Here is a good one about EGR valves

[mcalvo]

Last thursday (4 days ago) I took my 1.3 L 4 dr 1996 metro to the "car doc" to get the EGR valve replaced. He did the job and I got out of the anoying "Check engine" light. The engine sound changed (now it sounds stronger but better) and my drive is better now. The only thing wrong with the whole thing is that instead of increase my MPG, I got it decreased about 7 mpg. Has anyone and idea what is going on? EGR valve was used but looked fair well.

Some ideas what should I check now? The feeling when riding on it is the same when you put one of those "20+ HP" resistors on the AIT sensor connector.

Any idea would be truely appreciated,


MC.

[geozukigti]

The EGR will cause the car to run a bit more rich. According to OBD-II, a more rich mixture will convert better to Co2 and H20 with less N2o when going through the cat converter. So you will lose a few mpg, but emissions will be emitting less noxious gasses, but almost doubling the output of carbon dioxide. Funny that they trade toxic gasses for greenhouse gasses. The functioning EGR will reduce combustion chamber temps, and extend the life of your exhaust valves and headgasket. So I'd say it's worth losing a couple MPG. Also, are you sure now that it runs better, you're not laying a bit more into the throttle?

[mcalvo]

Naaa Geo, it is the way it works now.

Not really sure. I thought EGR valve would help reduce mpg.

BTW, tell me something: Is normal also the "rotten egg" smell? I just hate it! :P

MC

[jamcllw]

rotten egg = bad cat converter

[mcalvo]

But all this happen after I changed the EGR valve. This has not sense to me. Kind of weird, isn't it?

MC