99 Navi

Hi .....

I recently purchased a 99 Navigator 4x4 with 74,000 miles from an original owner and love it. It has the 32 valve V8.

I have noticed it has a bit of and engine miss at idle. I ran some fuel injector cleaner through it with no benefit.

My guess is that the sparkplugs are original ...... so perhaps that is the first place to start? Should I use OEM plugs from Lincoln or is there a good after market brand?

Are there any other ignition or fuel delivery factors that I should look at while trying to eliminate the engine miss?

Thanks ...... Rob

rookie70

That's the first thing you need to do replace the spark plugs,make sure you use OEM s/plugs from motorcraft.

stang99x

Bah to the oem plugs. Use any good brand name platinum plug. No need to pay for any of the "splitfire" "u-groove" or other high performance plugs as you don't need them and they serve no benefit to unmodified engines. (on a side not, "shitfire" plugs don't do anything beneficial anyway)

You can use autolite, motorcraft, denso, ngk, etc....

If you are going to do it yourself though, be ready for a project. There are some people that can do it without removal of the fuel rail, but most have to pull the rail to access at least the #6 plug

My4sonburns

If you use Autolite, you MUST use double platinum plugs. Ford Requires it. And it is a pain to get to the number 4 plug, but I did the entire tuneup without removing the fuel rail. Invest in 2", 4" and 6" extensions and a couple of universal joints to get the job done. The spark plugs are difficult!!!

jwilson

I had the same problem at idle and when running, went to advance to put it on the machine, said spark plug #1 misfire, replaced plug ran ok for 30 minutes , went back next day same reading, I then replaced the wire going to that plug and it fixed the problem!