Hello, I have a 2003 L that has started giving me problems. The truck in not throwing a mil/check engine light so I have no codes to cross reference. The truck will intermittently stumble or miss at idle but a blip of the throttle gets it going and idling normally. When it starts the stumbling and you give it gas to accelerate it will stumble at first then go as normal. Today it started stumbling and giving it gas does not stop the stumbling any more. It will accelerate but with power loss. I have changed the spark plugs, fuel filter, and cleaned the K&N air filter with no improvement. I purchased two new o2 sensors but have not installed them yet. What is confusing me is that the problem comes and goes, the truck will drive normally for a few miles (with normal power) then it will start the stumbling/missing. What do you suggest I do next? Has any one had these symptoms?

 

Sounds like a coil pack is starting to go bad... been there. Where are you located?? I have my stock coil packs laying around if you need to use them to troubleshoot/fix your problem.

 

I am in McKinney TX, just north of Dallas.

 

How do you check the coil packs other than taking one off at a time and replacing them with a known good one?

 

Mine did that (2001L) at about 80K, and it was the idle control valve, it’s mounted on the Passenger side of the plenum. I also got a standard one (F-150) the only difference was that the lighting one has a 90 deg plug and the standard one is strait out, but it will work… It’s also an inexpensive item!

That will fix the idle stumbling problem, now the lack of power I’m uncertain, maybe you can use the fly swatter to check you coil packs!

 

What do you mean use the "fly swatter" to check the coil packs?

 

It’s a device that looks like a fly swatter, http://www.sjdiscounttools.com/wae76560.html $59.74 The link dos no longer work, but if you go to the HALO club site it will show you a picture of it.

http://haloclub.com/forums/viewtopic...338&highlight= Here is the tread at the halo club

 

http://www.tooldiscounter.com/ItemDi...le&kw=WAE76562

http://cgi.ebay.com/ebaymotors/Waeko...QQcmdZViewItem

http://www.thefind.com/garden/info-p...k-probe-tester

Found it see the top links, the price has gone up, WOW inflation I can’t believe it!

 

Dam i forgot about the IAC... could be the the problem. I have 104k on my 2000 and have been through 3 or 4 of those crappy sensors.

 

is the tune rich by any chance????