Popping on deceleration is BACK!!!

[FastGoose]

Once again, I must ask advice on what's causing popping on deceleration on my '08 Vintage. I went through the process of removing and sending my ECU to Todd for a re-flash. While it does run smoother, and all was well for a while, the popping has gradually begun bearing its ugly head again. I had my mechanic give it the once over; all seals tight, no air leaks, intake/mufflers cinched tight, etc. He did some slight adjusting of the throttle body plates but suggested that due to EPA regs, the plates are designed (restricted) to not close as they do with stock Euro specs. Adjusting screws are painted in an effort to discourage tampering.  If this is indeed the case, how does one go about bringing it to Euro spec to stop the shotgun-like blasts I'm getting on decel on an intermittent basis? (I'm not afraid of some paint on a screw if ya get my drift)

[rbm]

You're not specific on which model of Guzzi; that might have bearing on soliciting any advice.  Popping on decel could be leaks most anywhere in the exhaust system upstream of the muffler.  You've stated the mechanic declared the seals are tight; by this I presume you mean the exhaust manifold seals.  It is possible that any connection at the crossover or at an interface to the muffler could be leaking and causing the popping.  The reflash from Todd should clear up lean fueling that might contribute to the problem.  Recheck the clamps on the exhaust to make sure they are secure. 

[CalVin2007]

 If this is your CalVin, there's no reason in the world it should pop with Todds reflash and a proper set-up of the throttle bodies. I have the same bike with the same flash and it won't pop even if you wanted it to...something is amiss. Usually it's an air leak at an intake port connection, an air leak at the exhaust header somewhere, an unplugged vacuum hose, or a wrongly set TPS/air screw/ throttle plate setting. By the way there's no secret Euro-spec plate setting as far as I know. I just follow the common TB setting/balancing procedure after adjusting the valves,then finish up with the TPS setting and idle speed. Hope you can find the culprit...the Vintage can be a sweetie.

 Terry

[FastGoose]

Thanks, Robert. I should have mentioned it is a '08 Vintage with under 4K on it. I do believe he checked all exhaust connections, but I'll give them another look-see tonight. I have a phobia about breaking off an exhaust flange nut thought, as I did that on my Bassa and had to drill it out.

[FastGoose]

CalVin2007, could it have anything to do with the pressure I get in my tank? I'm not sure if it's normal, but in warm weather or after riding for an hour or so, even if it's been sitting for a while, if I open the tank I get a very strong "whoosh" from the filler opening.

[CalVin2007]

CalVin07, could it have anything to do with the pressure I get in my tank? I'm not sure if it's normal, but in warm weather or after riding for an hour or so, even if it's been sitting for a while, if I open the tank I get a very strong "whoosh" from the filler opening.

   I don't think so, but I have mine vented directly from the tank nipple down a hose tied to the frame down-tube. The charcoal can is missing, as is the one-way check valve in the original hose by the steering neck. The two hose nipples on the intake manifolds are now connected with a piece of vacuum hose. It sure won't hurt to try venting the tank directly.

  Terry

[fotoguzzi]

There is nothing sacred about that yellow paint the factory slathered all over the adjustment screws. If still full of paint you probably need a throttle body sync.
And the tank suck is something else to get fixed but not likely your reason for popping.

[jbell]

The real problem is pooping on hard braking.  Unfortunately, there is no known fix at this time.   

[Wayne Orwig]

What exhaust and/or intake mods have you made?

He did some slight adjusting of the throttle body plates but suggested that due to EPA regs, the plates are designed (restricted) to not close as they do with stock Euro specs.

Nonsense. Find somebody that doesn't whine and blame the EPA when they can't figure it out.

[oldbike54]

What exhaust and/or intake mods have you made?


Nonsense. Find somebody that does whine and blame the EPA when they can't figure it out.

 I believe you meant to write DOESN'T Wayne , but yes , blaming the EPA shows a lack of knowledge .

  Dusty

[Cam3512]

Yea, what mods are you running. I has Mistrals with open airbox and H-pipe.  Total shock and awe on decell, especially on a hot day. Going back to stock pipes cured it.