Hi

Bought a 1991 2.0 TD 2WD Townace in February. A replacement engine from API seemed to have sorted out serious overheating and crankshaft pulley problems. Even before that, the rev-counter was/is mainly on strike. Occasionally it decides to work, but mostly it makes a half-hearted little wave up to 3000 rpm and then returns to zero. On some trips it works fine, but not often.

Has anybody got any ideas what the fix might be?

Seamus at The Allt

- (#10146) Seamus H-K, 15 Apr 04 13:10

look farther down the board, this was discussed a week or two ago...

- (#10146) David Miller, 15 Apr 04 13:48

'Fraid not, Dave.

Connection at rear of injection pump between pump and engine block appears to be AOK.

Where are the electronics for the rev-counter? Maybe in a chip within the tacho display? If so, is it replaceable?

Seaamus

- (#10146) Seamus H-K, 16 Apr 04 10:40

yes, the tacho is a module all the electronics are inside. You'll really need to monitor the feed from the sender with an osilloscope the confirm whether it's OK or not...

- (#10146) David Miller, 16 Apr 04 12:28

Thanks Dave

I feel pretty confident that the signal from the sensor is unlikely to have deteriorated, or have become sporadic, given the essential mechanical simplicity of an inductive sensor.

It strikes me that the loss of dc signal voltage to the display may be connected to some capacitive, or loss of, some capactive effect.

Have you any suggestions as to where I might look for a replacement instrument?

Much obliged

Seamus H-K

- (#10146) Seamus H-K, 16 Apr 04 13:45

Breakers?

- (#10146) David Miller, 16 Apr 04 13:50

Seamus,

What makes you think that inductive sensors of any type are reliable?

Vauxhall have a massive problem with their inductive camshaft sensors, they fail for a passtime!

You will need to see if you have a, AC signal coming from the sensor & coming up to the tacho head, if it gets there the tacho could be at fault, if it doesn't get there the sensor could be out. To check for AC you'll need a 'scope, to check sensor resistance, disconnect it & check you have a resistance, with multimeter, open circuit means coils damaged & open, low resistance, then coils have shorted out to give no inductance.

Regards Rob.

P.S. just got back from a 3 day EDC, Common Rail Diesel Management tarining course, so my heads buzzing with this stuff now.

- (#10146) Rob Drinkwater, 16 Apr 04 13:53

like rob says...
the manual says 600-800ohms for the sender, btw.

so rob, you didn't happen to came away from your course with an obd-tuning dongle and software did you?

:-)

- (#10146) David Miller, 17 Apr 04 01:35

Not going to advertise where I live, of course, but I can have up to £30k of kit in the boot of the car at any one time, dependent on what demos I'm doing that day/next day.

So I can do almost anything.

Don't tell me, Mr Miller, trying to soup up your HDi even further?

Regards Rob.

- (#10146) Rob Drinkwater, 17 Apr 04 04:08

Haha, Rob. Upgrading from the tuning box to a chip. Nobody does OBD over here, so in a tossup between Superchips and Upsolute, UP wins thinks to the exchange rate- the rep's in Dublin.
Week after next, unless something changes...

- (#10146) David Miller, 17 Apr 04 07:05

hi rob

i must admit my main experience of inductive sensors is limited to the higly-reliable ones fitted to the rolls-royce rb-199 (tornado jet engine). in that application any problems encountered were normally with the integrating op-amp that creates a dc level to drive the display.(easier to change as well!)

anyway, i'll get a 'scope from work and see what the signal turns out to be. many thanks to you all for the valuable practical advice.

seamus h-k

principal lecturer, mechatronics engineering
university of ************



- (#10146) Seamus H-K, 18 Apr 04 08:07