5.4 liter preignition problem.
Thread Starter
|
New User
Joined: Aug 2005
Posts: 5
Likes: 0
5.4 liter preignition problem.
I need some help with a preignition problem. I have a 98 expy with a 5.4l. It has 166k miles on it. I am getting a lot of pinging under load until it is warmed up. After that I get some when it shifts into a higher gear but only for a very short time (2 or 3 pings then its gone) I'm not getting any codes. I have cleaned the MAS which helped quite a bit with the pinging on the shifts but no change when cold. I have replaced the EGR Valve and made sure the ports to the throttle body are not clogged with Carbon (No Change). I have also tried running sea foam trough the vacuum tube into the back of the throttle body (No Change). I have seen in other post that the DTFE sensor may cause problems with the EGR system but this normally throughs a code and causes idle problems.
What else should I look at? The plugs where last changed at just over 100,000 miles.
What else should I look at? The plugs where last changed at just over 100,000 miles.
Moderator
Joined: Dec 2001
Posts: 22,436
Likes: 17
From: Louisville,Ky.
Many 98 F150's had too much timing and required a PCM reflash.
Have you checked the fuel pressure? A partially clogged fuel filter can cause a lean condition. It needs to be driven with a real time data logger to watch the fuel and timing trims to see if either is out of range.
Have you checked the fuel pressure? A partially clogged fuel filter can cause a lean condition. It needs to be driven with a real time data logger to watch the fuel and timing trims to see if either is out of range.
Thread Starter
|
New User
Joined: Aug 2005
Posts: 5
Likes: 0
Thanks
I forgot to mention that I just changed the fuel filter 2 weeks ago.
It seems that the pinging is always coming from the left (Driver) side of the engine. Is there any chance I just need to change the plugs?
I forgot to mention that I just changed the fuel filter 2 weeks ago.
It seems that the pinging is always coming from the left (Driver) side of the engine. Is there any chance I just need to change the plugs?
Senior User
Joined: Feb 2004
Posts: 303
Likes: 0
From: "Garden State"
Whimsey
Moderator
Joined: Dec 2001
Posts: 22,436
Likes: 17
From: Louisville,Ky.
I too suspect a couple of broken exhaust manifolds studs.
I would double check the spark plugs to make sure none are loose or you could blow one out of the head and that is bad news. But, I would suspect the exhaust is leaking at the head. Pretty common.
I would double check the spark plugs to make sure none are loose or you could blow one out of the head and that is bad news. But, I would suspect the exhaust is leaking at the head. Pretty common.
