Hello all I just replaced my plugs on my '04 5.4. I know your wondering so here it is. We broke 6 out of the 8 and this was the second plug change at 238,000 miles. I replaced all the COP. Prior to the change The truck ran smooth with an idle around 900RPM. After the change the idle RPM after the truck warms up is around 500RPM and every so often I feel it skip. I have checked the connections on the COPs and all seem to be tight. Have any of you had an idle change after a plug change? I an not getting a CEL to come on so the scanner shows nothing. I am guessing one of the COPs may be bad but until it throws a light is there anyway to find out with our randomly changing COPs?

 

Hi.

Yes. You need a high-end diag scanner that shows Mode $06 stored pending misfire codes. Good shop or a dealer. Expect to pay a fee, though.

You used new boots, fresh dielectric, and used SP-515's right?

For COPS, Motorcraft or Visteon - else expect to have problems later.

A straight plug change should not change idle speed. That's fixed in the PCM.

Good luck.

MGD

 

Just fyi... the Torque Pro app for Android reads Mode $06 codes and is probably cheaper than a visit to the shop.

 

Thanks - I was hoping someone would confirm that.

Care to recommend a quality BT dongle for the OP?

OP - you have an Android smartphone or tablet ( that supports BLuetooth )?

This would be a great and much less expensive alternative. A dealer charges ~$90 to hook up to diags, once.

Thanks again, Theo!

MGD

 

I had this problem after my plug change. Got my code and I pulled those boot back off and put sure enough i forgot to put new dielectic grease on the boot end. put a dab on there and the idle came back up.

 

This dongle is the one I got:
It works well with Torque Pro, looks at the $06 information, very cool.

Edit: I am also getting a somewhat low and erratic idle after COP and plug change...the OBD tests indicate a very sporadic misfire on no. 1 cylinder, like one misfire in 30 minutes of driving , so I don't think enough to cause the low idle. Would one poorly installed COP be enough to cause this? I have a 600-650 idle, real time stats on OBD.

 

Just throwing this out here but did you try the battery relearn process after changing your plugs? Here I'd the thread on the process:

https://www.f150forum.com/f72/batter...rocess-133736/

I know it has helped others who we're experiencing similar issues to yours after changing their plugs.

 

I had a COP nightmare over Cmas, paid over 700 with towing to do the back rear COPS, when I got the thing back, I swapped out the other 6, and went through the relearn.

Then recently, I did the trannsmission pan drop, new filter, etc, and so disconnected the battery too (both terminals), got a whole slobber of red Vaseline stuff off the posts, put a nice thin coat of vas on, tied everything together and went through the tranny refill, THEN disconnected again, cycled through key on, lights, etc., put the battery back together, and specifically went through the learn process as outlined in the link.

 

What is the "cycle through key on, lights, etc" that you are referring to? Haven't heard of that before - only about the battery relearn process.

 

I was just referring to what some folks do when the battery is disconnected; they cycle through turning the light switch on and off, and the key on and off, just to purge any electricity in the system.