General new Ignition module also gets very hot

[UnoMia_SA]

Hi, I am from SA and bought a UNO Mia 1108cc a month ago to fight fuel costs.

Anyway after driving along happily for the last month, I received a nasty experience this week, when the car CUT OUT on me right in middle of traffic at the lights.

Anyway, I read the forum and replaced the Ignition Module with a new one from MIDAS this morning (not from Fiat because it was twice the price)

But I see this one also gets very HOT. You definitely can't torch it for too long. So was wondering exactly how HOT should this module get ?

It is also strange that the previous weekend I attached an after market REV counter to the -ve of coil. So I'm not sure if the current drain from REV counter thru the module made it go faulty. But since connecting the new module I removed the REV counter connection.

But it still gets hot. I also notice that the REVS are sitting at 1200-1500 on idle (hot engine with no choke), so not sure if the previous owner upped idle to prevent the CUT OFF but I think it makes it worst, as constant HI REVS would make this module hotter.

BTW, I check the earth connection on dizzy (new word I learnt here) and it has almost zero resistance to -ve of battery and chassis, so I'm sure it's ok. Also checked the sensor and it has about 800 - 900 ohms resistance which I think is ok from what I read.

Anyway like to hear your views. Changed the module Friday morning...so far no cut off but still concerned about the module being so hot and I don't know if I'm just being paranoid but the idle also seems a bit bumpy.

Thanks for any assistance.

 

[alexGS]

Presumably you read the thread directly below yours? https://www.fiatforum.com/uno/144932-fire-1108cc-electronic-ignition-module-overheats.html

I recall a note once (in FIAT documentation) that said to always ensure the coil holder is earthed before the ignition is turned on. So I suggest removing the ignition coil and cleaning where it bolts to its bracket - and in turn, where that bracket bolts to the car.

Then check the engine earth lead - actually take it off (the gearbox) and clean the terminal. Finally, check that your module is earthed to the distributor body. I think there is a small earth wire under it (at least on some models).

-Alex

 

[UnoMia_SA]

Hi Alex,

Thanks for the advice. I will look at the earth on coil, engine and distributor body.
But how hot should the ignition module get? I was hoping someone who doesn't have this problem would pop the bonnet and feel the module after a trip in traffic. Is the module warm, hot, very hot, or hot enough to boil water on it ?


Mine is very hot, too the point that I can only touch it for a few seconds or so.
If this how hot all modules get then I fine with it, but right now I not enjoying my UNO the way I use to because I'm always wondering when it's going to cut out on me again. So if someone could please give me an indication of how hot it gets normally I would really appreciate it.

Thanks.

 

[Chas Uno]

I don't recall any of my Uno ignition modules getting too hot to touch. As Alex says, check to see if it is earthed correctly as 9 times out of 10 that's normally the cause of them burning out. Also check that the two wires coming from the module aren't frayed and shorting out.

 

[UnoMia_SA]

Hi Guys,

thanks for the advice.

I am thinking of connecting a temporary thick cable from the module's earth directly to the battery negative and monitoring for a couple of days. I am also tempted to measure the current drain of the module at idle and maybe a higher REV. This should be a useful reference for the future and for others with similar issues.

Thanks once again for the help.

 

[ralphnz]

Hi there. You say you can't touch the new module for very long. I have a 1100 fire, and after 20km I can touch the module for just over a second before it gets too hot. So it's really not that hot, it just seems hot for an electrical component. It doesn't burn like the back of your hand on the exhaust manifold.
So what I am trying to say is that I think that is normal for these modules.
I have also heard that the after market modules don't last as long and run hotter than original fiat ones. I have a new fiat module on my other car, i'll check it out tomorrow.

 

[UnoMia_SA]

Hi Ralphnz,
Thanks for the update.
Yes, you're right, mine is exactly as you say. You can torch it for about a second or so before it gets too hot. Phew, that's a relief. I must admit I was a bit concerned about the heat. I bought my UNO from an old lady who bought it brand new. And I'm pretty sure she never drove it the way I have been since I bought it. Max. Power is at ~5000RPM so you have to take it pretty close to there to get it going. So I was a bit concerned that I broke it.

Thanks again for the feedback, will wait on the temperature of your other UNO's module.

 

[Davren]

If relevant, did you clean the mounting surfaces and apply heat sink compound when you fitted the new one? Usually a small tube of it comes with the new module. (but maybe not with a half price one from Midas)

Dave.

 

[UnoMia_SA]

Now that's something interesting. The module is a complete unit with heat sink attached to an epoxy resin which hides the electronics. Didn't look like you could take it apart. I will look at the one I took out, but it look pretty much the same as the new one. I would also take some pics of it and post it, maybe if you have pics of your module you can post it as well. Thanks....

 

[UnoMia_SA]

Pictures of the ignition module :


Don't see a way to separate the heat sink from electronics.

 

[Davren]

Certainly looks as though heat should be dissipated via the fins on the front of the module but I would still put heatsink compound on the metal part on the back of the module where it fixes to the distributor.

Dave.

 

[ralphnz]

If the heat is coming from the distributor then won't that make the ECU even hotter? I'm thinking a nice 5mm asbestos pad between it and the distributor might be a good idea.
Anyway, if the fins are hot then the chip or whatever it is is losing the heat you can feel.

 

[Davren]

If the heat is coming from the distributor then won't that make the ECU even hotter? I'm thinking a nice 5mm asbestos pad between it and the distributor might be a good idea.
Anyway, if the fins are hot then the chip or whatever it is is losing the heat you can feel.

The idea is to dissipate the heat produced by the output transistor situated within the module. This could be excessive because of a faulty module, poor connections to the module or a low primary resistance in the ignition coil.

The situation isn't helped by mounting the module on the side of the distributor, which is in turn mounted on the engine. Heat sink compound between the module and distributor would 'thermaly' bond them together helping to prevent the module getting any hotter than the distributor/engine.

There was a craze 10-20 years ago for the 'boy racers' to fit low resistance sports coils. To cope with the extra heat produced by the ignition module, it was often neccessary to move it away from the distributor with an extension lead and mount it on a separate heat sink fitted to the inner wing in cool airflow.

Dave.

 

[UnoMia_SA]

Hi,

Just to inform everyone. That the new (cheaper) module has been in for more that a week now and whilst it does get hot it has not failed on me. So (GOD willing) I hope it continues to give good services for years to come. Thanks for all the comments and advice.

 

[Chas Uno]

If the heat is coming from the distributor then won't that make the ECU even hotter? I'm thinking a nice 5mm asbestos pad between it and the distributor might be a good idea.
Anyway, if the fins are hot then the chip or whatever it is is losing the heat you can feel.

The module probably uses the distributor body to aid heat dissipation so isolating the two is not a good idea.

Hi,

Just to inform everyone. That the new (cheaper) module has been in for more that a week now and whilst it does get hot it has not failed on me. So (GOD willing) I hope it continues to give good services for years to come. Thanks for all the comments and advice.

That's good news! Hopefully it will continue to run without problems

 

[ralphnz]

Unmiasa, the brand new ECU on a fire 1000cc gets as hot as the 1100 ECU after about 20 minutes, so it has to be normal. It's the same temp as the distributor.
And 1986uno45s, personally I think it's the distributor that makes it so hot, if the designers were going to use an engine component to remove the heat from the unit they wouldn't have stuck it on something which gets as hot as the head. I think it's a design flaw, unless the ECU uses the engine temperature to regulate the timing, in which case surely it'd be a sensor and not how hot the chip was getting??? Anyway main thing is the car runs. Always good to have one in the glovebox though on long journeys haha

 

[sniperkroz]

Hi, i'm from SA as well and my opinion is that the genuine module is well worth it as i had pinking and high fuel consumption problems with the midas and autozone parts. If you live up in JHB it might not be a problem but at the coast it does make a differance.

 

[Richard Africander]

Hi my name is Richard Africander go to gallery check out my pic i posted ..i think that will help you a lot

 

[Davren]

Hi my name is Richard Africander go to gallery check out my pic i posted ..i think that will help you a lot

An interesting solution, albeit somewhat overkill, however this thread is over 6 years old. I suspect the OP has resolved the problem by now.

 

[CamaroMan]

hi guy - im hijacking sorry - but im trying to help a friend diagno a no spark situation (im overseas) on their family uno which i rebuilt (rings / valve seals etc)..

we swappe dout a ign module (cheapy) - but not im wondering if its shot (about 3 months driving perfectly till it just died)..

is there a way to test these off the car and on? this is what i have -

according to this diagram

the "B" green wire is triggering the coil -

any ideas to do a step by step test (on and ff car) of this module and the coil?

thanks