Jittery Rev Counter

[ollielawson 0]

Hi All,

 

I'm sure this has been discussed before but I can't find the thread. My revcounter has the jitters, the needle will keep dropping and raising even at a constant rpm. Usually the higher the rpm the worse it is and sometimes at idle the needle won't have moved off the stop. I'm sure it's a bad earth or pony voltage regulator but any light anyone could shed on to the problem would be much appreciated.

 

Cheers

 

Ollie

[Critical_Mass 10]

sensor on top of the gear box?

[Henny 0]

sensor on top of the gear box?

 

That's for the speedo, not the rev counter...

 

Dodgy rev counter would point to a dodgy earth or dodgy clocks to me... ;)

[Critical_Mass 10]

sensor on top of the gear box?

 

That's for the speedo, not the rev counter...

 

Dodgy rev counter would point to a dodgy earth or dodgy clocks to me... ;)

 

Ah good point.

[ollielawson 0]

Yeah that's what I suspected. I thought maybe if it was a bad earth all the dials would be playing up?

 

Ollie

[Henny 0]

the rev counter is a bit more sensitive to dodgy earths than the rest of the gauges... :wink:

[Supercharged 2]

Mobile phone interference can also cause symptoms like this..

[ollielawson 0]

Mobile phone interference can also cause symptoms like this..

 

I guess there weren't many mobile phones when these cars were designed lol

[CazzaVR 0]

Mine used to do this. Turned out to be a loose earth cable on the circular earth point behind the dash/above fusebox.

[ollielawson 0]

Mine used to do this. Turned out to be a loose earth cable on the circular earth point behind the dash/above fusebox.

 

thanks I'll take a look. Probably wouldn't hurt to clean the connections anyway.

 

Ollie

[soopercat 0]

:wave: Hi,

did you ever get to the root of the problem?

Mine has started to do this now, but very intermittently, whats the most weird thing about it is... when i turn the lights on it stops?

[ollielawson 0]

:wave: Hi,

did you ever get to the root of the problem?

Mine has started to do this now, but very intermittently, whats the most weird thing about it is... when i turn the lights on it stops?

 

I reckon its a bad earth somewhere. Weirdly mine goes away when I tap the front so it might be a dry joint on the board somewhere. I'll let you know if I find anything!

[soopercat 0]

mine has gone a bit weird now, when i turn on the lights it works fine, when i turn them off the revs starts jumping???

Im confused!

How can they be related?

Anyone?

[ollielawson 0]

mine has gone a bit weird now, when i turn on the lights it works fine, when i turn them off the revs starts jumping???

Im confused!

How can they be related?

Anyone?

 

hmmm that sounds like a voltage problem. Does everything else work ok? Are your lights relayed?

[iceviolet 0]

I have just changed the clocks on my vr to try get the coolant light to stop flashing as i had tried evrything else i could think of. Sure enough it did cure the flashing light problem but now the rev counter reads approx 400 rpm higher than the actual engine speed. i.e when on idle 680rpm on vag-com the rev counter is reading just over a 1000 rpm.

 

Any Ideas????

 

Get some more clocks! lol!! :lol:

[soopercat 0]

Hi Ollie,

what did you mean by relayed?

Just to let you know, my wipers, fog lights & demisters sometimes stop working also, but if i run a power jumper to one of the fuses (as they are all on the same backplane on the fusebox) they work?

I have recently taken out the dash controls and checked all the wiring and no bad joints or blown components.

I beleive it is either a bad earth (somewhere) or a power cut as some cables behind the fusebox seem to have inline fuses which i dont understand why? if one of them has broken then that could be the problem.

 

I have started a new post for a wiring diagram on the fusebox.

 

all the best

Gary

 

 

 

mine has gone a bit weird now, when i turn on the lights it works fine, when i turn them off the revs starts jumping???

Im confused!

How can they be related?

Anyone?

 

hmmm that sounds like a voltage problem. Does everything else work ok? Are your lights relayed?

[soopercat 0]

Has anyone got to the bottom of this problem?

I decided to take out the clocks and test the voltage on the 3 voltage regulators and the all have good readings. there is a main regulator on one side in the corner and 2 side by side in the middle of the clocks.

I tested them and got 13V on one pic and 9v out on one of the others.

I could give you all more exact readings if you think this would help resolve my problem.

I have also cleaned the earth pins above the fuse box and still the same problem. But its not just the rev counter but the miles clock also that jumps. until i turn the side lights on then alls fine????

 

Any one got any other ideas as to how to fix this?

I need this done pretty soon as i have put the car up for sale in autotrader now and need to get it fixed to sell it.

Any help would be greatly appreciated

[ollielawson 0]

Hi mate,

 

mine is still a problem although when I tap the front of the clocks it starts working. I need to find someone with a VR6 locally to see if its my clocks or the engine speed sensor in the engine (which brings up a fault code in VAG Com). Where are you located I might be able to help more as I have a full version of vagcom.

 

Ollie

[soopercat 0]

Hi Ollie,

What is "vagcom"? sorry im not sure, and how would it help.

 

Im in north London.

Mine is really weird, it used to be intermittent but only recently started to be doing it all the time. I am convinced it is a wiring problem, but as to where to start.... i have no idea. the thought of stipping the fuse box and making sure if all the wiring is correct just seems daunting.

If i could sell it with the problem and let someone else fix it i would!

 

Hope to hear from you soon mate.

 

If the vagcom is a document could you email it?

 

Gary

 

Hi mate,

 

mine is still a problem although when I tap the front of the clocks it starts working. I need to find someone with a VR6 locally to see if its my clocks or the engine speed sensor in the engine (which brings up a fault code in VAG Com). Where are you located I might be able to help more as I have a full version of vagcom.

 

Ollie

[ollielawson 0]

Vagcom is diagnostic software similar to what the dealers use. I'm in Bournemouth mate otherwise I'd come scan it for you! You might be able to find another person on here nearer. I'm pretty sure it's a bad earth somewhere where the connections have oxidised over the years. Check all the earth points near the clocks and give them a rub with some sandpaper to remove the oxidisation. Good luck with it and let me know how u get on!

 

Ollie