Miss at 6-8000 rpm - Ducati.ms

Hypermotard1 · Apr 27th, 2008, 9:39 pm

I need some suggestions here on getting this fixed at my dealer.

I have a miss at anywhere between 6-8000 rpm. If you accelerate gradually to redline, no miss. If you roll it on hard at 5000 and above it will break up and miss between 6-8000 rpms just like you were hitting the rev limiter.

Riding it yesterday and today I played around with it to see if I could make it do it and when. Again, smoothly slowly roll it on no miss. Open it up hard like in a passing situation the miss occurs, most often at 7000 rpms.

Spoke with Marty at Seattle Ducati (great people there! wish they were close) and he said to check the plugs, wires, battery terminals, coil and speed sensor to see if anything was loose. Everything is good there so I'm thinking it needs more fuel like it's starving on the top end under hard acceleration.

Any help or suggestions greatly appreciated.

dukepilot · Apr 27th, 2008, 10:11 pm

Is the bike stock, any mods? Did this suddenly occur or has it been a problem since you picked up the bike? More info is needed.

AXE · Apr 27th, 2008, 10:29 pm

It sounds to me like you may have something partially plugging a fuel line or an injector. When you gradually roll on it stays the same, but hard roll ons the particle becomes lodged or sucked into a position of blocking the fuel when demand is highest.

I have seen this in the dirt, but never on the street and this is my first FI rig, so I have no experience with trouble shooting that.

Out!

lelenb · Apr 28th, 2008, 12:13 am

Was anything changed before this happened? Does it seem like both cylinders are miss firing if it is possible to tell? Any popping or backfiring?

Hypermotard1 · Apr 28th, 2008, 12:12 pm

Quote:

Originally Posted by dukepilot

Is the bike stock, any mods? Did this suddenly occur or has it been a problem since you picked up the bike? More info is needed.

Mods: Full Termi and DP Cams. The bike started doing it in October but quite a while after putting on the Termi. Adding the cams may have made it happen a little more often.

Hypermotard1 · Apr 28th, 2008, 12:14 pm

Quote:

Originally Posted by lelenb

Was anything changed before this happened? Does it seem like both cylinders are miss firing if it is possible to tell? Any popping or backfiring?

No popping no back fire. It actually runs great except in this situation.

dukepilot · Apr 28th, 2008, 12:59 pm

Quote:

Originally Posted by Hypermotard1

Mods: Full Termi and DP Cams. The bike started doing it in October but quite a while after putting on the Termi. Adding the cams may have made it happen a little more often.

On my bike, the ECU that comes with the cam kit goes way rich at around 7000 rpm on a full throttle dyno pull. This is with the stock cams. Assuming that everything else is OK, (belt tension, valve clearances, TB synch and balance) you might want to dial in your fuel map using a PCIII or Rapidbike unit. Also put some Iridium spark plugs in your bike.

shat · Apr 29th, 2008, 5:37 am

Fuel pump. Just had similar with a 907i.e. Highest demand, can't keep up--engine stumbles.

Hypermotard1 · Apr 29th, 2008, 11:49 pm

Quote:

Originally Posted by shat

Fuel pump. Just had similar with a 907i.e. Highest demand, can't keep up--engine stumbles.

So you think it may be defective?

shat · Apr 30th, 2008, 1:37 pm

Process of elimination. What marginally fails at higher revs?

Spark? - too new a bike and usually that's associated with temp as in bad coils but not both at the same time.

Ignition timing? - no because if it were that, it would show up long before 4-6k.

Compression? - no, again too new.

Fuel? - Maybe, especially on a high pressure f/i system. If you can rig a test pressure gauge and observe psi fluxuations. You don't have to rev the crap out of it to duplicate the miss. If the pump is fluxuating, the proble will show at higher throttle settings.

Steve