It is possible because if the 02 sensors are still cold, the system is in open loop where the fuel mixture is not controlled by the 02 sensors, but by a fuel map in the computer.

:yawn: Not even sure why you made this post. The Log may start with 0 depending on how the App syncs up with the data, often the first few lines are not very well synced and may register 0's.

But there is no magic either way if codes are cleared or not, the Adapations/Fuel Trims will be the same.

I am just too lazy to go outside in 20F temps to prove this to you, but you feel free to answer your own question and experiment for yourself, you WILL see, Fuel Trims will not be Zeroed out by clearing codes.

Only using a more advanced tool that supports Clearing/Resetting Adaptations or leaving the battery disconnected long enough for the DME standby capacitor(s) to discharge, something along the lines of a few weeks to a month on many vehicles. Touching the disconnected battery cables together typically does not Clear/Reset Adaptations or Codes, it can do other things, but it usually does not impact Adaptations or Codes. This is all part of the OBDII design parameters and why the Readiness Monitors were implemented.

OBD II readiness was implemented to prevent people from clearing the codes that are present in their cars prior to taking the car in for testing.

Well, Rookie has been uploading logs and the logs that were made after he cleared the code shows the long term fuel trim at 0, and it took quite a bit of time for the fuel trim to go from 0 to positive.

The last log Rookie uploaded was a log without a clear code prior to the logging, and if you bother to look at the log it showed the long term fuel trim at a positive value and NOT starting from 0.

Now Ottoi from Bavauto stated that you can reset fuel trims with clearing the code and Ross Tech said that you can reset fuel trims with clearing the code and Rookie has been resetting the fuel trim with clearing the code, seems like you're the one that don't get it.

You're right about one thing, it cold outside and I'm not going to be playing around with my X when it is working perfect.

Another part of OBDII was non volatile memory. Most was implemented with capacitor back up, but unlike OBD1, there was no disconnecting the battery to clear codes. Clearing/Resetting Adaptations is not part of clearing codes.

Rookie's vehicle has a rather unusual problem based on what I am seeing. Part of his problem may well be the fuel management system is doing bad things. Some things are not adding up the data that I am seeing, but I need to go over it again and look for some more clues.

Sorry but Otto and Ross Tech either mis-spoke and/or were/are wrong. People make mistakes all the time and things are stated incorrectly or incorrect info is put into print. I often verify things for myself because I have been involved in MANY industries where I have found plenty of incorrectly stated and documented things. Everything from bad/wrong info in service manuals, both factory and aftermarket, wrong specs, typos, you name it, I usually verify multiple times for myself how things behave.

What I do not understand is why you have never bothered to verify ANYTHING for yourself. You only are a master of the quoting things from the Internet.

Oh, I forgot, everything on the Internet is always correct!

You should talk, I given substantial evidence from people such as Otto from Bavauto and Ross Tech but you just claim that they are wrong without ever providing any evidence that you can not reset fuel trim with clearing the code. Where is your supposedly evidence or paper that fuel trim can not be reset with code clearing.

Even when Rookie post logs that support my claim that fuel trims can or is reset to 0 when you clear code you can't accept the fact and claim something else is wrong with Rookie car, but I have yet to see you post any type of help. You make excuses that you are so busy that you haven't the time to go over Rookie's log and that you will look at them later.

It just a waste of my time arguing with someone like you. Consider yourself added to my ignore list. See Ya.

Somehow I think I'll get the short end of the stick after that exchange...

I'm not experienced enough in the DME, clearing codes, and fuel trim logs to make a determination as to what is going on with my truck... Yet...

I appreciate both of your insights to the issue. I have stopped clearing codes, but other issues (scanner startup) may not provide proof to settle either of your claims. More data to come....


2003 X5 3.0i Sport MT
2004 M3 Coupe
1997 M3 Coupe

First off you are the one arguing, you do not seem to understand or believe what I am saying and this is probably because you have never spent a day in the field repairing OBDII vehicles for a living.

You present no evidence other than inaccurate 3rd party information from others that has been posted somewhere on the Internet.

So here is my proof, not an E53 but and E70 that I cold easily get access to. Ran a report right before codes were cleared and then once codes were cleared. Note the reports were less than 1 minute apart and the vehicle was only running for 24 seconds and no miles were put on the vehicle.

Notices that the LTFT are EXACTLY the same.

BTW, I am using the SAME App as Rookie. I could do this all day and the results would be the same. If I pulled out one of my Pro level scan tools, I could Reset/Clear the Adaptations and you would then see the Fuel Trims zeroed out.

Link for the 2 reports attached here - https://www.dropbox.com/sh/u9fnmfxe7...WfcZ88rMa?dl=0

I will also be posting this in the other thread as well.

Enjoy!

06 E53 3.0 P0302 303 304 PLUS INJECOR CIRCUIT ISSUE
 

Curious,

Having read through this whole string, it appears there are some knowledgeable people on this forum about this issue, but it is a old string, so I don't know if anyone solved problem or not, it was left hanging with an argument. I am somewhat a new poster, so I will give it a try.

I have 155K on X5, it started with an occasional misfire and injector circuit signal missing codes on #3 only, so I put some fuel injector cleaner in tank since it was very intermittent, low speeds and high speeds, no safe mode issue. I thought it was better for about 500 miles, but then I got same codes on 2,3,4 at same time and engine now barely runs obviously on only three cylinders. Codes come up for all three, so I was curious, what can cause this issue?

I have checked wire harness issues, connections, etc, and having this multiple issue now, even though I purchased new injector, I am now thinking it may be something else given it is not just one cylinder any longer. Is there a ground issue? The MAP sensor would be more random to my knowledge, not consistent to only three cylinders, so I don't want to throw parts at it just yet. The same is true for 02 sensor issues to my knowledge, so I am stumped, fuel pressure is fine, so I am stumped, any ideas out there?

Thanks,

I think you would be better off starting a new post instead of adding to this old thread.

I'll throw in my 2 cents when I see it