detenation-gctid352480

[Guest]

at WOT i have developed major detenation. Ive replaced plugs, wires, reset timing, replaced coil, checked distributer. Starts well, when I leave dock and it warms up, I give it full throttle and I have no power and major detentation. what else is next to do. Im at a dead end.

Thanks

Chuck

[email protected]

My Bayliner is a 1985 Ciera Sunbridge, Volvo Penta 350, duo prop, with 650 hours.

[Woodsong]

Are you using E10 fuel?

[Guest]

Are you sure the mechanical advance is in fact working as designed?

[Guest]

It sounds like a timing issue. If you're OK at other RPM's and WOT is the only place this is occurring, I suspect timing. Does your engine have a knock sensor? A bad knock sensor can really put your timing off at high RPM's.

[smitty477]

Hello chuck,

"at WOT i have developed major detenation. Ive replaced plugs, wires, reset timing, replaced coil, checked distributer"

If you really have gone through all of the ignition well it could easily be a lean fuel condition at higher rpms.

Most commonly I have seen it come from plugged or water logged fuel filters or poor fuel.

Less commonly it could be a poor fuel pump ,carb. or fuel delivery system.

Perhaps consider when you changed filters last and if any water was discovered.

Perhpas pull a few plugs that are easy to get to and see what they look like as a result of this 'detonation'.

Hope this helps

[Chief_Alen]

You checked compression ?

All the plugs out on a warm motor, throttle fully down.

http://www.secondchancegarage.com/public/186.cfm

[2850Bounty]

Pau Hana wrote:
Are you sure the mechanical advance is in fact working as designed?

IMO, this would be one of the first places to look.

See your OEM specs, and then see if your ignition is delivering the correct spark lead (aka progressive advance) at the correct RPM.

.

[Guest]

Consider replacing the rotor, especially if you have pertronix or other "electronic" ignition conversion and have any evidence of arcing under the cap.