Last week I put Tubi mufflers on my 06 997 3.6
Now I have a rough idle, especially upon initial start-up in the mornings. Once the engine warms up the idle is smooth. Comments?

 

Doctor K,

The reason for your rough idle at startup is because of the secondary air injection equipped on the 997. When you start up your car from a cold start, the secondary air pump kicks on and pumps air through the exhaust manifold to heat up the catalytic converters. This is for emission purposes. What you are noticing with your vehicle is totally normal. It is just a little more pronounced because of the higher flow Tubi system. No need to worry.

 

Thanks GoFast for the info. I can sleep better now.

Doc

 

The air pump will not cause a rough idle (unless it is not running), It increases the idle speed for a munite or 2 and then pulls it back. The idle should be smooth whether cold or hot.

The pump works in conjunctuion with the fueling which is richened up when the pump is running.

Have you tried cleaning the MAF?

 

Yes those are 20" RS128's.

 

Car has 2075 miles. I haven't touched the MAF.

 

Doesn't matter how how few miles you have, the car should run idle smooth at all times. Any other symptoms. Slight hestitaion or idle drop when starting out. maybe?

 

Dr K, I'd have the dealer check it our for you. Sounds abnormal and unrelated to exhaust to me. Doc, not time to heal yourself. Good luck!

 

Thanks guys. I am going to take the car in next week to the dealer as I believe the shifter needs an adjustment (going from 5th to 4th can be a little touchy and it wasn't this way 4 months ago.) I'll have them check everything at that time.