Ok so I am new to the site and just have a minor question that has been nagging me. I have a 2000 f150 4.2L. Within the past week I have give nthe truck a tune up.. all the works. My problem comes along the lines of changing plugs and wires. Upon tuning up the truck, took it for a ride and the truck ran great. Came home took about a 30 minute lay off and went outside to start her up. Well upon starting nothing but a misfire and rough running. So yesterday I changed the wires and plugs again and upon start up the same result ensued. So my question is what is the diagnosis of this. Ok yes i replaced the ignition coil pack, so that is brand new as well. My spark plugs come pre gapped as usual, also not a compression problem, i have checked all wiring as well and nothing is loose. I am grabbing a scanner so i can see if any codes come up, engine light didnt come up upon either times of starting the truck. So any help would be appreciated thanks.

 

Does your scanner show running conditions? If so, look at cylinder misfire count and see which is doing it...if its two, see if they are linked in the coil pack....also check your plug wires to make sure they arent grounding out...

 

You don't have enough to go on presently.
Why did you do your 'tuneup'?
Is the old coil faulty?
What else did you do?
Has anything changed since your last post?
CEL, codes etc.
Is it a really a missfire condition?
Looking for something to run with.
Good luck.

 

I havent ran the scanner yet, have been busy. But as far as the tuneup lets see plugs havent been changed for four years, neither have the spark plug wires. Changed oil, rotated my tires, got an alignment, basically everything else I did has nothing to do with this problem. Ive changed the ignition coil pack back to the original and I still get the same problems. None of the wires are grounding out around the engine everything is nicely fitted around. Again Ive changed the wires and plugs twice both with new products. Nothing has changed since I dont want to run the truck because of how horrible it sounds. Yes their is a misfire, its missing a cylinder. I need to get the computer on the truck.

 

You may want to check the connector to the coil pack as a loose or not well connected wire will wreak havoc on peoples sanity brother. Also a fouled plug will act up....

 

A hard miss usually results in a code for the affected cylinder/s if you see it that easy.
The crank sensor measures the revolutation time for each cylinder and can detect one or more that do not match the monitor table reference at the time it happens.
s
Should also hear it in the exhaust as a puff when the cylinder comes up for fire.
Good luck.

 

That's what I was thinking. Since it ran fine right after plugs/wires, you didn't cross the wires or cross plug threads. I wonder if you have a totally unrelated issue. I am sure the scanner or at least a code reader will give more info.