Clearing DTC codes and scanner operation

I just got a scanner, and also recently failed the emissions part of a NY State inspection because the test equipment indicated "not ready" for three functions: -Evaporative Systems, Catalyst, and EGR. (Car is a 1998 Windstar 3.8)

The "not ready" was almost certainly due to the fact that I had just had my alternator and battery replaced, and had not driven the car much before the inspection. (clearly a mistake). The Service Engine Soon light was not on before or after the test, and had not been on for many months of driving.

After driving about 50 miles, at high speed and stop and go, I returned to the shop, but the readout was the same, and I was told to drive it some more. In the meantime, O got the scanner (Actron 1975) and plugging it in, it registered the same 3 systems as not ready or incomplete ("inc").

I then drove another 150 miles, mostly highway, but with a good deal of stop and go, slow driving, and idling. At about 75 miles into this trip, the Service Engine Soon light came on. When I plugged the scanner in at the end of the trip, it showed 2 DTC codes - P 1537 and1538, ( I see a lot of posts and useful information on troubleshooting these-- identified as IMRC-- Intake Manifold Runner Control-- on the Windstar forum, and will follow up)


At the same time, one of the emissions systems- EGR-- now reads OK, but the other 2 still show "inc." Questions:

Are the emissions monitors reading inc/not ready because the car hasn't been driven enough after codes were cleared when the battery was replaced, or because there is now a malfunction in the IMRC?

Are these codes consistent with the 2 monitor systems that are not ready?

Could there have been some damage that affected the IMRC in the course of the alternator being replaced?


Thanks for your help.

IMRC's fail constantly on the 3.8L. It has nothing to do with the alternator

monitors don't just take miles, they take key cycles. Some are much more stubborn than others....they are supposed to be somewhat uniform with OBD2 standards, but of course, everyone has to do things a little different. The theory is if you do an exact procedure on a drive cycle, you can get most of them to clear, but I've never found that to be true personally. EVAP, for example, needs the fuel level in the tank to be between a certain range for some systems

But it is very possible that the code is preventing the monitors to finish. Some codes do bypass monitor tests. I couldn't say off the top of my head if the IMRC is one of them, but since you have to fix the IMRC anyway, might as well start there

drive cycles to set monitors. Steady throttle is the best. no flooring than lifting. I realize that some of this is pretty technical but just do what you can. Hope this helps

http://i217.photobucket.com/albums/cc176/higgimonster/drivecycle.jpg

Thanks, Uncle Bob and higgimonster.

After posting, I spoke to the techies at Actron, and they confirmed that the DTC codes could prevent the monitors from re-setting.

I was able to clear the codes, and then went to my driver's manual, and followed the instructions there for resetting the monitors-- which I had not done before (and which the repair shop never suggested). That resulted in resetting 2 of the remaining 3 monitors-- but the EVAP monitor still showed "not ready."

I then followed the instructions on the last post, and that did it! In the meaintime, I had called the NY State DMV, who informed me that I could have passed inspection with two monitors showing "not ready"-- but the repair shop (recommended by Car Talk and Angie's list) never told me that!

Anyway, I'm now totally clean-- passed emissions inspection on all monitors, on the last day I could drive legally.