I am trying to track down a issue in my L and want to know if anyone has an idea if its tunning or parts issue. At high boost or comming out of low rpms, I get some breaking up in the engine, kinda feels like a miss. It dosent do it all the time, but I can feel it when I stand on it, or when I hit it in high gear to speed up. Truck has stage 2 cams and heads, LTs to X to cat back, and has a tude on it, but from the paperwork I have, that was back in 07. Not sure what else has been done to it since then, can tell a diffrent pully is on the lower, and the truck came with a diablow handheld, so someone has added a tune or adjusted the tune. In low boost and like part throddle, its smooth and no shuddering, but if I really hammer it, I get all kinds of random shuddering in the rpm range. So anyone that has an idea where to start looking, do I need some new plugs or something, or am I in need of a new tune on a dyno?

 

first of all I wouldn't keep hammering on it to try to get it to do it again...


Does it sound like detonation? Chain dragging sound? Do you have any Air/Fuel ratio guage?

 

No, its not like detination, more like a miss/studder, like theres either too much air, or a spark being blown out. I dont hammer it, and havent done any WOT pulls, but what gets me is when it does it at low rpms in high gear, so Im thinking something with the fuel, spark so that will lead to tune or new plugs or injectors. I havent messed with FI before, so just looking on where to start the search for this issue. Also, no a/f gauge, just a boost and exhaust temp gauge that came with the truck. I dont want to go into tossing money into a tune right away when it may be a easy plug change. I am going to do a oil change and tuneup after the holidays just to have the knowledge of its done and so I can track maints on it.

 

Get down to basics first. Whens the last time the truck had a new set of plugs? Stall it up and see if it misses. Ever replace the fuel filter? Low fuel pressure can be a cause. Check the intake tubing (and while your there check all the vacuum lines) for leaks, as unmetered air can cause what your saying. How hot do the egt's get? To hot=lean mixture=lean misfire.

 

those coil packs are a really common problem on the ford mod motors. do a power balance test. might need a couple new coils. i've had to replace a TON of those at work due to that