Engine Miss but no codes using Innova 3100 code reader

I've had this '01 Disco for about 3 months. It has 69,000 miles. It is starting to miss occassionally when I have it under a load. The typical siutation is when i've slowed down and then go to accelerate and the tranny lags in 4 gear and the engine is lugging a bit. It is usually a single miss (rather than a bunch of them) and it seems to be getting worse.
So far my Innova 3100 OBDII reader says "no codes".

The Rave CD basically sayss to rely on diagnostic codes to daignose igntion issues.

I don't have a problem getting a tune up but wonder if I should wait for a code to show up in case it is related to something else.

If I go for the tuneup...is there more to do than plugs, leads and coil packs? Are there other maintenance items that are best done when you are doing the coil packs/leads?

You may have sticky exhaust valves, try having a decabonize done to the engine, it may clear it up , if not the heads have to come off and replace the valves with the updated ones, with new seals, before you do anything check the basics, plugs , wires, sometimes those scan tools dont pick up the misfire codes.

Are you still running the original plugs and wires?


If so the first thing I would do is change them both and use Magnecore 8mm wires. LR wires are not that great to begin with and after 8 years yours have lasted longer then most.

Cheapest place I have found for the wires and they ship fast!

http://www.apexperformance.net/CartGenie/prod-1155.htm

Steve