jeffrec

2009 C2S 6MT and I have the same problem. Here is what the guys at PCA told me when I posted on their website.

While this is not a known issue with a published repair I believe I am familiar with your concern. I believe what you are experiencing i a mix of the vario-cam system actuating in conjunction with the tuning flap in the intake manifold. While the exact RPM varies dependent upon engine load and other factors, the variable lift begins to change from low lift to high lift around that period of time you describe. Also, the intake manifold tuning flap closes at 2600 rpm to help increase mid-range torque on these engines. It is very possible that you are noticing these events which are not a problem so much as a part of the normal operation of the engine management system.

Bruce In Philly

Good stuff, that is what I understand also.... and given that I alse hear a "Phss****" at the same time.... makes sense.

But..... doesn't the flap OPEN and not close over 2600?

Peace
Bruce in Philly

keinmitleid

2011 c2s, no hesitation, but with straight pipes on my car it is extremely noticeable noise-wise.

MichaelC4

2006 C4 6 speed mt - I was going to ask about this "flat spot" I have. Thanks.

FireHouse1

It would be great if someone had a fix. Hopefully someone out there can help.

platinum997

997.2 .. I noticed this today when I was in 3rd. I am never in 3rd under 3k rpm so first I noticed it. Don't have the issue in 1st or 2nd.

With that said, there is a noticeable sound increase at 3k in any gear.

Bruce In Philly

It is not related to gear per se (gear changes load)..... it is related to the load and how much throttle you have (and assuming the vaiocam starts out in low position as you accelerate). If you floor it, you will never feel it.

I suspect Porsche can mitigate it by moving the thresholds a bit via software.

I still have hope for a solution but it ain't gonna happen. Call it charm.

Peace
Bruce in Philly

platinum997

That makes sense.. I don't floor it but do drive the car moderately aggressive typically. Today I was just cruising around in 3rd and lightly went through the rpm in 3rd (2000-5000).

I am typically always at 3500-4000 cruising around regardless of gear which is above the trigger point it sounds like.

westgate997

same here....

docdrs

Oh great, you mean I now have to feel for this when I drive.....is this the new ims or borescoring telling me my engine is about to spin a bearing

Bruce In Philly

LOL! The neurosis spreads.... heheheheheh.....

A: this is not new..... been around for a long time... for me, my '09 is eight years old.
2: there are no failures from, repairs for, or ways of mitigating this issue I am aware of

Again, it is charm... or as we used to say in the software business, "An undocumented feature".

Peace
Bruce in Philly

lowbee

I have softronic tune and the "pazzzzit" sound around 2500-2700rpm under light application of throttle is more noticeable than before but I never felt a flat spot or hesitation before or after the ECU tune..... so who knows....

lowbee

This "pazzzit" sound is on my mind today ...... I am sure this is something related to the aging of our cars as I've never heard this sound 6 years ago when I first got the car.... I am quite sensitive to sound so I would have noticed it if it was there. In fact, thinking back this sound might have just started happening this year. Hopefully, someone figure this out soon....

the_buch

For some reason I think the variorum actuator is oil-pressurized, which has me wondering if it gets a bit lazy as the oil pump wears over time? For me, this characteristic is worse first thing, but I wouldn't know if that's because it improves after warming up or if, once warmed up I'm likely to blast through this rev range a bit more ambitiously? I'd also presume if there is some sort of actuator it/they can be replaced?

Bruce In Philly

Hehehhehe. Hehehhehe hehehehh..........

Peace
Bruce in Philly