ZHP engine shutting down while driving/stopped - Faulty DME?

[brettbimmer]

Hey Gents,
Been chasing a weird one in my 2004 ZHP lately. She's a garage queen, and very well kept. I was about an hour into a three hour drive when at about 60MPH the engine completely shut down. Triwd to restart and it will crank & crank (like. a bad fuel pump, which is operating normally). When this happened, temp gauge went from normal to pegged, and car would not restart until about 15 mins later when something reset and temp gauge came back to where it should be. Turned around and drove the hour or so home with the car doing the same thing - randomly shutting down while driving, unable to restart for a period of time. Probably happened 12 times over the next hour. I have been searching thr web trying to read about possible problems, but have not seen anything concrete except that this seems to be pointing to a DME problem.

Here's what I know:
Car is not running hot or overheating. Fuel pump is working perfectly. Swapped the battery just to see if it was a low-power issue, and it made no difference. No dash lights on normally, yet I would get some sometimes after this happens until it resets, then occasionally thereafter a few would stay on until I restart. Engine grounds and battery terminals are all tight - even tried a hard reset disconnecting the battery for a period before reinstalling. Car will run flawlessly up to temperature and usually beyond, then it will randomly shut off. This happens under load or sitting at idle not moving. Ironically never sets a check engine light, but scans reveal CAN BUS errors.

So any ideas Mafiosos? Think I am on the right track pointing to a bad DME/ECU? Thanks in advance for your collective wisdom & experience.

Here are a few pics. Temp needle pegged is after shutdown. Next is after sitting when I can restart it.

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[az3579]

Makes me wonder if the car is designed to shut the motor off automatically in an extreme overheat situation. If so, perhaps you have a faulty coolant temp sensor that is tripping it?

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[brettbimmer]

Makes me wonder if the car is designed to shut the motor off automatically in an extreme overheat situation. If so, perhaps you have a faulty coolant temp sensor that is tripping it?

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Thanks BP. Possible, but wouldn't I see a spike in the temp gauge before it shut itself down, esp. with your special coding work eliminating the traditional factory dampening of the gauge? Temp. is 100% normal, engine shuts down, needle pegs. Here is the one article that I can find on this:

http://autotechdiagnostics.com/?p=213

[brettbimmer]

Screenshot from the scan of the system:
]

[az3579]

Thanks BP. Possible, but wouldn't I see a spike in the temp gauge before it shut itself down, esp. with your special coding work eliminating the traditional factory dampening of the gauge? Temp. is 100% normal, engine shuts down, needle pegs. Here is the one article that I can find on this:

http://autotechdiagnostics.com/?p=213

My friend confirmed that the car is NOT designed to shut down on an overheat situation so I guess there goes my theory.

I think you need a proper scan with ISTA-D to try to get more detail. Those errors seem incredibly vague.

[slater]

it definitely seems heat-related because you said it runs fine all the way up to temp, and beyond - then it dies. is the DME overheating? maybe pull the DME cover temporarily to monitor (and check the wiring at the DME while you're in there).

[Hornung418]

When you code a car, the temp needle will move to the red when it's complete. That's my only experience with the needle and makes me think it could be DME related.

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[brettbimmer]

it definitely seems heat-related because you said it runs fine all the way up to temp, and beyond - then it dies. is the DME overheating? maybe pull the DME cover temporarily to monitor (and check the wiring at the DME while you're in there).

Thanks. Interestingly all cooling system components were preventatively replaced less than 10K miles ago. I did not change any sensors, but everything else was swapped.

When you code a car, the temp needle will move to the red when it's complete. That's my only experience with the needle and makes me think it could be DME related.

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Thanks man. Thinking that my next best approach is to pull the DME and ship it off to BBA-Reman up in Mass for a bench test for $100. They tell me that if it is faulty and they can repair it, cost is $530. Full replacement with rebuilt unit is likely $900 or so. They ended up being my source for ABS module replacement on my old X5 too. Good folks there.

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[ELCID86]

Brett, sorry for your troubles. Not sure what Terraphntm is up to this summer (he's in Med school), but he seems to be a wiz with DME and other electronics. Maybe he'd take a look.

Do you think it's worth trying to replace the temp sensors just in case? Maybe not...

[brettbimmer]

Brett, sorry for your troubles. Not sure what Terraphntm is up to this summer (he's in Med school), but he seems to be a wiz with DME and other electronics. Maybe he'd take a look.

Do you think it's worth trying to replace the temp sensors just in case? Maybe not...

Thank you Sir. Hmmm...maybe I need to track down Tony before shipping any components off for investigation. Suppose I could swap some sensors, but I really think this a computer problem, esp. given what BP was able to confirm for me that they will not auto-stop if overheating is detected.

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