Re: O/T Lambda sensors/EGR valves

Cheshire Steve wrote:

Emimec wrote:


Sorry this is off topic, but before trawling the net, I wonder if anyone on
this site can educate me about Lambda sensors and EGR valves.

This is due to the wife's car now being on its third EGR valve at only 47000
miles and I cant get to grips with the relative associations of the valves
to each other and why cleaning an EGR valve makes it work? What's on it and
why?
Bob


Bob,

The only vehicle I had with EGR was a V8 LandRover and I was told the
EGR was nothing but trouble, and to throw it all away. Which I did. I
don't remember any valves, just some corroded leaky pipes connecting
the exhaust to the inlet. It struck me as a silly thing to do in the
first place, and the MOT man says it has very low emissions.

So from the little I know the EGR allows some exhaust gas to be
recirculated through the inlet manifold. The EGR valve presumably
prevents any chance of the flow going in the other direction, which if
it did would cause the Lambda sensor to give the wrong reading (as it
detects oxygen). It would draw air into the exhaust which will be
detected by the Lambda sensor, so the computer will think the mixture
is lean and richen it up.

The action of the valve is guesswork on my part. Does this tally with
the symptoms ? I suppose it would go rich on the overrun.

Steve

If lambda sensor is the same as Oxygen sensor...

The O2 sensor runs the fine tune on the mixture, with the computer reading the voltage generated and richening or leaning out the mix on the fly.
The EGR valve draws dirty old exhaust back into the nice clean engine in an effort to help balance out the emissions on the over-run. The system on my diesel truck is vaccuum operated. The one on my Mazda car has a 6 or 8 wire plug on it and runs off a stepper motor ($$$).
The one on my truck is slowly being made redundant. I ignore the check engine light on the car that says that there is an EGR fault. I suspect actually that the EGR is fine, the wiring however is suspect. I set the valve in the closed position to avoid continuously sucking burnt gasses back into the engine (who thought that was a good idea anyway?)

Cheers
Trevor Jones

.

Relevant Pages

  • Re: Oxygen Sensor Solutions
    ... in to some location on the exhaust manifold or exhaust pipe, ... Also called Lamda sensors. ... I know most of you know what and EGR valve is, ... The car stalled whenever it came to a stop. ...
    (sci.energy.hydrogen)
  • Re: O/T Lambda sensors/EGR valves
    ... to each other and why cleaning an EGR valve makes it work? ... So from the little I know the EGR allows some exhaust gas to be ... recirculated through the inlet manifold. ... it did would cause the Lambda sensor to give the wrong reading (as it ...
    (uk.rec.models.engineering)
  • Re: Cinqeucento Fuel Injector Warning Light
    ... The car was previously a good runner but a couple of days ... after we replaced the exhaust centre section the Injector Warning ... Lambda / Cat .... ... signal whatsoever on the Lambda sensor black wire. ...
    (uk.rec.cars.maintenance)
  • Re: Cinqeucento Fuel Injector Warning Light
    ... know with full MOT (car not seller) with advisory on a bandaged ... centre section of the exhaust (we knew about this before the guy ... signal whatsoever on the Lambda sensor black wire. ... When the Fuel Injector Warning Light isnt illuminated the Lambda ...
    (uk.rec.cars.maintenance)
  • Re: O/T Lambda sensors/EGR valves
    ... This is due to the wife's car now being on its third EGR valve at only ... Flow) sensor, it knows that exhaust gases are getting through (so ... and the Emissions warning lamp turned on). ...
    (uk.rec.models.engineering)