Misfire on boost

[Xrcossie]

Hi there, This is my first cosworth powered car and i'm having a few minor issues. My car is an XR4x4 with a Escort cosworth 4x4 transplanted into it, I rebuilt it earlier this year after it spun a big end shell whilst on a dyno being tuned. Anyway my question is as follows:- When i am on boost it occasionally misfires like it coughs but it isn't constant and it doesn't do it all the time either What would be the remedy? Will runing a bigger sparkplug gap help if so what size should it be? I'm runnig after market fully mappable ecu, Coil pack, 440cc flow injectors, mongoose exhaust, rs500 70mm core intercooler, T34 hibrid, pipecross cone filter, Bailey oil breather, ARP stud & nut kit, WRC multi layered head gasket, I'm running 19psi with 22psi peak with 320bhp @ 6700rpm & 300lbs torque @4200rpm. Once i can get this sorted i want to get more power from the engine, What is the most it can be pushed with being reliable. on my current mods? Many thanks, Simon

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[cossie4i_]

You need a smaller plug gap to stop misfires

Steve

[avid-fan]

Originally Posted by Xrcossie

Hi there,
This is my first cosworth powered car and i'm having a few minor issues.
My car is an XR4x4 with a Escort cosworth 4x4 transplanted into it,
I rebuilt it earlier this year after it spun a big end shell whilst on a dyno being tuned.
Anyway my question is as follows:-
When i am on boost it occasionally misfires like it coughs but it isn't constant and it doesn't do it all the time either What would be the remedy? Will runing a bigger sparkplug gap help if so what size should it be?
I'm runnig after market fully mappable ecu, Coil pack, 440cc flow injectors, mongoose exhaust, rs500 70mm core intercooler, T34 hibrid, pipecross cone filter, Bailey oil breather, ARP stud & nut kit, WRC multi layered head gasket, I'm running 19psi with 22psi peak with 320bhp @ 6700rpm & 300lbs torque @4200rpm.
Once i can get this sorted i want to get more power from the engine, What is the most it can be pushed with being reliable. on my current mods?

Many thanks,

Simon

How much petrol in your tank when it coughs

swirl pot issue maybe ..

[bernardd9]

hey i had the same problem wit my old one so i looked into this ford said not to use motorcraft plugs the give me the name but i cant remember it now and i needed to change the ackueater ( not sure if thats spelt right but you should know wat it means ) anyway i had to get a D3 one for it and that sloved all my problems

hope it helps

[tabetha]

Changing the plug gap will only cure it if that is the problem, which it doesn't sound like.
The best thing you can do is get it fully mapped as it has a mappable ecu, as when it misfires it will give clues as to what's causing it, as emissions are watched.
Could a plug breaking down, could be a dodgy connection, maybe a injector overheating, could be lots, check the usual suspects, cps/connector, phase sesnor, check gaps for both, set plugs to around 0.9mm, I use IK27 plugs, as found the IK31 too cold running.
What are the emissions ?
tabetha

[Xrcossie]

When it does misfire it doesn't matter how much fuel in the tank,
It miss a couple of times yesterday with 3/4 tank, but today not a thing.
And i pushed it over the speed a few times on my way home tonight.

If there was a fault with the cps wouldn't it play more oftern?
On boost the afr gauge is about 12-13.

I am running standard plugs will invest in a new set, But will need help with which are best for me please,

Thank for your help

Simon

[mtommi]

did you notice if it is worse when it is wet outside. I find that with mine.