Volvo 440 mis-fire

[olly]

My 440 has a misfire (uses the 1.8 Ranault 19 engine)

It's very obvious at idle, and when using lower revs - not sure higher up the rev range.

I've replaced HT leads, distrubutor cap & rotor arm (have also tried all of the above from a car that is running fine). I've just replaced the plugs as on inspection 1 was perfectly clean, where as the other 3 had normal deposits.

But I still have a misfire.

It's a single point injection, so it's not the injector.

All I can think of is I have a sticky valve/broken spring. Is this possible, or am I overlooking something ?

Thanks for any suggestions !

(the fault code box is reporting a faulty lambda sensor - I've got a new one, but not fitted it yet - but I can't see how this would cause a mis-fire)

[paolow]

compression check? before that though - while at tickover pull off and replace the leads one by one. when you get one that doesnt change the engine revs or note - thats the iffy cylinder. is that plug sparking? if so and theres compression i would look at a gummed injector.

[olly]

The 440 is (apparantly) remowned for having a bit of an iffy tickover (my sister had 1 for 4 years & it did the same at idle, but as soon as you were off tickover it cleared).

The "clean" spark plug was number 2 & when I removed the HT lead from it - both at idle & holding 2,000rpm there was no change, so thats my iffy one !

There is a spark, although it doesn't look that strong to me - but the plug is spotless, so I was thinking there is no fuel getting in there to burn/make it dirty.

Time for a compression check me thinks !

Thanks

[annodomini2]

olly said:

(the fault code box is reporting a faulty lambda sensor - I've got a new one, but not fitted it yet - but I can't see how this would cause a mis-fire)

Over/under fuelling?

[olly]

That was my initial thought, but only on 1 cylinder ? (1 spark plug spotlessly clean - all other "normal"

Will swap tha lambda over the weekend (hopefully - too hot today !) & reset the codes & then go the compression test route

[thong]

if the comps are ok,inlet manifold gasket leaking.