Trouble with read troublecodes

Hi,

I have a ELM323 Scanner and it works 2 years ago fine.
Now I want to read freeze data because our 98 Lumina 3.8L get 15 Liters per 100 km.

But every time I read the freeze data I got diffrent values. But there must be a failure because the level from fuel and oil is jumping but I was in park position.

Did anybody the same symptoms? I think about fault ecm because the Lumina get never more then 11 Liters in City before 1 year.

I assume you are after fuel mileage increases, the gage readings are not part of this issue, correct? If so, look for fuel trims on your scanner long term will give you the most info, this time of year, in the nothern part of the US, it has not gone above freezing for 2 weeks, my 3800 Buick is down about 3 mpg. My engine is running well. I would suspect driving conditions, number one, maybe a tired o2 sensor number 2. There are no live fuel trim readings in freeze frame, don't use this mode to check live data such as fuel trims or 02 sensor activity.n Also does the engine reach 195 degrees fahrenheit in a reasonable warm up time?

I don't think that the temperature here is the problem, because the higher milage began at begin this year.

I would read the Air / Fuel ratio and other relevant points, but every time I refresh the freeze data there are other values then before.

If the temperature outside cold like -10 degree celsius then there is knocking noise from the engine. It goes after 2-3 minutes. So my diagnosis was in the oil is too much fuel but without values from OBD Interface I don't know if the mixture are ok, or the sensors...

Again, don't use freeze frame values, do a live data scan look at fuel trims, especially long term, freeze frame will tell what the data was when a code is set.

Ok but with ScanXL I can read just rpm, speed, temp...

Which Software would zou use?

I have an Actron 9145.

Can anybody tell me what is the different between ELM 322 and 327? And can I use 327?

Happy new year!