I had a B302 code a few weeks back in my 97' 4.6L. The code was caused by a dead short on the number 2 cyl.(water around the plug). I opted to have all the wires and plugs changed instead of just fixing the bad set on #2. Before the change I could run 87 octane gas and have no knocking while climbing hillls with an average of 12.5 MPG almost every tank. Now I have to run 92 and it still has some clatter to it while going uphill and my MPG seems to have dropped about 1.5 to about 11. If I put 87 in it she sounds like a Freakin' deisel when going up hills. HELP!!!

Would having 2 plug wires possibly crossed cause this, gap to big or small on the plugs??? Nothing else was changed. They used Platinum BOSCH plugs and 8.8mm wires. Could the coil be F-d and just not bad enough to cause another code, nothing is coming up. I am miffed and aggrevated, the gas is still kinda high and paying an extra 30 cents per gallon is really pissing me off.

Again, anyone HELP???

 

If you have a miss, you'll know it. The whole truck will shudder when driving at a constant speed, and it'll bounce idle. Plus, you're CEL will tell you if there's a misfire somewhere. If two wires are crossed, same thing. A coil could be weak, but you're problem doesn't sound like that. I would get some SeaFoam, and add it to the gas, oil, and remove you're brake booster vacuum line and put it there also. Sounds like a EGR problem. If the SeaFoam doesn't work, remove the throttle body (real easy job) and check the EGR passages. Both of mine were completely plugged, and had a knocking before I cleaned them. Take a drill bit, by hand and run it though the ports. Use plenty of carburator/ brake parts cleaner, and clean it all out. Let me know how it works out.

 

SEAFOAM as per their directions? I use it in my boat, quad, bike and mower during the winter, but have never thought I needed it in the truck. I drive it so much I figured she'd be clean. Oil is fresh, less than 500 miles since the last change...

 

These years of 4.6 engines use coil pack ignitions. The coil fires two cylinders at a time. One of the cylinders will be on the compression stroke and the other one will be on the exhaust stroike. Normally the one with an already burnt fuel - air mix has higher resistance so the one with an air - fuel mix will fire. If you crossed the wires and only mixed up opposing cylinders there should be no problem. If you mixed non opposed cylinders it would run like crap and you would know it. Check the plug gap and the wires. What was remove dto install the new plugs and wires. Look for something that was not put back properly.

JMC

 

I had the work done at a shop, I brought it in to have the code read and the truck was severely misfiring(wicked shuddering under load). They had the space and I had to work anyway. I just wondered about the wires cause the routing looks all F-D up to me now, but they may be correct... The other thing that comes to mind was the TSB from FORD saying the catalyst could be damaged with a dead short in one or more of the cyls. I drove the truck about 60 miles with the misfire. Is that enough to foul one or more of the cats?

I put in 22 gallons of 89 tonight and added one pint of SEAFOAM to the gas. I'll get some more for the oil...

 

I don't think that's enough to foul up a cat... When a cat gets messed up from a misfire, it's because so much unburned fuel goes through the cat, which saturates the honeycomb material, causing it to break apart. The particles then get caught at a screen in the back of the cat. The most noticable effect is lack of power and the motor will not rev up. I actually had this happen on my wife's 94 Grand Cherokee 5.2 . The EGR got stuck open, thereby allowing unburned fuel into the cat. Would not wind up above 3500, and MPG dropped from the normal 21 on the highway to 13.

 

i've heard alot of bad things about using bosch platinum plugs in the modular motors. apparently they just don't work together for some reason. i don't know anyone that actually has a set of bosch platinums in their car or truck right now. i've actually had more than my share of problems with them in vw motors. i swore off bosch plugs completely about 7 years ago and haven't tried them again.

hearing what i've heard about the problems i would start with putting a set of motocraft plugs in to see what happens.

 

Sparky what is your average MPG with that setup?

I'm gonna try cleaning the MAF etc...

 

I put Bosch Platinums on my '97 4.6L and it ran better than new. I did run into a problem with the new spark plug wires. The wire going to the #1 plug would consistently pop off causing a rough idle. I exchanged the wire and everything ran fine. That engine also blew several Motorcraft plugs in the #7, but never blew a Bosch.

That 4.6L never did like 87 octane. It would run, but knock under load. If I put a couple tank loads of gas from on base, it was horrible.

 

i get about 13-14mpg but i also drive it pretty hard now that the power is there. on the highway at 90mph the mileage probably drops to about 10mpg or less. at 60-70 mph it revs in the mid 2000 rpm range so the mileage isn't so bad there.

 

what brand wires did you use? and replace the coil packs.. i replaced mine very noticable gain. but if you have a harder spark u can burn more fuel make more power.. so u may actually loose some mpg because your using more fuel but in turn u develope more power as long as u have a nice complete burn.

 

I've had really poor results with Bosch Platniums. They worked good for a couple thousand miles, then went to crap. The Bosch Super copper core 99 cent plugs are the best plugs I have ever used, but they have to be replaced every 35K. I don't want to do that on these Triton engines. What a pain in the *** to change plugs!

Due to the plug change nightmare, I use the OEM 100K plugs. I have had excellent results with those Motorcraft Platnium plugs (part number is: SF32FMF4). The plugs MSRP for $10.25 each. If they don't offer them to you for $4.25 each, tell them that's what you were quoted. And yes, too big a gap can cause pinging. 4.6L and 5.4L Gap for these plugs is 0.054".

Avg quality wires won't help either. MSD Super Conductor wires (Summit Racing has them ~$70 & well worth it!).

Before you try new plugs and wires, remove the + and - battery cables from the battery. Touch them together for 10-15 seconds. This will reset the brain box to default settings. The cpu's "learn" and over the years will adapt to driving habits and Octane (i.e. advance timing too much).

 

What is Seafoam? Where do I get it and how do I use it? What is it used for?

Steve
2000 F150 Lariat 4x4 S/C 5.4L