Misfires

[Flying Scotsman]

Hey all,

I know some causes as I have researched a little but im looking for a comprehensive list of all the possible causes and remedies for misfires.

My car developed a misfire during its last bought of work on it, but puzzled to what it could be.

So if you're in the know-how, drop a cause and solution below.

 

[Anonymous]

From personal experience (but not guaranteed):

Coil Pack
HT leads
Spark plugs

 

[Flying Scotsman]

From personal experience (but not guaranteed):

Coil Pack
HT leads
Spark plugs

I take it you mean failing in some way... care to elaborate?

Thing is, the only thing i could concluded was spark plaugs and leads as i changed them on mine.. but then i re changed them but still the misfire... I couldn't think of what else... would the lambda effect it?

 

[Anonymous]

I would say failing in some way, yes.

Mine was a pain in the proverbial... kangarooing and bouncing around.
I changed the coil pack and also did the leads too, just for peace of mind.
I changed the spark plugs as the tops of them were too small and didn't 'clip' into the new leads.

As for the Lambda.... to be honest I can't really say. I suppose it may cause a misfire if it thinks it's over fuelling then tells the ECU to cut/reduce the fuel......??

 

[PumaNoob]

Comprehensive list of possible misfire causes

Over fuelling : Lambda failure, MAF Failure, coolant or air temp sensor failure, fuel pressure incorrect, damaged fuel return line.
Under Fuelling: all of the above, also fuel pump and fuel feed line.
Low compression, incorrect ignition timing, incorrect cam timing, ht leads, coil pack, coil pack wiring, spark plugs fouled or damaged or incorrectly gapped, spark plugs not screwed in properly, damaged injector/s, faulty wiring to injectors, poor quality fuel (it would have to be very bad to cause a misfire), water contamination in fuel

That's all I can think of at the moment, but see if any of the above ring any bells as to why it might be happening!

 

[Flying Scotsman]

Then I reckon its the lambda that has failed as it was a bodge job.

Thanks very much Erroll


On that note, does anyone have a spare FRP lambda going spare, I need the long one...

 

[Anonymous]

Comprehensive list of possible misfire causes

Over fuelling : Lambda failure, MAF Failure, coolant or air temp sensor failure, fuel pressure incorrect, damaged fuel return line.
Under Fuelling: all of the above, also fuel pump and fuel feed line.
Low compression, incorrect ignition timing, incorrect cam timing, ht leads, coil pack, coil pack wiring, spark plugs fouled or damaged or incorrectly gapped, spark plugs not screwed in properly, damaged injector/s, faulty wiring to injectors, poor quality fuel (it would have to be very bad to cause a misfire), water contamination in fuel

That's all I can think of at the moment, but see if any of the above ring any bells as to why it might be happening!

There always has to be one clever sod!!

 

[PumaNoob]

There always has to be one clever sod!!

Yup, its always me!! :lol: Dont ever ask a question like that with a nerd like me lurking on the forum, waiting to share my masses of useless information!!

On that note, does anyone have a spare FRP lambda going spare, I need the long one...

You can use a standard lambda, the FRP just has a lambda extension, i made my own from a nackard lambda plug, and the wiring loom of a puma someone was breaking. Or you can buy it already made, but im not sure on the cost.

 

[Flying Scotsman]

Yeah mine has been extended in a similar fashion... still, it may not even be the source of the issue, but i re changed the leads and plugs and still it persisted. Something i did notice is that in the wet it is at its worse... and sometimes only happens in the wet?

 

[PumaNoob]

That would lean me more towards a wiring issue, or depeending on what type of induction you have, the induction could be sucking water and affecting the MAF. The lambda shouldn't be affected by water, unless water has got into the wiring.

 

[superpumaz]

could be crank sensor could dirty needing a clean replacing etc worth a try buddy!

 

[Flying Scotsman]

could be crank sensor could dirty needing a clean replacing etc worth a try buddy!

Where might I locate the crank sensor?

That would lean me more towards a wiring issue, or depeending on what type of induction you have, the induction could be sucking water and affecting the MAF. The lambda shouldn't be affected by water, unless water has got into the wiring.

I have got a new induction filter for that reason but still leads me to think its the lambda.. its over stretched and was done in a hurry...

 

[PumaNoob]

Crank sensor is below the starter, a bit of a bugger to get to!

 

[Flying Scotsman]

I think i know where it is. Possible i could have danaged that when changing the gearbox.

I will see if my efforts tomorrow win through or not.

 

[PumaNoob]

There's not much chance of you damaging it when doing the gearbox unless you removed the flywheel too, it's behind the flywheel.

 

[Flying Scotsman]

Okay then it's not that

 

[madhillbilly17]

just another thing to add to the list lol, you said you have a new induction filter what type? most aftermarket foam and cotton filters come pre oiled which can coat up the MAF in oil in no time.

 

[Flying Scotsman]

Well an update on it. It still misfires but 99% of the time in the rain. Massively in the rain. The other 1% is when moving from stationary, its hesitant and i have to lead foot it to get it going.
Changed the air filter to a RamAir filter the other day and when during the rain, i noticed it was soaked... But unsure how it is getting so wet.
I have a direct air feed that im going to remove and i have a heat shield for thew turbo that may be useful as water protection?