EGR function

[SLATRON]

So car is 07 Sebring 2.7l with 185k. I'm wondering how the egr operates for this application or all-around.
Late last summer threw egr code, part looks pretty crusty n was gonna replace. Some time passed and engine light went off if sat for awhile. Only comes on when hot outside 70+ as it is now. And won't come on during city driving or highway if on the throttle. But say on highway getting off ramp or long coasting downhill, foot off gas, the light pops up. All winter code stayed off since last sept I'd guess.
I'm just wondering if anyone can explain this for me, ive gotten so I can pretty much keep light off by how drive which seems strange to me. I asked mechanic whose gonna fix this and had no idea, just probably thought I was weird.

 

[BigCahuna]

I replaced the sensor on my Explorer when it thru a code. I checked around online, and the general thought was the EGR valve rarely goes bad, but the electrical sensor which reports to the computer is more then likely the culprit. Plus the sensor was $22 vs $79 for the actual Egr valve.I'm not saying that's your problem, but do a search online. It might save you some bucks.,,

 

[eljefino]

EGR is a source of inert gas to cool combustion and keep NOx emissions down. Since exhaust has no oxygen it's a convenient source.

When it opens, typically, it changes the vacuum slightly in the intake manifold without the throttle moving. The computer monitors both and knows if the change isn't enough, and flags the code.

Vacuum leaks and sticky EGR valves are the biggest ways to run into trouble. Sometimes you can pluck the EGR valve off, clean soot out of it, and out of its passages to the manifolds. If you run the car without the valve it should

1) make exhaust noise from that end and
2) idle high from the intake leak.

 

[Astro14]

and...

3) ping like an SOB...because the spark advance was predicated on a mixture that was diluted with exhaust gas...the computer might be able to compensate...might not...

 

[SLATRON]

Thanx guys, that's basically what I found looking at sites but was wondering why only does it when hot 70°'s+. Stopped completely for 7-8 months, it must be used more to cool than reduse emissions? The first day it was over 70° out CEL popped up driving down big hill.

 

[Merkava_4]

If it's an electric solenoid operated valve which it probably is, it could stop working if it gets too hot. Those electric EGR's are constantly moving all the time. The solenoids burn out over time. The best way to check it is to hook the car up to a scanner that reads EGR opening percentage.

 

[Warstud]

What EGR code are you getting?

 

[SLATRON]

Don't remember off top of head, I'll get it, can't be done with key "dance"