4.3 running very rough - Advice ?

[TeGriffic]

I seem to have developed a problem with the V8 4.3 (Griff).

Coming down the motorway today, the car was running very lumpy at around 2000 to 3000 steady revs. It idles perfectly at 900 or so without variation. Under acceleration it becomes more smooth but I’m pretty sure the acceleration has decreased slightly. This suggested to me a problem with one or more of the sparks – ie. not firing – it has been recently serviced though.

However, I’ve noticed over the last few weeks that it’s taking more petrol (I’m used to the normal consumption) and the lumpy ride certainly has a flooding feel about it.

Can ayone offer some advice or experience whether I’m on the right track or whether there mght be something else to be looked at.

[andy43]

I've had probs with the plug leads breaking down - but on mine it ran fine at speed, no really noticeable lack of smoothness or power - but the idle was really lumpy with the odd back-fire. If yours is running crap at higher revs it could be the ignition amp or coil on their way out - higher revs=higher loads on the spark supply bits. That would explain the higher fuel consumption - more pedal to the metal for the same speed. Easy way to test the leads and the plug-on insulator/suppressor things is to unplug each one at a time (with ignition off!) and see if there's a change in idle. If not its something else more difficult to detect - if its recently been serviced, the easy bits like rotor arm, fuel filter and plugs should be ok... have fun!

[seasider]

check all the plug leads are pushed on properly i had one that wasn't contacting properly, gave the same sort of symptons...... a bl!!dy big bolt as i found out which one it was...

[kevinday]

Does it have a stepper motor? If so, try cleaning this.

[donatien]

Could easily be the coil compounded with water ingress. When my Griff became lumpy under accleration it proved to be this. Heath at the factory showed me the unit they took out - completely shot

[Tegriffic]

Thanks for the responses. Turned out to be dodgy shrouds.