Hi folks,

Car runs a bit rough every now and then (not always though,most noticed on cold mornings), feels like engine is not coming into boost and losing power. I also get hesitation on high boost with half throttle (24psi). I have replaced the plugs (NGK ILFR7H), fuel pump (Walbro 255), MAF sensor, getting new NGK ignition coils and leads also front O2 sensor.... I was wondering if this could be a boost or vacuum leak or air temperature sensor??? But it's weird as the problem doesn't occur always! Dyno test was done and the power was dropped by 20kw@wheels compared to 5yrs ago when it tuned. I like to hear some expert advice. Thanks

 

maybe do a compression check. how about the turbo wg actuator?

 

Compression test was done and they all seems to be healthy. Engine had no sign or missing or detonation on Dyno test. I was told, drop in power is normal it could be related to many parts especially the aging spark plugs, so I replaced all plugs with Brisk, engine ran fine for a couple of days after I started to get misfire #4 error code so re-gapped the plugs but the problem returned. So, I replaced Brisk with OEM NGK plugs and that fixed the problem.

if the turbo wg actuator ceased or stuck, shouldn't it be a problem that occurs every time I drive?

 

Boost leak?