w123 230e rough idle

[montz230e]

firstly hello everyone i am new

i have just brought a very clean 1985 w123 230e auto and allthough i love it i have a problem with idleing
it also has been lpg converted which is working fine it will even start on lpg !
the problem is there weather its running on petrol or gas
it will start hot or cold and tick over about 900rpm but very lumpy i have replaced plugs leads to rule out missing as thats what i first thought
it runs lumpy when its cold or hot it makes no difference and the engine shakes

when driving it when first putting it in drive or coming to a stop the revs are really low and it feels like it wants to stall
when driving off from 1000rpm to say 2000rpm ots lumpy and you can feel theres a problem but over 2000rpm it seems to go and the car flys
In neutral when you rev it you can hear this also above 2000rpm it seems to be fine

want to know what i should be checking and whats a good order to check

i wanted to try adjusting the petrol mixture but the screw hole where u pull out gromit on air filter was really rusty
but wondered maybe its not mixture cos it does it running on gas
thanks for taking the time to read

 

[montz230e]

anyone??

 

[jaymanek]

The misfire will still be there above the 2000 rpm but due to the higher revs you just wont notice it.

LPG cars are an absolute pain as they usually open the doors to intake leaks, poor fuelling etc etc.

It really needs someone to go over all the systems one by one... Spark - check plugs, leads, caps, rotor etc.
Fuel - Check fuel pressure, fuel distributor, injectors etc
Air Leaks - Check around maniflod area..

Doubt it will be a simple quick fix unless its bad spark plugs or something.

When running on petrol the idle CO should be 1.5-2%. You will need to ask a friendly MOT station to read it for you.

 

[Vlad]

I agree with all that Jay says above, but one further thing to bear in mind, is that if the LPG is running too lean and has been for a prolonged time it can burn out the valve seats which will give you an uneven idle.

Also bear in mind that the LPG system on a W123 will not be very accurate as it will be an old style LPG system blowing through the inlet manifold rather than a later multi point/ECU system.

 

[montz230e]

hi guys, thanks very much for your replys
i did have a look and listen round for air leaks but will inspect further
i hear you regarding valve seats but where this is an 1985 didnt they come with hardened seats ?
when i checked the timing i did notice that if i advanced it ,it run faster and seemed better
when its in gear the revs are dropping to 600rpm what should they be and is it a vacuum systen that is ment to make it rise ? an where is it ??
i can adjust the gas mixture but as i said the petrol screw seems rusted up is this common ?
thanks again and sorry for all the questions

 

[montz230e]

problem solved!!!:bannana:

yesterday i had some time so i went and started checking over and found it had no compression on cylinder4 ,it surns out previos owner i suspect had adjusted valve clearance and done them to tight hence valve not closing
now runs like a dream
thanks again

 

[louwdj]

Lucky you to find the problem!

 

[jaymanek]

Very lucky!

 

[Redfoxie]

Please, I need to adjust my valve clearances too (mine are rattley) but can't find the specs. Could you please tell me what they need to be set to?Cheers

 

[balge]

Is it possible the seats are recessing, leading to the valve clearances tightening up? Worth keeping an eye on.