1999 5.4L feel weak?
Thread Starter
|
Posting Guru
Joined: Jan 2008
Posts: 2,408
Likes: 0
From: Trenton, MI
1999 5.4L feel weak?
It in 99 Expedition eddie bauier. Bought at 157K back in March 3 Now it had 179,700 miles.
What I have done to it.
New exhaust manifold on passenger side. #1 had big hole it rot out.
New spark plugs/ boots
Thermostat. Old one was open at 173oF
air filter
flush coolant it was NASTY
vacuum hoses
Fuel injectors
Fuel filter
Mileage was used to be 17-19 but now it just downhill to 13-15. I ever clean MAF and put new air filter.
Engine seem to having issue with power lately. It doesn't had peppy at high rpm it just rev way high it struggling.
It had miss at random times sometime it ran so smooth then other time it just shake very tiny like every-time cylinder fire it stumble.
No engine light on. Plan test sensors tomorrow with AE scanner to find out.
What I have done to it.
New exhaust manifold on passenger side. #1 had big hole it rot out.
New spark plugs/ boots
Thermostat. Old one was open at 173oF
air filter
flush coolant it was NASTY
vacuum hoses
Fuel injectors
Fuel filter
Mileage was used to be 17-19 but now it just downhill to 13-15. I ever clean MAF and put new air filter.
Engine seem to having issue with power lately. It doesn't had peppy at high rpm it just rev way high it struggling.
It had miss at random times sometime it ran so smooth then other time it just shake very tiny like every-time cylinder fire it stumble.
No engine light on. Plan test sensors tomorrow with AE scanner to find out.
Senior User
Joined: Nov 2011
Posts: 179
Likes: 0
From: Eastern WA
So no codes at all then? It could be EGR stuck open that causes poor top end performance, and/or something with the exhaust system, clogged or failing cat etc.. O2 sensor?
Not exactly sure without more info.
Not exactly sure without more info.
Thread Starter
|
Posting Guru
Joined: Jan 2008
Posts: 2,408
Likes: 0
From: Trenton, MI
When I bought it was average 13. Bad thermostat open at 170oF.
Passenger exhaust manifold had giant hole on #1 port so I think valves burnt but it just randomly idle smooth/rough after 20K miles same thing. I replaced that manifold it was PITA job.
New spark plugs/ coil boots same issue it had tiny miss.
EGR Valve work good I test.
I think cat convertors could be plugged I will need get laser thermometer to find out what temp.
Passenger exhaust manifold had giant hole on #1 port so I think valves burnt but it just randomly idle smooth/rough after 20K miles same thing. I replaced that manifold it was PITA job.
New spark plugs/ coil boots same issue it had tiny miss.
EGR Valve work good I test.
I think cat convertors could be plugged I will need get laser thermometer to find out what temp.
Senior User
Joined: Sep 2011
Posts: 448
Likes: 1
My 2000 f150 5.4 was getting bad gas mileage and I didnt bother looking for it until I had a drop in rpm sitting a the light, changed the Aftermarket Iac I put in 6 months ago (BWD), with motorcraft and not only did it fix my idle drop, but fixed my bad gas mileage, win win., just my experience
Trending Topics
Thread Starter
|
Posting Guru
Joined: Jan 2008
Posts: 2,408
Likes: 0
From: Trenton, MI
I did check IAC back in March or April try solve rough cold idle it never cure.
I would love to buy smoke machine so I can find if there vacuum leak on this one.
I would love to buy smoke machine so I can find if there vacuum leak on this one.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Fords to Drive Before You Die
Joe Kucinski
3 Best / Worst Features Of The 2025+ Ford Expedition
Brett Foote
10 Ways Ford is LOSING to the Competition
Joe Kucinski
Top 6 Best Deals Available on New Fords & Lincolns Right Now
Brett Foote
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Verdad Gallardo
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
Thread Starter
|
Posting Guru
Joined: Jan 2008
Posts: 2,408
Likes: 0
From: Trenton, MI
YIKE I hope it not. It just PITA to do in Expedition. I rather do on superduty.
Going need smoke machine to confirmed if it intake gasket.
Thread
Thread Starter
Forum
Replies
Last Post
jarch
1987 - 1996 F150 & Larger F-Series Trucks
2
Oct 18, 2005 03:43 PM