Ladies and gentlemen, start your.....FANS!?

[jaylibby]

Quick question....s....
Is it just my smart, or do all of them have that crazy fan noise in the back whenever you start up? It starts as just irritating for about 10 seconds, then it goes to a high pitched winding spinning sound for about 5 seconds...then stops and all is quiet. It's hard to keep my passengers convinced it's not electric when the fan sound is drowning out the engine! I don't really mind, just curious..

Also, when in reverse does your smart sound like a wind up toy too?

[John_H]

Reverse on almost all cars has a "sound" to it when you go more than 3mph as far as I can recall.

A rather long quote from the tech "Introduction into Service Manual" for the other issue:

Secondary air injection

Engine 132 is fitted with a secondary air injection pump (electric air pump), which injects additional fresh air in order to reduce exhaust gas emissions after a cold start and to accelerate the warming of the catalytic converter to its reaction temperature.

The necessary air is injected into the exhaust ports in the cylinder head by the secondary air injection pump via the combination valve. The secondary air injection pump is actuated by the ME-SFI [ME] control unit via a relay.

The secondary air injection pump switchover valve is supplied with vacuum from the vacuum reservoir at the intake manifold via a check valve.

When actuated, the secondary air injection pump switchover valve releases vacuum to the combination valve. This opens and the air injected by the secondary air injection pump passes through to the exhaust ports in the cylinder head.

The injected air reacts with the hot exhaust gases in the outlet port. The carbon monoxide (CO) and hydro-carbon (HC) are oxidized. This "afterburning" process increases the exhaust temperature and reduces pollutants.

The duration of secondary air injection is dependent on the coolant temperature.
The secondary air injection pump is only actuated at a coolant temperature of 45 °F to 97 °F (7 °C to 36 °C) and for a maximum duration of 33 seconds.

[jetfuel]

Originally Posted by jaylibby

Also, when in reverse does your smart sound like a wind up toy too?

...what do you think gets you to go forward?

jetfuel

[sato7]

Jetfuel you are a riot!

[Woody14619]

Originally Posted by jaylibby

Quick question....
Is it just my smart, or do all of them have that crazy fan noise in the back whenever you start up?

It's part of the emissions system that turns on when the engine is cold. I actually asked about it the first time I turned my car on, and the sales person didn't know what it was either. Worse, when we turned it on a second time, it didn't do it, because the engine was already warmed up. We started another car on the floor though, and it did the same thing, and the tech knew what it was.

As for the reverse noise, I've heard worse. I had a 85 Nissan Sentra back in the 90s that was 3 times louder in reverse. I swore I could hear the spring coiling like in those old toy cars you could pull back and then let go and launch across the floor.

[SmartDigger]

I think it is a blower fan on the cat to speed up emission control.