Misfire/coughing on idle!!!!!

easy way to check. with the car running, unclip the connector to each coil one at a time before reconnecting it a few seconds later.

if the engine sounds like its about to stall in those few seconds the the coil is functional if however the car is still running unaffected the thats the dead one thats being carried by the other 3.

happened to me 2 days before a trackday due to water ingress into one of the coils.

http://www.rsmegane.com/showthread.php?1633-Dave-s-super-clean-trackday-machine/page20

 

Swap the coil pack from cylinder 4 to a different cylinder, clear the fault then see where the fault reappears - if it's moved it's your coil pack

 

New injectors sorted my slight misfire/cough on idle. Didn't bring up any codes through.

Quick comparison video I did

http://youtu.be/6_Xu9UEgS40

 

Allegedly the oem brown top beru ones are the one to go for

 

Unsure on price (i have around £40 each in my head for some reason - but may be well off!) ads will most likely have them as there oem.

James157 (i think) runs the green valeo ones (much much cheaper, think you can get all 4 for around £40!) with no problems, although i've heard mixed opinions on those not lasting / not powerful enough spark etc

 

Just had a quick look on ebay the beru ones seem to be around the £30 mark each, although if you do want to try out the valeo ones i've got a set here never used / tried i bought a complete set a while back as was having misfire codes but got my injectors cleaned while waiting for them to arrive and it cleared up my problems so never fitted them.
If you fancy trying the green ones pm me an offer

 

Tbh you've done the usual suspects of plugs, injectors and now coils, I'd wait till after the coil has been swapped see if that fixes it.
Coils can slowly break down, not just die so will hopefully be something simple like that!

 

I do have the green top ones and won't hesitate to buy them again. These are at least 3 years old and have been perfect, never had a misfire once.

Will find out in 2 weeks if they are powerful enough for over 300bhp.

 

Over 300bhp, you sure?? (-;

 

Its got everything it needs to easily reach it.

Must admit though I did forget about the rumours concerning the Valeo coil packs.Guess I'll soon find out.

 

Have you got a backbox/ midbox chop on your exhaust? As that will make it pop to a certain extent?
The fuel filter is built into the pump from what i remember no inline one

 

sorry for late reply on this. spark no3 here looks way too lean.

 

were they cleaned after these photos were taken? it only takes few miles of driving for the plugs to show the latest condition.

a photo of the plugs now would be also helpful, also a picture showing deep down in ceramic.

 

Not enough fuel. Its the air fuel mixture that is lean not the plug. However it is seen on the plug.
It would be god to get an onb reader and look how the fuel trim is

 

That is as far as i can help as I dont own one.
I suppose you should reset the ecu somehow so it recalibrates the injectors. But someone else should confirm this

 

Hello,

Thought I'd share my exp with this problem, I've had my megane r26 since November 14 and mine too had this problem. I replaced plugs and packs but still the problem persisted so my next step was injector cleaning or replacement. I was aware the previous owner filled up with normal 95ron fuel all the time and I've always used she'll vpower on the Meg and type r before it. Since November the megane has had several tanks of vpower through it and slowly but surely the cough on idle is disappearing. To the point as of the past 2/3 weeks it's gone. My car has 26k miles and fsh so injectors shouldn't need doing, I'm not going to get them done until the problem re surfaces either. So, my advice try running higher Ron field you aren't already as it solved my problem. Or spend 90 to 140 quid on injector cleaning or replacement! This is not a vpower plug and I don't doubt the benefit of injector cleaning. Just my experience.

 

this could also be, but I wouldn't neglect the lean cylinder.

 

Have you checked the wiring to the injectors and coil packs?

That's where I would look next.

 

Has it had timing belt done mate? I've heard these engines never run completely smooth but if the belt has been done maybe the timing is not set up properly?