Secondary Air Valve Replaced

[kulak]

Recently my check engine light came on. I noticed that my gas mileage seemed to drop noticeably. I was concerned but the engine was running acceptably so I drove it till I was at the 5K mark. I scheduled an oil change at the dealer in Sacramento, Ca. I told them to check the engine light codes to see what the problem was. Evidently it has a bad secondary air valve, whatever that is, so they replaced it.

That seemed to fix the problem. No engine check light and the car did seem to be running better however I have never been able to get close to the 50 mpg mark since. At one point just after I got my Smart Pure I calculated that on one trip I got 51 mpg! Now the best I can get on a highway trip at 60 mph is 42 mpg?

My questions are.
1) Has anyone else had this problem and noticed their MPG go down?
2) Does 42 mpg seem correct for a trip at 60mph?

[h20m0f0]

Yes I had the same thing happend about a month after I bought my Smart Car and I too ask pretty much the same questions as you. The secondary air intake has somthing to do with the exhaust system I was told and yes my MPG went down as well, But 42mpg is all I get and I think thats pretty good.

[JPaul]

Originally Posted by kulak

...
2) Does 42 mpg seem correct for a trip at 60mph?

It seems a bit low to me.

I got 44 MPG on a round trip DC-NYC at ±70 MPH.

But then, everyone's driving is different. And let's not forget that there are so many variables that a one tank's average is not enough to have a valid estimate.
In my roundtrip example, the leg North was a stunning 47.6, but the return was only 40.6. This is possibly due to the different pump used in NYC. But, as an average, I did use the same pump before and after the whole trip, at the same click, at the same time of the day, but three days apart, and it came out to a more realistic average of 44.13 MPG.

[Old smart]

Originally Posted by kulak

Recently my check engine light came on. I noticed that my gas mileage seemed to drop noticeably. I was concerned but the engine was running acceptably so I drove it till I was at the 5K mark. I scheduled an oil change at the dealer in Sacramento, Ca. I told them to check the engine light codes to see what the problem was. Evidently it has a bad secondary air valve, whatever that is, so they replaced it.

That seemed to fix the problem. No engine check light and the car did seem to be running better however I have never been able to get close to the 50 mpg mark since. At one point just after I got my Smart Pure I calculated that on one trip I got 51 mpg! Now the best I can get on a highway trip at 60 mph is 42 mpg?

My questions are.
1) Has anyone else had this problem and noticed their MPG go down?
2) Does 42 mpg seem correct for a trip at 60mph?

What was the car's build date? That problem should have been factory-cured after about July '08.

[kulak]

Not sure about the build date but I took possession of the car back at the end of April. How do I find the build date?

[jwight]

Originally Posted by kulak

Not sure about the build date but I took possession of the car back at the end of April. How do I find the build date?

Sticker on driver side door jamb; look for the date on the top right:

[kulak]

Thanks mine reads 04/08

[Woody14619]

Also consider: The winter mix is in for gas right now, so MPG is going to be a little lower based on that for the next few months. Not sure how far north you are in Calif, but if you're mid to north, that may be affecting you as well. I've seen a good 10-15% drop in MPG since the winter mix and snow tires went on.