5.7 knocking and power loss

[Tunabass]

5.7 EFI began knocking and losing power today. right from clutch when I brought the RPMs up it would pop randomly and surge and loose power. It does not do it while in neutral and reved up. I finally got it up to 3200 RPMs and it ran fine. after running for 15 minutes I brought it down to clutch again and tried to bring the RPMs back up and it did the same thing. Takes 5-8 minutes of poping and surging to finally get on plane at 3200 RPMs, then it runs fine. The faster I try to accelerate (move the throttle) the more the poping and surging happens. If I gradually bring it up like really slow it does better but still would occasionally pop and surge. a guy at the ramp suggested cap and rotor as he had the same engine with very similar symptoms and he said that fixed his problem. I know its tough to diagnose the problem over the computer but i'm hopeful there are some ideas. Thank you.

 

[TunaFish389]

Check your timing, maybe something came loose, check if air filter is clogged.. Timing good than cap, rotor, wires and plugs wouldn't hurt. If problem persist than EFI pressure (pump/filter) would be my next suspect.

 

[alldodge]

What is the motor serial number?

The popping is your running lean in most cases.

 

[Rick Stephens]

Please be aware that if the popping is from running lean from dirty filter, failing fuel pump or whatever, that when you take 5 to 8 minutes of popping and surging to get up to speed you are likely doing major internal engine damage. The byproduct of running lean is detonation which causes higher pressures and more heat. It can literally eat your engine.

 

[Tunabass]

Replaced cap, rotor, plugs and wires. Also cleaned the flame arrestor. Just took it for a spin and as soon as it fired up it was evident it was fixed. Idled great and jumped on plane with no issues, popping or anything. The interior of the cap had corrosion on the points. Evidently enough to cause the issue. Just wanted to close the loop on this Incase it can help someone else.