Thread: 3.9 misfiring at high revs

1. Your fuel pump might be crook. You will need to measure the pressure in the fuel rail under load and see if it stays up to spec. You can use a VN-on fuel pump kit, Bosch part no. BFP772

2. Your ignition coil and amplifier might be weak. See this thread for an upgrade possibilities:

Lucas ignition amplifier replacement by Bosch 024

3. Your dissy might be firing on the very corner of the rotor button. Inspect the rotor button carefully and look for the burn mark from the spark. You can use a XF Falcon rotor, Bosch part no. GB864 which has a wider electrode tip.

thanks for that mate.

i ended up replacing all the ignition gear and it seems to have sorted itself out.

but am still unsure as to what it actually was?


davo

Originally Posted by D3V1L

i read that i should have a lcd display under the passenger seat. but ive looked and can not find one anywhere?
davo

That's because there is none.

i read that i should have a lcd display under the passenger seat. but ive looked and can not find one anywhere?

If you lived in the USA you would have one.
Its LED not LCD
I bought one for my RRC from a wrecker there but if your D1 is like my RRC , you also have to add 2wires minimum to your 40 pin plug.
Doesn't really show faults much especially if you do not have O2 sensors.
It will not show ignition faults as the ignition has no connection with the ECU in a 14CUX.
I have to pull my MAF connector off every now and then to be sure the display is working
Regards Philip A

hey guys ive still got this misifing at high revs issue.

im plum out of ideas.

have worked out that if ive flogged pretty hard, then the misfiring doesnt occur to higher in the revs and can rev out to 5500 without an issue.

anybody else got any ideas?

sticky valves possibility?

davo

Try running 1 step colder plugs, keep the plug gap to 0.8mm/0.032" and see how it goes.

ill give that a shot mate see what happens.

driving me nuts. cant do any big sand hill climbs

davo

When you replaced the ignition components did you do the amp upgrade as suggested by bee utey? It is highly recommended (should be mandatory!). I gained noticeable mid range torque when I upgraded mine and my original amp seemed to be working fine prior to replacement.