Im new to the thread. I have been having idle issues. I have a 99 xj sport 4.0. 291××× miles on it. When sittimg at idle engine sounds and feels rough. Never stalls just sounds and feels like a possible miss. I got a plug in ob2 scanner and obd fusion app to try to figure it out. Does anyone know wjat these values stand for. Apparently some things are off i just dont know what they are. Any input would be great on solution for rough idle or the values in the pic

 

Welcome to the forum!

Basically: Stop messing around in Mode 6. Ditch it; it's useless for what you are trying to do. Look at the error codes the Jeep is actually throwing, and if there aren't any either 1) stop worrying about it or 2) start diagnosing the problem the 'ol fashined way with a multimeter and stethoscope. Read on if you want some crummy unhelpful information about OBD2 Mode 6.

This is a complex and nuanced topic, so buckle up and be prepared for concepts most home mechanics don't think about. This is real DAS communication and programming!! = Engineer Languages.

OBD2 Mode 6 encompasses vehicle self-diagnostics to support emissions inspections in North America (starting in 1996). The Mode 6 values you are looking at are NOT codes, they are Test IDs (TIDs), also apparently known as Parameter IDs (PIDs). It is a supposed communication "standard" (heh lol), but isn't really standardized across auto manufacturers. INFO HERE. It appears that your device is reading the Hexadecimal IDs, not the Decimal equivalent IDs. However, Jeep XJ Cherokees might not conform to standard TID/PID definitions per SAE J1979. That is: what I am about to tell you next may or may not be accurate:

Per Standard Definitions:
TID/PID 11 = Throttle Position
TID/PID 16 = Oxygen Sensor 3
TID/PID 19 = Oxygen Sensor 6
TID/PID 1A = Oxygen Sensor 7

On second thought, the information you are reading is definitely inaccurate. Jeeps never came with 7 O2 sensors...so we can rule out your device's interpretations right now. Jeep is likely using their own self-defined parameter IDs, and your OBD2 reader isn't translating. HERE is some information on 1997-1998 TIDs, which may or may not represent 1999 model year. It's unclear whether or not those parameters are actually supported or not (look in the JTEC applications column). And 16 doesn't even exist on the list. Anyway:
TID 11 = O2 Sensor Half-Cycle Counter in 1 count per bit.
TID 19 = O2 Heater 1/1 Time to Reach Voltage in 11 milliseconds per bit
TID 1A = O2 Heater 1/2 Time to Reach Voltage in 11 milliseconds per bit.

To get actual real-world numbers, you'll need to convert your OBD2 reader numbers from ms/bit, mv/bit, or counts/bit into a real number to know what is going on.

For realsies: stop trying to use this information. This kind of information confuses and screws up us engineers who work with it on the daily (we're engineers so we're easily confused anyway!). Go back to basics, or get an OB2 reader that will give you actual error codes.

 

Yeah its not throwing any codes. Thats how i ended up in mode 6. I read that it could help you find intermitten problems before it actually trips a code. Im gonna check my IAT clean it then possibly my upstream o2 sensor. I also have low vacuum as well like 12.7 in hg at idle. Other than that tho for a jeep near 300××× it drives great. I get 22 mpg and drive it 1 hour both ways to work and back.