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bpu699 bpu699 is offline
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Join Date: Apr 2007
Location: wisconsin
Posts: 2,539
Originally Posted by JFairman View Post
The lambda pulse valve/inline injector returns fuel from the fuel heads lower differential pressure chambers to the fuel tank.

By returning variable amounts of fuel pressure from the lower differential chambers to the tank through the fuel return line the resulting small changes in fuel pressure in the lower chambers then has a subtle control pressure effect that raises or lowers the position of the fuel metering diaphram that is sandwiched in between the upper and lower chambers in the fuel head.

The diaphram is real close almost touching the bottom of the 6 seperate metering orifices that lead straight up to the injector banjo fittings. How close it is to those orifices is the final fuel metering valve in the fuel head. If someone like CIS Flowtech enlarges the inside diameter of those orifices by machining them a little bigger the fuel head will be able to flow more fuel when it is adjusted correctly.
The pulsing lambda valve gets removed when doing that and it's lower chamber female threaded fitting gets a plug and the return line short length banjo bolt that was in that fitting replaces the longer return line banjo bolt the control pressure regulator and lambda frequency valve banjo fittings were using together.

The lambda O2 sensor is a narrow band sensor. It reads and creates a micro voltage output in a very narrow range so it can keep AFR real close to 14.7:1 which was OK when gasoline had no ethanol mixed into it but that lambda AFR tune is a little too lean when accelerating using todays oxygenated ethanol blend gas and usually causes some mild surging you can feel during light throttle slow acceleration.

AFR gauges use a wideband O2 sensor that operates over a wide range. EFI designed and tuned for performance over fuel economy and emissions use them too.

There is oxygen in the ethanol molecule and it's 10% presence in E10 gas leans out the AFR a small amount.
Wow. Very helpful. Thank you.

So in this mechanism, why would connecting the o2 sensor make the afr richer? Shouldn't the o2 sensor read an already rich condition, tell the frequency valve on the metering plate to correct, and make the afr leaner?

If I check the voltage coming off the o2 sensor, and its correct, whats the next thing upstream to check as to why the system isn't correcting? Would it be the computer under the seat? If so, are their particular PIN volatges to check? Is there a voltage at the valve that can be checked?

As always, thanks!

Last edited by bpu699; 11-04-2014 at 06:18 AM..
Old 11-04-2014, 05:45 AM
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