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Mercedes-Benz 560SEL mod 91,MB 560SEL mod 90
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Hello guys,

Could some one explain how does the Fuel Control Valve work? If I am going to adjust the Fuel and Air mixture, should I do the adjustment while power to the valve is disconnected? I mean, should the engine be running smoothly without the power to the valve then I connect it later. Another question, is this valve should work at acceleration only or not? Any ideas you submit are realy helful and thanks.
 

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560SEC, 190E, Frontier, 240Z
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I've messed with that valve extensively and have my fuel control system doing very well. I have a wideband O2 sensor installed so I know exactly what it is doing.

* Check your Idle Duty Cycle and set it to about 50%.
* Raise the RPM to 2500 and see what the Duty Cycle does.
* The Duty Cycle percentage needs to go down to the 20-30% range.
This indicates the EHA is over-richening a bit and the comupter is compensating just enough.
* If not, adjust the EHA (search that) right rich, left lean to get the desired result.

For me this results in ~12 air fuel ratio at full throttle.
A little richer than stock setup which works real good.

I've never had drivability problems too rich. But too lean don't go.

I have written a hideously exhaustive (and evidently annoying) thread elsewhere.

Ciao.
Tj
 
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