ECU Cooling

[ET16]

It looks as if the ECU on my 05 Saab 9-3 is going. My tuner told me that in the summer months he does a lot of cloning/replacement as more ECUs fail because of heat.

That got me thinking. Has anyone done any cooling mods on an ECU? I was thinking that I could at least try to stand the ECU off the engine with some nylon washers to block direct heat transfer from the block, or maybe stick on a cooling fin.

 

[supton]

I wouldn't do nylon washers. I don't know which way heat is flowing--it's natural to think that heat is flowing from engine to ECU, but, ECU's generate heat too. It may well be using the engine as a heatsink!

Fan won't hurt, though. Cheapo biscuit fans usually aren't rated for underhood usage (water) but I'm sure you can find things.

In the past for items that make heat sometimes I would just take some heatsinks and find a bolt to affix it to. Hack but it's all about increasing surface area and getting airflow over that. If it has no fins then adding some shouldn't be going in the opposite direction.

 

[Virtus_Probi]

It could be that a direct connection to the block is actually helping cool the ECU.
It is true that the electronics themselves usually like to be cold (higher carrier mobility and other good things like that), but sometimes the solder joints don't agree and condensation can also hose you over.
Fins could also end up blocking airflow without a good analysis of how it's actually moving....

 

[Chris142]

Some cars put it inside the air filter housing.

 

[SwampSurvivor]

I have heard of people relocating their ECU to better locations. Never really heard of anyone adding cooling.

 

[andyd]

The classic failure mode of an ECU is loose solder joints on the power transistor legs . Open it up and have a look. A failed solder joint will have a thin black line around the top. The line is caused by arcing. A dab of flux,and a hot iron to re-flow the solder is all you need.

 

[WyrTwister]

Originally Posted by supton
I wouldn't do nylon washers. I don't know which way heat is flowing--it's natural to think that heat is flowing from engine to ECU, but, ECU's generate heat too. It may well be using the engine as a heatsink!

Fan won't hurt, though. Cheapo biscuit fans usually aren't rated for underhood usage (water) but I'm sure you can find things.

In the past for items that make heat sometimes I would just take some heatsinks and find a bolt to affix it to. Hack but it's all about increasing surface area and getting airflow over that. If it has no fins then adding some shouldn't be going in the opposite direction.


Take one of the IR Temperature " Guns " . Measure the temp of the ECU and of what it is bolted to . Heat will flow from the hotter to the cooler , no guessing .

 

[meep]

gen1 volvo s60s have oem ECU coolers. There's a t-stat operated fan in a plastic box surrounding the ECU. Fresh air is ducted via 2" pipe which pulls air from the passenger compartment above the glove box. You'll hear in running on shutdown during the summer time. Fan lasts ~10 years, and some late-in-life ECU failures are also found to have a bad cooling fan.

 

[bdcardinal]

Originally Posted by meep
gen1 volvo s60s have oem ECU coolers. There's a t-stat operated fan in a plastic box surrounding the ECU. Fresh air is ducted via 2" pipe which pulls air from the passenger compartment above the glove box. You'll hear in running on shutdown during the summer time. Fan lasts ~10 years, and some late-in-life ECU failures are also found to have a bad cooling fan.


Yup I was going to respond that my 2004 S60R had a fan on the ECU. I would hear it running after I shut the car off and was walking away.

 

[kschachn]

Yeah my old BMW has a cooling fan in the module box under the hood. Amazingly it still works after 25 years, about the only piece of original equipment that does.

 

[Audios]

Sometimes they ground the ecu through the bolts to the car, I wouldnt isolate it that way.

 

[nthach]

I've seen Chrysler ECUs installed into the airbox or ducted to one. My parent's Lexus has the PCM mounted in a box near the intake to provide some cooling and environmental protection.

GM/Delphi started using the PCM/ECU body as a heatsink. And everyone else followed.

 

[CBM20]

I literally created my account just to reply to this thread and combat a very dangerous and ignorant idea I saw here.
The intake manifold does NOT act as a heat sink for Saab 9-3 ECUs. After 15 minutes of driving the ECU's external temperature is 90 degrees F, while the intake header is at about 130 degrees. Do the math. The intake continues to rise as the vehicle runs and the ECU always follows it. Here's another experiment. If you shut off your car, the ECU will continue to climb in temperature until it finally reaches the temp of the intake. Then both will slowly cool together. If you remove the ECU, it will cool to room temperature fairly quickly. Hence, the internal ECU components are not the dominant heat source.

In summary, the much hotter intake manifold is BY NO MEANS a heat-sink for the ECU. The intense heat and vibration of the intake header is why the 9-3 ECUs die so quickly!!! There is even a small private market of cooling solutions for the ECU. Most common are plates with spacers to offset the ECU from the header. In Taiwan and China people even re-locate the ECU to the front subframe near the radiator. Nylon spacers, as long as they can handle the engine temp, should be fine. When I get my new ECU (old one overheated while bolted to intake) I'm going to relocate to the frame and might even add a CPU fan just to be stupid safe. I would relocate all the way to the airbox or battery if wiring was less of a pain.

Please, for the love of all Saabs, do NOT discourage people from protecting their ECUs as supton has done. Intake headers are not ECU heat sinks!!!

P.S. if you do offset your ECU, make sure to firmly re-attach the ground wire. I've seen people forget about that and it doesn't end well.