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4.4i X5 Misfires and Stalls, no DTCs
Bought used a ’03 X5 4.4i a couple months ago for my wife. She is the primary driver. Drove great until just a week ago. Big change in one day. Stalls at idle, bad misfire (bucks hard). Feels > than one cylinder. When this first happened I suspected bad gas, she had just filled up earlier that day and lost her gas cap the same day. I operated on only her description for the 1st few days. I started driving it to see if I could diagnose (20 years ago I was a ASE Master Technician with Advanced Drivability Specialist, so not totally green. Just with BMWs). The only DTC shown is the EVAP one due to the missing cap. Seemed to run good when 1st started, then would get worse on my half hour drive. Wants to stall often but could keep running using two foot driving technique. Under acceleration there is an intermittent stumble, like whole engine cuts out for ~ a second, randomly at different RPMs and loads. Sometimes multiple times over a short term (20 seconds), then it recovers and will eventually repeat again with-in 5 minutes. Service engine soon light never came on. But also runs strong for short terms between issues. Yesterday’s drive home was the worst, barely made it. Went to drive again this morning expecting it to run good at first, but I could barely get it started and down the street. Stopped and opened the hood and disconnected the mass air flow sensor (per what I had read here). It ran better, did not stall but I also kept driving using the two foot driving technique. After cooling for 4+ hours at my destination, plugged in MAF and read codes. Had air temp code, MAF code, and both banks to rich code. Cleared all and started and let run sitting in park. After about a minute idle goes way down and wants to stall, it recovered from this 5 or 6 times spaced out for ~5 minutes then it finally died. Service engine soon light never came on and no codes are present. Issue is still present when I drive. Can be hard to restart, must give considerable throttle. Has feel of loading-up (too much fuel) from exp. riding 2-stroke motorcycles. Does not have excessive fuel smell. I have a new gas cap on order and will install tomorrow. Gas has been purchased twice at two different locations from original day when issue occurred. I also thought I ruled bad fuel out as an issue when it would run great for the 1st 3 or 4 miles of my drive. From this groups experience, what is my best way to proceed before seeing a BMW dealer? My scan tool will not show engine data, only reads DTCs. Thanks in advance! |
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#2
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Could be a clogged fuel filter or faulty fuel pump... is it acting like it's starving for fuel? At that mileage, and if the filter has never been changed, I would be inclined to check fuel filter, pump/s and go from there.
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08/06 build 4.4i Stirling Grey over black |
#3
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Plan to take fuel pressure reading tonight. What is the specified range for this '03 X5 with the 4.4i V8? Thanks again.
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#4
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Sorry - can't help you with that. Loaned my Bentley manual out to a friend, but I'm sure other members with more experience will chime in and assist.
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08/06 build 4.4i Stirling Grey over black |
#5
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Ditto on clogged up fuel filter. They will be ok when the flow drops, but then flow packs the sediment tight and starves the engine. Next day will be fine for a while... Look at pressure under different engine rpm's and let it run awhile.
Bentley says pressure, key on, engine not running 50.8 plus/minus 2.9 psi Pressure, engine running 36.3 to 46.4 psi
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David.X5 2001 X5 4.4i Sport SOLD! at 160k miles |
#6
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Running too rich could be a vacuum leak to the fuel pressure regulator. With very little vacuum to the fuel pressure regulator, the pressure regulator is assuming that the throttle is at WOT. So it provides this info to the DME and the DME will open the injectors for a longer period of time.
If you have the App Torque you can check the vacuum as well as the fuel trim. Hard starting when the engine is hot could points to a fuel pressure regulator with a ruptured diaphragm.
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2006 Infiniti G35 2001 BMW 3.0I E53 X5 Build date 08/2000 SOLD Lotus Europa 1970 Destroyed by fire Lotus Europa 1970 S2 Renault Powered Lotus Type 52 1970 Twincam Webers Powered PORSCHE 911 Targa 1982 The Garage Queen Audi Avant donated to Kars for Kids BMW 525IT Sold Audi 4000CS Quattro Sold Jensen Healey Lotus Powered Sold Opel 1900 Sold Triumph Spitfire 1971 Sold Triumph Spitfire 1968 Sold Plymouth "Cuda" 340 Six pack SOLD Last edited by upallnight; 06-04-2015 at 07:45 AM. |
#7
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Installed a fuel pressure gauge today. Pressure is ~56psi. Ran engine until it stalled. During the wait it tried to stall ~5 times plus actual stall, fuel pressure never deviated more than 3 or 4 psi in that time. Restarted, took vacuum line from fuel pressure regulator and pressure increased a few psi. Returned vacuum line to the regulator and installed new gas cap and rechecked fuel pressure. Appears fuel delivery is OK.
After engine stalls with key still in 'on' position, throttle body is making vibrating/humming noise. Is this normal? Is this a part the experienced guys see fail often? Has anyone salvaged a malfunctioning throttle body by removing and cleaning? It is part number 13541435959-08. I hope I am on the right track with this. I thought the throttle felt as though the first 10 to 20% on movement did nothing when it was acting up. Also, when I spoke of hard restart it is in regard to immediately following a stall. I can usually get it started, it just requires pressing on the throttle quite a bit. Thanks |
#8
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Quote:
If you haven't replaced the fuel filter/fuel pressure regulator (they are a combine unit) I would try that.
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2006 Infiniti G35 2001 BMW 3.0I E53 X5 Build date 08/2000 SOLD Lotus Europa 1970 Destroyed by fire Lotus Europa 1970 S2 Renault Powered Lotus Type 52 1970 Twincam Webers Powered PORSCHE 911 Targa 1982 The Garage Queen Audi Avant donated to Kars for Kids BMW 525IT Sold Audi 4000CS Quattro Sold Jensen Healey Lotus Powered Sold Opel 1900 Sold Triumph Spitfire 1971 Sold Triumph Spitfire 1968 Sold Plymouth "Cuda" 340 Six pack SOLD |
#9
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No fuel leaking past regulator diaphragm. I had inspected when I had to hose off plus it operates correctly with pressure changing when manifold vacuum is removed and reapplied.
Also, on difficult restart I do not push pedal to floor for what I would call a 'clear start'. Only in the 1/3 to 1/2 apply range, just it won't restart with no throttle applied (when the problem is acting up), after it starts when issue is present I normally have to continue to hold the throttle open some (how much? maybe 10 to 30%?) to keep it from stalling. When issue is not present it starts fine and idles correctly until it happens again. Misfire is rather severe bucking, like maybe the throttle going away for a moment before coming back. Has someone seen any similar issues with the fly-by-wire throttle body that also appears to have all the idle speed controls built in? Thanks |
#10
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Hmmm - wondering if you can scan for faults with the fly-by-wire throttle system... maybe this is the problem (intermittent contact from broken wire or similar). From your description, this leads me to think in this direction.
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08/06 build 4.4i Stirling Grey over black |
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drivability, idle issue, misfire, stalling, throttle problem |
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