ECM Fault?

[Espen Hilde]

Hi!
Had a problem with a 95 Jaguar Xj 4l supercharge, sometimes it idles rough.
The factory are changing the exhaust valves on warranty, the valve stems
gums up at slow driving and the valves does not seat properly,if you run
the car hard , the idle is ok .
The cam chain on this engine rattles from 1500 to 2000 rpm, changed the 
upper chain and tensioner.......slight improvment but still there.The
factory
are changing everything on thiese ocations camshafts, chains,guides,
wheels.I am thinking of camshaft occilations.....???
Any one have had the same trubble ?
Espen 

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> From: David Cooley <n5xmt at bellsouth.net>
> To: gmecm at efi332.eng.ohio-state.edu
> Subject: RE: ECM Fault?
> Date: 7. desember 1999 17:45
> 
> At 09:51 AM 12/7/1999 -0500, you wrote:
> >MAP sensor is fluctuating constantly along with the idle - I think
that's
> >normal i.e. with RPM change you get pressure change. I did scope just
about
> >every signal, including the MAP. The map signal is not flat, it has
waves
> >corresponding each cylinder I guess, one of them is specially large. I
think
> >It is because it is close to that particular cylinder. Wave amplitude is
> >approx 0.1 to 0.2 V on the largest wave.
> >
> >I am desparately trying to complete the device to inject the fuel to
> >disconnect ECM and see if idle is still fluctuating. If it is, it would
> >indicate the mechanical problem.
> 
> 
> I think a good point of reference at this point will be a compression
check.
> Might also add a restrictor to the line to the MAP sensor to minimize the

> fluctuation and see what that does.
> 
> ===========================================================
> David Cooley N5XMT Internet: N5XMT at bellsouth.net
> Packet: N5XMT at KQ4LO.#INT.NC.USA.NA T.A.P.R. Member #7068
> We are Borg... Prepare to be assimilated!
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