<TABLE style="BORDER-RIGHT: 1px dashed; BORDER-TOP: 1px dashed; BORDER-LEFT: 1px dashed; BORDER-BOTTOM: 1px dashed" borderColor=#000000 width="100%" border=0><TBODY><TR><TD>Truck has had three sets of plug wires and plugs (best wires the ford place had and the best platinum plugs), new fuel filter and one new coil pack installed in the past year. Each time the service engine light would go off and stay off a few days before coming back on. After the light comes on the truck starts to miss at idle and while in overdrive and the truck is under a load such as pulling a hill at cruising speed. if truck is run for a couple of weeks the miss gets worse(runs like it is hitting on four cylinders instead of eight) and mechanics report that the plug wires and plugs are bad and need to be replaced. This has happened three times so this leads me to believe that the plug and wires are not the problem. Computer says that the code indicated the plug wires and plugs but a lot of money and time seems to disprove the diagnostics. Seems like the truck is firing way to hot or something and burning up the plug wires! Any ideas?</TD></TR><TR><TD> </TD></TR></TBODY></TABLE>

Sorry that i don't have the exact code. I'm not driving the truck at this time and i have my dad taking the truck to the shop for me and you know how that goes sometimes. Anyway i talked to him today and after putting on new plug wires this weekend the service engine light was turned off and the truck ran great for a day and half then the service engine light came back on. Took it back to the shop and the machine said(according to tech) that the truck had a bad catalytic converter on bank one. Does this make sense? the truck ran good for a few miles then it starts missing and this is becasue of the catalytic converter? Could this cause the plug wires the have trouble on the three sets that i pt on it in the past few months? Would a bad coverter cause the truck to miss? HELP PLEASE!!!!!!!!!

sorry so long

thanks
jason

 

Find a different mechanic.

Obviously, this one is NOT a good diagnostician.

It is pretty unlikely that a cat would/could cause any ot the symptoms noted. However, an extended misfire condition will load up the cats with unburned fuel and cause false cat efficiency codes, the only cat related codes possible.

Steve

 

You are right about finding a good diagnostician. I have taken the truck to three different mechanics and all have said the same thing and none can find or fix the true problem. Each mechanic has replaced the plugs and plug wires ( which seemed bad each time) and the truck runs good for a day or two and then the miss returns. Is there anything that can ruin the plug wires and plugs? Is there any sensors of control units that control the firing that may be bad? Any ideas will be greatly appreciated.

 

thanks for the information and i will gladly take any more advice.

 

My husband just bought a 97 f150 with the same problem.
we put new plug wires on it and it still misses . the truck runs as if somethings holding it back(not much power) and when climbing a hill it misses and will even back fire sometimes.we had it put on the computer and a code for sencors came up but the tech said it was because the battery cable was corroded.so we cleaned the cables and we still have the same problem.we bought this truck knowing it has problems but got a better deal(5000.00).we thought it would be an easy fix but cant figure out the real problem.
So i was wondering if you got yours running right and what you did to fix it?
or if anyone has any ideals please let us know. all help will be greatly appreciated!

 

has anyone checked the maf sensor if its unplugged or bad it't will sound like a really bad miss.

 

mustangsherry i have not got mine fixed as of yet. Since i put the new set of wires on it a few weeks ago it still misses and runs rough but the computer is only coding a bad catalytic converter. Can the computer code more than one problem at a time? mike I have not checked the maf sensor but i will as soon as i can. thanks for the idea! my truck has never back fired but it does start up weird sometimes.

 

...Welcome mustangsherry to Ford Truck Enthusiasts!

…..See you on the boards.

 

What plugs are you using. I finally purchased the Motorcraft plugs from Ford and this seemed to solve the problem. I also learned to change these on my own rather than taking it to someone else to do. The first time I took it "Flame"stone, where they worked on it for over 9 hours (I was out of town), reset the codes, and let me leave. Long story short closing time for them, they were gone in 2 minutes, my code turned back on in five. Turns out they never replaced plugs 4 & 8, the ones under the firewall. I have had to replace them twice since then. The first time after them working on it, then again at 100k, and again at 160k. No problems after that first time and learning to torque the plugs down properly.

 

JTM...have you tried reset the PCM? wouldn't hurt.....paul

 

If i reset the computer with a scantool (KAL) does it alsoo reset KAM?
Or do i need to unhook the battery cable?

 

most folks just disconnect the negatve side of battery for 10-15 minutes. And i understand leaving your lights on after disconnecting will help drain capacitors in the PCM faster. I really dont know if that makes much diff or not. paul... BTW..your scantool should be able to clear stored codes. But if the problem isnt resovled, you'll see CEL again.

 

I have not tried to reset the PCM but I will give it a try. Thanks. At this time the truck is not coding anything about a misfire or anything like that is just a catalytic converter code. Something that is weird is that the miss in the truck gets really bad and it has very little power when it is under a strain. I accidentally left the park brake on this weekend and tried to start off and I thought that the truck was going to go dead. It choked down and would not even try to move.

 

if possible it may not hurt to at least take the cat off and look at it. The catalyst could be melted from all the poor running, and also the catalyst could be broken and clog up the pipe at times. If the cat unbolts and you can do it yourself it may not be a bad idea to at least take it (or them) off and see what they look like on the inside.

 

How many miles on your truck? Since it's a '97 4.6, like mine,
I suggest the following: Replace your IAC, clean your MAF,
clean your throttle body egr ports of the carbon buildup,
replace the egr while your at it, reset your computer and
see how good it runs. All 4.6's will need the above sooner or later.
Mine was done around 127,000, or two years ago. It will not run worth
a crud with the above problems. You can do the work yourself. Good luck.