albertz
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| posted on 21/5/09 at 08:35 PM |
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Lambda Sensor query
I have been having trouble getting my engine to run right. The engine is a new 2.0 Zetec (blacktop) with Griffin inlet manifold and Omex 600 ECU. The
engine is running very rich and is misfiring slightly. I have pulled the plugs and they are very sooty and black.
Having spoken to Griffin today i was advised that the engine was probably drawing air somewhere, probably into the exhaust at the manifold which is
giving a wrong signal to the lambda sensor to increase the fuel to compensate for unburnt oxygen.
However, when i pulled the plug of the sensor there was no notable difference to the running of the engine in terms of sound or clearing the misfire.
I had expected that disconnecting the sensor should have made some difference whether better or worse, i expected to notice instantly. Is that the
case normally? Would disconnecting the lambda make a noticable difference?
Also, Griffin suggested as a last resort to decrease the microsec/bit (mspb) rate by 3-4 points to weaken the fuel mixture right across the rev range.
Does that sound reasonable?
Between the engine running rich and misfiring plus my problems with the cooling system i am getting really frustrated with it at the moment!
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Jasongray5
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| posted on 21/5/09 at 09:59 PM |
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If you pulled the sensor out and there was no difference in the engine running, then it would suggest that there is too much oxygen in your exhaust.
So air leak it does sound like to me?
How hard can it be?
http://www.flickr.com/photos/33261515@N03/sets/72157611049241239/
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MikeRJ
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| posted on 22/5/09 at 07:23 AM |
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Maybe you have a problem with the coolant temperature sensor? If it's telling the ECU the engine is cold all the time then the engine would run
rich and the lambda sensor would never be used.
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norm007
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| posted on 22/5/09 at 07:30 AM |
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I had a problem with my coolant sensor telling ECU it was cold which in turn richens the mixture.
New Omex sensor @ £20.00 did the trick.
Mine was also a Zetec engine, with single throttle body/Omex ECU setup, similar to Griffin
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mr henderson
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| posted on 22/5/09 at 07:54 AM |
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Drawing air INTO an exhaust system 
Seems a little unlikely to me
John
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cd.thomson
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| posted on 22/5/09 at 08:04 AM |
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quote:
Originally posted by mr henderson
Drawing air INTO an exhaust system
Seems a little unlikely to me
John
I think it could be possible if there was a gap in the manifold somewhere, i.e. in one or more of the headers. Air could get pulled through as the
exhaust gases create a vacuum near the head after the exhaust valves close?
Craig
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albertz
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| posted on 22/5/09 at 10:18 AM |
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The guy at Griffin told me that it is all too easy to draw air into the system, because my reaction was the same as yours, surely the air out would be
more likely, but apparently every pulse causes a small vacuum which is enough to throw the lambda sensor all wrong.
Good suggestion regarding the coolant sensor though, i will look into that. Isit possible to easily check the existing sensor or just replace it?
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