'08 King Ranch really this slow?

[Habbibie]

Possibly clogged cats.. replacing those on my 5.4 3v made a huge difference in the acceleration from a stop.

 

[Adieu]

Possibly clogged cats.. replacing those on my 5.4 3v made a huge difference in the acceleration from a stop.

Were there OBD codes?

CEL on and regular emmissions codes? Or Ford-specific ones scannable only via Forscan or a Ford diagnostic tool?

 

[Habbibie]

There were no codes for me, and the code for clogged cats is p0420, if you erase it it'l take about a week or two before it comes back on

 

[34Ford]

Wouldn't clogged cats cause it to loose power weather it was cold or hot?

 

[Russell Lewis]

Bad cats generally glow hot you can see under vehicle or if dark at night.

 

[deweysmith]

Have you looked into the cam phaser issue at all? That COULD cause poor performance when warm, but I have a hard time believing it would be THAT bad without throwing a couple of codes.

 

[John Christopher]

Yes, I can pull out from a dead stop and mash it down,, it slowly builds speed and not really pulling me into the seat.

When I go to buy it this evening I will see if temperature is a factor. I also have to see how to turn the air bags back on.

I was just reading your post about the slow acceleration and I was surprised to see you purchased the truck without finding out what was causing the problem. Maybe it had a great price. I can tell you the acceleration on my 2003 Expy EB 5.4 is pretty good from 0 to 40 but falls off from 40 to 60. I also have a 2013 Navigator with the 5.4 and it's quicker than the 2003 but still falls off from 40 to 60.

 

[34Ford]

I cleaned the MAF sensor last week and it seems to have made a big difference. Although I haven't really stomped it lately.

Magnaflow cat back on its way.

 

[Shabadoo]

Could be your timing is getting pulled when the engine heats up. Could also be you have a leak in your exhaust, before the O2 sensors. If cleaning your MAF made a huge difference you may have been running lean beforehand. Not only would this cause sluggish acceleration but an increased propensity for detonation and preignition. A cold engine is able to run more timing and is running in open loop so your O2 sensors aren't affecting your fuel/air mixture. Lot of ifs and maybes, though it's something to think about. If you have any way to datalog the vehicle, you can usually see what spark advance is being run and how much the knock sensor is meddling with it.

 

[34Ford]

Datalogging? I do have a blue tooth obd2 adapter that is working and I downloaded Torque Pro.