Cosmo

Evening all, the other day i posted up regarding a missfire i had on the 3dr, unfortuantely i'm still no closer to sorting it?! It just started to happen the other day out of the blue, the cars been driving great up until then!

The symptoms are, the car appears to drive ok up until the car hits boost, as soon as my boost gauge goes past 0 on the boost gauge i get the missfire!

so far i've changed:
Fuel pump
Fuel filter
Fuel pressure regulator
MAP sensor
Checked plugs (all seem to have good burn and spark)
Disconnected the brown plug (ACT) sensor and it made no difference
I've done a test with WD40 to see if i have any air leaks etc with no difference
I have good power to the fuel pump so am happy with that.

I've ordered a phase sensor, crank sensor and coolant temp sensor.(although not sure what the symptoms of a failed coolant temp sensor are?)

Anyone had this problem before?? Am i on the right tracks? Seems odd as soon as the car comes on boost, it literaly is as soon as the gauge moves above zero! Car seems to drive ok up until then?!

As per usual your helps much appreciated guys!!

tabetha

Have you tested your fuel pump supply UNDER LOAD ?
They can test perfect with no load(idling) but when under a bit of strain the wiring can be unable to deliver the required amperage needed which will cause massive voltage drop.
Just hook some thin wire into the plugs on the pump before pushing the plugs back on the pump, trail wire through window hook up to digi metre and watch it as you drive, may give a clue.
Was the map sensor brand new or a known good one ?
tabetha

martysmartie

iTrader: (1)

What are the plug gaps? As said the pump power needs to be measured under load as this is the actual problem because the old wiring cannot supply the power needed as it degreades over time building up resistance.

Martin

Cosmo

I was assured the MAP was a good one (was second hand), but now am questioning it? The only difference i noticed was my old 3bar MAP had a grey top, the replacement was all black? Dont know if that makes a difference? I had a MAP fail some years back and it does feel like that did, but when my last one went the car missed then died on me on boost, this time it still drives just missfires like hell as soon as i hit 1 psi and then obviously i cant go any faster/hit higher boost then. If i rev the car while idling it can sometimes show the signs of the miss, get a bit of popping through the exhaust (more than i would consider normal so to speak)

Anyone live near chester with a known good MAP i could try/borrow for 10min to rule it out completely??

neilscott83

Had the same problem with mine turned out to be the ignition leads.

Cosmo

From the ignition barrel?

Steve the Plumber

iTrader: (11)

Mine misfired above 3K only, was Spark plug leads.

martysmartie

iTrader: (1)

HT/Ignition leads same thing.

Martin

Cosmo

Oh, i get you now. Not long had these, be gutted if they've gone.

Unfortunately there arent many cossie owners round my way to have someone nearby to loan parts off to try them out so its costing me a fortune buying new everything to find it wasnt that after all

rsnissan

iTrader: (9)

deffo one of these if its not the plugs; ign amp, leads, phase sensor, dizzy cap

jon@work

iTrader: (5)

check the vacuum hose between the inlet plenum and the fuel pressure regulator

Cosmo

Replaced that too unfortunatly

Danny @ Enhanced Performance

iTrader: (3)

New set of plugs bcr 8es ngk and try that or check when itd dark and look under the inlet plenum to see if your plug leads are sparking together,two cheap options to check...


cheers danny