"Pending" P030X codes, occasional engine misfire

jdstrickland · #1 01-05-2016, 03:25 PM

If you have P0301 thru P0306, then P0300 just says that you have the others. P0300 is MULTIPLE RANDOM MISFIRE, whereas the individual misfires are reported separately.

If the Check Engine (SERVICE ENGINE SOON) light is not on, then I'd suggest that you do not want to reset the codes. Codes come in two forms, active and pending. Until the check engine light comes on, the codes stored are pending. This means that an event happened once and the computer is waiting to see if it happens again, at which point it will become active and trip the light.

The 3.0L engine in your X is the same M54 that is used in the 3 and 5 Series cars. It's a little bit different than the earlier, M52, but there are similarities that might be well to keep in mind.

I bought a 323 that was giving P0300 codes, and every once in a while a MAF code would come up. I also had a few instances of P1188 and P1189, which are BMW codes for deviations in the air/fuel ratios -- basically the mixture swings from rich to lean and back again. The problem ended up being the MAF.

What the MAF does when it is working is measure the air density so that the fuel delivery can be such that the ratio is 14.7:1. This ratio is not so important to the engine, but the CAT likes it a lot. Turns out that the chemical reactions that take place inside of the CAT allow an even distribution of molecules when the ratio is 14.7:1. Bottom line is that the CAT wants a steady A/F ratio. The engine cares somewhat, but has a much wider range of acceptable mixtures, so the CAT is what is driving the bus here.

In any case, the MAF can fail in such a way that while the air density is a constant, the reports to the computer is that the air density is changing, the result being that the fuel delivery also changes and this causes the mixture to swing from lean to rich and back again. If the air density really is a constant, but the MAF is reporting it variously as dense or thin, the fuel ratios would be changed as the reported air quality changes.

I'm not suggesting you rush out and buy a MAF, I am only suggesting that you keep it in the back of your mind that it might be the root of your problems. My issues were with the M52, and the M54 can easily be different. But the M54 could be the same, I simply do not know.

I struggled with my car at home for a weekend, and then drove it across town to a BMW guy that I see once in a while. He hooked up his GT1 diagnostic, and said within about 3 minutes that a transistor gate was shorted to ground inside the block of epoxy that houses the circuits inside of the MAF. I was having similar problems as you, P03nn codes without any noticeable affect in drivability. I had the P1188 & P1189 codes, which are cousins of P0171 and P0174. Technically, they are the same as P0170 and P0173 FUEL CONTROL/TRIM MALFUNCTION. Fuel delivery faults can be reported as lean, rich, or malfunction. My logic says that rich and lean are consistent errors in one direction or the other, malfunction would be errors in both directions.

So, work through the cheap stuff first, but be prepared that somebody might tell you that you need a MAF. Due to the cost of a MAF, I'd go ahead and pay for a scan with the GT1 diagnostic package that most shops will not have because it is expensive. I'd call the local Independent BMW garage and ask if they have the GT1.

upallnight · #2 01-05-2016, 03:33 PM

Quote:

Originally Posted by jdstrickland

If you have P0301 thru P0306, then P0300 just says that you have the others. P0300 is MULTIPLE RANDOM MISFIRE, whereas the individual misfires are reported separately.

If the Check Engine (SERVICE ENGINE SOON) light is not on, then I'd suggest that you do not want to reset the codes. Codes come in two forms, active and pending. Until the check engine light comes on, the codes stored are pending. This means that an event happened once and the computer is waiting to see if it happens again, at which point it will become active and trip the light.

The 3.0L engine in your X is the same M54 that is used in the 3 and 5 Series cars. It's a little bit different than the earlier, M52, but there are similarities that might be well to keep in mind.

I bought a 323 that was giving P0300 codes, and every once in a while a MAF code would come up. I also had a few instances of P1188 and P1189, which are BMW codes for deviations in the air/fuel ratios -- basically the mixture swings from rich to lean and back again. The problem ended up being the MAF.

What the MAF does when it is working is measure the air density so that the fuel delivery can be such that the ratio is 14.7:1. This ratio is not so important to the engine, but the CAT likes it a lot. Turns out that the chemical reactions that take place inside of the CAT allow an even distribution of molecules when the ratio is 14.7:1. Bottom line is that the CAT wants a steady A/F ratio. The engine cares somewhat, but has a much wider range of acceptable mixtures, so the CAT is what is driving the bus here.

In any case, the MAF can fail in such a way that while the air density is a constant, the reports to the computer is that the air density is changing, the result being that the fuel delivery also changes and this causes the mixture to swing from lean to rich and back again. If the air density really is a constant, but the MAF is reporting it variously as dense or thin, the fuel ratios would be changed as the reported air quality changes.

I'm not suggesting you rush out and buy a MAF, I am only suggesting that you keep it in the back of your mind that it might be the root of your problems. My issues were with the M52, and the M54 can easily be different. But the M54 could be the same, I simply do not know.

I struggled with my car at home for a weekend, and then drove it across town to a BMW guy that I see once in a while. He hooked up his GT1 diagnostic, and said within about 3 minutes that a transistor gate was shorted to ground inside the block of epoxy that houses the circuits inside of the MAF. I was having similar problems as you, P03nn codes without any noticeable affect in drivability. I had the P1188 & P1189 codes, which are cousins of P0171 and P0174. Technically, they are the same as P0170 and P0173 FUEL CONTROL/TRIM MALFUNCTION. Fuel delivery faults can be reported as lean, rich, or malfunction. My logic says that rich and lean are consistent errors in one direction or the other, malfunction would be errors in both directions.

So, work through the cheap stuff first, but be prepared that somebody might tell you that you need a MAF. Due to the cost of a MAF, I'd go ahead and pay for a scan with the GT1 diagnostic package that most shops will not have because it is expensive. I'd call the local Independent BMW garage and ask if they have the GT1.

I think someone already mentioned that at the beginning of this thread.

jfoj · #3 01-05-2016, 03:35 PM

I will RESTATE exactly what I said in Post #48.

Clearing the codes DOES NOT clear/reset the Fuel Trims.

Resetting/Clearing Adaptations clears or will zero Fuel Trims and standard/non Pro OBDII tools do not support Resetting/Clearing Adaptations.

Apparently some people DO NOT understand this.

I guess I will have to submit PROOF because the arrmchair mechanics DO NOT UNDERSTAND, HAVE NEVER EXPERIMENTED OR CHECKED ON THIS THEM FOR THEMSELVES.

@ upallnight, the you asked why the LTFT were 0 in the Log in post #34, I am not sure. I do not have all the details on how what happened right before the Log data was grabbed. But this may be the part of the problem that Rookie is having, something very unusual is going on with his vehicle that is NOT NORMAL and the data does not seem to fully account for what is going on.

I have yet to be able to get my head into the latest Logs, then I will have to go back and look all of them over. I review about 20 Logs a day so sometimes it is hard to keep them all separated in my head.

Fuel Trims/Adaptations are only zeroed when a tool is used that SPECIFICALLY has the ability to Clear/Reset adaptions. A generic OBDII tool does not have this capability and clearing codes WILL NOT clear/reset adaptations, it will erase Freeze Frame data, erase DTC's, erase Readiness Monitor Status and will start the Readiness Monitoring Status process over again.

upallnight · #4 01-05-2016, 03:53 PM

Quote:

Originally Posted by jfoj

I will RESTATE exactly what I said in Post #48.

Clearing the codes DOES NOT clear/reset the Fuel Trims.

Resetting/Clearing Adaptations clears or will zero Fuel Trims and standard/non Pro OBDII tools do not support Resetting/Clearing Adaptations.

Apparently some people DO NOT understand this.

I guess I will have to submit PROOF because the arrmchair mechanics DO NOT UNDERSTAND, HAVE NEVER EXPERIMENTED OR CHECKED ON THIS THEM FOR THEMSELVES.

@ upallnight, the you asked why the LTFT were 0 in the Log in post #34, I am not sure. I do not have all the details on how what happened right before the Log data was grabbed. But this may be the part of the problem that Rookie is having, something very unusual is going on with his vehicle that is NOT NORMAL and the data does not seem to fully account for what is going on.

I have yet to be able to get my head into the latest Logs, then I will have to go back and look all of them over. I review about 20 Logs a day so sometimes it is hard to keep them all separated in my head.

Fuel Trims/Adaptations are only zeroed when a tool is used that SPECIFICALLY has the ability to Clear/Reset adaptions. A generic OBDII tool does not have this capability and clearing codes WILL NOT clear/reset adaptations, it will erase Freeze Frame data, erase DTC's, erase Readiness Monitor Status and will start the Readiness Monitoring Status process over again.

Why don't we wait for Rookie to post some more logs where the code hasn't been cleared and we can look at where the Long Term Fuel Trim starts. Bet you it doesn't start at 0.

Rookie48 · #5 01-05-2016, 04:32 PM

More logs for your enjoyment - these are recent logs, but with the clearing of codes prior to each run. I will stop clearing the codes now and let them ride...

Ambient temps are below 32F in these files below...

Misfires/limp mode at 12:31:22 PM:
https://dl.dropboxusercontent.com/u/...20Noon%29.xlsx

Misfire/limp mode at 3:53:24 PM (with diagnostic report):
https://dl.dropboxusercontent.com/u/...5%20PM%29.xlsx
https://dl.dropboxusercontent.com/u/...2016-01-04.pdf

Misfire/limp mode at 10:12:11 PM:
https://dl.dropboxusercontent.com/u/...to%20H%29.xlsx

Rookie48 · #6 01-05-2016, 06:41 PM

Data logs and diagnostic report (freeze frame) from the ride home tonight...

Limp mode entered at 4:38:37 PM:
https://dl.dropboxusercontent.com/u/...5%20PM%29.xlsx

https://dl.dropboxusercontent.com/u/...2016-01-05.pdf

Remember - I have to shut the truck off and back on while rolling to clear the limp mode, so PID values during that restart may be zeroed out or frozen during the reset.

It is quite possible that the "0" values in the fuel trim values to due to the wireless connection from the OBD II adapter and the iPhone app for the first few seconds.

I have not cleared the codes, and will log again on the way to work tomorrow.

upallnight · #7 01-05-2016, 07:01 PM

Quote:

Originally Posted by Rookie48

Data logs and diagnostic report (freeze frame) from the ride home tonight...

Limp mode entered at 4:38:37 PM:
https://dl.dropboxusercontent.com/u/...5%20PM%29.xlsx

https://dl.dropboxusercontent.com/u/...2016-01-05.pdf

Remember - I have to shut the truck off and back on while rolling to clear the limp mode, so PID values during that restart may be zeroed out or frozen during the reset.

It is quite possible that the "0" values in the fuel trim values to due to the wireless connection from the OBD II adapter and the iPhone app for the first few seconds.

I have not cleared the codes, and will log again on the way to work tomorrow.

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.

jfoj · #8 01-05-2016, 09:37 PM

Quote:

Originally Posted by upallnight

Why don't we wait for Rookie to post some more logs where the code hasn't been cleared and we can look at where the Long Term Fuel Trim starts. Bet you it doesn't start at 0.

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.

upallnight · #9 01-05-2016, 09:55 PM

Quote:

Originally Posted by jfoj

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.

jfoj · #10 01-05-2016, 10:12 PM

Quote:

Originally Posted by upallnight

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.

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.

Quote:

Originally Posted by upallnight

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.

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.

Quote:

Originally Posted by upallnight

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.

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!