It gets a bit annoying.

I noticed that my truck starts has quick vibration like 1-2 sec then it's gone it's between 40-65mph. it happens once a while. No wot, just normal driving , not downshift. Only upshift

I feel like I hit rumble strips by side of road.

What's it ??

No engine tool light on.

I'm clues less

Thanks!

 

Does it do it under light acceleration right after it shifts into overdrive? If so, that's a low grade misfire - plugs and/or cops.

 

Yeah sound like that.

Low grade misfire - what does that mean? Soon to be fail ?

I replaced the plugs approx 15-18k ago

Its now 112k

The cop is original-

Guess try cop first?

Will ford or shop test it for me to see if its low grade misfire or cop is shot? Instead for me to keep guessing ?

Thanks!!!!

 

Did you use Motorcraft plugs?

Testing the cops is difficult - you pretty much have to troubleshoot by substitution unless you can get it to throw a CEL or you have a scanner that can monitor Mode 6 data.

 

Yup, motorcraft plugs ��


I guess I'll wait for tool/engine light on.

I do have scanner for it (scan gauge II) it's basic cheap one ha.

Thanks

Jake

 

When you replaced the plugs, did you replace the COP boots? If not, I would start with those. Think of them like ignition wires. Clean the contact in the cop with a fingernail file, and use a small dab of dielectric grease where the boot spring meets the cop and plug.

 

No, do not put any grease on the spring - only on the inside of the boot.

 

No i didn't replace COP. Just sparks.


Thank you all for help me out.

Jake

 

You can buy boot and spring kits for a fraction of the cost of cops.

 

Updated:


I wanted to try cheap way first before dump $250-300. So I put approx 30 oz of Techron Pro fuel injector cleaner, cleaned throttle choke and map throttle and I haven't notice any sudden rumble at all for almost 2 weeks

Hope it is not tempy fix LOL

Thanks