Engine Issues at WOT, Ellison TBI

[rv8ch]

Originally Posted by Hawg Driver

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Always open to other ideas out there…

Sounds like you've eliminated ignition, which leaves fuel and air.

How do the plugs look? Oily or dry and grey? Might give a hint if it's getting too rich or too lean.

Have you tested with no air filter?

You might also try a fuel flow test to see how many GPH your electric fuel pump can push out. You might also see if there are some bubbles in there, supporting the theory that there's air getting sucked in.

I'd also check the fuel tank vent lines for mud daubers.

[rjcthree]

What do your EGTs do as you advance the throttle? Do they head over 1400F or head south? I think that’s the easiest way to tell what side of the mixture curve you’re on.

I’m over fueled as a result of tweaking the spray bar when I had an advanced timing problem in the dual mag I was sure I didn’t have. As a result, RC can get to 200F ROP at WOT at -500 ft DA. I’m always leaning for DA. I live on EGT as my primary input most days.

[Hawg Driver]

Originally Posted by rjcthree

What do your EGTs do as you advance the throttle? Do they head over 1400F or head south? I think that’s the easiest way to tell what side of the mixture curve you’re on.

I’m over fueled as a result of tweaking the spray bar when I had an advanced timing problem in the dual mag I was sure I didn’t have. As a result, RC can get to 200F ROP at WOT at -500 ft DA. I’m always leaning for DA. I live on EGT as my primary input most days.

Sorry I didn’t reply sooner, but I did do a deeper dive into the EGTs after rebuilding the TBI to the best of my abilities. Too rich a mixture may be part of the problem, but it’s not the only issue. Even after leaning to max RPM, then just a little rich of that, I’m seeing +-100 RPM at WOT…so there is still something wrong. I’ve spent more time on this TBI than I should have - time to move on to a new solution.