I've got a GReddy turbo with bigger secondary injectors and full control of timing, fuel, and boost via an XEDE.

Under ~6# of boost, I've noticed a bit of jerkiness and 'stuttering' under boost in higher gears (3-6)...more pronounced in the higher gears and at mid-RPMs. It runs smooth as butter when not in boost.

I'm running 2 gallons of 104 octane per tank of 91, so I don't think I'm pinging...I certainly don't hear anything.

Could this be a problem with the plugs or the coils? Any suggestions on how to diagnose it further?

 

If it happens in low-mid rpm when you are in boost at higher gear, it may simply be that you are running too rich at that particular load and rpm. It happens to mine also, but mine is interceptor. Mine happens if I am at 3000 or lower rpm at 5th or 6th gear, going from vacuum to boost. Do you have wide-band, and do you know the a/f at that load & rpm?

 

I don't have a wideband, but the car was competently tuned and didn't do this until fairly recently.

 

I don't know what else to tell you, but at least get a wide-band. For most of the case, it will require both dyno tune and street tune. Did you do both?

 

Who runs boost without a wide-band? Why would someone do that knowing how temperamental the Renesis is?
That is just foolish.

 

I did both a dyno & street tune.

OK, so a wideband sounds like a good idea...once I have the cash to pay for it.

So, no guesses or potential diagnoses are forthcoming?

 

Yes. Your mix is wrong at some point. That is abundantly obvious.
You may be running so rich that you are extinguishing the spark, though surging is usually an over-lean condition.
Without a WBO2S, you should park the car or, at least, stop venturing into boost.

 

or it could be something as simple as a boost leak?

double check your vacuum lines and clamps, maybe air is leaking when the system is pressurized. or maybe there's a crack in a line. i've had a crappy vacuum line crack on me on my mr2 turbo at the external wastegate nipple, most likely from the heat.

 

I will take your advice, and also compliment you on your avatars.