SX dropped RPM in gear

[crestapre]

I'm running twin 1994 Ford 5.0s with Cobra SX drives. Things have been running great until Saturday on my return back to the dock. I was running her WOT for a 10-15 minutes and pulled into a harbor for a few minutes. After getting back underway we took a hit (bang) from a wave, so I slowed down. I then noticed that the port engine wouldn?t got over 2800 rpm in gear. In neutral I could rev up to 4200 as normal. Again in gear it really didn?t feel like there was any real torque behind her. The other engine/drive feels fine.

It did seem to gain RPM as I neared home running both at ~3000 rpm. The temp was ~160 but the SB riser did feel hotter than the Port. By the time I reached my dock (20 min at no wake) she seemed to be pulling harder with more RPM at the same temp. I tied her to the dock and reved in gear to 3000.

Any ideas of what was going on?

 

[QC]

Re: SX dropped RPM in gear

Did you try WOT in gear again? I can't really tell from above. Who knows what the "bang" coulda knocked loose, could be anything from a plug wire to linkage to something with the fuel supply. You really need to go through an entire low power check if in fact you can't reach WOT RPM.

Also, revving in neutral really doesn't mean anything . . . no load, you're only asking to over rev and float valves etc.

 

[crestapre]

Re: SX dropped RPM in gear

Yes, WOT was only getting to ~3000rpm and it felt like there was no power behind it.

I only did a quick blip in nuetral to see if the engine would rev over 3000.
It did run righ t up and sounded smooth with no hesitation.

Oh yeah, the engines are fuel injected if that make any difference.

 

[QC]

Re: SX dropped RPM in gear

Yeah the point on the revving thing is that you still haven't proven anything as under load requires 10 - 20 times more fuel, so it just doesn't tell you much. We see a lot of "it goes 4600 RPM on the trailer, I don't understand why it won't when I am underway" . . .

It's going to need proper troubleshooting though unless you get lucky and tune up type stuff fixes it . . .

 

[Bondo]

Re: SX dropped RPM in gear

Ayuh,..........

Change your Fuel Filters,+ Try it..........

In Gear,........ As noted by QC,..... Reving in Neutral means Absolutely Nothing.......