Help diagnosing a misfire

[rickyquicky]

Left work yesterday, and the car wasn't keen on starting.

Pulled out of the car park and the car seriously bogged in 2nd gear then was fine. A few minutes later down the road and the car was misfiring on 1 cylinder. Loss of power and can hear the occasional pop from the exhaust.

would like to try and diagnose this as I suspect it's either ignition leads or a coil pack. How would you test if its an ignition lead or coil pack?

 

[rickyquicky]

Oh, and if it helps the engine check light flashes on and off. When I first start it though the light doesn't come on.

 

[MikeClio172SPT]

You'd need to start with diagnostics dude to read the misfire error codes. But if the engine management light is flashing.... usually an injector gone down mate.

 

[rickyquicky]

You'd need to start with diagnostics dude to read the misfire error codes. But if the engine management light is flashing.... usually an injector gone down mate.

Thanks mate, have been reading up about it, was thinking an injector also. Only thing is I can smell petrol whilst driving, is that a symptom of faulty injector?

also, the fact there are pops in the exhaust makes me think unburnt fuel is getting into the exhaust which would mean faulty ignition rather than injector?

need to try and fix this one myself as I don't fancy anything more on top of the £900 bill I'm going to get for the new rear bearings, recon box, front suspension refresh! Not happy.

 

[MicKPM]

I second your conclusion; a fuelling issue is unlikely and more likely to be on the ignition side (coil pack, plug lead, plug).

 

[Smnwllms172]

You haven't cleaned your engine bay recently? I had a similar problem after degreasing and then rinsing the grubby parts on my engine. I got some water/cleaner down a couple the channels where the spark plugs go, which made it sound like a Scooby and throw a few pops and bangs out the back. I took it apart, cleaned the sh*t out and now it's back to normal. Just a thought.

 

[ThomasBrentnall]

Coilpack

 

[DannyR]

100% injector.

It's fuelling more because the lambda is seeing 25% less fuel and running it richer.

 

[mitch1503]

had this happen Thursday, put spare coil pack i had on and still done it, turned out to be injector again as i had 1 go down around a month ago

 

[DannyR]

It happens almost everyday on here, same symptoms, same post, same comments, its and injector.

People need to learn to search. Only need to search misfire!

 

[mitch1503]

tbh i thought it would be an injector again but wanted to try coil pack just incase, that's injector 4 then 3 now it only leaves 2 & 1 and i'l of changed them all lol

 

[rickyquicky]

Thanks, appreciate the replies.

I did jetwash the engine bay last sunday, did wonder if it might be related to that, but it was fine during the week until Friday.

Will be looking at it again tomorrow morning, noticed a sulphur-like smell coming from the exhaust earlier when I started it, anyone experienced that before?

Danny - I have searched, that's how I have narrowed it down to coil packs/leads/injector. Just trying to narrow it down as much as possible to the most likely cause given what i've described here.

 

[MicKPM]

The sulphur smell is unburnt fuel burning off in the CAT... this is why the management light is flashing rather than on solid as it is warning you that the fault has potential to damage/destroy the CAT.

 

[MikeClio172SPT]

Thanks, appreciate the replies.

I did jetwash the engine bay last sunday, did wonder if it might be related to that, but it was fine during the week until Friday.

Will be looking at it again tomorrow morning, noticed a sulphur-like smell coming from the exhaust earlier when I started it, anyone experienced that before?

Danny - I have searched, that's how I have narrowed it down to coil packs/leads/injector. Just trying to narrow it down as much as possible to the most likely cause given what i've described here.

Fair play to you for your research into what it could be.... but honestly.... chuck it on the diags somewhere, and read the misfire codes.... or even if you know somebody nearby with a clio sport, ask to just swap coil packs etc. you could by a coilpack put it on & its still the same becasue its an injector issue. Eventually Catalyst damage will occur.

 

[rickyquicky]

Ok thanks for all the information guys.

Considering you can only go by what i've described here and can't see the car i'd say you've narrowed it down for me pretty well.

I'll also make sure not to drive it and cause more damage!

One last thing. If it does turn out to be plugs, leads, or coil packs i'll get them replaced as a set. Is it neccessary/good practice to replace all 4 injectors if one is faulty? Or get them all refurbed? What are my options?

 

[DannyR]

Replace one injector at a time in my opinion.

Unless your buying new then do all four.

But your problem is an injector 100%

 

[rickyquicky]

Ok guys, took half day at work today as I really wanted to get it running before saturday, as it is booked in for a major service and really want to get it all running sweet ASAP!

Had my injector delivered yesterday. Started by testing which cylinder wasn't firing properly by pulling the connector of each injector one by one, found out cylinder 2 was the one with the issue. Took out old one, lubed up the new one and slipped it in! Started it up, STILL MISFIRING!!!

Thought I had a dud injector, but thought as it was getting serviced anyway, and I had bought the NGK R spark plugs already to give to the garage, I would go and buy some ignition leads and put the 2 in together at the same time.

Problem solved!

Not sure whether it was the lead or plug on cylinder 2 as I didnt test them, but just got back from a 2 hour drive and its running sweet as a nut!

Thanks for all the help guys

 

[DannyR]

If it didn't have NGK before then that was probably the problem.

 

[rickyquicky]

Yeah I wondered what plugs I would pull out after all the info about how fussy Clio's are with spark plugs, didn't want to be dissapointed as the previous owner insisted he pampered the car and bought all the correct recommended parts for it etc.

I pulled out 4 NGK R's so that was promising at least, it had the proper plugs in it.

 

[Smnwllms172]

Replace one injector at a time in my opinion.

Unless your buying new then do all four.

But your problem is an injector 100%

I love this post ^^^^^^ It's an injector! It's an injector! It turned out to be the plugs. Which is what i said. What happened to him is exactly what happened to me. I cleaned my engine bay, got some water/cleaner down where the plugs went and that's what buggered the plug causing the misfire. I cleaned out the crap, changed the Bosch plugs (god knows why they were in there?!?!) for the right NGK ones and hey presto! It's not always the worst case scenario.

 

[Smnwllms172]

If it didn't have NGK before then that was probably the problem.

Thought it was an Injector, 100%. ?? :rasp:

Im just pulling your leg buddy.

 

[DannyR]

I'd expect it to have NGKs.

Injectors are easier to check than plugs too.

 

[Smnwllms172]

I thought mine did until I had this problem and when I took them out, BOSCH! Literally. Lol

 

[-Sparky-]

I am having this problem, after reading through this thread i will now check my plugs, leads and injectors.

Cheers.

 

[The Russian.]

My mrs 1.2 Clio was running like that.The first thing i changed was the lambda sensor, Nope still kangaroo-ing.

Then spark plugs and Bought new coil pack and leads, changed the leads first.

Hey presto

Long way round it but runs like a dream now.

 

[-Sparky-]

Right so I have changed the plugs, went out for a drive thought all was going well then it just bogged down again so I let off and dropped down a gear and gave it done throttle... Car was running sweet then bam bogged down again!

Im ruling out injectors, my guess is its the coil pack or leads?

 

[-Sparky-]

Anyone think it may be the coil pack?

 

[DannyR]

Why are you ruling out injectors?

Have you plugged into diagnostics yet?

 

[Alex_6n2]

Mine was exactly the same. I changed my plugs and that didn't fix it too.

The problem went away for a bit like yours, but the next time it started mis-firing I used my Bluetooth OBDII box and the "Torque" mobile app to determine which cylinder was the problem (No. 2). Unplugged the injector for cylinder 2 whilst it was running and that made no difference. Fitted a replacement and that fixed it. And a second hand one only cost me £10

Check your injectors properly before looking at everything else. Unplug each of them one by one to see if that makes a difference to how it idles.