Hello,
I have an 2000 F150 4.6 super cab off road. The engine has a miss. It only happens when im going at a steady pace or acceling slightly in OD without acceling too much as to downshift it. It just seems like when I press the gas down going up a small grade without pushing it down to downshift it start missing, bucking. I have new coil packs and plugs. I have
gas dryer in the tank, and have good fuel in the tank. The dealer suggested buying gas somewhere else and I did at couple different places with no avail. Any ideas?
Thank you.
1stfordowned

 

New plugs and coil packs - how about wires? Did you use dielectric grease?

 

Was the dealer able to duplicate the misfire? I can't believe they would send you down the road with a misfire and not pursue trying to fix it. Is the Check engine light on? If so go get the codes read to see which cylinder is causing the misfire. If the light is not on the misfire rate is stored in the OBD Mode6 data. Isolating which cylinder is causing the problem is the first step.

 

Had exact same problem in my '01 , changed coils ( Global autoparts ) and sparkplugs (Motorcraft) , problem solved .

 

Yea , the dealership could have stress tested it for you - Confirm that you have "Coil Packs" or possibly a "COP" Ignition. All 2001 V8's had COP systems , but I've run into few 2000 4.6L models that have had either or. They must have COP'ed the 4six in the ladder half of that year. So just tell us if you have plug wires on that motor first, that will confirm the ignition type.

 

Yes it has COP's. The dealer replaced 6 out of the eight COP's. Why they didnt do them all I'm not sure. "Did they replace the wires" I dont think so.
The two they didnt do are on the right front as I look at the motor, I could get to them pretty easy. Do you guys think I should replace the two that arent done yet and how hard are they to install. Thank you guys for all the help.
1stfordowned

 

I forgot to mention that no check engine lights so far when it starts missing.
1stfordowned

 

You don't have plug wires if you have COP's . You can replace the two up front , but it really doesn't make sense that they didn't. I would lean more toward one of the new coils being bad. Huh, that's strange

You describe a low grade misfire - A common load failure point IS right after the shift into overdrive @ low rpms.

I can't believe the dealer won't do anything about it. I would be in there face with this one. That must have cost you quite a bit to have all that done..

Well, you can try to isolate the misfiring cylinder .

Attempt to force a Malfunction Indicator Light (MIL) by kick starting the misfire monitor . It's difficult for the Misfire monitor to pick up a hard to detect ignition problem (low grade misfire) . This procedure may wake it up enough to detect. First make sure your Check Engine Light works. Turn your key to the run position. - It should be illuminated.

Drive Cycle - Speed up under normal acceleration to 60 mph. Take you foot of the gas and DON'T touch the brakes until you decelerate to 40 mph.

Do this twice within the same drive cycle. It doesn't have to be consecutive ,but needs to done twice to start the monitor.

With the monitor active , find the rpm range where the engine misfires and hold it there.

Watch for a blinking light thus revealing the cylinder # fault when scanned. Code is set after the blinking sequence.

If this doesn't produce a blinking light - Speed up normally to 60 mph one more time and decel down to 40 mph. Maybe something went wrong with prior attempts . Then find the misfire point and hold it their once more.

This has worked in the past for me & others - But it doesn't always. It's worth a shot. Watch for a blinking light , it will blink for a little while and then go out. The light will not stay illuminated.


Personaly, I would take back dealership - a little upset. That's just not right.

Good Luck.

 

Thanks Jbrew, I'll give it shot tommorow and post the results. I guess i could then drive to a advance auto to have the code scanned. Again thank you.
1stfordowned

 

Jbrew,
Can you tell me if "service engine soon" is the same as check engine? I put the keys in and looked in the dash and service engine soon came on, I wasnt sure if that is a check engine light or not.

I took the truck out this evening and got it up to 60 then coasted to 40
and then got it to miss but no light. I'll try tomorrow to though maybe I didn't
do it right.
Thanks!
1stfordowned

 

Hey Loweman,
Thanks! Are they hard to replace? Does the throttle body need to come off?
Tx again, great info.
1stfordowned