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2004 Breva 750-rough running sorted, now EFI light weirdness

Re: 2004 Breva 750 Running rough on constant throttle

Mmmm so I though I had this worked out.

With the O2 sensor plugged back in after running for a while (feels like 5~7 min) the red EFI light would illuminate. Restart bike and light would stay on for a little while, but then go out. Not really running for long enough to see if it would come back on.

That was pretty consistent behavior with time being the only variable, but then I ride home today and the EFI light didn't come on at all. Mysterious self repairing electrics :lol:

Of course since none of this makes any difference to how she runs the "fix" (assuming the red EFI light is going to come back on) is to plug the black box from the PC-III back in but it's an intriguing puzzle

(I also wonder what this Service Bulletin - faulty illumination of EFI light had to say)

p.s. since reverting the PC-III to the zero map not only does she now run smoother but the bluing on the headers is disappearing. LHS header now has a big chrome strip up the middle where it use to be blue.
 
Mal, I added the plug pic above... certainly running far too rich. The EFI light is likely due to the OEM sensor left in, unpowered, will cause the sensor to collect build up and read improperly.
The PCIII is a tuning tool, and more often then not, mis-used. Sounds like the wrong map was installed. The PC's really get a bad rap with most small block owners, as fuel usage goes way up because (like all the other newer Guzzis) fueling is set critically lean for emissions. Feel free to send me the PCIII map to have a look at direct e-mail; Todd at GuzziTech.com - certified PCIII & Tuning Link Tech, and Technical Advisor to Dynojet for all things Guzzi.

Hope that helps.
 
My gas mileage dropped a lot from 48 to just over 30 with the first mapping. They had the idle way too rich, had it remapped and now average between 40 to 45 mpg. I could smell raw gas when sitting at a stop light. I will give up 5 mpg for the much improved performance I get now. Running has been smooth now for 4 years. The only issue is sometimes the idle & air mixture needs to be reset but this has nothing to do with the PwrCmdr. With the slip-ons, BMC air filter, & PwrCmdr the bike pulls considerably stronger especially noticable in fifth gear. I looked at the plugs when the bike was stock and it was very lean, now they are a nice dark tan.
 
Thanks for the link NOLAGuzzi my O2 sensor looked like a coal candle :( I'm betting the catalytic is not doing much converting anymore :lol:

So I cleaned it off with a rag, There were literally 3mm chunks of carbon on it. I though it was the same diameter as the plughole. Could see a tiny hole in the end and eventually the fluted sides of the sensor.

Reinstalled and went for a ride. Seemed really smooth on 15km of hill but I tried idling back in top gear in the 60km zone and got the EFI light on again. But it did go out after a bit and the ride really did seem smoother this time on constant throttle. Perhaps working intermittently?

I took the O2 sensor out after the bike had cooled down and wiped a bit more carbon off it. Pulled the plugs too but they looked ok. Metal thread and side Electrode was still some slight carbon black but porcelain looks excellent, nice brown colour.

I've also sent the PC-III map off to Todd (thank you)

Fuel range is no too much of an issue on the 750. We always stop ~2 hours (ever hour works better on full day trips) and if she will do get 200km from a tank she will get between wherever we want to go.

Unlike my 1200Sport which I would really like to get 400km or at least 360km from a tank (which it can do often around 380km
) I like to go Townsville-Cairns without stopping for fuel when by myself and enough range for Charters Towers-Clermont would be nice. It's the same distance ~370km but that road can cause increased fuel consumption so I'll have to be a bit careful there. Would not be a nice place to run out.
 
The correct way to clean a lambda sensor is with a torch. Physical contact is not good as the sensor material is a little fragile. If you are using the lambda, and after cleaning with the torch it doesn't function correctly it may need replacement. Do you have VDSTS and if so are you getting any error codes?
 
The closest I've got to a torch is a lighter :( but I think I can get access to one. How do you clean it? Hold one end in pliers and heat it up a bit with a blue flame, till it looks clean? I'm hoping it's not till it glows red hot.

Haven't got the VDSTS yet. One day :) but I can stick a multi meter on the plug if someone can tell me what I need to check for.

The bike itself will be going in for a service soon (30,000km, change everything) but it's already $550 for the service, so I don't really want to be paying to try and diagnose intermittent faults. If I'm still having issues then I will just plug the PC-III black box back in.

Dare I ask how horrendously expensive is a new o2 sensor?
 
You just need a bottle torch like a plumber uses to solder pipe. Just heat with teh blue part of the flame until it looks clean. If you can hook a DVM to it while you are heating you should get voltage readings. If you do not, it is junk. There are four wires that go to the sensor. Two are the same color and are for the heating element. Connect your DVM to the other two. Doesn't matter if you read negative or positive voltage, so long as you see voltage changes as heat is applied and removed.

These articles may help http://auto.howstuffworks.com/question257.htm

and http://www.ehow.com/how_5916731_clean-s ... source=ask

I don't do the water dunk as the heat is usually enough.
 
Thanks I'll have a play with it on the weekend.
 
Warning! Be careful with your multimeter! The O2 sensor should put off a tiny voltage when heated, and you can set your multimeter for that, but DON'T test for resistance. The slight current the meter sends out for the resistance test will harm the sensor.

The voltage the Lambda sensor (O2 sensor) puts out is very low, and a standard multimeter may not pick it up. I heated mine with a torch and checked it with a better meter from the electrical shop at work. Interesting, but the voltages swing so much I couldn't get a single value.

The sensor may be shot anyway, as they have a limited shelf life and anytime they are in the hot temp of the exhaust they are "working" even if not connected. They are approx. $200, and because of the limited life don't bother buying one from a salvalge yard. Hope you can clean yours and get it working. Let us know.

Joe
 
Mal, I have one or two low-mile OEM 02-sensors I can part with if you need one for a fair price.
 
image-CB1F_4AC4C070.jpg

Here are the specs for the sensor from the breva manual.
I thought you needed to test the resistance for the heater?
 
NOLAGuzzi said:
image-CB1F_4AC4C070.jpg

Here are the specs for the sensor from the breva manual.
I thought you needed to test the resistance for the heater?
That is for the TPS.
You can measure for resistance across the heater leads, but be careful that you don't do it to the actual lambda leads as mentioned.
 
:oops: :lol:
No wonder I was confused about the resistance.

At some point I will put the crack pipe down.

Maybe.

This is the one i meant to post
 

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Thanks everyone. I've had to take a step back on this one for a bit.

I got the other half to take me down to the shop to pick up my 1200Sport on Friday. The EFI light went on while we were riding the 750 and I suspect it did the same when she was riding her home. She is a bit cranky at the moment anyhow with exams and stuff so I got told to "stop f*ing around with my bike and f*ing it up" and to go and play around with mine.

:( I think I sounded a bit too enthusiast with "But I can fix it with a blowtourch!" :lol:

So at the moment it is all riding on Todd coming up with a working PC-III map as I've had to reconnect the PC-III black box to remove the EFI light issues. (At least the bike is running well :) )

Thanks for the sensor offer too, but if we need to get one apparently she would rather just buy a new one. She would also prefer to just take her to shop and have them fix it. Girls! Where is the fun in doing that. The reason I wanted Guzzi's (apart from the great looks) is because they are easy to do mechanical stuff on.

p.s. Since she is a shift worker I'll eventually get a chance to have a go at the O2 sensor if she leaves the bike at home when she is at work. I'll just have to be able to get it all back together before she gets home :cool: but the continual EFI light issues make me lean towards the O2 sensor being stuffed.
 
Hi,
I am having a similar issue , with running rough, EFI light comming on at random times.
I initaly thought i had dirty fuel. Have since ran 2 tanks through with some injector cleaner
still having problems, with surging and rough idle. This bike has No power commander fitted
and has not been modifed in any way.It is my daily commute with only 14k on the clock,
Any clues to the outcome of the previous posts would be helpful.
thanks in advance
Marco
 
Marco, so you've got rough running and the EFI light coming on. A diagnostic machine should be able to see what's setting off the EFI light and also causing the roughness. The machines are available at a dealer and are called Navigtor or Axone, depending what year and version. Home mechanics can get something similar called as VDST (vehicle diagnostic scan tool), from a US company Technoresearch for $220. If you ask around you might find another Guzzi rider with one. At rallies there is usually someone with one set up too.

In 2008 there was also a Tech Note about the EFI light coming on inadvertently, but I think yours is coming on correctly, because of the rough running.

Let me know how this works out.
 
Mal said:
So at the moment it is all riding on Todd coming up with a working PC-III map as I've had to reconnect the PC-III black box to remove the EFI light issues. (At least the bike is running well)...
Mal, you can either have a map built on a dyno, or hopefully one day soon I can build one using an AutoTune module. Best bet is the former.

sign216 said:
Marco, so you've got rough running and the EFI light coming on. A diagnostic machine should be able to see what's setting off the EFI light and also causing the roughness... Home mechanics can get something similar called as VDST (vehicle diagnostic scan tool), from a US company Technoresearch for $220.
Or you can buy it right here, from me/GuzziTech; https://www.guzzitech.com/store/TR-VDSTS.html
sign216, did you just not know I sell it (I've been for almost 5 years now) or ?
 
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