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VDSTS and lambda sensor questions

NOLAGuzzi

NOLAGuzzi

Cruisin' Guzzisti
Joined
Dec 5, 2008
Messages
102
Almost every day I ride (04 breva 750) I get a sporadic efi error light. Two separate axone equipped dealers have looked into it but they just clear the errors and say that ought to do it. Still the light will come on and then later go away. The common error message is open circuit to lambda sensor. When I plug in the VDSTS and select the lambda sensor parameters this is what I see at idle with a warmed up engine.
lambda2.jpg


or sometimes the lambda % will jump up to 24 like this if I fiddle with the wires on the sensor going into the crossover. (If anyone could shed some light on what the % lambda is measuring I would be most appreciative.)
lambda1.jpg

The voltage should not be 0 though? right? And is this the voltage across the sensor or the to the heater? There are two voltage measurements available in the VDSTS software lambda and lambda_1 and both will stay flat at zero at idle.
Is it safe to assume the sensor is faulty based on the computer diagnostics or would it be prudent to check the sensor with a meter? I know the repair manual outlines which pins to test and the expected proper voltage and resistance. Do these correspond with the lambda parameters in the software?

This error goes on every day and has been buggin me for about three years now. I could continue to ignore it but I would rather figure out what is going on.

Thanks in advance,
Mark
 
To answer your questions, voltage will be zero until the sensor warms up. The voltage the software reads is the voltage generated by the sensor. It is a heated sensor so it shouldn't take long. Voltage should be changing rapidly with the engine running. Also for the 15RC, the correct channel to be viewing to see the real throttle position is alfa_line_0. Don't know why that is so but that is what Marelli named the signal the ECU uses to read throttle position. I don't bother with % lambda, just make sure the voltage is changing.

Are you using the singe ECU version? I'm using the pro and have many more parameters displayed on the dash screen.

I'd check it with a meter, it sounds like broken wires to the sensor. If you need a new one, and you aren't under warranty, you can get one form these guys

http://www.automedicsupply.com/index.ph ... height=960

It is only $50.00 delivered if they haven't increased prices from last year.

Ask for Paul, I've worked with him in the past to obtain the correct sensor for the Guzzi.
 
john zibell wrote:
Voltage should be changing rapidly with the engine running.
Click to expand...
That is what I expected

Also for the 15RC, the correct channel to be viewing to see the real throttle position is alfa_line_0.
Click to expand...
Thanks, that is not something I was aware of.

Are you using the singe ECU version? I'm using the pro and have many more parameters displayed on the dash screen.
Click to expand...

Yes it is the single ECU package. I think i can put up to six different parameters on screen at any given time. I just put four on so that I could get a readable pic with my camera.

I'd check it with a meter, it sounds like broken wires to the sensor.
Click to expand...

Now when I test the sensor with a meter do i just pull the sensor to ecu plug and read the pins on the sensor side with the bike running? Sorry to ask what are probably very simple questions but I am still new to this stuff.

Thanks for the response!

Mark
 
John, thanks again for the tips.

I pulled the sensor out this morning and it looked like this. I've been running a bit rich I guess.
lambdadirty.jpg


The sensor was completely covered in layers of soot.:( I cleaned it up as best I could
lambda.jpg

And then stuck the sensor tip in a burner on a gas stove. Once it got hot the voltage began to change when measuring pins 1 and 2. However I also read the heater resistance on pins 3 and 4, at the prescribed 68 degrees F, and the meter just gave me a 1. It seems reasonable that the EFI error is due to the heater in the sensor. Something like every time the heater tries to come on it throws an error and once the exhaust temp gets high enough the sensor comes on and the light goes out? Maybe?? Any way I will check with the website you gave and see about getting a replacement.

Also the sensor I pulled out of the bike is a NTK OZA341-A1 but NTK lists a different sensor (OZA341-BB1) for the lil' breva I wonder which one is right.:blink:


Mark
 
I thought that I posted my result, but I guess not. So here it is in a thread revival.

I tried to get a lambda sensor from automedic supply but to no avail, the guzzi part is expensive (prohibitively so). However, a while back one of the Seattle area Guzzisti went elk hunting with his 1100 griso. Dude got hurt but thankfully by the looks of the pics the elk took the worst of it. Keeping in mind John's last post about the same sensor in the B750 and B1100 I took a look at the 1100 griso part # and it was the same as well. The elk assassinating griso wound up parted out on ebay and the lambda sensor found it's way into my breva.

As soon as I put the sensor in the efi light disappeared, the fuel economy improved a good bit, idle became more stable, and when I checked the plugs they were no longer covered in soot. When I plug in the VDST I see the sensor voltage change very rapidly. :woohoo:
 
NOLAGuzzi,

Thanks for reporting back.

"When I plug in the VDST I see the sensor voltage change very rapidly"

What was the max/minimum voltage you observed?
 
madhatter wrote:
NOLAGuzzi,

Thanks for reporting back.

"When I plug in the VDST I see the sensor voltage change very rapidly"

What was the max/minimum voltage you observed?
Click to expand...

I haven't a clue :( My bike is under the knife at the moment and I will be using the VDST to set everything when I get it back together. I'll look at those parameters and let you know.
 
I would like to know the same thing. Especially because I specifically asked them both to check it out more than once. Maybe they did it with the axone, or just cleared the errors, but I know they did not pull the sensor. It was covered in road crud just like the rest of the underside of the bike. Neither are particularly enthusiastic about guzzis and I have no plans to use either for future service or new bike purchases.
 
Brevabrabo wrote:
What I don't understand, is why the dealers didn't pull out the sensor and gave it a look? But I'm happy for you that the problem is solved.
Click to expand...

They were sellers, not dealers is my suspicion.....
 
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