My '99 F150 5.4 has had a bit of a "shiver" to it at idle after it warms up for some time now. I changed the plugs (bosch double platinums as I couldn't manage to find 8 motorcrafts that weekend) and cleaned the injectors at 98k miles. It ran beautiful, I mean like new, for exactly 2 weeks. Then it kinda just went back to the way it had been. Around this time the MIL light came on and it popped code P0455. I tried all the usual suspects to no avail. I ran it this way for about 3 months. I inquired about it here and racerguy was kind enough to point out my idiocy after I posted a pic of my VMV. I had left a small vacuum line off (which was nicely tucked away on the opposite side of the engine bay). That cured my code problem. It still had that "shiver" to it along with some mild pinging under very light acceleration. Being the genious that I am, I poured about 2/3 of a can of Seafoam down the brake booster vacuum line. It stumbled a bit, but didn't act like it was going to quit while I was pouring it in. I shut it off and let it sit for about 1/2 an hour. I started it up and there was no smoke whatsoever. I had heard there would be. I drove it up the street and the pinging was horrible. Most of the pinging went away after I drove it a bit (couple miles). The problem is now that the power sucks (as in it will barely make a screech when I nail it at a full stop and seems to accelerate slower than normal) and it pings more than it used to. I am on my 5th tank of gas (different brands and vendors) since the aforementioned events of trial and error. So, finally to the real question, what did I mess up?

There are no stored codes, I cleaned the MAF, ran a bottle of Techron fuel injector cleaner. For an idea of my driving habits, I drive 38 miles each way to work, 32 miles of which are highway. I run at 70-75 depending on how many bear I see. There is never any stopped traffic and I hardly even get to use my brakes. There is a grand total of 4 stop signs and no lights on my route. I didn't need to change my original front brakes until 82k and the rears until 112k, all of which still had about 1/4 of the pad thickness remaining. It now has 117k miles.

Thanks for your help and suggestions,
Jody

Edit: I also tried the Ford standard- I ran it hard. 3000-4000 rpm varied for several miles (2nd gear, 60-68 mph) on several occasions.

 

Did you replace plug wires? You may have a problem with arcing. The pinging leads me to believe this could be the problem. I had a similar problem on a 93F-150 and it drove me nuts for months and just kept getting worse. I chaged plugs, cap, and rotor with no luck. I had no replaced plug wires because they were good wires and were not old. Problem was with how I had routed on of them. Caught the problem by looking at the engine compartment in total darkness. May not be your problem but could be a cheap fix. I hd others I truly respect look at it and they could not find it either. I was amazed at the effect this small problem had on performance. Rerouted the wire and it ran like a champ ever after.

 

It's a 5.4l, it has COPs. There are no plug wires.

 

Oh Ok Never Mind.

 

Man! when I saw you topic headed "I did a stupid thing..."
I thought your were going to say you traded your truck in for a Dodge , or worst yet a nissan titan. .

Ha! Ha! Ha!

no serious LOL!!!

I did the same thing w/ my 97 4.2 f-150, with seafoam and had not a lot of smoke like others described

 

I have never heard of A Moter whith no plug wires. Please clue me in.

 

The coils are right on top of the plugs. Coil on/over plugs. COPs. Neat huh? LOL Rob.

 

Each plug has it's own coil pack that fits right over the top of the plug. It's called a COP (coil over plug).

No Dodge for me...

 

Oh I see. Thanks Guys

 

Just a thought. If he had a bad COP wouldn't it throw a code?

 

one other thing....it's gotten harder to start over the last few weeks as well.
It doesn't seem to miss, it just pings more than it ever did and it seems low on power. 0-60 is roughly 9 seconds. I was thinking I'd change the fuel filter tomorrow and check pressure at the fuel rail.

 

I still think somethng is arcing.

 

For anyone interested...I checked fuel pressure at the rail and it was as follows:

Key first switched to run: 35psi
After pump kicks off with switch in run (engine off): 30psi
At idle: 25psi

My book says it should be 30-45psi at idle. I can imagine what it is while running 75 down the highway.


As for arcing...I have experienced that on on 84 t-bird 5.0, but I'm thinking it would be hard to find without pulling the COPs out. I can definitely see how they could arc inside the spark plug well

 

Sorry...that should have read:

Key first switched to run: 34psi
After pump kicks off with switch in run (engine off): 30psi
At idle: 24psi

With the engine at idle 24psi and when I disconnect the FPR it jumps to 33psi. I drove it to town with the FPR disconnected (and vacuum line plugged) and it was better, but still not right....so out I go, fuel filter in hand.

Update:
After installing new fuel filter: 23psi at idle and when I disconnect the FPR it jumps to 33psi.

 

If it's pinging, I don't think that it is a fuel delivery problem. It is either fuel quality or an electrical problem that is screwing up the timing (like and arcing problem somewhere) Because this started after you put water in the enginer compartment, I suspect that something got wet and is holding moisture.

Good Luck with it.