Everything is a shot in the dark other than that. I'd suggest putting a good fuel injection cleaner (Techron or equivalent if available) into your tank and driving out on the roads this weekend. It may or may not work, but at least you'll be out enjoying your car.

Let us know what it turned out to be, please.

 

Hi Dadio, I'll try check the throttle body this weekend. The bit that worries me the most is when the hesitation happens it's always at about 1200 RPM consistently.

Hi JB, will post the update on how it goes. Thx.

 

A build up of a oily mist and dirt tends to accumulate at the very bottom of the intake plenum where the butterfly rests at idle. At 1200 RPM's the plenum is only open slightly at which point the grime may well be blocking the air flow, if only slightly, between the plenum itself and the walls of the throttle body. Resulting in hesitation until the throttle is open further and the air flow is more normal. Cleaning with throttle body spray ( would suggest throttle body cleaner over an older style carb cleaner as it evaporates more quickly and may be less caustic ) cleaner will remove any buildup which cold be causing your hesitation.

 

I agree with this. Make sure you drive it as if you stole it. Put as many miles as you can. I use Techron every 1,000 miles before each oil change. If you have full tank, I think you would need 2 bottles.

You have nothing to lose experimenting with this route

 

Stop that. The stutter/lag you notice is the result of the switch over from low lift to high lift (courtesy the VarioCam Plus system). My info is it switches over around 1400 rpms.

 

Does this mean it's normal? Bad switch? Where is the switch?

Thanks.

 

Do you mean this is the normal result of the switch? Or a bad timing of the switch / between the two sensors? I thought the VarioCam kicks in base on the driving behavior and condition, not always at a certain RPM?

Thanks

 

FYI, I just drove my 997 and I don't have that stutter.

 

Having the exact same problem so checked the throttle body as suggested, mine did have some oily residue buildup but what I did notice is that the butterfly does not completely close off unless pushed back in position....is this how it should be??

 

You might find my thread about throttle body cleaning helpful.

https://www.6speedonline.com/forums/...-cleaning.html

 

Yes. That is the normal position of the butterfly. Did you clean the throttle body and check to see if it eliminated the stutter ?

 

Thanks for that, good to eliminate the butterfly as a problem. Just in the process of waiting for my K&N filter to dry out after a clean out then will see if that fixed the problem

 

Quick update:
- MAF, Airflow sensor, and throttle body were cleaned - problem remains
- spark plugs were replaced - problem remains, but slightly less frequently and doesn't stutter / lag as bad as before

 

One more no cost suggestion, try disconnecting the battery, negative terminal only. Let it sit for 10 minutes an reinstall. Process works like rebooting your lap top and restores original factory settings.

Beyond that, have you checked for any codes with a code reader ? Misfires would show up on a Durametric tool and narrow down the possibilities. Maybe a coil pack on the misfiring cyclinder.

 

one more step from my local well-respected indy: after batt reconnect, turn your key on to pre-ignition (or whatever it's called) but dont start...keep it there for a minute, then turn off again. after that, the reset should be good to go.