Contour Enthusiasts Group Archives Forums General Troubleshooting EGR Valve ? what is that

A while ago my car started 'choking' and trembling when in gear. I went around to car shops trying to figure out what is wrong. They change a O2 sensor even though it is not that problem.

Finally the guy plucked out the little hose that connects to EGR valve or what not. The car runs fine but the CEL turns on.

What does EGR really do? what would happen if I do not fix it

Thanks

The Exhaust Gas Recirculation valve lets exhaust gas back into the intake manifold. This reduces peak cylinder temperatures to reduce oxides of nitrogen which causes smog. It also allows more ignition timing advance to be run because it slows down the burning process.

Without EGR it may not pass emissions tests and the engine will ping or knock at moderate throttle.

The problem you are having is caused either by a leaking EGR control solenoid, or a bad DPFE (differential pressure feedback EGR sensor).

If pinging is occuring, run higher octane gas untill you get it fixed.

There is not pinging and nothing is wrong when the EGR tube is pulled. However it chokes and goes on the verge of stalling if it is in. So I should change the entire EGR unit?

NO

The EGR valve is open at idle because of the DPFE or the Solenoid.

Unplug the electrical connector from the solenoid. It's black plastic and bolted to the back of the UIM just to the drivers side of the coil pack. Put the vacuum hose back on the EGR valve and try it.

If it still idles bad, it's probably the solenoid.
If it idles OK, it's probably the DPFE. The DPFE is a rectangular block about a foot below the EGR valve. It's bolted to a plate on the back of the block. Two fat hoses run from it to the EGR tube near the back exhaust manifold.