Rev counter readings, then misfire?

[davetherave1970]

Hi All

Anyone any ideas?
Cerbie used every day and a week ago I noticed the rev counter started "bouncing" while at a steady rev. Badly doing this at around the 2k mark. Car and power didn't feel any different.
Last night, while the engine was under light load was not firing on all 8 but as soon as you give it over quarter throttle all 8 fire nicely without power loss.
On tick over, before last night, use to be quite high at 1,100 but now dropped to 800-900.

My first thought is Coil packs but not 100%. If so, does anyone know costs?

Thanks in advance

Dave

[crazycats]

Morning Dave,

Could be the big fuse, one of the symptoms of this failing is am erratic rev counter,

[Julian64]

also cerb ECU needs that rev counter input to fuel the car properly so check its reaching the ecu better than its reaching your rev counter.

My guess would be engine rev sensor.

[mike_e]

Does it turn over on the starter OK? Most likely the charging fuse if starter is getting slower.

[davetherave1970]

Starts fine. I'm 'popping' it into Castle's in the next couple of days for a laptop connection. Hope it's sorted enough for VW this weekend!
Thanks all for your replies. I'll let you know the outcome.

Dave

[Julian64]

There's an awful lot of people round here on PH capable of doing the laptop thing.

Don't get charged for the checkout if you can get it for free.

[davetherave1970]

Just an update.

Cerbie is sorted now.
It was a faulty coil.
I had both throttle pots replaced while it was in and now it pulls without jerking at under 1,500 rpm. (never done that since I had it)
Rev counter steady now.
Nice big smile on my face again