weird noise on idle 172

[wilky19]

ive got a weird noise coming from what seems the head on my 172 ph1 engine.

the noise only happens when its on it low idle(800ish rpm) not at the 1000rpm idle . its hard to describe what it sounds like but its almost like its missing but it not. this sound gradually goes till its warmed up, then doesn't do it at all when warm.

anyone got a clue what it could be?

 

[clarkiev6]

dephaser i expect mate.

 

[wilky19]

the dephaser is brand new only fitted when i fitted the engine a couple of months ago

 

[BoroGTI]

the vast majority of clios sund rough when cold, mine does, u sure its not just that?

 

[wilky19]

they do but this has just come on last night when i was leaving work.

 

[BoroGTI]

does it stop when you dip the clutch?

 

[wilky19]

pretty sure it doesn't but its also a new clutch fitted at the same time as engine going in.

its sounds like a top end noise around the cylinder 2 area.

 

[wilky19]

right noise is still there at the moment but doesn't seem to be as bad as the other day but it was warmer last night.

it only does it when cold, when warm doesn't do it at all.
only does it on the low idle(800 rpm)
it sounds like it chugging almost as if idle to low, but has a "f7"ish tappy noise to it aswell. the tappy noise is only there when its chugging.

could it be a blown sensor with it only doing when cold?
or could the ICV be on the way out letting idle to low?

 

[sideways danny]

does it sound a bit like a diesel?

edit, just re-read that you replaceed dephaser so not that.

possibly a sensor not adjusting the idle for cold start correctly, or very possibly the idle control valve

 

[wilky19]

no

 

[sideways danny]

see my edit

 

[wilky19]

what sensors adjust the cold start idle as well as the ICV.

 

[sideways danny]

well both air and water temperature sensors effect it, but mostly water

 

[wilky19]

right ive got a spare air sensor and ICV, so ill swap than over and see if that makes a difference. if not ill try and get hold of a water temp sensor.

are they easy to get hold of from most motorfactors.

 

[sideways danny]

never tried for a non genuine one. Renault should be able to sort you easy enough though

 

[wilky19]

little update

tried my spare ICV and it idled at 4000 so the spare is goosed, tried the spare inlet temp sensor no change.
but noticed that the cables to the dephaser solenoid have rubbed against the bonnet and the casing have come away.

would that cause it to idle like crap?

not had time to go and get a water temp sensor yet but will get one and see if that solves it

 

[wilky19]

fitted the new water temp sensor and has made no change to the noise. its also happening when warm now, but not as prominent.

i tried to video it doing the noise it can be heard a little bit during this video sorry for the quality was done on my ancient phone.

also the engine had started to warm up a bit so not as loud as when stone cold

anyone else got a suggestion what could be causing it and where to go from here.

 

[wilky19]

anyone else got any ideas.

 

[my leige]

little update

tried my spare ICV and it idled at 4000 so the spare is goosed

Did you disconnect the battery before you restarted the engine? If not this might explain the 4000rpm idle speed. I had a similar problem when changing an ICV on another car and all was fixed after leaving the battery off for a few minutes. You'll hear the ICV cycling when you reconnect the battery.

 

[wilky19]

Did you disconnect the battery before you restarted the engine? If not this might explain the 4000rpm idle speed. I had a similar problem when changing an ICV on another car and all was fixed after leaving the battery off for a few minutes. You'll hear the ICV cycling when you reconnect the battery.

i didn't will give that a go tomorrow.

 

[my leige]

Also check main earth cables. Battery to chassis and Battery to gearbox. These can sometimes make an engine idle poorly if they're on their way out. You'll need to look closely at the ends and feel all along the sheathing.

Please update with your findings as I've a similar problem with my idle and low speed running.

 

[wilky19]

after leaving it over night and changing the air temp sensor, Idle Control Valve and Coolant Temp Sensor. the noise is still there but is not as loud, but now wont idle as low as before when cold.
I've checked all the earths, checked to see if anything is loose and nothing is.

what else could be causing it? screwed lambda? something wrong with the ecu? damage to topend?