Does anyone have a list of codes for a 97 that will effect your performance - such as - the O2 sensor which goes into closed loop. Are there any other codes that hurt your performance/mileage/driveability like this?

 

Arenyou asking for trouble codes..

http://shbox.com/1/Dtcs.htm

 

Yes, I meant the SES codes. I know the bad O2 sensor code puts the PCM in a "default " condition. The correct question is "Does any other SES codes place the PCM in a default mode or degrade the engine's performance."

 

Sure.... lot's of them do. The PCM needs the info from the knock sensor for example... if it doesn't get it, it starts applying up to 15deg of knock retard, based on internal calculations. If the PCM loses the MAF signal, it defaults to speed-density. Ditto with many of the sensors.... if it can't get the correct info from the MAP sensor, TPS, coolant temp, IAT, etc it has to go to a default system to provide the requried data, or the engine won't run. How much affect that has on power and operability depends on the specific sensors or combo of sensors that are defective. It needs the data to run the egnine correctly. But if it dosn't have the data, its going to have to make it up to keep the engine running.

A lot of people refer to these defaults as "limp home" mode, but that isn't correct terminology, until the PCM has so little input data that it has to go to a true limp home, and will barely be running.

Some sensor losses will shut the engine down. The main one is the low resolution pulse signal from the Optispark optical sensor. If the PCM can not find the signal for 2 crank revs, it shuts down the fuel pump and injectors.