Simple question but probably not a simple answer.

2000, 5.4L, 114K miles

Changed the plugs today and they are all showing that it's running rich.
No codes, no other signs.

Where to check first?

Makes me want a carburater. 1/4 turn and problem solved......

Ohh if it helps, spuraticaly it has taken spells, maybe 3-4 times the last month, where it won't idle for a litle bit or idels rough at about 400 rpm "in park". May or may not be related.

 

airfilter, fuel filter, IAC valve, o2 sensors? any of those get replaced lately?

 

Air filter always changed at 10K and blown out with air at each oil change.
Fuel filter was just changed about 3 weeks ago about 3K miles on it.

The rest is a big no.
Atleast not in the 65K miles that I've owned it.

 

Haha , yea , carbs were easy to tweak out back in the day - or just swap out the jetting..

Your looking at either a dirty throttle plate (throttle body).

An IAC problem.

Manifold leak. (vac leak) - Check w/WD 40 or propane - propane the best..

Or a a Dirty MAF sensor..

 

do you have a picture of your spark plugs?

 

BTW - If it's been running rich for a long period of time , your forward O2's could be spent. I've read that it doesn't take long for those to go bad on yuh when it's rich..

 

Here is one, they all look pretty much the same.
Really not bad especially considering this is the first time I've changed them in 65K miles and likley the original plugs....

 

that doesnt look rich... looks like nothing i've ever seem before.

 

They are all red, however evenly colored red..... for what that's worth. I suppose that might mean it has an even fuel distribution/saturation, throughly mxing with the air in the combustion chamber on each one.

Red is Rich
Green is Lean

 

Yea if they are original, then 114K miles they dont look like new anymore.
65K they don't look new anymore either.

You should see the ones in the 302 in my boat. Probably originals too, 30 years old, but likely dosen't have more than 336 hours on them (tops). Purrs like a kitten. I pull each one out and check them every year, spray the threads with WD40 and stick them back in.

 

When you first start the truck it's in open loop and not using the o2's right?

Think I'm getting ready to get the fake O2's and put on it as the exhaust system is about to become a few pounds lighter........

I'm going to go out and clean the IAC now.

 

That reddish color could be the result of fuel system additives used, or the additives used by the gasoline vendor.

 

^^^^^ + 1 ^^^^^
It looks like rust, or the camera is not getting the color right?

Here's a chart, and the closest match is normal, or well done normal.

http://www.aa1car.com/library/reading_spark_plugs.jpg

 

Hey Mag
I was always taught not to blow the airfilter out with compessed air.
It willbreak down the paper fiber that catches the fine particals.
Although in the ozarks isn't dusty like some places. May not be a problem there. I liked the jeep story would like to see all four barken at once

 

According to that......

It looks most like high speed glazing + worn...... :o

which is likely. lol


My friends and collegues joke that I dont need a throttle, I just need an on/off switch, because it's all or nothing.

I've never had that happen before though, of course I've never ran a set for 65K+ miles either.