Power issue 03 5.4

[Fanatic1074]

I am not able to check spark retard. :-(

The plugs are now brand new. I changed them when i pulled the intake off to change the Knock sensor.

Its repeatable about 90% of the time. Expecially when its hot out.

No its not always under load, I have had it happen to me one day when it was just me in the truck and i needed to dart across the road. I hit the throttle and the thing just crawled across the road. :-(

 

[Whack]

Do you have any modifications to the K&N filter? or is it completely stock?

What is the k&n model #?

Were the injectors bench tested?

 

[FordandPolaris]

It could be something with the custom tune as well. What gears do you have?

 

[Fanatic1074]

Do you have any modifications to the K&N filter? or is it completely stock?

What is the k&n model #?

Were the injectors bench tested?

No mods to the filter or the CAI at all its the 57-2538 kit from K&N.

The injectors were not bench tested. To be honest im not sure how to test them. When i pulled them out to change the knock sensor i visually inspected them and they looked great.

However if you know of a way to test them its really easy to pull them out. Would prolly take less then 30 min to get them all out.

 

[Fanatic1074]

It could be something with the custom tune as well. What gears do you have?

Well the custom tune is not really custom its a superchips programmer.

However i am running the new computer right now and i have not applied the Superchips programmer yet.

The computer is completely stock.

Im pretty sure its the 3.55 gears. However i have had this truck for 7 years and this issue just started up about a year and a half ago. Before this i have never had the issue. So i doubt gearing is the issue.

With that said i have seen the TSB about the ECM needing a software update for issues during warm weather however, i would assume that with the new computer that it would have the new software??? I got the computer from Autozone.

Or.... Would the Superchips programmer make the needed changes???

 

[Fanatic1074]

Trying the forum again...

I have changed out the EGR valve EGR solenoid and TPS.

I also had a shop drive the truck around for several days and logging data. They said the only thing they found was a small misfire on 5 of the 8 plugs. The guy said he thinks its my CAI. I cant see how it would cause this issue, expecially being intermittant.

The other day i was out with it and had started it and put it into reverse and it stumbled alot like it was going to die and then i put it into neutral and it straightened up.

Anyone got any other ideas?

 

[01yellerCobra]

Did you ever load the tune into the new ECU?

Misspelling brought to you by Tapatalk

 

[Fanatic1074]

After I put the new ecu in I drove it stock for about three weeks and experienced the issue maybe a dozen or so times. So I then put the tune back on.

 

[Jb14]

I have and 05 expy 5.4 I've was having power issues as well plus terrible gas mileage. Im not sure if this will help but I did get my issue resolved. Your symptoms sound pretty close to mine.

I had two issue one was with the MAF wiring and throttle body.

First the MAF. There was a wire that split and was touching but not completely, when I cleaned my throttle body it completely separated the wire. So in the wiring leading to the MAF the broken section got fixed and now is working perfect. But after it was fixed the truck ran worse because the throttle body was bad as well. I replaced the throttle body and now with both fixes it literally runs better that new (124K mile) my gas mileage is also great now.

One other note I had a great mechanic that was with ford for 18 years and has owned his own shop for 7 specializing in fords what thing he mentioned was with replacing the stock airbox with an after market intake. He stated that the box is designed to have the air pass the MAF in a certain way and that if its not it can send mixed signals. Not sure if true but thought Id mention it..

Good Luck

 

[Big White]

The accel cops enjoy a *very* less than stellar reputation on other forums. Might wanna try some ford ones. ($$). I remember one guy saying he ripped out the accels after stupid low miles with them. The fact that you are recording some misfires supports that also.