Vz running rough when overtaking or going up hills not misfiring either

[Vz04dylan]

hi I have a 04 vz v6 it's the 175 kw the problem started today. I was coasting down a hill at about 80 ks and noticed the taco went up to 7000rpm and bounced on there like it was limiter bashing then went back down to normal rpm. A few minutes later I put my foot down to overtake and the car start jerking like it was misfiring and the speedo dropped down to zero all other gauges were operating like normal and the check power train came up the disappeared no other warning lights came up either also done it while going up hill with under light acceleration. I checked for codes put no codes were present. The timing chains plugs and coils and gaskets were all replace about 2 months ago and o2 sensors also.

 

[greenacc]

The jerking when you press the throttle sounds like the on the Electronic throttle body faulting.
So when the revs went up was it accelerating like mad or are you saying it's just the dash doing funny things ?

 

[Vz04dylan]

Kind of like it was starving for fuel. Wouldn't it log a code if it was a fault with the throttle body

 

[greenacc]

If the computer recognised the fault...
But it shouldn't hit the limiter if it's starving for fuel.

 

[Vz04dylan]

It didn't actually hit the rev limiter with the engine. The tacho went up to 7000rpm and started bouncing like it was on limiter but the engine didn't increase in rpm at all. With the tacho doing that and the speedo dropping to zero when it's like it's starving for fuel and check power train warning comes up for a couple of seconds then disappears is what makes me think there is an electrical fault

 

[greenacc]

Yes it sounds electrical. Check the fault codes with a scanner.

 

[Waughy]

My wagon did this about 6 months ago, can't recall if the tacho did what yours has been doing, no warning lights etc though. Had the hesitation when accelerating, I thought fuel filter or plugs. Ended up being a bad coil pack. Had the 6 done, has been running great since.

 

[Vz04dylan]

Did that also cause the speedo to drop to zero with no warning lights also. I'll try a different set of coils and see how that goes.

 

[Waughy]

Off the top of my head I can't honestly remember, I don't think it did though. I only recall it hesitating under load and me going WTF? Come to think of it, the tacho dropped, rather than jumping up, I was hoping wouldn't stall in the middle of busy traffic.

 

[Vz04dylan]

All good figured the problem out. Was a bad earth on the pcm on the engine.