Starting issues

[Ditchy11]

So I’m having an issue with my e53 3.0d on a 2006. So this issue is my temp gauge shoots straight up to the red and the fuel inject. System comes up, it doesn’t do it all the time and I can eventually get the car started but other times I can take hours to get it started. I’ve had the ecu out and reflowed and it’s made no difference. I also can’t communicate with the ecu (using snap on solus legend)

I’ve hear reprogramming to ecu can sort the issue, but when I went to get it reprogrammed he couldn’t communicate with the ecu, even when I managed to get the temp to stay in the blue

Any one able to give me any help with this. Thanks

[Ditchy11]

I’ve also tried to see what happens when the ecu is completely unplugged and the temp still shoots to the top, hopefully this extra info helps

[X5Sport]

Have you done a full fault code readout? What makes you think it’s the ECU as there are other systems in the starting circuitry including the immobiliser. With a full fault check, preferably with something that can correctly report the BMW fault codes and not generic OBD2 ‘P’ codes you might be able to narrow it down. It could be a binnacle fault, wiring fault, other module fault, the list goes on.

[Ditchy11]

Thanks for replying. I can’t communicate with the ecu once the fault happens. When I do a scan of any other module it doesn’t bring up any faults for it. Also the eml/dde light has never once lit up on the dashboard. I took the car to get the ecu reprogrammed and the guy couldn’t even reprogram it as he couldn’t communicate with the ecu and he also tried with Israeli and still couldn’t which led me to believe it was the ecu at fault. Outside of the ecu, I’ve unplugged the ecu and turned the ignition on and the problem still happens. I’ve also unplugged the temp sensor on the block, and turned ignition on and it still happens. Also wouldn’t have though immobiliser would have put the temp past the red. Any other ideas?

[X5Sport]

What is the Israeli connection with the ECU?

Warning lights don’t always appear, hence needing a full diagnostic check using the right tools. Not all tools can talk the ‘right language’ so can’t get a response from individual modules. Try a different diagnostic tool and see what gets reported. No idea why your guru can’t talk to the ‘ECU’ off the car, but that could be a computer language/interface issue rather than a fault. BMW do have odd access controls in place, though I thought that was on later models.

If it’s intermittent then that’s a pain to find! Wiring should be looked at, as should any sign of water ingress anywhere. Try a diagnostic when it is working as those sort of faults should be being logged anyway, whether current or historic.

[Ditchy11]

Warning light in general doesn’t appear like even when ignition on, I’m able to communicate with the ecu when the car works and everything reads fine and also able to connect with every single module, even when it has the issue I can still read all modules bar ecu. I’m gonna check the grounds etc. He said he was trying to re program it but he couldn’t get the correct file as it’s the latest one and he didn’t have it. I could try someone else mind. He’s had the ecu open and there was not one sign of anything damaged or corroded inside and he re soldered it all as a ‘just in case’
He also did try and read it with inpa/ista and he was having the same issue as me but couldn’t understand as to why it had the exact same issue of it pegging to red when the ecu wasn’t plugged in.

Do you reckon I could potentially pull of the temp sensor and try bridge it and see what happens then? Might just buy a new loom and try that way lol

[Alan Gunn]

Just change the temp sensor not a fortune and easy enough to do.
Reading the posts bring Mountain and Molehill to mind.
I would try the sensor first.

[Greydog]

What leads you to believe it is an ECU fault just because you cant see it doesn't mean it is at fault, faults else where can block communication.
Forgive an "Old Bloke" but if the fault is there with the temp sensor disconnected or connected then to me that would point me at the wiring having a dead short somewhere.
You say the EML doesn't illuminate with or without the fault present, so is that relevant? as has been said the fault could be with the binnacle, or has someone disabled/disconnected the EML/Engine lights? If they aren't working it shouldn't pass an MOT

When in business I spent 50 years heavily involved in Industrial Controls so have a "need to know" mentality, that lead me to have tools on my Laptop that would let me understand what Dealers were/weren't doing to my car, when engine management started in the late 80's. I now have programs for Volvo, Mercedes/AMG, BMW, and Subaru, plus for the Kids I have Toyota and Peugeot/Citroen. I totally agree with X5sport having the specific tools for the job is sometimes the only way.

[Ditchy11]

Just change the temp sensor not a fortune and easy enough to do.
Reading the posts bring Mountain and Molehill to mind.
I would try the sensor first.

so I’ve unplugged the temp sensor and it still comes up with the same issue mate.

What leads you to believe it is an ECU fault just because you cant see it doesn't mean it is at fault, faults else where can block communication.
Forgive an "Old Bloke" but if the fault is there with the temp sensor disconnected or connected then to me that would point me at the wiring having a dead short somewhere.
You say the EML doesn't illuminate with or without the fault present, so is that relevant? as has been said the fault could be with the binnacle, or has someone disabled/disconnected the EML/Engine lights? If they aren't working it shouldn't pass an MOT

When in business I spent 50 years heavily involved in Industrial Controls so have a "need to know" mentality, that lead me to have tools on my Laptop that would let me understand what Dealers were/weren't doing to my car, when engine management started in the late 80's. I now have programs for Volvo, Mercedes/AMG, BMW, and Subaru, plus for the Kids I have Toyota and Peugeot/Citroen. I totally agree with X5sport having the specific tools for the job is sometimes the only way.

I led it down the the ecu to start with due to seeing someone had literally the exact same issue with ‘fuel inject system’ and ‘trans failsafe prog’ and the full temp gauge. But now as I’ve had the ecu out, and tried turning the ignition on the exact same issue happens which is now turning me away from the ecu. Another reason I put it to the ecu is that I couldn’t communicate with the ecu when this problem was occurring but can when the problem goes away.

That’s what my though is now of the eml/dde light due to it not coming on at all, even when I read all the modules they all flash on the dashboard when that certain module is being read but the eml does so that’s gonna be checked out.

So it’s got to be a wiring fault doesn’t it, if I unplug the temp sensor and see if I can get some continuity in the wires and see what’s going on, I ain’t the best with wiring so I can get the lad at work to test the wires for me.

It’s just annoying as if I go shopping we have to go as a family and one of us stay in the car and keep it running cause if I turn it off the possibility it doesn’t turn back on for a few hours is very high lol