Air Pump = Hesitation/Stutter
#1
Air Pump = Hesitation/Stutter
Does anyone's 996 hesitate when you first start the car with the air pump on? If I just jump in and drive right away it stutters and hesitate for a couple seconds..
#2
Nordschleife Master
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I really don't have that issue....before I turn the ignition off after a drive I turn off the radio, A/C or any other gizmo that pulls power from the car. I do this on any car except rentals. When you start the car up with everything on, it really is hard on the car.
I also try to make it a habit to when after the car has started, wait the minute or so to allow the car to idle down before I take off. And while we are at I wait until engine temps are up before I go over 4K RPM's.
Stuff you might want to think about......
I also try to make it a habit to when after the car has started, wait the minute or so to allow the car to idle down before I take off. And while we are at I wait until engine temps are up before I go over 4K RPM's.
Stuff you might want to think about......
#3
Rennlist Member
My car has always been a little cold-natured on startup, but runs fine after a few minutes of driving. No change whatsoever when the plugs were replaced a couple of months ago. I might give the 60 second warm up a try to see if it changes anything.
+1 to what Sneaky says about keeping it under 4K until the temp comes up to normal.
+1 to what Sneaky says about keeping it under 4K until the temp comes up to normal.
#6
I hear you, mine is the same, during the first 60 seconds the throttle is not fully responsive, engine is sluggish to rev up. To prevent this frustration I usually wait 15 seconds before I even get out of the garage then while the garage door closes I add another 30 seconds until the car idle settle down. For piece of mind I also usually shuts down the AC before stopping the car, and same at start I usually shuts down radio and AC, also help listening to the engine just making sure it sounds alright.
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#8
Odd Posts
Rennlist Member
Rennlist Member
what's an "air pump
#9
I had a 2003 C2 that would stumble a little on start up during the winter whan I couldn't drive the car as often as the rest of the year. It was never hard to start. Once in a while, during the winter, right after the car would fire up you'd feel the idle drop down a bit below high idle, and then come right back up. My service rep said this was actually common on 996 Mk.2 cars. When I could drive the car every other day or so throughout the rest of the year, the stmble didn't occur.
#10
#11
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Sorry.....I mis-interpreted what you were explaining. During the first minute of starting I do let the car idle down and during that time there is a higher pitched sound. First the sound goes away than it idles down. I wait until that happens before moving the car. I think this is what you are explaining(?)
#12
ahh, very good. I did not know.
Sounds like maybe it has a clutch, like the A/C compressor.
This sounds like an interesting approach to reduce emissions without reducing horsepower.
thanks Fergus
Brian
Sounds like maybe it has a clutch, like the A/C compressor.
This sounds like an interesting approach to reduce emissions without reducing horsepower.
thanks Fergus
Brian
Last edited by brnrkm; 06-08-2010 at 12:29 AM. Reason: spellin
#13
Race Director
I almost always let the engine idle until the secondary air pump shuts off.
After it shuts off the engine is very tractable. All I do from this point is keep reves below 4K (and I try to keep them below 3.5K) until engine fully up to temperature.
Once in a while I drive off before the secondary air pump shuts off, sometimes right after starting the engine, and the engine's a little bit less tractable with a mild, very mild but noticable stumble off idle.
The Turbo's the same way. Also, I believe the Turbo's VarioCam system is operational after cold start and the lower lift cam lobes are being used. I like to let the Turbo engine warm up until the idle slows down and smooths out.
My concern is that if I drive off before this the VarioCam hydraulic lifter selectors are being activated and deactivate as the engine rpms rise and fall when the engine warming up. To avoid this and possibly wearing out the VarioCam selectors I let the engine warm up.
Sincerely,
Macster.