Greetings,
This is my first post however have been reading for a while. I have a 1998 Expedition with the 5.4 ltr engine. The truck is used only once or twice a month, however towing is it's primary use. I like to tow a 7000 lb boat long distances a few times a year, and this tow is coming up soon. Anyways, last time driving the truck, it was pulling a 5 x 10 utility trailer, carrying maybe 6 or 700 lbs of stuff. Upon accleration, the revs went up, the engine sounded normal, but the truck seemed to accelerate very slowly. Also, the last time pulling the boat out of the water, it barely made it up the launch ramp, when it normally pulls it out just fine. Once on the highway, it seemed fine. The engine is not throwing any codes. Just wondering what could be the problem. Is there a problem with the transmission? Filter? Oil?
Thank you for help.

 

Have you checked the fluid? Sounds like trans might be slipping...

 

How many miles on the truck?

 

You ever change your fuel filter ?

 

There is about 130,000 km on the engine and 250,000 km on the transmission and the rest of the truck. In the past year, I replace all 8 plugs, ingnition coils, and fuel injectors. Has a clean KVN air filter and a new fuel filter. As far as I can tell, the engine is just fine. As for the transmission, I have not had to do any work other one time when I needed to replace the speed sensor. If the transmission is slipping, can this be fixed with a filter and replace the oil from the pan, or do I need to do a complete flush? Or, is it going to continue to slip? I know very little about transmission.

 

KVN air filter ... Do you mean K & N Air Filter ? If so, over oiled and damaged the MAF ?

 

Sorry. Your right. K & N Air Filter. I will check the filter however if it was over oiled and clogging the MAF sencor, shouldn't I be getting a check engine light?

 

Not always ! You can have a skewed MAF signal and no CEL or codes . Live data can tell you if you have fuel trim issues . Fuel trims should be + or - 5 % As close to zero as possible .

 

So if it a matter of cleaning the sensor? And filter of coarse. Or would the MAF need to be replaced.

 

I have had some luck cleaning them . But , If oil is baked on , it may not clean up . If using a K & N filter , be sure to not over oil it . A little goes a long way .... Best of luck !

 

With 155K many miles on the tranny it's not unusual for it to be slipping, especially if it ever was a tow vehicle.

 

So did you check the fluid level? Smell and see if it has a burnt smell to it and if color is bright red or dark. If the transmission is slipping then it will need to be rebuilt/replaced.

 

No I haven't had chance. Fridays are a very busy day for me. Hopefully tomorrow morning or Sunday afternoon. I will post what I find. Thank you for your concern.

 

With slippage as noted, sounds like a tranny issue. It would be more obvious when pulling a boat up a launch ramp.

What maintanence has been done on this tranny? Mfg recommends changing out tranny fluid every 35k.

To the comments of others, fluid level, color, and smell will help to answer your questions.

 

So I finally had a chance to do a little work on the Exped. I cleaned the MAF Sencor and air filter, and looked for anything loose or not connected. I did not see anything wrong. CHecked the tranny fluild and I thought that it looked surprising good. I have never done any work on the tranny however I have only had the truck for 3 years, and only drove it during our short summer. I have put less than 10,000 km on it in that time span. However, a rough guess is that about 3000 km would be towing. Half of the towing would be a 2500 lb boat, and the other half of the towing would be a 7000 lb boat. I have never had a engine or tranny problem while towing. About the only problem I had was when an exhaust manifold snapped in half while towing it up over very large hill. Anyways, this week I will have the tranny flushed and add some anti-slip goo, then see how things go this coming long weekend.
Thank you for your help.