06 X5 3.0 Open Loop Fault

**Jbgwsp** · 05-13-2019, 07:31 PM

My 06 X5 has been having an intermittent issue, where it stumbles and feels like a misfire. It doesn’t happen everyday, but today I caught it with the scanner hooked up. Driving along about 60mph and the stumble starts. Scanner shows a open loop fault with a cylinder 6 misfire (p0306)and a bank 2 fuel trim rich. The bank 2 rich is almost always there and I haven’t been able to clear it and the bank 2 fuel trim is pretty normal. Where should I start?

**dworthy** · 05-14-2019, 04:24 AM

Welcome to the Forum!

So on that truck, there was a cross-over during 2006. Do you have the older E-53, or the Newer E-70? Two different motors, for 2 different body's.

Also if you don't know, just post the last 7# of the VIN, or put it in here: http://www.realoem.com/bmw/select-us/select

Lastly, BMW recommends replacing Oxygen sensors every 120k miles.

**Jbgwsp** · 05-14-2019, 06:37 PM

It’s an E53

**Jbgwsp** · 05-14-2019, 07:14 PM

It’s been throwing the bank 2 rich fuel trim code for a while now, which has dumbfounded me because the fuel trim isn’t rich. I believe the LT is around +2

**dworthy** · 05-15-2019, 02:10 AM

Thank-you, so you have a M54 engine.

Typically when you get fuel trim codes, it normally means you have a vacuum leak on the intake. There is a simple way to check, is to look at the large black rubber boot for cracks, splits, ect.

If you don't see anything that look bad, then I would suggest getting a smoke test completed on the intake, for there are lots of places that a vacuum leak can form.

Lastly since you do have a hand scanner, can you post the codes and the exact wordage of each code.

**Jbgwsp** · 05-15-2019, 07:08 PM

A few months ago I was getting lean codes after rebuilding the VANOS and replacing the ccv system. I went thru everything and found it to be a loose valve cover bolt. P0306 cylinder 6 misfire detected, P1093 pre catalyst fuel trim system too rich bank 2, and a new one today P0102 mass or volume air flow A circuit low

**dworthy** · 05-16-2019, 06:33 AM

Would be worth cleaning the MAF, and inspecting it to see if that helps.

With low Volume, that tells me you have a vacuum leak, for there is unmetered air entering the intake.

**MarcoZandrini** · 05-16-2019, 08:43 AM

I concur with Darin’s recommendation for a smoke test. This is the only way to find all of the vacuum leakS. Go to www.bimrs.org to find a reputable indie shop that specializes in bimmers.

**Jbgwsp** · 05-16-2019, 09:49 PM

Thanks, I’ll do a smoke test. Today I pulled over when it started stumbling. And #6 cylinder was dead. Unplugged coil with no difference. If you cut car off and immediately restart, runs fine for awhile. If it was a vacuum issue, wouldn’t the problem be present consistent and not inconsistent? Also my fuel trims at idle are +2 and -1.8

**dworthy** · 05-17-2019, 02:18 AM

That is normal fuel trims. It's when they get around +/- 10 is when it sets a lamp.

So move #6 coil to the front Bank (1-3) and see if the misfire follows.

You maybe dealing with multiple problems here, that are not connected.

**Jbgwsp** · 05-17-2019, 07:24 AM

That’s what I did, moved 6 to 1

**dworthy** · 05-17-2019, 08:07 AM

Originally Posted by Jbgwsp

That’s what I did, moved 6 to 1

Okay, did it follow?

Look, on a Forum, there is no such thing as too much information. You also have to remember that I am not standing at the fender looking under the hood with you.

In my business I have been taught to ask open-ended fact finding question, so when the reply is so short, I am worried that I didn't ask the right question.

**Jbgwsp** · 05-17-2019, 09:21 AM

Sorry, just did it yesterday and issue hasn’t resurfaced again yet. It doesn’t do it driving around town, only on highway

**dworthy** · 05-17-2019, 12:53 PM

Okay, good to know. Let's keep an eye on that, for it might have been just a loose connector. In my experience, the #6 coil tends to be the first one to go bad, then it just cascades from there.

I always kept a used one on hand, but in the wagon, it went thru two in about a week, I just replaced them all a week later with new.

**Jbgwsp** · 05-18-2019, 09:39 PM

So I put a good 150 miles on it with no issues, other than the bank 2 rich code. Until today. It started acting up and I threw my fuel pressure gauge on and it was reading 28 lbs. I need to confirm with my other better gauge set.

**dworthy** · 05-19-2019, 02:49 AM

Yes that is very low, should be around 51 PSI.

Low fuel pressure can cause misfires too, how old is the fuel filter? IIRC the fuel filter also houses the fuel pressure regulator, so that would be worth taking a look at too. Also inspect the vacuum line that runs down to it, for if it is bad, it will mess with fuel pressure as well.

**Jbgwsp** · 05-20-2019, 10:57 AM

I’ve had the car around 6 months and haven’t gotten around to the filter yet. I’m gonna guess it’s never been changed. That’s next on my list. So far I’ve changed plugs, replaced valve cover gasket, rebuilt DISA, cleaned icv, rebuilt VANOS, replaced AC compressor, replaced ccv, changed differential oil, and changed transfer case oil

**Jbgwsp** · 05-20-2019, 07:01 PM

So I was able to borrow my buddies Bavarian Technic equipment. Here are the codes: 236, 13, 243, 3, 8, 120, and 14. I haven’t played with it enough to figure it out yet, but I did check out the MAF data and it was 19 kg/hr, which I have no idea how that reads lol

**shadowpuck** · 05-20-2019, 07:14 PM

did you capture the wording/description that goes with the codes? that's what is important....

if you were watching the maf at idle, a reasonable rule is 1 gram per second per liter.

**Jbgwsp** · 05-20-2019, 09:00 PM

236-o2 control upstream bank 2 13-Plausibility cooler exhaust temperature 243- Burning fail cylinder 6 3- Ignition cylinder 6 8- Airflow meter 120- not plausible gas+brake 14- TAL

**Jbgwsp** · 05-22-2019, 02:23 PM

So I cleared the codes, and the 3 that reappear are the o2 and the 2 cylinder 6 codes. Also, about a month ago, I replaced one coil pack and one upstream o2 sensor with aftermarket parts.

**dworthy** · 05-23-2019, 02:12 AM

Which Oxygen sensor did you replace? Is it the one giving you the code?

Bosch is the OE supplier for Oxygen sensors and Coil Packs on the M54 motor, and you can get the oxygen sensor from amazon for less than 100 bucks each. A full set of coils ran me around 140 bucks shipped from Amazon as well. Normally when 1 goes bad, the others will be close behind.

**Jbgwsp** · 05-23-2019, 08:27 PM

I’ll have to check which one it was, the coil pack boot had been standing in oil from a leaky valve cover gasket and disintegrated when I pulled it, so it wasn’t necessarily the coil that failed, but it definitely wasn’t a Bosch it was replaced with, cheap Advance Auto part.

**dworthy** · 05-24-2019, 01:06 PM

Yeah, those motors are known for doing so, and of course wreaking the boots. On the older models, you could just replace the boots, but with these ones, it is all 1 piece.

**Jbgwsp** · 06-02-2019, 09:53 PM

Finally found the issue. Rechecked fuel pressure with another gauge and it checked out fine. Pulled all the plugs again and noticed #6 plug has a hairline crack running the entire length of the porcelain. I probably would have never noticed it if it didn’t have a small black spot where it had been arcing around bottom of boot to the head. NGK plugs with probably 7000 miles