Fixed - speed and reference sensor '87 5ktq - test?

[Ben Swann]

I narrowed down this peculiar set of problems to a faulty ECU.

Once again, diagnosis often leads one to look in many different directions
before finding the actual culprit.

Ignition did play a part in severity of symptoms, but swapping the ECU
virtually eliminated any lag symptoms.  There is still a tiny bit - my
presumption is with the Charlie spring and fuel-pump lead wired to ground,
the fuel/timing maps are not correct for pressures over 1.4 bar.

So the QLCC chip will not be an option when I sell the car, it will be
already installed.

Ben

On Thursday, August 22, 2002 10:22 AM, B Vibert [SMTP:blur at sympatico.ca]
wrote:
> Hi Ben
>
> A few notes of my experience with these sensors.  The timing reference
> sensor is only used for starting and can even be unplugged after
> starting. The speed sensor outputs a sine wave increasing in frequency
> with the RPM.  Perhaps a frequency counter could catch this.  I used
> an oscilloscope, which showed my timing reference was dying when it
> heated up.  So, it's not the timing sensor in your case but it may be
> the engine speed sensor. I can't remember if it will start with one of
> these bad or not.  Maybe I should go unplug it and see.
>
> Oh yeah, I had a cracked distributor cap which showed similar symptoms
> as yours.
>
> Burl
>
> Ben Swann wrote:
> >
> > On Wednesday, August 21, 2002 12:59 PM, Ben Swann
> > [SMTP:bswann at worldnet.att.net] wrote:
> > > Patient: '87 5000 Turbo Quattro
> > > Symptom: hesitation at high load, boost and RPM
> > >
> > > I am following upon a check engine light 2111 code pulled which
> > corresponds
> > > to the RPM/speed sensor.
> > >
> > > I have also been having a symptom of hesitation at higher load and
RPM(3k
> > > on up).
> > >
> > > I installed new plugs cap and rotor which helped, but there is still
some
> > > hesitation at 1.3 bar on up to 1.7bar - yes the car has a mod.  This
> > > symptom has been present on the car since I purchased it 10 months
ago,
> > and
> > > I'd like to get rid of it, even though the engine otherwise runs
fine.
> > >
> > > I pulled out the reference and speed sensor assembly to clean, and
there
> > > appears to be some physical damage - particularly the speed sensor is
> > > dented, and you can turn the sensor with respect ot its connector.
> > >
> > > So although I will likely get a replacement, can I check to see if
these
> > > are still good even though they appear damaged?  There was a bit of
crud
> > to
> > > clean, and some metal filings held onto both sensors magnetically
which I
> > >  suspect could have contributed to faulty operation.
> > >
> > > Ben
> > >
> > OK - Now I cleaned the sensors and re-installed.
> >
> > I now consistantly get a 2142 - knock sensor.  Also a second code of
all
> > blank occurs when I insert fuse a second time - end of diagnosis or
???.
> >
> > Does someone want to confirm any bad news or perhaps give me some good.
> >
> > Ben