O2 sensor adaptation limit

[john2459]

Hi all,
Had a problem with the car yesterday and wanted to see If the knowledgebase could shed some possibilities on what it may be.
The back details: 1998 528i (E39), M52 single vanos, 280+k miles and ran like a champ until that morning. Gas mileage was 25 – 27 (this was according to the dash computer).
So I was driving ~65 and all of a sudden it starts losing power for about 3-5 seconds but picks back up and runs great for about 5 to 10 minutes and then it does it again. It does this several more times so I figure I’ll turn around and head back home. After I turn around it does it again and then the SES light comes on. At this point the time it’s losing power are getting longer and longer and finally it quits. I try to start it and it runs for about 5 minutes and quits again and won’t stay running.
Now fast forward to the afternoon the tow truck brings it home and I stick the code reader can on it and it pulls a “E3 - O2 sensor adaptation limit, cyl #1-3” and “E4 - O2 sensor adaptation limit, cyl #4-6”. So I clear them and try to start the car… It starts! I have not taken it out for any length to bring it up to temp. My problem is I have read several of the threads and none mentioned the losing power and quitting. Some go down the poor gas mileage but up to that point it was great. I’ll check the plumbing and hoses for vacuum leaks up to the air box (free), and then start pulling parts (not free). So my question is has anyone heard of those symptoms? And any Ideas?

I appreciate the help ahead of time I hope everyone is having a great day.
John2459

[bmwdirtracer]

Hi John, and welcome to the forum.

Do not throw parts, until you know what parts to throw. Diagnose first.

My wild assed guess is that your fuel pump is failing. If you brought the car to me with these symptoms, I'd:
1) read the BMW codes (not just P-codes, which suck)
2) smoke test the intake system
and (3) hook up a fuel pressure gauge, tape the gauge to the windshield, and go for a drive until the symptoms manifest, then look at the gauge.

Again, my guess is that you've got a fuel delivery issue, but don't throw parts, until you know, because it's only a guess. If you end up replacing the pump, make sure to replace the fuel filter at the same time.

[MIKYZZ4]

+1
Totally agree with Chris,
if I had to guess, points to fuel pump.
Follow the excellent info provided.

[john2459]

Thank you Chris. I'll look at that.

[john2459]

Just a quick question what is the difference between the BMW codes and P codes and how do you read them? What is a smoke test?

Thanks again.

[shadowpuck]

bmw codes are the actual error codes which bmw developed. they can be read by software designed to read BMW codes (either produced by BMW or others).
p codes are universal translations of those specific BMW codes - so, much can get lost in the translation from BMW error trapping to universal descriptions.

often times, we've found that the p code (or, typically OBD-II code) can be misleading and just flat out wrong. there are numerous examples of this.

it's also important to note that error codes are only a signal that there's something wrong - they are often not going to point to the exact cause of the error. a quick example - a code for an oxygen sensor can be a wide variety of issues ranging from a bad sensor, to an air leak, to even bad components on the intake side of the engine! much like personal computers, error messages take interpretation, knowledge, and experience to understand.

a smoke test is a test of a system's ability to be airtight. often used to check for air leaks on an engine, or leaks within the emissions components. a specialized smoke is injected into the intake side of the engine using a smoke machine. the technician then looks for smoke coming out of what should be an air tight, leak free system. smoke tests are a critical troubleshooting step because they can pinpoint very tiny leaks (OBD-II leaks can be as small as 1/2 mm in diameter). air leaks can cause various issues including poor fuel economy, poor response, etc.

[john2459]

Good afternoon Chris,
Hope all is well. I had a chance to look a little deeper into this issue and I agree with you better to nail it down before I throw parts. I also agree that I think it's a fuel delivery problem. I have attached 3 vids showing you what I see. 1.) is key on (not start), 2.) Is the actual engine running briefly and is 3.) relay removed and pump jumpered. The Bently says for an e39 M52 the pressure should be ~50 psi but I just don't understand why it is fluctuating so badly when it's running. could it be an issue with the pressure regulator? What are your thoughts and thank you for you time and help. I found out I can't send videos through this forum do you have an email?

[john2459]

Gotta love technology!
Ok, all posted. 1.) is key on (not start), 2.) Is the actual engine running briefly and is 3.) relay removed and pump jumpered.




Thanks again
John

[bmwdirtracer]

Hi John,
Your fuel pump is DEAD.

Buy a new OE BMW pump unit and new tank o-ring from a good BMW specialist supplier. Make sure to replace the fuel filter as well. I recommend FCP Euro.

https://www.fcpeuro.com/products/bmw...39-16146752368

There's also this OEM Pierburg pump only, however I'll tell you that I would ask for the OE complete unit, at work. Otherwise, you might suddenly find that you've installed a new pump, with a big mess, and after a P.I.T.A. afternoon, and you still have the same issue, because some of the 20-year old plastic hoses or connectors is trashed.
https://www.fcpeuro.com/products/bmw...mp-16146752368

If it were my own car, I'd pay the extra money for the complete unit, as broke as I am.....

[john2459]

Took your recommendation and it worked out great. I was a little concerned when I had it running as it had a bit of a skip at idle. But it worked out. So thank you so much for your time and effort.

John