Low Rev Misfire - Serv Light + Plug popped

[Donny_Dog]

My neighbour has just bought a 172cup.
Drove OK on the test drive until he was on is way home and it was misfiring.

Under the plenum one of the spark plugs wasn't in tight and the plug lead had popped off and was completely knackered.

He's bought brand new leads from renault and the car is definately firing on all cylinders BUT....

Under 3k rpm it still feels it is missing a little and hesitant on the power. Above 3k, then its not noticeable.

The SERV light is on, but EML is not. Just SERV.

I've got a 182, so he'll try the coilpack, which is nice and easy, later tonight.

....I've been thinking that it could be the timing? But then, he'd have noticed this issue on the test drive.... or maybe not. I remember reading about inaccurate timing after a belt change, caused a plug to pop out - can anyone else confirm I'm not making that up?
I see some tipex timing marks on the cam cover - potentially a sign it hasnt been locked correctly when the belt was done.. but would timing cause a serv light...

Any other ideas - I don't think any sensors are shot. Genuinely think its either coils or timing. I just can't stop thinking about that plug and lead...

CLIP will be next, just to see. but any other ideas welcome.

 

[MicKPM]

Needs a proper check mate... I did the same on an RB182 yesterday with a minor, temperamental misfire but we fixed that (Needed a plug and injector on No.1)

Check injectors, plugs, leads, compression and finally timing in that order.

 

[Donny_Dog]

Needs a proper check mate... I did the same on an RB182 yesterday with a minor, temperamental misfire but we fixed that (Needed a plug and injector on No.1)

Check injectors, plugs, leads, compression and finally timing in that order.

If its not the coils, I'll tell him to trailer it to yours! Cheers mick.

 

[Griff81]

Hi all,

first post so bare with me!

I was about to start a thread for the exact/similar problem. Spluttering and missfire like symptoms at low revs, but fine at higher revs.

Ive just bought a 2002 172 which was fine during the test drive but on the way home it started to stutter. The engine management light was coming on intermittently and now the serv light is perminantly on. I took it this week to a trusted garage who diagnosed split spark plug which possibly could have been damp getting into the coil pack (machanic advised commen fault past 70k?)

Anyway the split coil also took out the HT lead so we replaced the coil pack, installed NGK spark plugs and replaced the HT leads. Got it back yesturday and the car initially felt fixed. However today the splutter is back under 3k revs so im gutted. I really dont think its a massive issue but im worried I have bought a lemon!

Any ideas welcome.

 

[Griff81]

PS, not trying to hijack your thread K9, just interested to see the outcome

 

[Donny_Dog]

Turns out it was the plugs. Coil pack made no odds, so some new plugs were bought and solved it.