I have an idea (DANGER)

[Texas Diesel]

If the O2 sensor has a range of 0-1 VDC and 14. 7:1 is 0. 5VDC. 0. 6VDC is what then? Lean or rich? Anyone know or have a website on O2 sensor operation?



The idea I am after is to manipulate the O2 sensor reading to make the ECM think the engine is running LEAN, thereby in reality, making it run slightly richer.



Case in point is my BMW R-1100R, to be CARB compliant it is engineered to run so lean that it actually (at steady throttle) surges or hunts. That problem is fixed by adding a Techlusion fueling box that plugs in between the injectors and ECM. This fueling box adds width (or time) to the injection signal thereby causing the engine to run slightly richer. This legal off road only :-laf



The Techlusion detects 3 modes, idle, steady state, and WOT which correspond nicely to pilot, intermediate and main jets. You have to disconnect the O2 sensor and force the ECM to run open loop.



I think that fooling the ECM by manipulating the O2 sensor reading would accomplish the same thing but allow the ECM to run closed loop which would take into account intake air temp, engine temp, altitude etc. Things that are not utilized in open loop operation.



If we can figure a way to manipulate the O2 sensor then any changes wouldnt be detectable by the ECM and (should) be easily reversable for emissions check.



If you swallow the current EPA/green-peas/john denver/tree hugger/wacko nonsense then PLEASE dont read this thread.



My goal is to make my machines run CORRECTLY and I dont give a knats hiney about being EPA compliant.

 

[dslmacdown]

Higher O2 sensor voltage means a richer mix.

 

[WDixon27]

check this out even if you don't want to go this far it's a good read, i am thinking about building a mega squirt for my 325is bmw if i ever get time to build the evil motor i've been planning



http://www.msefi.com/viewtopic.php?t=6844

 

[Texas Diesel]

That is really cool!! Definately worth looking into but I want to try my idea out first.



It seems all we have to do is manipulate the O2 sensor voltage a slight amount to make the EFI think the engine is running lean. Then the EFI will increase the injector PW to richen it out.



According to the above post, greater voltage = richer then could something as simple as a resistor (think voltage drop) inline move the O2 output lower (leaner) and make the EFI richen the mixture to bring the O2 voltage back to target?



Perhaps a forward biased doide to give ~. 2 volts drop?



This is worth pursuing. I like the idea of being able to tune on the fly with the MegaSquirt though.



Thanks!

 

[KBennett]

You are going to see more than . 2 across a diode, probably more like . 5 . Do you have a way to put a current meter in series with the O2 sensor? while the engine is running?



You could calulate the resistor based on the known voltage and current.

 

[Texas Diesel]

I was thinking that a Shottkey (SP?) diode had a very small froward voltage drop.



Yes I have a Fluke 87 and once I figure out which lead is the signal lead I can make some measurements. It has 3 wires and I need to determine which is which so I dont cut all three. Lets see, ground, signal and ????

 

[WDixon27]

if it's two white and one black wire it's the black wire and ground to the exhaust/sensor body



ps the two whites would be the heater

 

[Texas Diesel]

I'll go out and look tomorow, thanks.

 

[BigGunZ]

There's a cool little gadget available for OBD II compliant vehicles that have been cammed. It's called an 02 Simulator. It plugs into the O2 sensor harness and tricks the ECM into thinking that the sensor is hooked up and working properly.

 

[nickleinonen]

There's a cool little gadget available for OBD II compliant vehicles that have been cammed. It's called an 02 Simulator. It plugs into the O2 sensor harness and tricks the ECM into thinking that the sensor is hooked up and working properly.

those are mostly for feedback o2 sensors in a post cat o2 sensor for monitoring if the cat is in place and functioning. if you were to fool the pre cat one, your A/F would be all over the place and could damage your engine [if using one of those simulators]

 

[WDixon27]

ditto, probably run like crap too

those are mostly for feedback o2 sensors in a post cat o2 sensor for monitoring if the cat is in place and functioning. if you were to fool the pre cat one, your A/F would be all over the place and could damage your engine [if using one of those simulators]

 

[Texas Diesel]

Not so, they always run better with no CAT.



The Dodge has 2 O2 sensors, one before the CAT and one after the CAT. The one before the CAT tells the ECM the O2 level, the one after the CAT measures O2 efficiency ONLY. So adding the O2 emulation device in place of the second O2 sensor, simply allows you to remove the CAT and not set a CEL.



The BMW in question has one O2 sensor. I am trying to figure a way to make it run a little (LITTLE) bit richer. Currently I run it with no O2 sensor (open loop) and use a fueling box to richen it up. The fueling box is not as precise as closed loop operation and I know my emissions are up. If I can successfully find a way to manipulate the return O2 sensor voltage enough to cause the EMC (Motronic) to richen the mixture a bit, then I can set the HC level to Canadian standards instead of CARB (Kalifornia) levels. Which is where the lean burn problem comes from.



How many of you would buy a Kalifornia EPA equipped Cummins? You only lose MPG and 15 HP :-laf



No takers? Didnt think so, so understand where I am coming from.

 

[WDixon27]

you may play with the resistance of the temp sensor a little, 500-1000 ohms one way or the other may yield a good result

". So adding the O2 emulation device in place of the second O2 sensor, simply allows you to remove the CAT and not set a CEL. "

it sounded to me like it was suggested to use the emulator inplace of the single 02, that would be bad

 

[Texas Diesel]

Temp sensor? Engine temp? Try to fool the ECM into a richer mode by increasing the resistance of the temp sender?



Any expereince with this approach?



I suggested that years ago for the 24V engine temp sender (not IAT). Was going to see if fooling the ECM into more injection advance but never tried it.



Ever notice the extra loud rattle when the beast is cold?

 

[BigGunZ]

Couldn't you accomplish the same thing by playing with the MAF signal?