speedo pulsing while reving in park..also noise

[jas98]

ok so i got my self a VR wagon...it drives fine (considering that i live on 2.5 acres and the car is currently unresisted lol) BUT when i rev it while in park (not sure about netrual) at about 2500-3000rpm there is a noise that sounds liek its missing, but sounds like the rev limiter...Daaa daaa daaa....also while it does this the speeddo pulses from, 0-20 like it goes 0-5 then 0-10 or just jumps up and down from zero etc but only when this noise happens and engine feels like it drops revs but revs stay teh same. otherwise this car is good


only thing i can think of is something in teh engine or alternator....even so why is the bloody speedo pulsing while reeving in park?

cheers

[moff_man]

jnot too shure about the spedo etc but the noise you are getting is a miss fire, could be plugs or leads, through to coils and dfi module, also could be burnt valve but this would be more noticabol all the time etc..... start cheep and change the plugs and leads

[jas98]

yeh will changes coil/dfi and leads/plugs with some spares i have....i really have no idea what it is as the noise happens the speedo moves up and down liek the taco??????

also took the belt off and started it and reved it and it does teh same

[ScoHar]

the speedo i've noticed seems to be a V6 thing, i've had several holdens VN VP VR VX V6's and they've all done the speedo needle jump when revving on a stand still. there is a reason for them doing that someone will be able to explain a bit better, its got something to do with the engine/gearbox moving while you rev it making the elec sensor thinking your moving.

[Doctor Bob]

the speedo moving when revving is simply the output shaft vibrating, the tone wheel moves slightly near the sensor & it registers as speed.
if the speedo moves that much while driving i would be looking at a bad earth or power connection dropping power to the majority of the car

Rob

[jas98]

the speedo moving when revving is simply the output shaft vibrating, the tone wheel moves slightly near the sensor & it registers as speed.
if the speedo moves that much while driving i would be looking at a bad earth or power connection dropping power to the majority of the car

Rob

thanks...the speedo moves (jumps) up and down from zero and can go up to 20kph and drop but it only does it if i keep a steady rev ...i.e if im reving at 2500 rpm the speedo will do nothing then all of a sudden move up and down with this noise teh engine makes....while keeping at 2500rpm...if i rev more the noise goes and teh speedo does nothing.

either wy ill check what you said as i have to take it off as its leaking oil anyway

cheers

[jas98]

wel after changeing coil pack, plugs, leads, and giveing a compression test it is still doing it but only up untill it heats up (have to rev for a while) compression was 180-185 psi in each cylinder.

still doing teh noise and speedo thing GRRRR