Hi all, from the UK and purchased a 2007 f150 harley Davidson roush supercharged few weeks back but some just doesn't seem right with the power, previous owner replaced all the cam phaser related parts aswell as new rockers and lifters, oil pump and water pump all at the same time back in 2018 and then they fitted the jdm Uprated 10 psi pully and tune truck has only done 54,000.

Now I've owned a few v8 trucks over the years ranging from 4.6, 5.3, 6.2 they all had the get up and go factor smiles per a gallon.

But this 5.4 even though it has a roush charger just seems very lazy and doesn't pickup and go like all my previous v8 trucks and its starting to bother and worries me, since I've took owner ship its had a full over haul service all oils engine and diffs and transfer case, new pully set on the engine, aux belt and super charger belt imported the ht0 spark plugs from jdm, I've fitted obx longtube headers with the sports cat y pipe.

When you go wide open can't even hear the supercharger whine, there's no engine lights no error codes starts up fine no problems but also only getting 7-8mpg at best.

So I'm trying to reach out and see if any one would have any idea why the truck seems so lazy any help would be greatly appreciated.

 

You sure the cats aren't plugged?

 

I've just fitted brand new obx racing longtube headers with there sports cat y pipe so definitely not the cats.

 

Just a guess, but it sounds to me like the supercharger isn't working.

 

Problem now solved it was the throttle body motor trucks idle and driving rpms where limited due to motor being faulty. New one fitted now boosting back to 9psi