sundera86

car runs perfect for 20 -25 km and after that it start to missfire. I cant understand why it start to missfire , every time it runs perfect at the begining but after some drive it missfire or cut out on 4000 rpm

Fil

Sounds like something getting warm and breaking down ?

HT lead?

jamie's

leads, plugs coil etc,
or could be cts leaning it out when its warm etc
few differant ideas but start with the easiest 1st,
is it just missing when under load or at idle as well?

CosworthGuy

mine does this between 3500 and 4500 rppm when fully warm, only under 100% throttle. fine at 75% throttle. ive put new ford plugs gapped correctly new motorsport leads and new dizzy cap and rotor arm from matt lewis. also runs on three for about 5 seconds when first started in a morning, i took plugs out the other day and number 3 was almost looking rusty and what looked like a bit of water on top of piston, ive resigned myslef to the fact the head gasket is on the way out as my mates escos has just been doing exacly the same and his was the head gasket. Dont matter though as its a excuse for a wrc head hasket and arp stud and nut kit, then......... More boost and a damn good set up. who shall i take it to though, im thinking harvey gibbs as he's not far from me at all

jamie's

cant go wrong with scs mate

charlie luciano

iTrader: (3)

Its the process of elimination with any annoying miss-fire check and if needed change all the cheapest options 1st, plugs,leads,coil, dizzy phase sensor,TPS,crank sensor, once all those avenues are exhausted its time to look at the engine loom


Luciano

sundera86

it is missing only at full load, at iddle car sounds perfect

charlie luciano

iTrader: (3)

What's the rev counter doing under load when it misfires? is it jumping around?


Luciano

big mac

iTrader: (7)

if its at 4000rpm every time i would say phase sensor

Glenn_

iTrader: (1)

take the dizzy cap off and check the phase sensor wires. Normaly the plastic wire protection cracks and the wires touch. I would be trying plug leads as well.

Bullett

iTrader: (2)

before doing all these.the cheapest check is to pull apart the wiring blocks that are clipped on to the baulkhead above the back of the engine(where they get very hot and can corrode) i had misfire problems and it was down to these.pulled them apart and cleaned them,put them back together and never had the issue again. after that try the other cheap options

Glenn_

iTrader: (1)

I also did this too. I bent the electrical connectors slightly so they made a good connection.

Glenn_

iTrader: (1)

also check the crank shaft sensor connector cause mine was full of water and the pins had gone green.

BRAM

iTrader: (1)

coolant temp sensor

sundera86

yes it is jumping around

mattman1234

mine does same when misfiring,tell me more

VEEDUBBED

If it is that shiyte Marelli cts,don't bother replacing it with another shiyte Marelli one.
Do like me and fit the sensor fitted to '92 Vw corrado/passats,exact same thread and very similuer values.
I've change 3 on my cosworth managed car and ever since using the Vw Bosch sensor i've had no problems since(i've got both sensors fitted onto the cyl.head side by side).
Cutting out,missfiring when under load(very dangerous when trying to overtake),pissing black smoke out of exhaust etc,etc..

Rs(555)

iTrader: (8)

My money is on the phase sensor.
Wires corroded ,sticking together

sundera86

i start the engine, wait to get working temp and after that i drive to the rev limiter without any problems! After 20- 25km racing drive the car start to missfire, there is no black smoke from the exaust??