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-   -   Unable to fix misfires, ready to get rid of car (https://xoutpost.com/bmw-sav-forums/x5-e53-forum/101607-unable-fix-misfires-ready-get-rid-car.html)

SarTech 09-01-2015 03:56 PM
Quote:
Originally Posted by RFaber (Post 1049609)
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
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.

Joshdub 09-01-2015 05:01 PM
Quote:
Originally Posted by SarTech (Post 1049616)
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.
Are you just using a generic scanner?

Junkycosmos 09-01-2015 05:36 PM
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

upallnight 09-01-2015 06:09 PM
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.

upallnight 09-01-2015 06:12 PM
Quote:
Originally Posted by Joshdub (Post 1049631)
Are you just using a generic scanner?
The codes that he posted are normally from a generic reader and not a BMW specific scanner.

SarTech 09-01-2015 06:57 PM
Quote:
Originally Posted by Joshdub (Post 1049631)
Are you just using a generic scanner?
Yes a generic OBD II scanner.
Would be interested in any recommendations.

upallnight 09-01-2015 07:06 PM
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.

SarTech 09-01-2015 07:13 PM
Quote:
Originally Posted by upallnight (Post 1049642)
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.
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.

Joshdub 09-01-2015 07:30 PM
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

18rabbit 10-06-2016 10:45 AM
Sartech: did u ever solve the misfire problem?


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