Thread: 3.5 consistent misfire for 5klms

Hi all .
My 3.5 efi rangie has started to misfire badly on start up and initial drive off for approx 4 or 5 klms then performs perfectly once past that distance . It does this at worst when cold but also does it on hot starts (doesnt do it if you restart within say 5 mins though ).
I done compressions thinking maybe head gasket or cracked head but results were very consistent comps around 140 -150 on all cylinders .
All ignition components are new , Im thinking its related to computer temp sender .
Anyone got any ideas ?

Originally Posted by Davehoos

I have a similar problem with a 3.5 disco.

I replaced AFM-battery-earth conections-water temp sender-thermostat-rad fan-leads-dist [not the coil]-plugs last about 5 000km.
recently replaced the fuel filter-it was using lots of fuel and now its back at a sencible rate.week half and still going on the tank.manifold doesnt seam to have any vac leaks.

the engine missfires for 5-7 km on cruise throttle of a 18 km drive mostly when cold.630-7am.very rare but sometimes it does it on the way home about 4pm
.
ive blamed water but the only thing i havnt tested is the coil.
the sencor I havnt tested is the fuel rail temp sencor.or the fuel pressure reg..but it looks like a possibility.

Does your disco use any water ? Im sure mine doesnt and its a real mystery to me . I fear its a major problem within my engine . Im worried its head gasket failing then taking up when hot if thats possible in these engines .