When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Well, I changed the plugs and the miss went away. FOR ABOUT A WEEK! It's back just like before, mostly while engine is under load. The check engine light does not come on. PLEASE HELP!
Welcome to the only family Ford Truck site, on the net. If you have a minute check out the Guidelines, it will help you to navigate through and understand FTE.
Enjoy FTE …..
Alot of modules will set codes but will not turn on the check engine light unless the code is set for a given number of ignition cycles. Most car it's 3 ignitions cycles that the fault has to be present for before the light comes on (obviously, more important things like oil pressure are reported immediately, but emmisions and other BS is on "Ignition cycle counting") This same counter can be used to clear the Service Engine light, but the code will remain in History.
I'm a EE at a Automotive part company that sells parts mainly to GM (please don't grill me) and this is what we do. I assume Ford will do the same, it's pretty common
I just changed the plugs AGAIN and still the miss without engine light coming on. The plugs I removed didn't look too bad either. Please help! The extended warranty doesn't cover this. :-(
Your dealer can use their WDS scan tool to monitor the cylinder power balance with the engine running and can usually see quite easily which cylinder is misfiring. That is usually easier and cheaper than just throwing parts at it.
A bad coil doesn't always turn on the check engine light or set a code even though it theoretically should.
Does it miss just under load or at idle or?
Initially it was just under load, but not anymore. It'll even miss at idle. Today at a red light the rpm's jumped from about 600 to over 1000. Oh well, I guess I'll have to visit the dealer soon.
A miss at idle is usually easier to figure out. With it idling you can remove one COP connector or injector connector at a time and note what it does to the idle. If you remove one and it doesn't change the idle speed or smoothness you've found which cylinder is misfiring.
The jump in idle speed from 600-1000 rpm doesn't sound like just a misfire though. It could be a vacuum leak or a dirty IAC etc.