Re: Problem with 75 TS

[Anders Nilsson <anders.nilsson@domain.elided>]

jonathan coates wrote:

<snip>
> Have you checked that the crank sensor is close enough to the teeth?
Yep, somewhere between 0.5 and 1.0 mm ( 0.5 - 1.5 allowed )

> Is the toothed pulley clean, I'm guessing that dirt in the teeth will
> not help.
As long as the dirt isn't magnetic, it shouldn't matter ?
Or am I completely off in this field of electromagnetic sensors?
Anyway, it's clean.

> It does sound to me that it is either the sensor or the ECU.
> If you get the oscilloscope you should get a big peak from the missing
> tooth, followed by a series of smaller peaks for the teeth.
Got the scope yesterday. It worked when I tested it on my kitchen table, but
when it was time for serious testing it decided not to :-(
Was I a really happy guy at that time? NOOOOOOO!

What I finally did, was to use the Voltmeter in AC mode and measure the ignition
pulses from the ECU to one of the coils. Since this signal can be described as
pulse train ( 0 or 5? 12? ) V with a frequency proportional to the engine revs,
you an AC Voltage reading which is also proportional to the revs.
At idle it read about 0,2 V
At 2000 rpm it read about 1 V.

When the engine died, it read as low as 0,0 or 0,1 V without the revs being
_that_ low. It is a bit hard to verify due to the delay of the Voltmeter, but I
think my results point in the direction that the ECU is not sending ingnition
pulses, which in turn points out the ECU or crank sensor as the culprit.

> BTW what is the imfamous 5 lead switch? Never heard of this.
I meant the 6 way connector (with 5 connected )near the relays on the passenger
side (LHD).

> Wild guesses follow:-
> Making lots of sparks loads the ECU so that the ground connection is OK
> for a few sparks but no good for lots, especially with the injectors as
> well. Same goes for power feed.
> Inductive sensor makes more volts with more pulses, or faster pulses and
> when it makes enough volts it sparks across and stops feeding the
> signals.
Sounds like what I'm thinking too.

Regards,
Anders Nilsson
Malmo, Sweden.
- -90 75 2.0TS

------------------------------