‘03 z4 starting issues.

Me again :rofl:

Another thread:

https://www.bimmerforums.co.uk/forum/f18/2003-e46-320d-temp-gauge-rises-red-car-wont-start-t313825/

If you know a helpful and friendly Z4 owner with the same engine, perhaps you could try fitting their ECU to your car to see if that eliminates the issue? If it IS your ECU, it could be repairable.
 
Thanks for the links...something to dive into.
The temp guage stays on center while engine is running and warm...you could see it sweep all the way to center while warming up. No running issues once started.
I checked data and engine coolant temp was at 84*C and the coolant temp radiator was -45*C....plugged and unplugged the socket and it read normally after that.
Car started right up this morning...I want to say that porblem was fixed...but I know I’m only kidding myself. :D
 
Will order a new thermostat since i’ve had the 279b code twice now...while am at it, might at as well replace both coolant sensors and see what happens.
I know I’ll save a lot doing this myself one weekend...so here goes.
Thanks for the help guys....
 
That's interesting, and suggests perhaps some corrosion on the sensor terminals and/or the loom connector was the cause? If so, clean them up, bit of electrical grease and hopefully all will be well for a few more years without needing to replace anything!
 
I’ve read the links and one of them is exactly same as what’s happening on my z4...i guess sensors and thermostat is the way to go. Was just wondering what sensor on the thermostat they are taking about? I know there is plug on the thermostat but it’s for the heater element right?
 
Had nothing to do the whole day so I figured I’ll try to start the z4...it fired up and idled smoohtly. Went for a 60 mile drive up the mountains using the Angeles Crest Highway....no issues came up. When I went home, turned engine off...got myself a drink and came back...no start and temp guage on red zone again. Did the cluster test and engine temp reading was 000. Does it mean the engine temp sensor was giving no signal? I still had a lot of time before the sun sets so I opened the hood....looked into the thermostat,engine coolant sensor,radiator coolant sensor and the crankshaft sensor,now I pretty much know how to replace those components when my parts arrive. I disconnected those sensors one by one and tried starting the car...still no start and temp guage on the red. Now here’s my question...if the engine coolant sensor is not giving any signal...shouldn’t the temp needle remain in the blue zone?
 
Not necessarily. It depends on the characteristics of the sensor (i.e. whether its resistance rises with an increase in temperature or falls with an increase in temperature).

It sounds as though your car is doing the same as one of the cars in one of the links I sent. Works fine until up to temp and switched off. Once switched on again, the hot needle sweep happens and it won't start.
 
Because it's cheap, starting with the coolant temp sensor replacement idea is worth a shot. This could turn out to be an ECU issue though.

Just had a look to see what ECU Testing offer for the Z4. "ECU rebuild" is £300 :cry: I did notice this service too (for 3 series with your problem): https://www.ecutesting.com/common-faults/bmw/bmw-320-td-e46-ecu/ . Maybe it's worth an email to see if they can gjve a specific quote/diagnosis for your issue?
 
Just an update...changed my temp sensors both on the radiator and the engine and I also swapped DME relays with my e46 but still the same. After waiting for a week for my appointment with an independent BMW specialist, car was finally diagnosed and everything points to a faulty DME. If the engine starts it all goes well...if it doesn’t, it’s because there was no communication with the DME. It’s either the DME or something within the harness. For them to move on,I would have to get a new DME...an expensive proposition. I don’t mind spending that much if that would really cure my starting issues,but they said there is no guarantee. So instead of me getting a new DME they pointed me to another shop that specializes with the DME and electrical stuff. So waitng for another week so that I could bring my car to that other shop. :x
 
Yup. They reffered me to a shop that specializes in that....they can repair or clone one for your car. I hope they finally fix it. It’s the long wait that stresses me out. :D
 
Just an update...brought my car to this new shop that specializes in BMW electronics...turns out my ECU/DME is faulty. Question is....do I get a new one from BMW at $2500 includng programing or a used one reprogrammed for my car for $1200? The new one doesn’t come with warranty but the used one does... :o
 
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