Hesitating Off Choke? :(

[griffo20022]

Hey guys, well Vince seems to have started playing funny buggers tonight on the way home from my gf's

Started driving as normal and as the engine warmed up slowly took off the choke as usual. Although tonight once i'd got down to very little/off choke completely on part throttle it'd hesistate pretty badly, on full throttle it'd be fine.

With the Choke on about half way or so it'd be fine at both part throttle and full throttle! It was like this all the way home (approx 20miles!)

It idles fine with no problems at all. Having a think, surely if it's running fine with some choke does it show that it's possibly running lean so reducing the air intake (by choke) mixes the fuel:air ratio as it should? Could be way off the mark but that's how i'm thinking it out in my head lol.

Going to have a nosey under the bonnet tomorrow, just to kill curiosity I opened the bonnet tonight and checked for any arcing etc but there was nothing so I think ignition side of things is all good (especially as I replaced pretty much everything only weeks ago). I'll pull the plugs out tomorrow and see if they give any tell tails

If you guys can give any advice i'd really really appreciate it! Ta'!

BTW for reference it's a 1990 1.4 fitted with a Weber carb

[griffo20022]

Hey guys, well I fixed the problem! As soon as I spotted it I knew thats what was causing it as it proved my idea right

When I first drove the car home and it broke down blah blah blah. When the AA bloke refitted the bottom part of my air filter housing I don't think he fitted the little hose on properly that goes to the rocker cover, it must have just been sitting over the fitting. With the engine vibration etc using it day to day it must have eventually shook loose meaning the hose was sucking in from the atmosphere obviously then causing the carb to take in too much air and leaning out!

Stuck it back on and the boys running like a dream again It's the top hose on the picture that had come off...



Mr Griffo is a happy chappy once again!

[Chris_C]

Great news mate! Nice to see it's something easy

[volvodspec]

hmm, i'm not convinced. with the breatherhose off you wouldn't notice a thing about the engine, at idle; load or high rpm.

what you might have experienced could be carb-frost. is the pipe running from heatshield on exhaust manifold to the front of the airfirterhousing still intact? what setting is the front pipe piece on (summer/winter)? and does the thermostatic flap inside the airfilterhousing work?

[griffo20022]

I know what your saying as it is such a minor pipe, although i'm just going by what has changed since doing so.

I changed the pipe your on about today as it didn't have one fitted before (in the 2+ weeks i've now owned it, Check my little project thread) I haven't driven it since I fitted it, so I don't know if the flap still works or not. I have given the flap spring a quick spray over with some silicone oil, with the pipe missing the flap probably hasn't moved in a while! Didn't realise there were summer/winter settings? Wheres that and how do you adjust??

I'll find it very strange if it is carb frost as it's the first time this has happened since i've owned it and we've had far colder weather since this had happened? I dunno, end of the day it's working so i'm happy

[volvodspec]

hahaha, haven't got time for that mate will check it out this afternoon/evening

the damps from the crankcasebreather are not allowed to be ditched in open air by vehicle manufacturing regulations; besides that the breather pipe has to enter on the inside of the airfilter because if it was outside of the airfilter it would be connected to open air and get the air filter oily attracting more dirt and clotting the filter up.

but in any way this wouldn't compromise the way the engine runs. there is a reason why it idle's fine; heat from the exhaustmanifold automatically gets to the airfilteropening even if the hose running from heatshield to airfilterhousing is perished. under driving this is not te case because of the driving wind; causing the carb to freeze.

i bet that if you try driving without that hose again in similar weather conditions; and leave the crankcasebreather hose on you will experience the same thing.

about the winter/summer setting; on hot summer days you twist the front pipe to the hole next to the headlight, in the winter you twist it so it gets behind the radiator. only a feature on 1.4 340's

[griffo20022]

Oooo nice tip on the summer winter adjustment thing, i'll check to see what it's on before I leave for work in the morning