Misfire at 4k help please

[Drew jdm]

Hi guys my 8 has recently developed a bad misfire at 4k and above its fine until then but anything after That it misfires splutters and pulls back I have checked the plugs and regapped them first to 0.55mm then 0 .25mm neither made a difference was thinking about some injector cleaner as its the cheapest fix first as money's a bit tight. I had the map tweaked about 3 weeks ago if that helps but it was fine till the other day any help would be much appreciated thanks

 

[evonewbie65]

Try changing the plugs for new ones, you may have a plug going down now after the remap.

 

[Dirtmatt]

Checked the leads?

 

[Drew jdm]

The leads are ok apart from 1 has a split in it and has insulation tape around it but it has been since I've owned it but I suppose it's nt a good thing

 

[Dirtmatt]

I have the stock ones from my 8 taken out only has I got ralliart ones..worth a shot so you can have them

 

[Drew jdm]

Ok cheers mate appreciate it I'm going to get some plugs tomorrow anyway but I will have them off you would you post them if I payed the postage through PayPal

 

[Dirtmatt]

That's fine mate.. Drop me a pm

 

[B6lee]

check all vac pipes as one might of popped of, sounds like one off the fuel reg

 

[Drew jdm]

Ok cheers mate I will have a look at that thanks

 

[Drew jdm]

Rite then I have changed the leads with the ones dirtmatt gave me thanks mate and ive gapped the plugs but still no joy a local mechanic said the one of the plugs looks like its been running hot whatever that means lol and thinks it could be fuel pressure maybe the pump on its way out what do you think ??

 

[Drew jdm]

O and its got a sard fuel reg on it that when I got it mapped at ac speedtech Andy Clark said it was only running 1.4 bar fuel pressure with the injector duty cycle at 100% so he sorted all that out and been fine for 3 weeks since if that's any help

 

[Dirtmatt]

Rite then I have changed the leads with the ones dirtmatt gave me thanks mate and ive gapped the plugs but still no joy a local mechanic said the one of the plugs looks like its been running hot whatever that means lol and thinks it could be fuel pressure maybe the pump on its way out what do you think ??

No probs mate he'd it may help.. Did you do what lee suggested and checked the vacuum pipe to the fuel pressure reg? May explain the plug issue if its not supplying the fuel. Would of expected a walbro pump in your car with the work that's been done

Check the vac lines or just replace see if it helps..

 

[Drew jdm]

Ok mate I will give them all a good check and yeah it is a walbro mate

 

[Drew jdm]

So just checked them all now and everything seems fine I've noticed that one of the plugs does look a very slightly bit melted at the end compared to the other 3 what would be the cause of this ???

 

[B6lee]

if its only 1 plug then its only one cylinder. id be looking at getting the injectors tested

 

[Drew jdm]

Ok mate so get the injectors tested is it worth changing the plugs or leave it for now as I have only gapped the ones that were in

 

[gooner8]

sorry did you change your plugs or just regap them? Had the same prob and it was the plugs! I just hold of a set of copper one's for £10 for a full set and that sorted it. I re gapped mine first and it didn't work!

 

[evonewbie65]

If you haven't already changed the plugs, get them changed. What cylinder was it that has the damaged plug? In my opinion if you were running low fuel pressure before the remap and it has since been raised and also you are now running more boost, the symptons are pointing towards the spark plugs. The fact one of them looks like it has been melting (running hot) would suggest that the engine has been running lean which would tie in with the fact you had 1.4 BAR fuel pressure before your remap.

Just my 10 pence worth,

Keith

 

[Drew jdm]

Yeah that seems to make sense mate to be honest I will change the plugs anyway I suppose it can't hurt can it the dodgy plug was on cylinder 3

 

[evonewbie65]

Yep won't do any harm, although maybe worth having the injectors looked at too at some point. But lets see how you get on after you change the plugs.