Hi Guys,

I have an issue where intermittently the engine (EPC) light would appear and the car would either go into half limp (turbo does not spool and cannot exceed 4k revs) or full limp (car will not rev above 2k) and when in full limp the car misfires badly. Most times it seems to help just restarting the car but other times the problem persists for a day or so. I have been looking into this and I get everything from basic coil packs to fuel rails. Any way I could test this?

 

First thing to do would be to pull codes. This should tell you where the engine is having trouble. Is it multiple misfires or only 1 cylinder? If it comes down to 1 you could move the coil pack and see if it moves along.
Codes should also help with seeing if the engine is having other sensor related issues, or if you are running lean, etc. Bottom line unless you have more information on what exactly is going on - it comes down to a wild guess and a wide range if things to replace (spark plugs, coil packs, fuel related things, throttle body or air intake, etc - the list goes on).