griso o2 sensor get around

[duc]

HI all bear with me I am new to forums.For anyone wanting a quick fix that works gets around jerky throttle pop due to lean condition and more power in mid range actually pulls smooth from about 2500 to red line in either 5th or 6th gear.There are 4 wires on the o2 sensor black and grey are signal 2 whites are heater.Get a 330 ohm resistor from radio shack I used 1/2 watt install in line on grey wire before connector then try it out. If throttle bodies are synced tps set correctly and stepper by passed this should work great and not set any codes for service.It woeks even better if you loop the two wires with the risistor but will set code I am speaking from thoroughly experimenting with this set up hope this may be helpful!!!!!!!!!!!!!!!!

 

[sign216]

Sounds similar to the Fat Duc 02 Manipulator, which I think uses a Rheostat (variable resistor). Something I've been curious about. Another one on this theme is the Hyperboost 02 module, which is probably a diode with fancy packaging.

http://www.engineperformancechip.com/performance-chips-c-1/oxygen-performance-module-p-7.


I'm eager to learn more. Where did you pick up the value of 330 ohms?

Joe

 

[duc]

there are several threads on line under differnt headings about o2 eliminators made by companies such as dynateck for jap bikes using 330ohm resistors and I figured if it worked on them it was worth a try.One fellow has a post of how to make your own o2 sensor eliminator wish i could take the credit but I only expanded on his idea.the sam question was posed to him not a quote but close he said someone just measured a commercially available one.

 

[double.d]

duc wrote:
I used 1/2 watt install in line on grey wire before connector then try it out.[/quote]

Hi Duc, can you elaborate a bit more on this sentence, i don't understand what you mean

 

[duc]

I am not much at electronics but thought a 1/2 watt resistor might hold up better than 1/4 watt which were my only two choices at the local radio shack.As I said before I am new at forums and may not explain myself well. there are 4 wires from the o2 sensor black and grey for signal you should install the resistor in-line on the grey wire coming from the sensor to the connector.hope this helps clarify things.

 

[sign216]

There are 4 wires on the o2 sensor black and grey are signal 2 whites are heater.....
I used 1/2 watt install in line on grey wire

Duc, I'm glad to hear this topic brought up, as I have been thinking about it myself. How did you figure which wires were the signal wires, and that the grey wire was the appropriate one for the resistor?

I did a net search regarding the value of 330 ohms, but most of the sites brought up were for "02 sensor eliminators" and not 02 sensor signal modification, which is what we are trying to do. We just want to dampen (reduce) the signal voltage from the 02 sensor so that the engine will run slightly richer. Not eliminate the 02 sensor signal altogether. Too large a value will make the engine too rich, and generally make everything worse.

02 sensor signal voltage should run from 0.1 to 1.1 volts. The other part of the electrical equation is current, measured in amps. Any ideas on how many amps the sensor signal is? Any sites that might shed some light on this?

Joe

 

[duc]

Joe,if you go to the griso service manual look under electrical checks for o2 sensor it tells you to check voltage between pins 1 and 2.
If you look closely at your pin connector on your bike you will see it is numbered one through four.It will also tell you to check heater
ohms between pins 3 and 4.
No idea about amps sori.hope this helps.Manual can be found on guzzi tech web sight.

 

[Spaceclam]

Guys,

The problem with this fixed resistor stuff is this. The bike is super lean in the mid range, and super rich on the top already.

This is evident when you take a long ride on the freeway at high rpms. You will notice your bike will idle low until the engine heats up again once you get off, unless the weather is kinda warm. Also, the bike doesnt ping above 5k, because the mixture richens up.

So you can offset the sensor with a fixed value, and while it will help the midrange a bit, you will be blowing fuel out the back end when you are idling and when you are on the freeway and stuff. You will probably LOOSE horsepower.

Also, any commercially available plug and play unit that actually does what i describe below (perhaps that engine performance chip link, i cant tell) will keep your air fuel ratio at optimum. THIS IS REALLY BAD FOR AIR COOLED ENGINES. Aircooled engines need to run richer

I had an idea a while back to create an "equalizer" which would essentially be a varied offset based upon engine speed. It wouldnt be perfect, as it would not be taking into account the throttle body angle, but the concept went something like this.

Every time the engine fires, it creates a pulse in the o2 sensor voltage. since we have v twins, if you were to plot the voltage pulse off the o2 sensor on a graph, you would see two very distinct pulses, out of phase with eachother by 180 degrees on a 720 degree cycle. The unit would essentially amplify or deminish the signal strengh, based upon the frequency of the pulses (RPM). This should not throw up an ECU flag, because it is not altering the pattern of pulses, and it would respond to any mixture changes the ECU makes, which apparently it does constantly to monitor the system.

I did not recieve the support necessary to develop such a thing, and to be honest, Todd's solution is better anyway. Such a unit would be a good improvement certainly, but a custom map including RPM vs TPS data, as well as revised timing is by far better.

 

[duc]

Look, you bring up valid points. But the o2 sensor is only used below 4000rpms so you aren't affecting top end anyway. The bike is too lean at idle as-is so richening the idle circuit is desirable. My bike is not loading the plugs at idle or giving any other sign of being too rich at idle. Just try it. Check your plugs for yourself. You will see the bike all around runs better.These fuel changes are very minor in total scheme.

 

[Spaceclam]

the super lean spot is between 4.2 and 5.2, which is open loop. In between this range, the engine looses almost 5 foot lbs of torque, and the HP curve goes almost flat.

Im sure it runs better, but unless there were no other options on the horizon, i would save my money.

I understand that a variable offset will not correct this problem either. However, it would certainly make the most out of the closed loop portion.

 

[duc]

well everyone I had not mentioned the cost of what I felt would help any one not wanting surging poor throttle response and the pop that really annoys me but I guess the 1.00 for the resistor could be a strain and the 30 minutes to install could be too time consuming.As Forrest Gump would say thats all I have to say about that.

 

[Spaceclam]

I guess if you have problems with surging and poor throttle response, it's well worth it.

 

[cheese]

I tried this resistor fix on my Norge over the weekend, I installed the resistor in line on the grey wire, with a SPST switch accross the resistor so I can jump it back to stock instantaniously, and with stepper circuit plugged at the air box connection. Here are my observations :
Tried 220, 330, and 500ohms. 330 worked best. smoothed things out in low rpm situations like just puttin' through town in a relatively high gear at 2200-2500 rpm. Also feels much smoother in my normal cruise range of 3-4000rpm. Gas mileage has dropped somewhat, from about 55 to 45 when in this cruise range. Idle feels much improved. Motor does not appear to respond immediately to the increased resistance, but seems to take 30 or 40 miles. Adaptation table perhaps? Don't know. Otherwise, in higher rpm range performance seems unchanged, which in my case is good. Have run this way for 500 miles with no Ill effects that I can tell. Don't own a CO meter to check mixture. Cost $3 for assorted resistors, $3 for the switch, an hour to install.

 

[sign216]

Cheese, it's good to have someone like you, who has "walked the walk" and even done it with a variety of resistors.

Thanks for posting.

Joe