Lumpy engine on tick over

[col.decker]

Morning all. My 1.9 water cooled is giving me some agro at the moment. The tick over is very lumpy, yet it drives fine. I've changed the leads, s.plugs, dizzy cap & rotor, and its made no difference. Whats left to check? The box of electronics & the coil I guess but don't they either work properly or not at all, there's no in-between? Or could it be a loss of compression in one of the cylinders?

While it was ticking over I pulled the s.plug leads out on each cylinder in turn, 3 of the 4 caused the engine to die, 1 of them made no difference at all.


Any ideas or pointers?

[Ian Hulley]

Duff plug or lead by the sound of it .... swap for a known good one and if it persists swap for a known good lead. Keep the last set of known-good ignition components so you can do a 'system restore' if you have problems.

Ian

[itchyfeet]

as you have changed the leads and plugs could be a burned out valve, you need to do a compression check

[col.decker]

hmmm sounds like a trip to the garage then.



bugger

[itchyfeet]

or buy the tester yourself for about £30
search on gunson hi-gauge, easy to use just threads in the spark plug hole one at a time

it's not cyliner no 3 is it? if so a vaccum leak on the servo hose to the manufold may do this.

[Ralf85]

or buy the tester yourself for about £30
search on gunson hi-gauge, easy to use just threads in the spark plug hole one at a time

it's not cyliner no 3 is it? if so a vaccum leak on the servo hose to the manufold may do this.

Stop press - this tester is now available for £20 on Amazon at the moment.

[what2do]

@itchyfeet,

I'm always up for learning, could you please explain why the leaky vacuum hose would affect no. 3? Thanks, Mitch.

[itchyfeet]

on a 1.9DG the brake servo hose attaches to the manufold by No3 cylinder, if there is a leak it will draw in fresh air rather than air/fuel mix from the carb becuse of path of least resistance, more vaccum at idle so problem worse than with throttle open.

[col.decker]

or buy the tester yourself for about £30
search on gunson hi-gauge, easy to use just threads in the spark plug hole one at a time

it's not cyliner no 3 is it? if so a vaccum leak on the servo hose to the manufold may do this.

nice one thanks I'll invest in one of them


Say I do find low compression in the cylinder, what's next? Re-grind and seat the valves? Easy job? It's cylinder 1 that's playing up.

[itchyfeet]

Say I do find low compression in the cylinder, what's next? Re-grind and seat the valves? Easy job? It's cylinder 1 that's playing up.

Valves means head off, 'easy job' depends on your skills, no point worrying about that until you have done the compression test

[scunnerd25]

Calm down folks you have the guy "pooh" himself start with the basics first jesus . How can you go with a slight missfire on one post then a bit down its the engine out

[Mocki]

Personally I would be swapping the plugs round and see if the "questionable" cylinder moves , and then the leads , just change them around, don't replace with others.

[Graham81]

Brake servo hose and various other vacuum leaks were making mine run crap. When the engines running, grab hold of the servo hose and see if the revs rise.

[itchyfeet]

Op says changed the leads, s.plugs, dizzy cap & rotor, and its made no difference