Cold engine and rough idle

[riquuu]

Hey,

couple tiny problems/questions:

1. My Boxster is a bit "abrupt" when the engine is cold. When taking off and changing gear from 1st to 2nd etc. it feels like throttle stays on. After the engine warms up a bit, the problem disappears.

2. When starting the warm motor, idle is normal. After few seconds idling and revs starts to go between 600-800rpm. It does that rough idle couple seconds and calm down. Then the car works norm... perfectly .

I have changed spark plugs and air filter, cleaned coils and cleaned MAF with some special cleaner.

Any ideas/reasons for this kind of problems?

And of course the car has the manual gearbox.

Thx for help

[yimmy149]

Have you cleaned the throttle body (if you have eGas)? That can get gunked up and may not be operating smoothly. I forget if the non-eGas cars have an idle air control valve, if so, maybe it needs to be cleaned or replaced.

[j.fro]

My vote is that you have a very small vacuum leak in the intake tract after the TB. Check the hose connecting to the air oil separator for cracks or a bad seal. Next, check the rubber boots connecting the intake plenum. Any of those will cause the engine to still be getting air, making the revs not drop when you let off the gas. With a really small leak, as the engine heats up, things will expand, closing the leak.
Happy hunting

[thstone]

Cleaning the MAF will not fix a failing MAF. Try disconnecting the MAF and see if the car runs better. If so, then you've found at least one piece in the puzzle.

[riquuu]

Thx for help!

I'm quite sure there was a vacuum leak after TB. I tightened all 4 clips which connect intake tract and tb. All clips were very loose.

I've started the cold engine couple of times today and no problems at all! Also when the engine is hot, idle is very stable. When pressing the clutch rpm's drop to 800 and stays stable. Before rpm's went to 600-650rpm and then raised to 800. The car is now much easier to drive in city.

Anyway, i may change it to ´86 911 next week :\