How hot is too hot for the ecu?

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Rob C
MegaSquirt Newbie
Posts: 9
Joined: Fri Mar 28, 2008 10:26 pm
Location: Lebanon, OR

How hot is too hot for the ecu?

Post by Rob C »

I have a V3 board, running MSI.

I haven't gotten that much time running it in my car yet. However, I have put on 200-300 miles and gotten a decent tune. I'm incredibly happy with one exception... I have a problem with the ecu shutting down. It has only happened 3-4 times. I mounted the ecu under the dash right next to the heater box and right under a defrost duct. Every time this has occured I've been running the heater and running the air to the defrost when this shut down occurs.

I can turn the ignition on/off (power cycle) the ecu but I don't get any of the LEDs on the side of the box to flash. Last night I was able to check the relay that provides power to the ecu and it is getting power. It is also relaying the power when the ignition is turned on. The ecu is mounted in the dash in a way that I can't get the wire harness plug off the box without removing the box. Before I did that, I tried to start the car again. It started so I just headed home. It ran fine all the way home.

I'm guessing that location is too hot for the ecu and powering it down. Then in the time it takes for me to try to trouble shoot it, it cools off and starts working again but I don't know that this is true. The ecu case was quite warm to the touch when it failed but not "burnt my hand warm". I was scared to drive it to work today because I had a dentist appt but tomorrow I'll give it another try. Currently, the ecu is laying on the car's floor so I can have quick access to the harness when/if it fails again. I really don't enjoy being stuck along side the road though so if anyone has any other good ideas, I'd love to hear them. Thanks!
Matt Cramer
Super Squirter
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Joined: Sat Jul 03, 2004 11:35 am

Re: How hot is too hot for the ecu?

Post by Matt Cramer »

It's designed to take internal temperatures up to 100 degrees C or more. However, a faulty solder joint may not react all that well to heat.

You might want to use something like these temperature labels to see just how hot the case is getting.
Rob C
MegaSquirt Newbie
Posts: 9
Joined: Fri Mar 28, 2008 10:26 pm
Location: Lebanon, OR

Re: How hot is too hot for the ecu?

Post by Rob C »

Well, I'm sure it's not hitting 100 degrees C or that would have really hurt to touch it. :mrgreen: I drove it in to work this morning (~26miles) and it did fine the whole way. Once I got to work, I felt the case and it was cool to the touch (it has been removed from the dash and is still on the floor). I think I'll drive it a couple more days with the ecu on the floor and make sure it doesn't act up again. Once it's in the dash, I can't access it quick enough to check wiring before it works again.

Would a IR temp gun be accurate enough for getting case temp? I could easily put my gun on it in the dash. If not, I'll gladly get some temp labels.....

I'm guessing a faulty solder joint that is acting up would be VERY hard to find?
Matt Cramer
Super Squirter
Posts: 2951
Joined: Sat Jul 03, 2004 11:35 am

Re: How hot is too hot for the ecu?

Post by Matt Cramer »

Rob C wrote:I'm guessing a faulty solder joint that is acting up would be VERY hard to find?
It depends - ones without enough solder are pretty visible, and they should be fairly shiny with no cracks or the like.
Rob C
MegaSquirt Newbie
Posts: 9
Joined: Fri Mar 28, 2008 10:26 pm
Location: Lebanon, OR

Re: How hot is too hot for the ecu?

Post by Rob C »

Well since it's nice and easy to get at the ecu right now, I'll have to visually inspect each solder tonight. Thanks!
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