Hi there, since my previous thread got lost I'll try again:

My 93 won't pass smog test at idle...2500rpm test shows very low emissions but at idle she's a gross poluter. Does anyone have an idea how I can correct idle A/F mixture with out messing up drivability or cruising emissions? Obviously it is rich only at idle so there must be someting wrong there. There are no other problems that I know of, i.e. drivability and power are good (except for a very occasional stumble when up shifting, right after releasing the clutch).



I have installed new plugs, wires and air filter. The cat, egr and air pump are not likely to be an issue since they don't come into play until higher rpm and load conditions are present.



The exhaust smells realy rich at idle so I wonder about things like:

TPS, MAP sensor, temp sensor, air leaks etc.

Can any one tell me what these should read and how they would mess up idle but not drivablity?

 

Is your car stock? If not, what mods do you have?

 

I'm not sure where you got this information, but it's 180 degrees from the truth.

The catalytic convertor is 100% of the time the single biggest factor in emissions, idle or otherwise. Yes, the EGR is triggered at idle, and absolutely the air pump is running at idle! In fact, idle is the only time when the air pump should be running. Check out your airpump, be sure it's connected properly and that it's drawing air from the filter. You might consider diagnosing and cleaning the EGR as a stuck closed EGR will cause an overly-rich condition. (The opposite is true if it is stuck open - overly lean causes a rough idle)

 

egr in the fd only works at cruise, and its very small.



important things are the cat and the air pump air control valve

 

Also, make sure the cat is hot. Drive the hell out of the car and then let it idle in the parking lot before the test. The cat works best when it is hot. Perhaps your car failed at idle because the cat was not hot enough.



-Max

 

also check the fpr vac hose. if it is split or is leaking unmetered fuel will be entering the engine. a cracked vac line will also raise the fp at idle when it should not be