Missfire

[Mart 85]

Wonder if anyone can help???? I took my 172 to the rollin road day today at Runcorn fab day but when I put mine on the rollers they discovered a low end misfire at 1800 rpm under load now the coil pack leads and plugs were all changed in 2014 so can't seen it been that is there anything else i need to check etc

 

[bloke]

what leads did you put on it?

 

[James363]

Check the plugs if you haven't done so already. Other areas worth a look are the injectors, ECP has them for £40, If you know its not the plugs, just buy one, and swap it round until the misfire goes away. Also, the coil and leads could be shafted if they weren't good quality ones (not accusing you of buying rubbish ones or anything).

 

[Mart 85]

Check the plugs if you haven't done so already. Other areas worth a look are the injectors, ECP has them for £40, If you know its not the plugs, just buy one, and swap it round until the misfire goes away. Also, the coil and leads could be shafted if they weren't good quality ones (not accusing you of buying rubbish ones or anything).

So basically start with plugs and work my way up if you no what I mean

 

[Mart 85]

what leads did you put on it?

Unsure nothing special I don't think would you think it would benefit from some updated ones

 

[welshname]

I was told the chance of my misfire being injector was pretty much zero

Checked everything first... Turned out to be the injector

 

[bloke]

Unsure nothing special I don't think would you think it would benefit from some updated ones

they don't like cheap leads, no need to spend a fortune, the standard renault ones are good. did chris not give you any idea what the misfire might be?

 

[Mart 85]

I was told the chance of my misfire being injector was pretty much zero

Checked everything first... Turned out to be the injector

How did you no which one was at fault

 

[Mart 85]

they don't like cheap leads, no need to spend a fortune, the standard renault ones are good. did chris not give you any idea what the misfire might be?

We'll he said possible crank sensor ???? He also said if it was the coil pack it would bring an engine light on the dash,it's a weird misfire does it if your turning into a corner in second gear just under 2000 rpm and give it a bit of throttle just misfires then goes through it then it's ok

 

[welshname]

How did you no which one was at fault

I knew which cylinder the misfire was on by looking at the spark plugs. Any causing a misfire will be black rather than the brownish colour they should be. When an injector goes bad it tends to leak rather than stop adding fuel all together so you end up with a black plug. Once you know which cylinder the misfire is on you can try loads of things.

I'm lucky and had (probably still have somewhere) loads of Mk2 spares for diagnosing issues, coilpacks, leads, injectors. Started by swapping coils out, then the pack itself, and then the injector which cured the problem.

Plug colour will make it obvious where the misfire is regardless. Are you running the correct plugs too? They tend to spit their dummies out with anything other than the recommended NGK PFR6E-10.

 

[Mart 85]

I knew which cylinder the misfire was on by looking at the spark plugs. Any causing a misfire will be black rather than the brownish colour they should be. When an injector goes bad it tends to leak rather than stop adding fuel all together so you end up with a black plug. Once you know which cylinder the misfire is on you can try loads of things.

I'm lucky and had (probably still have somewhere) loads of Mk2 spares for diagnosing issues, coilpacks, leads, injectors. Started by swapping coils out, then the pack itself, and then the injector which cured the problem.

Plug colour will make it obvious where the misfire is regardless. Are you running the correct plugs too? They tend to spit their dummies out with anything other than the recommended NGK PFR6E-10.

Unsure I've got quite a lot of paperwork with the car I will have a look tomoz il get there eventually

 

[James363]

Yeah, make sure the plugs are correct. Mine did the same thing, misfired around 2600 under load then stopped. It got worse though, so when it was fixed it was such a relief.

 

[bloke]

We'll he said possible crank sensor ???? He also said if it was the coil pack it would bring an engine light on the dash,it's a weird misfire does it if your turning into a corner in second gear just under 2000 rpm and give it a bit of throttle just misfires then goes through it then it's ok

crank sensor is possible, worst thing with them is they can be iffy and not bring up a code.

 

[Mart 85]

Just to let you all no who replied I put new plugs and leads on today and was quite surprised it sorted the misfire out happy days thanks for all your advice/replies

 

[James363]

No worries, that usually is the problem, glad it's fixed, misfires are no fun at all.

 

[MJRacing]

How much did you pay for the leads Ifor you don't mind me asking? Genuine Renault items?

 

[Mart 85]

How much did you pay for the leads Ifor you don't mind me asking? Genuine Renault items?

No just non genuine 60 quid

 

[MJRacing]

OK no worries. Thanks

 

[Mart 85]

No worries, that usually is the problem, glad it's fixed, misfires are no fun at all.

Ye was relieved

 

[bloke]

what make of leads? non genuine will probably end up giving you trouble.

 

[Mart 85]

what make of leads? non genuine will probably end up giving you trouble.

Can't remember off top of me head I had them from ces