High Compression on 1 cylinder

[Barnett182]

Hi all, im in a bit of a pickle with this. So i recently done a cambelt change on my 182 and everything has gone smoothly apart from cylinder 4 is now misfiring... i thought it could be the coil leads at first as they weren't in great condition so i have change those out for genuine ones and still no luck. i started to get worried thinking that the timing was out so went back and checked it multiple times and it all seems perfect.

I ran a compression test on the car today and noticed that cylinder 4 was up on compression by around 10-15 psi so its reading around 210 compared to the other pistons which are all reading around 200 psi.

can anyone suggest why one cylinder would have higher compression than the others? and how i may resolve this?

Thanks

 

[Brigsy]

Compression is within 10% by the sounds of it so not an issue, its decent overall and generally you would need a big drop in compression on a cylinder to get it to misfire.

If the timing is correct, id say its injector fault or ign related, resistance check the injectors.

Next step for me would be to swap cyl 4 injector, then spark plug to a different cylinder and see if the misfire follows suit, give you an idea whats playing up

 

[Barnett182]

Compression is within 10% by the sounds of it so not an issue, its decent overall and generally you would need a big drop in compression on a cylinder to get it to misfire.

If the timing is correct, id say its injector fault or ign related, resistance check the injectors.

Next step for me would be to swap cyl 4 injector, then spark plug to a different cylinder and see if the misfire follows suit, give you an idea whats playing up

How do you restart check the injectors mate?

 

[Barnett182]

Compression is within 10% by the sounds of it so not an issue, its decent overall and generally you would need a big drop in compression on a cylinder to get it to misfire.

If the timing is correct, id say its injector fault or ign related, resistance check the injectors.

Next step for me would be to swap cyl 4 injector, then spark plug to a different cylinder and see if the misfire follows suit, give you an idea whats playing up

sorry auto correct there...

how do you resistance check the injectors?

 

[Krarl]

sorry auto correct there...

how do you resistance check the injectors?

Stick a multimeter on both the pins and set it to ohms/resistance mate

They should be 14-14.3ohms iirc

 

[Barnett182]

Stick a multimeter on both the pins and set it to ohms/resistance mate

They should be 14-14.3ohms iirc

thanks mate! ill give that a go later today

 

[Krarl]

thanks mate! ill give that a go later today

No worries

Failing that, pull the rail off with the injectors in, stick a sheet of cardboard in and crank the car a few times and look at the spray pattern and volume of petrol

 

[Barnett182]

No worries

Failing that, pull the rail off with the injectors in, stick a sheet of cardboard in and crank the car a few times and look at the spray pattern and volume of petrol

Cheers mate. There is good resistance on the injectors so that next up then!

 

[White16valver]

leads on correctly? (right order?) lol

 

[Barnett182]

leads on correctly? (right order?) lol

ye aha ive checked that a number of times lol. as mentioned i bought new leads from RPD so they shouldnt be the issue

 

[TheEvilGiraffe]

Hold up .. so you changed the leads, randomly ?

Did you check the plugs !?

 

[Martin_172]

A lead trapped under the inlet manifold, I've cured a miss fire when I found that before

 

[Krarl]

Leads, plugs, coilpack & injectors are all things to check

Easiest thing to do is just to swap plugs from one cylinder to the next, then injectors and if you have a spare HT lead then keep moving them around and see if you get any changes

 

[Barnett182]

Leads, plugs, coilpack & injectors are all things to check

Easiest thing to do is just to swap plugs from one cylinder to the next, then injectors and if you have a spare HT lead then keep moving them around and see if you get any changes

Yes I think I’ve found the problem! Cylinder 4 injector is not outing any fuel out! All other injectors are working...

 

[JamesBryan]

Excellent compression that 200+ 👌🏻

 

[Barnett182]

Excellent compression that 200+ 👌🏻

I thought so to! Considering the car is on 130k lol I thought it was doing pretty well 😂

 

[JamesBryan]

I thought so to! Considering the car is on 130k lol I thought it was doing pretty well 😂

Anything over 190 is decent really.

Yours is probably better than factory 😂

 

[Barnett182]

Anything over 190 is decent really.

Yours is probably better than factory 😂

Lol not sure how it’s managed that 😂 maybe my excellent ability to time the engine 🤔

in all honesty the car is in Vee good condition mechanical and is actually better than my past Clio’s that had half the mileage

 

[JamesBryan]

Lol not sure how it’s managed that 😂 maybe my excellent ability to time the engine 🤔

in all honesty the car is in Vee good condition mechanical and is actually better than my past Clio’s that had half the mileage

Some engines just are.

Good valve seating and piston rings.

 

[Brigsy]

Probably thrashed from new and the rings bedded in really well

I would bosh a new set of injectors in at 130k. I replaced all of mine after one failed and it ran great after, miles better than with the old injectors.

 

[JamesBryan]

Probably thrashed from new and the rings bedded in really well

I would bosh a new set of injectors in at 130k. I replaced all of mine after one failed and it ran great after, miles better than with the old injectors.

This.

Keep the 3 working ones as spares.

 

[Barnett182]

Probably thrashed from new and the rings bedded in really well

I would bosh a new set of injectors in at 130k. I replaced all of mine after one failed and it ran great after, miles better than with the old injectors.

Well after finding one to have randomly stop working this will be the next thing to replace.

it still baffles me as to how it stopped working while I was changing the cam belt... then again it’s French 😂

 

[VXR killer]

You moved the injector to make sure that its the injector and not a loom/signal issue

 

[Barnett182]

You moved the injector to make sure that its the injector and not a loom/signal issue

I did try this straight away and it wasn’t the loom thankfully! I managed to get an injector from someone local who was turboing their Clio so had one spare to give me 👍🏼

Car is no running perfectly

 

[Brigsy]

The injectors are fragile if original. I knocked one of mine when changing the oil filter and the plastic connector part simply fell off as brittle and old.

 

[Barnett182]

The injectors are fragile if original. I knocked one of mine when changing the oil filter and the plastic connector part simply fell off as brittle and old.

lol. the connector for the injector that failed was wobbling and could move back and forth but it was definitely still working but just blocked up... you need to be super careful when pulling them out. as you say its very easy to break them

 

[Robbie Corbett]

I just fitted a set of new injectors after one failed - bought from Autodoc on one of their discount days and paid £123 for all four, might be worth checking them out rather than ecp.