Unable to fix misfires, ready to get rid of car
 

In January shortly after I replace a failed electronic thermostat we started getting random misfire and misfire with fuel shut off codes. Never the same cylinder.

Some times the car would code after driving 2 miles, other times it would be 80 miles before a misfire. I have to pull over shut the engine off and restart to make it run ok.

I have replace: spark plugs, all coils, air flow sensor(MAF), all CCV valves and hoses, Pre cat O2 sensors, inspected and cleaned and replace O-ring on DISA valve, inspected and cleaned throttle and idle valves, replace intake boot, replace fuel filter, removed cleaned and tested injectors, replaced every vacuum hose I can find, engine oil flush and clean. I also washed and waxed the car.
I even took it into a local european import auto repair shop where the guy charged me a lot of money to tell me he couldn't find anything wrong.

I have done everything I can find to do or someone tells me to do. Also checked the compression which is all good.

This is going on for 9 months, we cant take the car anywhere to far from home or on the freeway due to having to pull over and restart.

I have really like the X5 but this is no longer fun.
Im a 30 year licensed aircraft mechanic with quite a lot of mechanical experience and have up till now been able to fix any issue.

Since all this started shortly after I replaced the thermostat, last week I replaced it again using an BMW brand electronic thermostat. Same problem, no change.

Any last suggestions before i start parting the thing out?
Any one interested in a manual transmission X5 with a lot of new engine parts?

Not to be the bad guy, but I'll buy your x5. I'm local :) pm me if your serious

Have you hooked it up to INPA?

What about crank position sensor? Have you checked that.

^I literally came in to post CPS. Has your indy logged it on an Autologic to see if he can get some real time data on the misfire?

Random misfires checklist:

1. Check for leak in vacuum hoses. Some of them are under the I.M., and difficult to see/detect.

2. Cam Sensors (BMW brand only)

3. Crank Sensors (BMW brand only)

4. Coolant Temp Sensor, located near 5th and 6th cylinder area...

You're not a bad guy, if you are willing to buy his broken X. You're only a bad guy if you offer him less then what it's really worth.

Sounds like you been just throwing parts at it hoping it will fix the problem. A misfire is interpreted by the ECU as a cylinder that is not producing the same amount of power as the other cylinders. How can a computer determine this? By noting the rpm of the engine. A lean cylinder could also be interpret by the computer as a misfire. Before throwing more parts at it, you need to perform or have perform a good diagnostic of the engine.

What was the reason for replacing the thermostat? Was it stuck in the open or closed position? You said that you checked the compression? What were the readings? If they are not with in 10% of one another that could be your problem.

You say that this has been going on for 9 month, but it only started after you replaced the thermostat last week. I'm confused????

Do you have a Check engine light on? If you do what was the trouble code?

If you had a rich or misfire condition for the pass 9 months and just ignored it, your cats could be toast. You need to post some more info in order for people to help you.

I may be throwing the hail mary pass, but ive had it once, where the fuel pump /fuel filter, wasnt able to supply enough fuel and thereby caused a misfire, (BMW also adds fuel cut off if it detects too lean (no fuel??) and shuts off the injector(s) in question.
I was able to solve this issue by changing out the fuel filter and reconfirming fuel pressure from the pump. (but not untill most of the ignition system was changed.!)
my big clue was that even with NEW coils and NEW plugs i still had a RANDOM misfire with fuel cut off. meaning there was still not enough fuel randomly dribbling out of an injector somewhere to produce adequet spark!
just my $.02 worth

Upallnight, thanks for the reply. We have chatted about this in the past.

To clarify some things. Original, in January the thermostat stuck open, I replaced it then, a couple weeks after the replacement is when I started getting the misfires. Last week I replaced the thermostat again thinking that since it was an off brand it might be giving bad info to the ECU.

Yes I get a check engine light with these codes; P1351,P0304, P0302, P0306, P0303, P0301, P1345, P1342. P1349,

I understand that the cats could be failing but Im not replacing them until I get the misfires fixed.

Compression test reviled 165 psi cyl 1-4, 160 psi 5 & 6.

I have replaced the fuel filter and I replace the fuel pump when the car rolled over 100K, it now has 170K.
I have checked the fuel pressure and it has been with in limits but there is no way of knowing what the pressure is when the car experiences a misfire. I have suspected a poor fuel supply but never been able to verify.
Thanks for the input. Might put in another fuel pump?? Wish I had saved the original one.

Are you just using a generic scanner?

I was going to post same on crank sensor but also wondering how your electrical system is too. Is the batt newer and alternator in good shape? Any corrosion on grounding straps etc. Is there astern on when it misfires, cold, idle, driven hard coming off highway etc ?

I second trying to catch it in the act with computer scanner connected ala diagnosis vs guess. I have been so frustrated at many "know to be good" shops around me who just hunt and peck or toss customer dollars at issues instead of actuall diagnosis.

Gluck

Since you are getting multiple cylinders misfire with fuel cut off I would look at the CAM Sensor(s).

A shop that has the equipment to read freeze frame can look at the what the engine was doing when the trouble code was thrown. This will tell you at what speed the car was traveling, the engine rpm, the throttle position, etc. when the trouble code was recorded.

I don't think that the thermostat replacement had anything to do with the misfire, not unless you remove or relocated the line connected to the CAM sensor.

EDIT: If you do decides to replace the CAM sensor, don't buy a cheap eBay or Amazon sensor, buy a BMW sensor.

The codes that he posted are normally from a generic reader and not a BMW specific scanner.

Yes a generic OBD II scanner.
Would be interested in any recommendations.

I use the app Torque and Torque Pro to read live Data on my cars. You need to be able to read live data in order to narrow down the problem. Torque doesn't read components such as crank position sensor or cam position sensor but it has the ability to read timing value. From the timing value you can see if the engine timing is advancing as the rpm increases. If it doesn't you know you have a signal problem from one of the sensor back to the ECU/DME/PCM.

I live in the far NW corner of Washington state. The closet good shop is three hours away. I have no way to test the CAM Sensors.

I didn't think the thermostat was the problem, I had to change a leaking water pump so I thought I would do the thermostat while I was there.

Thanks for taking the time to offer advice.

How far? I am assuming way out there. I am in Seattle. I'd suggest getting the INPA/DIS software. You can get it off of ebay for $50 or less including the obd2-usb cable. This will tell you more than a generic obd scanner.

This is what I have

BMW USB OBD Diagnostic cable INPA Ediabas NcsExpert DIS v57 SSS v32 Progman GT1

Sartech: did u ever solve the misfire problem?

Looking at all of Sartech's posts, I don't think he ever found the solution to his problem, and he probably got rid of the X.

I know that feeling ..........

Thanks for you concern.
I still have the X.
Well, I did not specifically find the problem, but it seams to have gone away on its own...
I have not had a misfire for probably 8 to 10K miles. Knock on wood.
I think the piston oil rings were stuck. I have change oil type and have done two oil flushes. After the first oil flush it appeared that the misfires lessened. So I did another and likely will do another at my next oil change.
I used Liqui Moly Engine Flush and have been running Liqui Moly SAE 5W-30 Fully Synthetic oil.
I still have excess oil consumption, about one Liter per 1500-2000 miles. Also we are now approaching 200K on the X.

Another theory I have is that it might of been caused by water intrusion in some electrical component or connection. I had look for that in my troubleshooting but found none. But the improvement in the misfires also came about the same time as spring or summer when was much dryer than winter. It that is true, it is raining much more now and the problems should come back. I hope not.

When was the CCV replaced? At that mileage, the CCV might not be working as designed and that is the reason for the high oil consumption. See a video that I posted earlier today about the Best CCV delete video.

Yes the CCV was replaced.
That was the one of the first things I did when I started having these problems.

IVM Replacement / Troubleshooting - Bimmerfest - BMW Forums what engine do You have?

He has the M54 with a manual trans.