Valver revs go crazy at warm idle

[james_16v]

Just when I thought I sorted my idle troubles the past 2 days its developed an embarrassing new problem. When up to temperature and I dip the clutch the revs often stick then start bouncing around very erratically. Sometimes it will idle steadily (1000rpm) then increase to 3000rpm then randomly up and down from with the rev counter needle going mental.
The rev counter also show revs dipping to 0 although it has never cut out whilst doing it.
I have no clue what to try next ISV is fine, 3 temp senders are fine microswitch clicks when off throttle, cable not sticking etc.
Anybody have any suggestions?

[monzablue16v]

Bad earth I would say buddy, check all the earth straps and mounting points for breaks and rusty bolts etc. Temp sensors was my first though but not with the rev counter. Could be a faulty coil I suppose or Hall sender?

[james_16v]

Had a nose around this morning and one of the temp sensor heads fell off when checking the connections. I have 3 new GSF senders in the house but didn’t have time to fit them as I had to get to work, so just swapped it for the temp gauge sender. This didn’t cure it though.
The main earth on the gearbox is looking pretty grimy and the wiring to the temp senders and hall sender have seen better days (lots of frayed wires).
Ill clean up all earths, fit a new temp sensor, sort out the exposed wiring and crimp on a few fresh connectors on the weekend and see where that gets me.
Thanks for the suggestions monza 

[monzablue16v]

No worries, let me know how you get on with it as I chased a similar fault for ages, changed the ecu, ISV box, Ignition amp, ISV allsorts. Changed the temp sensors and it never happened again

[james_16v]

Will do fella
Must be a common fault with these monza blues eh?? 

[monzablue16v]

It's because they are so awesome!

[james_16v]

Update - Just had a look at the coil and there seems to be a missing wire???

Worst part is I cant see any trailing wire to reconnect to
Anyone know where this should connect to???

[maxp]

Had a nose around this morning and one of the temp sensor heads fell off when checking the connections. I have 3 new GSF senders in the house but didn’t have time to fit them as I had to get to work, so just swapped it for the temp gauge sender. This didn’t cure it though. ...

I dont think they are supposed to be interchangable?

[james_16v]

Im pretty sure all 3 on the side of the head are the same part & resistance so are interchangeable.
I swapped them around this morning and it ran exactly as it did before (albeit without my temp gauge working!) so I think my fault lies somewhere else.
Ill investigate further tomorrow 

[rubjonny]

that plug on coil is supposed to look like that, it is there to stop the coil terminal earthing out, as it is live with the ign. you are correct all 3 sensors on side o head are (should be!) the same

check your idle switch clicks, and the wires to it are ok