the car drives fine when below 4500 rpm, and it accellerates fine under WOT, only when light acceleration is applied and there is some boost built will there be slight bucking/hesitation. Could this be a TPS out of adjustment? That seems like the most likely cause to me. Anyone with a similar problem?

M2 ecu, m2 intake, downpipe, exhaust. Relatively new plugs, wires, fuel filter.

 

Could be alot of things, first thing that comes to mind is a grounding issue with your secondary injectors? (Bucks about when they come on.)

Hopefully somebody else can chime in!

Does the hesitation happen when you are not under load?

-rotary4tw

 

well if ur driving slow up to that rpm it might just be dumping extra fuel cause thats when the secondarys come on, why dont u shift at like 3,500 if ur gonna drive slow.

 

do you have an EGR valve? if original they are known to stick open sometimes...

 

Have factory EGR, happens with some load on engine, like when part throttle out of turn or balancing in a turn. There is some boost and it is steady. Boost pattern is good. Almost feels like knock sensor pulling timing. Could it be that? I have some upgraded ground cables. I have added one to the iron between the spark plugs, and changed the factory ones to better wire and ends. What are symptoms of TPS out of adjustment?

 

just checked TPS and it is in range. Does anyone know how to retrieve check engine light codes? I will try to search now.