engine lies down at 4000rpm

[TeamSvenske]

Hey pals! I've seen similar posts, but perhaps a fresh set of eyes can help me out?
My '05 4.0sohc starts and runs perfectly until.....I go down the road under acceleration and at or near 4000rpm the engine will lose power(lie down) and SES will flash. If I continue down the road at reduced speed it will regain power and run fine until I once again step on the pedal and put it under a load. 3500-4000rpm it will do it again, and again regain power. Compression is good, plugs, wires, coils--all good.
No codes or pending codes whatsoever. No vacuum leaks. My reputable mechanic is bewildered as am I. IDEAS???

 

[Mbrooks420]

The CEL flashing means you are having a misfire condition, if it's the same as the second gens. How do you know the wires, plugs, and cools are good? Have they all been recently replaced?

 

[CarlosHRNYC]

Just a hunch but maybe it has something to do with the fuel system? the pump or filter? something's restricting the engine at high RPMs. Did your mechanic check the fuel pressure?

 

[swshawaii]

Interesting. 4k rev limiter on 2004 and newer with throttle-by-wire?
SOHC Won't rev above 4k | Ford Explorer and Ford Ranger Forums - Serious Explorations

 

[Mbrooks420]

I really don't think there is a 4K limiter.

 

[TeamSvenske]

Thanks guys. Fuel pump replaced. Fuel filter new. Plugs, wires are new. Coils checked out good. Also, I'm not saying there is a rev limit, just that once I accelerate and get to about 4000rpm then the engine seems to go into a "safe" mode and stay at about 2000rpm. SES will blink. I can drive a mile or so and SES stops blinking but stays on and car will regain power. Once I accelerate and hit that range it will do it again.
Yes, it is extremely odd. Some say it may be the cats but there are no codes. Some say perhaps trans sensors or computer rerlated.

 

[swshawaii]

Fail safe mode? Hope not.
https://cse.google.com/cse?cx=partn...99/#gsc.tab=0&gsc.q=fail safe mode&gsc.page=1

 

[TeamSvenske]

I don't believe it is the actual "fail safe" mode because it will regain power and run fine until I go into that power band again.