Help with bad running cup 172

[rickyj]

HI all I have a 172 cup on 52 plate which runs lumpy as hell. It is maainly up to 3k revs but most noticable on idle. There is a misfire every other second. I have changed the lambda sensor to no avail. It has recently had full service including plugs. My worries are loss of compression which is always a serious thing. ANyone else have any ideas? I do know they r lumpy when cold but this is all the time. Acceleration is not all that great till the 4k mark.
cheers all

 

[MRBILLYUK]

I was gonna suggest plugs , as my 172 was running rough up until around 3k , loss of power , lump etc ... i took it to the local bosch main agent who put it on the comp and it showed the plugs needed changing , changed the plugs and it was fine .

What plugs did you put in ? Maybe the gap on the plugs isn't set correctly even though they should be gapped for your car when bought new .

 

[rickyj]

it was done on the renault 36 service which was 5 k ago

 

[MRBILLYUK]

Was it running ok after the plugs where changed ? Has it just started to run rough recently , if so it could still be your plugs then .I know the plugs have a recommeded life of 72k but imo thats very optimistic , mine lasted 30k .

 

[Gaz_]

any diagnostic lights on? washed the engine recently?!!!

 

[rickyj]

bought it after the service which was done by renault. Got reciepts for it
Have a bosch diagnostic place near me in reading so may take it there

 

[rickyj]

no gaz
engine dirty and no lights on

 

[Gaz_]

i only ask that as i hosed the engine down and water sat down the plug holes and caused a miss fire, pretty bad

can't you take it back if they serviced it before you brought it? these engines on the whole are bullet proof, there will be no headgasket trouble at 40 k etc

 

[MRBILLYUK]

bought it after the service which was done by renault. Got reciepts for it
Have a bosch diagnostic place near me in reading so may take it there

So has it just started running rough recently ? Did you get any sort of warranty with the car ? Seems a bit funny why Renault would change the plugs at 36k when its not due until 72k .

 

[rickyj]

yeah got a 2 year warranty. Its one of those RAc 5 star ones. I thought plugs were due every 36k on these? Will check my booklet for that mate.
And Gaz head gasket was one of my biggest worries as it is a symptom of that running. Yeah could be something real small and easy. Gonna have to look at it soon though. Just working 7 days a week at moment as work for myself so getting 5 mins is a nitemare at moment.lol
Mrs driving it to work and back and even she notices the lumpy idle. Now a woman noticing that does say a lot cos she dont even know where the oil filler cap is.lol

 

[Gaz_]

yeah dont worry its probably just a faulty coil pack or something

 

[172cupwizard]

HI all I have a 172 cup on 52 plate which runs lumpy as hell. It is maainly up to 3k revs but most noticable on idle. There is a misfire every other second. I have changed the lambda sensor to no avail. It has recently had full service including plugs. My worries are loss of compression which is always a serious thing. ANyone else have any ideas? I do know they r lumpy when cold but this is all the time. Acceleration is not all that great till the 4k mark.
cheers all

hi mate! what fuel ya using? its best to put shell optimax in, check your air filter and replace with a K & N direct panel replacement filter and stick some denso iridium spark plugs on! mine runs sweet!

 

[team_penetrator]

I know it sounds daft but.... Are you sure its not the standard rubbish idle. They all idle badly even when warm. If it feels like its missing a bit, but the rev counter never seems to move....thats just normal. Have you tried another one before you start spending cash??

 

[rickyj]

Hi wizard yes I do use optimax at all times. Will prob end up replacing filter with another panel one. Wanna keep completely standard so no 57i kit.
Hi Penetrator, I did test drive a few cups before buying this one and yes they all felt lumpy but this does feel considerably more than the others. It does misfire every other second. I could spend loads changing items like ht leads, plugs etc but think the best option will be to take it to bosch diagnostic place by me this Saturday. My first day off in 21 days.haha
Will let you all know the results and thanks for all your suggestions