[ludacris]

Just picked up an '89 Taurus L, 3.0

The previous owner ran it through smog and everything passed with flying colors....but the NOX. The limit here is 2.50....the car spits out a 6.47

The car idles high, maybe a vacuum leak or IAC valve crapping out, EGR? Would that be a cause? If I recall right, high NOX readings come from a lean condition.

Any experience with this guys? Any help would be appreciated!

 

[shoz123]

EGR and timing are the key to NOx control.

 

[ludacris]

Retard or advance the timing? Could the EGR be sticking open and causing the idle problem? I'll have to take a look....

 

[901-Memphis]

replacing the EGR is the first route, and cleaning the pathways around it if you can with some sort of cleaner, maybe brake cleaner? But getting to it all could be hard.

 

[shoz123]

It is easy to see if the EGR valve is working. The valves themsevels seldom go bad. Attach a piece of vacuum tubing to it and apply vacuum. See if the stem moves.

More than likely the passage way between the valve and the intake is clogged if the valve woks.

You would retard timing to reduce NOx. High timing would cause a high idle. If the EGR was leaking at idle the rpms would be low.

 

[ludacris]

I'll hook up my mighty vac to it and see if it moves. Could I just unhook the SPOUT connector and retard timing while taking the test?

 

[shoz123]

Yes. There are two on the older cars IIRC. One in front and one in back. I believe the one in the back will retard timing 2-3 degrees.

 

[KhanTyranitar]

If your idle is high, a lean condition is propbaly a culprit.

 

[ludacris]

Finally got some time to mess with it....found some interesting stuff. Car has no EGR so that problem is out. No vacuum leaks. Checked the timing...way out of whack, way advanced. Also I noticed a piece of lamp chord going from starter solenoid to the ignition switch, bypassing the neutral safety switch and ignition module. Fixed that all up, timing is now correct, idle problem is gone. I'll run it through emissions later today is we'll see what happens. Thanks for all the info!