BMW X5 Will Not Start Even After Extensive Diagnostic Effort

start
bmw
x5

#1

2001 BMW X5, 4.4 with 120K miles.

Will not start- put in new ignition coil, not burnt fuses, not relays, not EWS/immobilizer unit or antenna. ECU is not throwing any codes or faults. Used to start fine, then over 3 months, got harder and harder to start (cranks over but won’t catch and fire up). Will crank and crank until battery is drained. Tried both keys. BMW certified garage cannot isolate the problem and the car will not start - period.


#2

thanks for the heads up, I sure wont buy one of these, since the certified guys cant even figgure it out.


#3

Open the air-filter box, give it a shot of starting fluid while cranking. Does it start momentarily then? If so, there is no fuel delivery. Buy a “Test Plug” at any auto-parts store, $4. Connect it to one of your spark plug wires and watch for spark as you crank the engine. Do you have spark?? One or the other is lacking…Step 3 would be to run a compression test…


#4

If there were no pressure at the fuel rail, the shop would have caught that in a moment.

Therefore, I tend to suspect something that seems to test OK but isn’t. Look carefully at the lead from the crank position sensor. Is the insulation/shielding degrading, allowing electrical interference to get in and corrupt the signal? Is the sensor all the way into its holder or is it coming loose?


#5

Thank you “Manolito.” I will forward your response to my shop to see if they have checked on the shielding and check to see if the sensor is indeed fully inserted.
If you have any additional theories, please submit. vincejohnson


#6

Every single car maker out there has at least a few of these for every single model from newish to old.


#7

A certified garage certainly has access to the OEM diagnostic troubleshooting charts. Following these diagnostic “trees” leads the mechanic through the possible causes, eliminating them one by one. If the testing is done correctly and the results believable, they tend to end with; if the ECU is not setting any codes and everything else has been ruled out (no spark signal, no injector pulse, immobilizer inactive, proper input signals from crank trigger etc) then the ECU is assumed to be at fault and replaced.

However, your description of the symptoms does not appear to perfectly match an ECU failure mode so I would be a bit skeptical of the mechanic’s testing/results/conclusions. In my limited experience, slow deaths like you describe are usually something other than the ECU.

This should not be all that difficult for an experienced diagnostician, especially an expert on the make IMHO. But you may need someone with more advanced electronic skills who can understand what the immobilizer output signal should look like and be able to view it (if it’s a pulse train for example) using the right tools, as one example. It might be time to let another shop take a shot at it. Not all shops are created equal when it comes to sophisticated electronic problems…


#8

Well, the garage (Memphis Motor Werks) is certified and has a “BMW Certified” tech on the case. They hooked the car up to the computer and were assessing ea. of the systems/functions yesterday. Thanks for the information. I Do Not want to buy a new ECU for this car.
Thank you for your support and information.


#9

Then start looking for a used one…


#10

Does the “certified” lable on the Tech mean any more than the “certified” lable on the car?

It is certified by BMW that I took classes X,Y,Z but I never made Master Tech. Did the man working on the car reach Master Tech level? this would mean alot more than just certified a few classes were taken as to become Master Tech you need “hands on time in type”

I worked for a guy that listed “factory Trained Mechanic” on the sign for his VW shop. It turned out he worked less than a year at the factory as a fill in where needed. VW made hime re-word the sign.


#11

Good and fair question. The mechanic in question is in deed a certified master technician. Certified by BMW. He formerly worked at the local Memphis dealership.

Does anyone else have additional ideas (beyond the ECU) as to what electronic gremlin has taken over this car?


#12

If a certified guy/dealer mechanic can’t find it, it often means that it’s a problem the computer doesn’t have a sensor for. It’s usually more an indication of the quality of the mechanic, rather than the quality of the car.

In all the stuff you said it was not, I didn’t see any mention of fuel. Has anyone verified that fuel is flowing? Also, has anyone checked for spark (by which I mean actually removed a spark plug and cranked the engine while looking to see if it sparks, not “checked the computer to see if it told them the car wasn’t getting spark.”)

A good rule of thumb is to check fuel (in all cylinders), check spark (also in all cylinders) and if you’re getting both, check timing, because if the spark is coming at the wrong time, it’s entirely possible the engine won’t be able to start.


#13

You are on the right track with your Master Tech. This designation is always something I wanted to get but in the Dealership environment they can send who they want to school and without enough schooling by BMW,no Master Tech designation. Since I am out of the loop now this will never happen for me. Perhaps some say, “no indication of ability” but it really was something I wanted.

Comparing the ASE Master tech designation to the BMW Master Tech designation is, well there is no comparison.

With BMW the Dealer will not get paid for a warranty job if the tech that did the work is not schooled in that car (this is a general policy that is broken everyday). There is good and bad with this policy as it kept me away from endless warranty work on the new 7 series in 2001 since I was not “schooled” in this car.


#14

Dear Oldschool,
I hear that those 7 series cars continue to be “tire challenged.” This is based on what I read in AutoWeek magazine with regards to their long term test car. Lotsa flat tires.
I experienced the same challenges with our '01 330ix sedan. That aspect ratio was hell with the pot-holed New Jersey roads that I had to use. I bought 3 wheels and probably 6 tires due to road hazard, pot-hole adventures. It made me a believer in not ordering the Sport package ever again on a BMW. Our '01 X5 (with the phantom starting issues) has not had anything like those tire problems. But when it comes time to replace those big old “Demaris” model tires, you’d better have just gotten paid!


#15

The 7 series was plagued by electrical/software gremlins. The only tire issue I know of (and like I said I am out of the loop) was way low mileage for run flat tires. My recollection is 7 series came with a spare.


#16

Dear Oldschool,
I recommend that you go to the AutoWeek web site and check out their writings on their long term 7 Series car. Sounds like the electonics (from '01) may have polluted our X5 (same vintage).


#17

THIS PROBLEM WAS FOUND & FIXED!
the Memphis Motor Werks team kept our 2001 X5, 4.4 for 5 days running all manor of computer tests, etc.
The problem turned out to be a relay malfunction. In an effort to improve the CAFE rating, BMW used/uses an electronic relay that activates with the coil. During the combustion cycle, this relay keeps the coil firing for a nano second after spark plug has triggered the fuel burn explosion in ea. cylinder. By keeping the fire going after the primary burn, this burns the remaining fuel vapors to achieve a more thorough use of the fuel. This Unload Relay was “stuck” on/open so the ignition coil was malfunctioning.
Here is the replacement parts list:
1- 61 35 9 145 097 Controller $137.
1- 61 36 8 373 700 Relay 14.
1 -61 32 6 901 962 Ignition Switch 79.
The car starts and runs as it used to. This case is closed. Thank you to all of the forum contributors who weighed in with suggestions. VinceJohnson