A question I have been wondering for sometime is if everyone else experiences a big drop of HP while accelerating? I have a Scanguage II in my truck so I can monitor the HP. I'll be accelerating like from a stoplight and the HP will climb to over 70 and then when it shifts (into 3rd I believe) the HP will drop down into the 40's. It really feels like my truck is going along great and then the HP drops and it feels sluggish and slow.

Is anyone else having the same experience and is this just a normal thing these trucks do? I have a 3" AF1 CAI, custom SIDO exhaust with magnaflow muffler and both Troyer & VMP custom tunes (it feels the same way no matter which tune I have loaded). I'm almost thinking it may have something to do with the muffler, but not sure.

Thanks

 

Isn't the Scan Gauge HP readout to tell you howmuch hp you're "using"?

 

don't know about how much HP it's using, but it makes sense that you feel sluggish.

the gearing is pretty steep in these tranny's. you have that thing 2000-4500 rpm and then hit 3rd and suddenly it's about 1500-2500 rpm. dropped from the peak of it's HP to a "low point" for HP

 

So what I'm feeling then is normal?

Not sure. I thought it was a readout of the HP you're producing though.

 

It's a truck and made to haul and tow. The ECU cuts the power to the engine just before the transmission shifts. This keeps the engine from tearing the tranny apart while hauling or towing. Get a tuner and set it to the performance setting, and the power will no longer drop just before shifts like it does now. Just be sure to tune back to stock before towing or hauling anything.

 

The OP said it does this on both his Troyer and VMP tunes. I still don't think anything is wrong. I think you're thinking way too far into it.

 

Yep does it no matter which tune I'm running. You're probably right, just a normal occurence, just wondering though.

 

Sorry, I missed that. After I tuned my 04 F150, I no longer had the HP drops before shifts. My truck would shift so hard that my serpentine belt would squeal for a second or two every time the tranny would shift from first to second and from second to third.

 

You sure it's 3rd gear that's dropping off? Our trucks tend to pull nice and consistent into 4th until the torque converter locks up then you feel a drop in power as the rpms fall out, especially under lighter throttle. If that's it talk to Mike or Justin about adjusting for it. It can be smoothed out quite a bit.

 

mine does that occasionally right now with no programmer. scared the bejesus out of me the 1st or 3rd time it did it. It's been so long since I had a true hot rod that did that stuff

 

Uhhh......maybe Im not reading this right but...the higher the RPMs the more power....when you accelerate and run it up to whatever RPMs you might be making 70hp, and then when it shifts, obviosly your RPMs drop. Less RPMs, less power.

 

I'll have to really pay attention to it on my way to work tomorrow because it could be the shift form 3rd to 4th.

I understand the HP's are going to drop as the truck shifts and drops RPM's, but should it drop that drastically? It's not like I'm flooring it to get it up to speed, I accelerate slowly (don't want to punch it and burn up gas at $4.39 a gallon). I think the spped it usually around 40-50 mph when I see the big dropoff.

As I mentioned above, I'm really going to pay attention to the shifts and the speeds where this happens and I'll post'em up.

 

if you look at the HP/TQ curves for the 5.4

the TQ curve is damn near flat and is making peak TQ before 2,000 rpm

the HP curve is almost like any other traditional HP curve. low at first and peaks at 4,500 ish and starts dipping back down slightly

so yes, when you hit 3rd gear and suddenly drop from 4,500 ish rpm to about 2,000 rpm, you are effectively cutting 1/2 the available HP. I'm surprised you see that big a difference though. don't you have 4.56 gears? almost sounds like your tune may be off or something

 

Try turning the OD off and see if it still does it.

 

third gears suck in almost all cars, except for that viper i drove once