Engine start up quirk

[Andy_V35Sky_350GT]

Its been a while since I've posted anything, but lately I've found when I'm turning my ignition on from a cold start, the engine will rev to its usual 750-1000 rpm, drop down to zero (almost like a stall) before returning to 750.

Is this normal? This only seems to have been occuring since I had my last service.

[joe603]

6MT or AUTO?

[Poyzinous]

what was done on the last service?

[Andy_V35Sky_350GT]

Auto.

Just an oil change and minor service. I also had the AC belt and bearing changed as it was wearing, but a part from that, nothing unusual.

The car has also taken on a deeper growl from both the engine and exhaust. Doesn't sound bad, actually quite the opposite, but this was related back to the belt change as before I had a very noisy belt.

[johnparkyourcar]

Its probably just a vacuum leak somewhere. Mine does that too so i have to rev it a little bit everytime i start it. But I know its from my plenum spacer. I'm just too lazy to fix it...

[joe603]

It could be nothing...or it could be more expensive. Our cars have variable timing and it changes with the engine temp. On a cold engine, you'll notice more engine growl. This is all controlled by the computer.

Good news is that if it was a major problem, you'd probably have some indicator lights.

Check around for vacuum leaks from the AC belt change (they may have disconnect items to get to it).

[Poyzinous]

it may also be losing line pressure when its off. Try this... before starting it, cycle the key to on, then off, then on again and start it. See if you smell a little bit of gas around the lines.

[tollboothwilley]

It could be nothing...or it could be more expensive. Our cars have variable timing and it changes with the engine temp. On a cold engine, you'll notice more engine growl. This is all controlled by the computer.

Good news is that if it was a major problem, you'd probably have some indicator lights.

Check around for vacuum leaks from the AC belt change (they may have disconnect items to get to it).

Its probably just a vacuum leak somewhere. Mine does that too so i have to rev it a little bit everytime i start it. But I know its from my plenum spacer. I'm just too lazy to fix it...

+1 This is probably the issue. I've also seen dirty Throttle bodies do this.

Let the car idle and listen for and air leak sounds.

[Andy_V35Sky_350GT]

Thanks for the advice guys, I'll look into it!