Random stutter/misfire

[Brunoandrade98]

My (just under) 80K-mile Clio 197, the gift that keeps on giving...

Two weeks before a road trip, the car has developed a bit of a stutter (maybe misfire)...

Engine is on low compression across all 4 cylinders, 120 PSI each. Feels low on power, but has run smooth so far. I did have a lot of shudder that felt like a lumpy idle, but it turned out to be a lower engine mount that had completely disintegrated after about 10k miles...

When driving normally, the car can stutter momentarily at any speed/gear, more noticeable going uphill.

It’s been to a garage recently for another wet & dry compression test and a quick safety check. I’m going to check for oil on the spark plugs, which I’ve seen before in small amounts and could cause ignition issues.

Other than that, is there anything else I can check?

Spark plugs are less than a year old. Coils are a possibility, but tested good a couple months ago.


Any input appreciated.

On a side note, if anyone has an engine for sale, I’m absolutely interested. Closest to Wrexham, the better, but will travel for the right engine.

 

[RSRowe]

Engine is on low compression across all 4 cylinders, 120 PSI each.

That still doesn't feel low to me, but the wet test will back up your suspicions.

 

[VeiRoNv2]

I measured on mine and it was around 165 psi but with throttle body open so possibly 120 about right but haven't tried with closed throttle.

 

[Brunoandrade98]

That still doesn't feel low to me, but the wet test will back up your suspicions.

The piston rings are worn, according to the dry vs wet numbers.

But I don't think this stutter or misfire will be related to the low compression, as the engine is still getting very regular oil changes every 6 months and should still have more life left in it, just a bit down on power is all...

I reckon it'll be something to do with ignition or fuel. Maybe oil-fouled spark plugs as the threads on a couple of them were wet with oil when I removed them, so oil is definitely getting in there. It's just a case of how much and whether that would affect spark in anyway, I suppose.

Or it could be something else completely fucking different...Love this car...

 

[Brunoandrade98]

I measured on mine and it was around 165 psi but with throttle body open so possibly 120 about right but haven't tried with closed throttle.

Mine was done with throttle wide open, too.

I measured 120 dry and 180-ish wet.

Garage measured 140 dry and 220 wet, apparently... Don't know how they performed the test, but I'd assume they'd know better and did it with the throttle open.

 

[RSRowe]

The piston rings are worn, according to the dry vs wet numbers.

Fair enough. It's just very odd to see all cylinders consistently low.
But the results are the results.

I'd still get them verified with a leak down test personally.

 

[R20BTG]

If you need coils and plugs to rule it out....

https://clio197.net/threads/various-parts-spares.67391/