VX Vectra Rev counter input?

Honest John Back Room » Technical matters
What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks
View Threaded
Fri 13 Jan 2006 16:44
VX Vectra Rev counter input? - Big Vern
Hi

I have a 98R 1.8 Petrol Vectra. Does anybody know where the rev counter takes it's input from?

I have a problem in that occasionally when driving at through traffic in 2nd or 3rd gear (possibly when I am easing off the throttle but can' swear to it) the engine gives a jolt - hiccup and within a few seconds the rev counter needle oscillates wildly for ~ 5 ? 10 seconds (actual engine speed sounds constant) and then the engine stalls when clutch is depressed.

Up until recently this has only happened when the petrol tank is less than ¼ full however it happened today with a ¾ full tank.

When restarted the engine management light may stay on for a little bit before going out and engine runs fine.

I am interested to see why the rev counter is acting the way it does which may help me isolate the fault. I plan to change the fuel filter as a first step as it probably needs doing anyways. The fault codes stored in the ECU as far as I can tell relate to an issue I had about 3 years ago, if I can find the Radio code I will clear the ECU to make sure.

Any help appreciated.

Reply | Report as offensive | Link
Fri 13 Jan 2006 17:38
VX Vectra Rev counter input? - Wales Forester
Sounds similar to a fault on Ford Focus models suffering from sweeping gauges and stalling, which is cured by fitting a new road speed sensor.
The fuel tank capacity may be coincidental.
Reply | Report as offensive | Link
Fri 13 Jan 2006 18:29
VX Vectra Rev counter input? - Screwloose
Big Vern

The exact engine code will be needed for a definitive answer to your query. The tacho feed is from the crank sensor, processed through the engine management ECU and the effect that you've noticed is merely a symptom of the underlying problem.

Possible causes include: the crank sensor itself; [common] a cam-position/crank sensor assynchronicity caused by a slack timing belt; the cam-position sensor or it's wiring; or, on the X18XE1 engine, a failing solder joint in the manifold-mounted ECU.
Reply | Report as offensive | Link
Mon 30 Jan 2006 20:21
VX Vectra Rev counter input? - Big Vern
Excelent advice. Crank and Cam sensor both replaced (belt and braces) and so far so good.

Thanks
Reply | Report as offensive | Link

Looking for a garage you can trust? Honest John's Good Garage Guide has thousands of reader recommended garages, plus how-to guides and tips on servicing.

The Good Garage Guide