Tacho goes to 0 when car moves.

[JfknR]

Hi all, first post here thanks for having me. My gu4 td42ti tacho is playing up. It was all working fine until yesterday not sure if its a coincidence that I blocked off the egr and gave the IC a clean out yesterday with kerosene then metho.

Now the tacho works fine when car is parked still, soon as I start to even roll out of the driveway it drops to 0 and starts jumping up and down when driving.

Any idea what's going on or where to look?

Cheers

[Cuppa]

Did you loosen or disconnect any earth wires?

[JfknR]

Nah mate I didnt disconnect anything, that was first thing I thought of, but didn't know which plugs to check incase I knocked something. Only one I knew to check was the rpm sensor on front of timing cover.. are there any others I should check in particular? I did go over all in the vicinity of where I was working but nothing seems obvious.

[Cremulator]

Maybe double check that you've done everything up again tightly?

[JfknR]

Yeh been over it like 10 times lol..

Maybe its a coincidence and the rpm sender just shat it self?

[0-TJ-0]

My sensor died a few years ago. Similar MO.. front of the engine up near the top behind the fan is where the sender is in mine. Try give the wire a wiggle with the engine running, might show your trouble. Don't stick your hand in the fan though.

[JfknR]

Update, played around with some of the wiring going into the fuse/relay box in engine bay and the tacho is now working fine.

I was leaning over the side of the engine bay on that side when I was working on the car so maybe dislodged a wire or something. It's fixed for now but I'm assuming it will haunt me down the track!
Cheers all

[0-TJ-0]

Mine was intermittent for months. It does effect the timing slightly on the Ti when it's not reading the rpm. Mine died properly on a trip and I got noticeably worse fuel economy and the power was down a bit. Looked it up after and apparently the ecu uses rpm as one of the variables to set the timing at the pump. Good news is that it won't leave you stranded, I think the ecu just defaults the timing to full safe/retard.