust manifold on the left side, this is where you connect the other end of hosing from the warm air outlet from the front the air filter box.
but my exhaust manifold does not have the plate so i just made mine longer and cable tied it and pointed it close and in direction of exhaust manifold for heat.
Nothing to do with anything else.
If you don't have the flap inside the cold part of piping from air box, don't worry, neither do i, i have solved this issue 3 year ago when i had the troubles with mine and i'd not ong fitted a new weber to it, simply have the warm air feed in colder months and your good to go.
If you put a performance air filter in that will help for better air flow to the carb regardless time of year but it is not the product to resolve the issue you have/had fella.
Pete  :wink:

.

Indeed…. We're all friends here

The point is the car needs warm air in winter especially in t'norf where its damp

OH FFS paul, can you not once just put it down in plain basics for once, it is not a bmw, VR6 nor a k-jet, don't confuse the lad, he just wants an answer and no-one is arguing, we are simply trying to help & simply putting it easy terms so he/she understands, nothing difficult about that.
Please try

yes you are right the air selector is on the left when looking at the engine. its been a long day sorry.

the heater you describe often called a hedgohog because of it's looks is an intake manifold heater.

it is still not called a throttle body. at best i can be called a venturi.
http://en.wikipedia.org/wiki/Throttle_body
(god bless wiki even if i can't be trusted most of the time)

now as above go take it apart or get something to replace it.
you can even take the hole lot of and put a peice of 2.5" ducting on to run from the manifold over the winter.

Wasnt there a carboard piece or something on the radiator, for 'winter setting' or did I dream that?

sounds like a previous car there mate.

Madferret said

Wasnt there a carboard piece or something on the radiator, for 'winter setting' or did I dream that?

The cardboard on either side of rad (Now plastic on later models cabby and on to mk2's) is to direct airflow to radiator and keep it cool, the small card piece on top is so you don't burn or slice your fingers on the fins
Pete :wink: