I have noticed from time to time my 5.4 Expedition seems very sluggish at light throttle. Then you can shut off the engine and come back an hour later and it drives normally. When I say sluggish, it feels like the trans is in too high of gear, but I don't think the trans is the problem. If I floor it, it seem ok. No check engine light or anything. Any ideas?

 

I've had the same on our '02 Eddie Bauer w/ 5.4L and no mods. Any insight would be greatly appreciated.

 

Do you notice it more when it's hot out? I've noticed this same thing lately, temperatures have been in the mid-90's, but in the mornings on my in to work it seems fine.

 

I've noticed it when its hot, my wife has noticed it when it is cold. Yesterday I drove it and it was very hot, and it did it. An hour later, it was a little cooler and it didn't do it. When I say sluggish, I mean it can't get out of it's own way unless I floor it. The engine is not missing or anything...

 

Check your tach when it becomes sluggish. Note the rpms and vehicle speed. Give it a little gas to speed up 10 mph. Note the rpm when you accelerate. When the truck goes bsck to normal go back the the speed that you noted when it was sluggish and repeat the acceleration test. Compair the tack readings at the different speeds. If the normal test has higher rpms during the acceleration I would suspect that the Torque converter is staying locked up when it should be unlocking.

regards

Jean Marc Chartier

 

JMC,

That describes what has been happening with our Expy. My wife even commented about it when it happened to me last week. Is there an easy fix for this? Reset the computer?

Thank you for your response.

 

02LaserRed,

Unfortunatly it requires more than that.
It is a dealer issue. It could be sooooo many things.

Regards

Jean Marc Chartier

 

Thank you, JMC. We'll keep tabs on it and hope it's something that will clear itself.

 

is your AC on when it feels sluggish?

My 2000 5.4L AWD expy feels really sluggish when it is hot and the AC is on. so i asked around and people were telling me that the ac compressor shuts off when under Wide Open Throttle WOT. well mine doesn't and before i installed my supercharger i had the shop dyno it. well i was right the compressor does not turn off under WOT and i lost 14 rear wheel hp with it on. which will equate to about 19 hp which is a hp number you will feel. now with the supercharger on and a hot day it feels real suggish until i hit about 2200 rpm when that extra 7 pound of boost kicks in and then it really moves. so this might me your problem.

if my truck is supposed to turn my ac compressor off when under WOT let me know how i can fix this issue

 

Took it to the dealer. I had a defective coil. They are also replacing the plugs and cleaning the injectors. They are probably working me on the plugs and the injector cleaning, but I was going to replace the plugs in another 10000 miles anyway.

 

Tenderpaw,

How many miles did you have on the plugs. If they are the OEM plugs thay are supposed to last X number of miles. If they did not you should not have to pay to replace them. It should be covered under warranty.

Regards

Jean Marc Chartier

 

I agree... Stock plugs are supposed to last 100,000 miles. If the plugs need replaced or if the injectors need cleaned as a result of the coil being defective, why should you have to pay for it? If your under warranty, it should all be covered.

 

I notice a HUGE difference here in michigan. My 5.4l dogs in 90 degree weather, but once it drops at night to 60-70's, it runs like a raped ape.

 

Yep, the heat, extreme heat especially like in traffic in 100 degree weather kills these things. Once I installed my Airaid, it did get quite a bit better but if I sit in traffic in heat, it doesn't want to move like it should until I get moving a little. Again, opening up the intake made a big difference.

 

I've got 45,000 miles, so the waranty is over. The plugs are supposed to last 100k miles, but I'm told you should really replace them at 60k because they really start wearing out after 60k. Also, if the plugs are in the head too long, there can be a reaction between the aluminum and the plug and strip the plug hole. A very bad and expensive thing. I figured if I was going to have them replaced at 60k, I may as well do it now...