Hello All.

I have a 2003 F-150 4.6L that just started to shudder whenever I accelerate. It even does it sometimes when idling, but not always. The check engine light has not come one at all, and that's what is confusing.

I went ahead and changed the plugs and fuel filter, because it was time anyway, but it didn't help. I also cleaned the MAF sensor.

Any ideas on what it could be would be greatly appreciated.

Thanks!

 

prolly is gong to be a weak COP ( coil on plug) .

did you use dielectric grease/compound on the boots when you changed plugs?? How about inspecting the boots themselves for pin holes or tears?

 

What^ he said, plus, what plugs did you use? Has the throttle body ever been cleaned?

 

Are you sure the shudder isn't from the rear end?

 

My money's on Coil On Plug too. Last plug change, did one or a few of the COP boots look funked a bit? Orangeish, swollen, just different than the rest?

 

Just had same exact issue. I got so mad because there was no CEL on so I went ahead and changed COPS and USED dielectrical grease. Problem solved! It was a slight vibration at accel then just got worse to the point it shruddered at idle.

 

My truck is a '99 4.6L and does almost the exact same thing. It does it only in first gear, though, right when engaging it. I don't know what it is either. I haven't done anything yet to try to fix it. I'm curious to see what others say.

Good luck!!

 

referr back to posts #2 & #3 & #5 the COP's just haven't detereiated enough to generate a code

 

My truck started doing the exact same thing last week, but my CEL actually came on and started flashing, so I figured it was a COP as well.
Mine would actually start shuttering around 30-40mph, but once it shifted and got past 50, it disappeared.

So from what I am reading and researching, the Global Automotive COP's are junk now... and i couldnt find any on ebay anyways... What does everyone recommend?

 

most are going to recommend to stick with motorcaft.
have you tried "rockauto.com" ?

 

It's been a while since I've bought anything off RockAuto. I'll check them out.

And I didnt continue driving the truck when it was misfiring. I had turned around about a mile from my house and was on a straight stretch and I just wanted to see if it stopped after a higher RPM. A few years ago I had a 97 F250 light duty with the 5.4 and I had to replace the COp's then, and I remember purchasing the Global's off ebay then. I didnt have any trouble out of them, but it was about 5 years ago.

Thanks for the info enriched!

 

I recently replaced my CoPs, I knew enough to stay away from the ridiculously low priced ones on eBay. I was debating between Motorcraft and MSD, but ended up buying Summit Racing house brand because of price difference - set of 8 for $175. Summit is always a rebadged product, but its almost always from one of the top brands. Example Summit Carbs are Holley. I don't know who makes their CoP's but I took a chance based on reputation and the price warranted the risk - half price can last half as long and all I am out is my labor. If it doesn't work out, I would use Motorcraft without hesitation.

I regularly use RockAuto and have no complaints. IIRC they were competitive but not the cheapest for CoP's on my 2v - I think Summit was still cheaper on most brands after shipping. I also recently bought a front valance from Parts Geek because their shipping was $35 on that part vs. about $100 for everyone else so I've added them to my list of sites to compare prices on. There is also nothing wrong with the local junkyard if they have a low mileage wreck and have a return policy.

 

I'm with several others, having the shudder at lower rpm/ idle and its getting worse.
How can I 'test' my COPs? For weakness? I tried unplugging/listen/watching method,but that has not work for me.
Thanks,
Matt

 

you can look for Visteon cops which are Europe version of Motorcraft

 

Finally fixed. I never received a CEL, but one of the COPs was slightly orange around the boot tip. I took a chance and replaces it, and all is well now. I also had water in the tank. Apparently my daughter thought her truck could float.

Thanks all, especially BLUE20004X4 for the hint on the orangish color.