Loss of power in topend, how to fix....?

[BlackFox5.0]

When I get on it, right around 5200 or so RPMs and above I have no power whatsoever, the car just stops pulling and the engine just makes a lot of noise (normal revving sound, only with no power to go along with it)

I have no idea why it's doing this, what could be causing this?

My father had changed the timing without me knowing so I have no idea what it's at, I think he might of said 12*, what should I change it back to? I had it at 14* before. Could this be part of the problem? I was thinking maybe fuel starvation....

 

[tvmango]

where you out tonight? Maybe just the cold weather,, cars run richer in cold weather, or a taste of crappy gas..alot of that going on in NH.alot of water in the gas.I dought 2 degees would do that but I'm not a ford 5.0 expert....

 

[BlackFox5.0]

It was doing it in the summer too, where the temps were around 80* or so...

 

[BlackFox5.0]

double post

 

[TheRedBlur]

Stock heads don't make power beyond 5200 rpms. A lot of things happen around there, fuel dropps off a bit, and spark gets weaker. It'd be a good idea to reset your timing. Accell power coils go for about 40 bucks and make a big difference when combined with spiral core wires.

and now for the "easier said than done" solution:
Get new heads cam and intake.
That oughtta solve your topend problems!

 

[93GrunT]

compression check on all cylinders usually rules out some problems and gives an idea of how your short block is doing pretty good idea along with a code scanner when ever you have engine problems you don't understand.

 

[BlackFox5.0]

This engine is fairly new, I ported the head myself, a lot, as well as my Explorer Lower Intake, and I put a cam in it already, which is not the biggest, but it's bigger than stock, looks like I forgot my sig, here it is....

 

[stangboy]

Sounds like you may just need a bigger fuel pump. Its probably starving for fuel in the higher rpms. I didn't notice in your sig. if you had a bigger pump, but if you don't you might want to invest in that.

 

[BlackFox5.0]

No I don't lol, I plan on adding bigger injectors though, 24# to be exact....

 

[Michael Yount]

The 19's are probably just fine for your mods. However, as the other poster mentioned, if you're running the stock fuel pump, you may be exceeding it's capacity. Did it just start doing this, or has this been a symptom since you made the mods or made a certain mod in particular? Did you change the valve springs when you ported the heads and added the cam? It could be that you're experiencing a bit of float. Tired stock springs have been known to float at even lower revs than that with the stock cam, let alone an aftermarket. As long as all sensors are working correctly, the cold weather should make one run better - lower intake air temps make more HP, not less, and the fuel injection/O2 sensors/computer adjust for the colder, denser air - so if all's working properly, they don't run richer when it's cold. You may want to pull the diagnostic codes and see if anything's amiss. And I'd put a timing light on the thing and see where it's at. 12-14 is a good place to start - although, even with iron heads you could probably get by with a bit more during the winter. You might have to set it back in the spring however. And if the timing was retarded by your father, you'd probably feel that change even more on the bottom end than the top end.

 

[BlackFox5.0]

I changed the valve springs, yes....they came WITH my cam straight from Crane Cams as a kit, so the srpings are specific to the cam.....

All my sensors work just fine, but i'm thinking now.....

My ACT sensor is just sitting on top of my intake (plugged in) because i never drilled my intake for it, so I have to put it inline on the intake tubing, but i'm not sure how I can do that, since all I have is the stock elbow, to the MAF, and a big filter on the MAF

What would happen if the computer was getting readings from the ACT that were like 90* (or whatever the temps above the lower intake get to) and the air the engine was taking in is like 35*ish, I'd run lean right?

I wonder if thats my problem...can I just extend the sensor and toss it in the fender? It doesn't matter if the weather is hot or cold, I only notice it when I get high in the RPMs, which I only do when I race....

 

[Michael Yount]

The ACT really needs to be in the intake airstream somewhere. I definitely wouldn't "toss it in the fender" (???) - just sitting out around the intake would be better than that.

Can't you cut a hole in the elbow, and silicone the sensor in place? Or drill and tap someplace on the upper intake for it? Either approach isn't that complicated, and will allow the sensor to do what it's supposed to do - tell the engine what the temp. of the air entering it is. Not sure if that's your problem or not, but it's certainly something that needs to be addressed.

Also, having a conical filter hung on the end of the maf where it's pulling warm underhood air is probably a worse set up than the stock box - which at least pulls cold air. Anything you can do to shield that filter, or get it in the fender will really help. HP increases 1/2% to 1% for every 10F drop in intake air temp; and it decreased for each similar increase in intake air temp.

Timing? You check it yet? Fuel pump - stock capacity?

 

[BlackFox5.0]

I haven't checked the timing yet, I still have the stock fuel pumpI need to change that, maybe when it gets warmer....

 

[Cobra1894]

I had the same problem, Timing is off. Double check it!

 

[94Silverbullet]

When I get on it, right around 5200 or so RPMs and above I have no power whatsoever, the car just stops pulling and the engine just makes a lot of noise (normal revving sound, only with no power to go along with it)

I have no idea why it's doing this, what could be causing this?

My father had changed the timing without me knowing so I have no idea what it's at, I think he might of said 12*, what should I change it back to? I had it at 14* before. Could this be part of the problem? I was thinking maybe fuel starvation....

check my thread out. it sounds very similar. I changed my distributor and coil and its back to normal http://forums.stangnet.com/showthread.php?t=400278