Backfire fix

[micha]

Hey gents thanks for all the posts. I hope this thread benefits the Guzzi community as a whole. The truth is when arguments arise we roll up the sleeves and go to work. :lol:
Foxter, your info will come in quite handy. I have found a patent pending on the 02 cheat, looks just like that.
I have been busy and haven't had time to collect any new data that would be of interest here. However my friend and coworker Jason did try a 2.2k Ohm diode fix on a Vintage and it appears to be of benefit. Me being a fan of quantitative measurements rather than of qualitative "works" or "doesn't" I will have to measure effects and share them here. 1.5M is a different beast altogether, simpler and I am not sure if at all it has adaptive capabilities. The only Guzzi 15m here in US with the closed loop circuit is the Vintage and I know it doesn't have adaptive error capabilities.
To make things even more interesting I was thinking of what actually shuts off the closed loop circuit on a 1200 Sport? Probably a TPS position or maybe a relationship of TPS and RPMs? Well, we could tell the ECU to shut off closed loop at 500RPMs for example thus effectively neutering the 02 sensor function. So I asked a friend of mine who writes code if he thinks this would be possible to which he replied "I wrote that code". :mrgreen:
He said to call him next time Iget my hands onto one of those and he'll bring his equipment. We'll see about that.

 

[Penis Rotor]

I used one for a while. whether it really made any difference is a moot point. I think it did have a minor effect on my 8VG but it also had the side effect of throwing up the 'Service' icon. When this occured, on some occasions I could feel a 'Change' in the engines' behavior, perhaps it was reverting to some sort of 'Default' mapping? I have no idea.

What I do know is that as soon as I'd loaded up the #68 map and stopped trying to run an open pipe the FD became instantly and absolutely redundant. I think its still in my toolbox somewhere? Free to anyone who wants it for postage!!!!

Pete

 

[davem]

A little light reading relating to Buells but maybe of interest to those looking for a greater understanding of tuning.

http://www.ecmspy.com/tgv2/guide2.shtml

 

[davem]

This is a Breva 1200 (not sport) with a Fatduc, GPR exhaust and Sprint competion filter.
The blue line (best figures) is with the Fatduc on richest setting.
The green line is with the Fatduc about halfway.
The red line is with the Fatduc removed.
At no time was the back firing eliminated, but was at it’s least on the green line.
The richest setting gave a fault light when ridden on the road this was eliminated by backing off
the richnesss slightly.
The lean fuelling graph is a mystery to me because the bike runs well and averages about 40mpg.
The plugs look a bit pale (they have from new) but do not give the appearance of running super lean.
Dave

 

[PP-1753]

So Dave, what would you recommend?

 

[Mi_ka]

So Fatduc plays some role even on full throttle/open loop ?
As for the lean readings, is this GPR silencer decatted or not? Could there be a pre-cat in the collector can? (I suppose the lambda sensor was set up right on the dyno so it could not suck any free air).

 

[davem]

The GPR exhaust comes with two baffles front and rear, these were fitted. I don't think they come with a cat fitted.
I don't know how the lamba was set on the dyno all I saw was a funnel tightly fitted over the silencer end and a take off from the spark plug lead.
Just to be on the safe side on the lean running issue I have re-fitted the standard air filter.

The Fatduc does appear to make a difference. I would recommned that if you are going to play around with fuelling
at least allow for dyno runs on top of the cost of the mods and then publish the evidence.
On the backfiring issue itself I haven't solved it on my bike for the modest outlay I've incurred (the Fatduc came off ebay) and have probably resigned myself to a comprise of good power and a manageable amount of backfiring without breaking the bank.

I would be interested to see a standard bike power/fuelling graph to use as a bench mark.

 

[PP-1753]

For the record, I removed the FatDuc yesterday and noticed two things:
- Backfiring is worse;
- Fuel consumption improved;

Both of these indicate that the FatDuc is indeed adding to the picture over all rev ranges. In January last year I did get the updated ECU map and the Fat Duc was already fitted. The new map made a huge difference so that I thought I was on a different bike.

On a ride recently, another Guzzi rider commented on the surging at low revs. I will try and pay attention to that point on future rides - as long as it doesn't affect the fun factor.

For now back to standard trim sans the airbox snorkel. I did buy another muffler yesterday but it required some pipework before fitting. I will report with photos when done.

 

[sign216]

As suggested by an earlier writer, I made an O2 sensor signal modifier(DIY Fatduc) by using a schottky diode. The diode is better than a resistor, although the variable resistor of the Fatduc is easier to adjust. I merely inserted the diode in the connection from the O2 sensor to the ECU.

This is on an 09 V7 Classic. It had no backfire problems, and ran well beforehand. The diode made it run much better when cold, both off the line and when idling. I couldn't tell any difference when running at speed. This spring I'll dyno the bike and check it out.

Joe

 

[GTM®]

Dave, assuming that the lower part of your graph is the AFR ratio? :blink:

Folks, for $125 I offer a proven 02-sensor offset "fooler." Contact me direct. When you are ready to make it run fantastically, contact me direct as well. I am now offering a PC-V for all new CARC & Cal Vin/V7C's for $399.95. Again, contact me direct. On the newer bikes with 02-sensors, only my full kit will resolve pop-on-decel, as well as resolve pre-detonation ("pinging"), along with some of the best throttle response you'll ever experience.