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Breva Runs Lean

Pinking (pinging) is cylinder detonation at the wrong time - pre-ignition. Possible causes in order of liklihood, IMHO:

Vacuum balance badly out so that one cylinder is getting a much leaner mixture than the other.
TPS setting out of tolerence range so that the ECU is being told the wrong information in relation to the actual throttle opening.
Excessive throttle opening for the engine revs.
Partially blocked or crushed fuel tank vent line causing fuel starvation. (The right hand side one on the tank underside.)
Faulty or loose spark plug which is overheating.
Reversed HT leads from a coil to the inner and outer spark plugs.
A tight valve tappet allowing a valve to overheat.
Poor petrol quality or octane too low.
Faulty fuel injector.
Faulty air inlet temperature sensor in the airbox.
Faulty crankshaft position sensor.
Faulty exhaust oxygen sensor.
Excessive carbon buildup due to oil burning.

Axone and VDSTS can identify many of the above.

Graham
 
Mike.C wrote:
Rob - got some info for you - courtesy of Australian Internet Guzzi Owner's Register (AIGOR)

Brad Black is another go, he was a spanner man at Moto One, here is his web site:
http://www.bikeboy.org you can email him on bikeboy@bikeboy.org he should be able to help..
Click to expand...
Click to expand...


Great Mike,

thanks for your time and effort. I'm off to the WSBK at Phillip Island in a few hours, away for the Labour Day weekend next week, then I will be contacting him to see what he thinks. I'll let you know.

(I'll try to remember to take some snaps and post them - I usually get sidetracked and forget)

cheers


Robert
 
GrahamNZ wrote:
Pinking (pinging) is cylinder detonation at the wrong time - pre-ignition. Possible causes in order of liklihood, IMHO:

1. Vacuum balance badly out so that one cylinder is getting a much leaner mixture than the other.
2. TPS setting out of tolerence range so that the ECU is being told the wrong information in relation to the actual throttle opening.
3. Excessive throttle opening for the engine revs.
4. Partially blocked or crushed fuel tank vent line causing fuel starvation. (The right hand side one on the tank underside.)
5. Faulty or loose spark plug which is overheating.
6. Reversed HT leads from a coil to the inner and outer spark plugs.
7. A tight valve tappet allowing a valve to overheat.
8. Poor petrol quality or octane too low.
9. Faulty fuel injector.
10. Faulty air inlet temperature sensor in the airbox.
11. Faulty crankshaft position sensor.
12. Faulty exhaust oxygen sensor.
13. Excessive carbon buildup due to oil burning.

Axone and VDSTS can identify many of the above.

Graham
Click to expand...


FYI - my Breva has suffered from this from day 1.

I can personally verify it's not 1-5 or 7 on my bike.

Can't say about 9-12, but I'd think Jason Speaker would have sad something when he checked it out.

I COULD be 13, a I was surprised at how much carbon I could see today, but it's happened since new, so I'll rule that out for now.

Assuming 6 is unlikely for now, I'm zeroing in on 8 - poor fuel quality/octane.

And in my travels last year when I made it away from the greater Philadelphia PA/NJ/DE region, to parts of the US that don't necessarily mandate the used of E-10 Oxygenated fuels - the PROBLEM WENT AWAY.

So I'm gonna ASSume that it's EPA lean tuning combining with E10/oxygenated fuels in my case.

I'll also note that mileage went up significantly 5-10 mpg in areas where I was getting conventional fuel (non-E10).

Kev
 
Fuel quality may well be the problem, but a couple of times I've re-fuelled using our 91 octane and still no pinging was noticed.

It would be interesting to know if pinging bikes have the "sacred screw" still as factory-set.

Graham
 
Well, I went down to the WSBK at the island on Sunday (great day). Anyway, I filled up at the same servo, using the same premium fuel. No matter what I did, no pinging. I wrung it's bloody neck including some seriously fast overtaking manouvers (I won't mention speed since NO Guzzi rider breaks road rules.

It was the best ride I've had in months. The only thing that was different - 15C. The last longest period I remember (we're in drought here) it has been up around 30C.

So either the servo has a better batch of fuel, or because of the varied temperatures here, I need two fuel maps, one for hot, one for cold.

cheers

Robert
 
GrahamNZ wrote:
Kiwi Dave how would you rate the NZ 95 octane petrol?

Graham
Click to expand...

Shit, just saw this Graham, sorry for being so slow.

I can't tell the difference between 95 & 98 except in the pocket. Even when forced to use 91 I don't get any pinging (with normal riding), but try to avoid it.

If you're asking me the difference between Kiwi and US fuel, I do notice that I seem to get more mileage out of US fuel, despite their gallon being smaller than ours. :laugh: Probably, the real reason is that temperatures are hotter there (California) most of the year, and this makes a huge difference.
 
GrahamNZ wrote:
It would be interesting to know if pinging bikes have the "sacred screw" still as factory-set.

Graham
Click to expand...

I have no idea what the sacred screw is, but I have a lot of faith in Speaker's.... If it was something that needed to be touched, I'd guess he would have done that before delivery.
 
GrahamNZ wrote:
Fuel quality may well be the problem, but a couple of times I've re-fuelled using our 91 octane and still no pinging was noticed.

Graham
Click to expand...

Not here in NJ (east coast). Totally different, as you know.
 
Kev

From what I've seen the only way to know if the "sacred screw" is virginal is to check if the head of the stop screw on the left throttle body is still filled with thick yellow paint. It's a small in-hex screw and the head points to the rear of the bike.

Graham
 
GrahamNZ wrote:
Kev

From what I've seen the only way to know if the "sacred screw" is virginal is to check if the head of the stop screw on the left throttle body is still filled with thick yellow paint. It's a small in-hex screw and the head points to the rear of the bike.

Graham
Click to expand...


I'll take a peek and get back to ya.
 
GrahamNZ wrote:
Kev

From what I've seen the only way to know if the "sacred screw" is virginal is to check if the head of the stop screw on the left throttle body is still filled with thick yellow paint. It's a small in-hex screw and the head points to the rear of the bike.

Graham
Click to expand...


Still coated with yellow paint, so I should ASSume the "sacred screw" (I'd like to know WHAT the sacred screw is and what it does) is still virginal?
 
Kev
That's good news. A bit like learning that your blood pressure is normal. Now to see what else could be causing the problem.

To find out about the significance and importance of the "sacred screw" perhaps read my post here about Breva vacuum balancing and TPS re-setting. The problem is that many mechanics, including old-hand Guzzi ones, can't leave that screw alone because they don't understand its function. It is NOT there to set the idling speed as it used to be on some older Guzzis.

What I'd do now is have the dealer do a vacuum balance and TPS reset after reminding him not to touch that screw under any circumstances.

Graham
 
Kev M wrote:
GrahamNZ wrote:
Kev

From what I've seen the only way to know if the "sacred screw" is virginal is to check if the head of the stop screw on the left throttle body is still filled with thick yellow paint. It's a small in-hex screw and the head points to the rear of the bike.

Graham
Click to expand...


Still coated with yellow paint, so I should ASSume the "sacred screw" (I'd like to know WHAT the sacred screw is and what it does) is still virginal?
Click to expand...

Also see chart 99 of this file: https://www.guzzitech.com/MGGriso/Manual ... iceMan.pdf
 
GrahamNZ wrote:
What I'd do now is have the dealer do a vacuum balance and TPS reset after reminding him not to touch that screw under any circumstances.
Click to expand...

Already done right before winter set it. I was standing next to Jason when he did it, hooked up the balance tubes and it couldn't have been more in balance. He said the TPS was set at the factory settings so he reset and tweaked it slightly using the AXONE.
 
Kev
Good to have that aspect put to bed.

Apart from the items I and others have listed as possible pinging causes I wonder if anyone has had experience with checking the crankshaft position sensor?? If that is out or faulty it could lead to incorrect ignition timing and consequent pinging. Oh, for the simplicity of distributor points!

Graham
 
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