My 98' Expedition sputters( most of the time) when I push the gas.But not past Sixty mph?

Question

I've already had the spark plugs, coils and fuel filter changed. Also, I've had it put on Two dianastics tests. Both said there is nothing wrong. Someone suggested to have the fuel P.S.I tested,that was fine also!My local auto shop is also stupped.I can't really afford to keep guessing! Please any suggeastions would help. I love my truck and would hate to give it up for something stupid.

Answer 1

NEVER replace a rart till you know the problem. I gather you don't have a check engine lite on ?? It makes a difference. If there is no lite and no misfire codes then a common cause of acceleration stumble is a bad throttle position sensor (tps). The tps tells the computer how far the throttle is open. The computer uses this info. to determine how much fuel is needed to maintain the correct air / fuel nixture and when extra fuel is needed if the throttle suddenly opens wide. Another cause is dirty injectors. If varnish has built up in the tips they won't spray as much fuel as normal, or will "dribble" fuel instead of a fine mist. This creates a lean fuel mixture and conditions that are ripe for stumble, hesitation and misfire. Other possible problems include vacuum leaks, low fuel pressure, weak spark caused by low coil voltage, retardedignition timing.

Answer 2

i own a repair shop,and i had one a while back that was running like that one is,i had changed a lot of parts at the customers request,,and i knew it wast none of the stuff he had me change,,the screen in the gas tank was getting clogged up on it,,at an idle it done pretty good but driving it ,,it didn't,,i also found that it wasn't advancing the timing as it should ,when i pulled the spark plugs out i found that they had not been gaped right either,,and he had installed these himself,,once i finally got through all this stuff it ran good but hesitated at low speeds,,i pulled the front cover off of it,,and it was just about ready to jump timing,,the chain and gears was so worn out in it,that it shouldn't have been running,,i replaced it,,and its running like it did when it was new again,,he,s happy,and I'm glad to see it gone also,,good luck with yours,,hope this help,s.happy new years.

Answer 3

check the egr valve