Re: VW Lambda Sensor Problem


"M Cuthill" <moray_dot_cuthill@xxxxxxxxx> wrote in message
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"Periproct" <Periproct@xxxxxxxxxxxxxx> wrote in message
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Plus all that could be caused by an air leak, in either the inlet system
or the exhaust, which can be enough to upset the system.

BMW 318i 1992 that used to run beautifully.

I have rough tickover and lack of low end power and a slight exhaust
leak. The ECU is saying there are no faults. I've changed a hell of a lot
of stuff to try and cure this problem.

Could the exhaust leak really be the problem? (I appreciate you've said
exactly that above but I'd prefer working on engine stuff before I
replace/change the slightly farty exhaust).

Secondly, could another fault destroy lambda sensors. I've changed it. A
garage then changed it later and then a second garage said the first had
used the wrong sort (titanium) and changed it again.

A leaking exhaust can be enough to throw emissions off.
Easiest way to find out is a tin of GunGum.

But given the age of motor, and the symptoms, it is likely to be something
else. But that something else, could take a bit of diagnosing.

Don't I know it. I've changed so much by guess work to start. Now I've
bought a scope and been looking at the waveforms from some of the sensors.
Using an HT pickup I found I seemed to be missing a spark every few turns of
the engine. Changin the coil made quite a big difference to the running of
the car but I haven't got the scope back on it since.

Found some really weird stuff like a near perfect sine wave from the plug
lead sensor. Don't understand that one.
And what looked like a load of mush from the crankshaft sensor. Changed it
and no difference to the running at all.

I had considered the GunGum option but I think the leak is right at the
front of the cat so the heat shield is going to have to come off so I might
as well have the whole lot off and see if it is weldable.



.

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  • Re: VW Lambda Sensor Problem
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    (uk.rec.cars.maintenance)