I have a 2013 MCS with 58000k miles on the clock. At about 35000 miles, I added the following mods: Manic Stage 2+ tune (93 octane), cold plugs, FMIC, DP with 200 cell cat, intake muffler delete pipe, GFB diverter valve and K&N flat panel filter. Needless to say, it's a blast to drive.

Several months ago, I began to notice that the power pulsates under moderate to hard acceleration. It does this on all performance maps including the stock map, so I do not believe it has anything to do with the tune. There is no CEL or other indication that anything is wrong. Fuel consumption is normal and it drives fine otherwise. I recently changed the plugs, serviced the air filter, cleaned the MAF sensor and pressure-checked the intake system to 25 psi, but it made no difference. Attached is a data log showing airflow and fuel flow pulsing at about 3 cycles/sec above 3000 RPM during WOT acceleration.

Has anyone else experienced this? Any ideas?

 

I have pretty much the same mods, including Manic Stage 2, and I see the same pulses. I also have a boost gauge, and I see the boost pressure perform the same dance at full throttle excursions. I was about to start a new thread, but since you have...

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Nik,

Thanks for the quick response.

I only notice this behavior when the engine is fully warm and winter/summer makes no difference. It did not do it when the mods were first installed.

I've even added 3 gallons of E-85 to a full tank of fuel to bump the effective octane. Again - no change. I am hesitant to start changing out sensors etc. without hearing others' experience first.

Rick

 

I am leaning towards the pressure control loop of the waste-gate in the Manic program. My car did not experience the behavior with the OEM tune, only after I had the Manic tune loaded. With the Manic tune, regardless which map, "Stock", A, or B, I notice the pressure control behavior.

I'm interested to hear what the experts have to say.

 

I have nearly identical mods as well (besides downpipe).
I think I have the same issue. Maybe MarioKart can chime in?

Although, I think at this point this isn't really a "stock" problem