164 Super 24V Second Front Coil Began to melt after coming from Mechanic - Alfa Romeo Forum
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(Post Link) post #1 of 12 Old 4 Weeks Ago Thread Starter
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Exclamation 164 Super 24V Second Front Coil Began to melt after coming from Mechanic

Good Afternoon,

I have a 1996 164 Super 24V and after changing the Cambelt Cleaning the Injectors and getting a full service I arrived at my garage to park it only to see smoke from the engine. I opened the bonnet and it was coming from the middle front coil and it was cracked and melting.

I ordered a new coil but it started to overheat only this one the others cold. I replaced the plug on the same cylinder and tried it again and it started to overheat again until bang and didnt work anymore.

I cant understand what is going on I gave it to the mechanic fine and returned with a faulty stereo, new battery, temp sender has a mind of its own, radiator fan is always on and stuck on rather than off and this.

I trust the guy and always perfect service but I am worried as I read that usually its a ECU problem but nothing was wrong when I took it.

I checked the ground (I do have a kill switch at the back not to drain the battery and its starting to play since it came back) was tight, nothing is showing a lack of ground but I am going nuts.

Any Idea what i Can do. I checked the Connector and one is 12V constant and the others I am getting -0.3 connected the positive multimeter sensor to the coil sensor.

I cant afford a new ECU and I love this Car Any Ideas would much be appreciated.

Regards,

Keith
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(Post Link) post #2 of 12 Old 4 Weeks Ago
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Take it back to the mechanic. Reading the codes would also be a good idea.
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Has the check engine light (injector light) turned on?

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Small suggestion to diagnosis. Could the ignition modules causing the melting? How about swapping them and trying?

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Morning, mine doesn't have a check engine light. I swapped the old with a new both work fine until I see them overheating and take them off. Thing is it's like I took off an HT lead as it works fine just melting them.

I honestly don't know where to start as my mechanic doesn't understand electrical issues and the second pin is showing current when it should be ground according to wire diagram.

I never opened up the round connector before and am really worried as you don't find ECUs for 164 3.0 24v these days

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Are the ignition modules jn the ECU ?

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Member car:

AR 166 2.0 TS

It must be something your mechanic has touched. Go through any documented guides available on the process for what he was supposed to have done, and look for what he could have done incorrectly or what he will have needed to unplug. Given that you've got a selection of issues in unrelated systems since you've got it back, he could have neglected to reconnect an earth wire somewhere, or a wire to a plug has come out of its connector. Do you have a wiring diagram so you can see if there's a common earth for the fan, temp sender, stereo etc.? The wiring for the coils route underneath the plenum chamber so he could have chafed or trapped one maybe when stripping down to do the cambelt, or wire in the plug/connector at that coil is loose or broken. Check the connector to that cylinder's injector also. You'll have to check continuity all over the place with a multimeter. But if this guy isn't willing to rectify the problems he's caused then threaten him with trading standards or that you'll rubbish him on the forums. It's not going to have coincidentally broken the ecu, he's ballsed something up.

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Quote:
Originally Posted by keithhm View Post
Are the ignition modules jn the ECU ?

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Ignition modules are located close to air filter box, towards the lower side. There are two of them. ignition coils are the ones that sit on 6 spark plugs.

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Thanks I didn't know that. I checked the wireing and found that Pin 1 was giving ground when it should be giving low voltage. I found that the clip holding the wires was pinching the wires going to the coil. I released it and placed it better and checked the pins and now there is voltage in pin 1. I tried it with a broken coil (The one that started to melt) and started it up. It was misfiring on that cylinder as it was gone but it didn't heat up, yesterday it was heating up again even if it wasn't working so I think I had a short with the ground.

I'll check again with a new coil and see what happens hopefully it's sorted.

Thanks again

Keith

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Quote:
Originally Posted by keithhm View Post
Morning, mine doesn't have a check engine light. I swapped the old with a new both work fine until I see them overheating and take them off. Thing is it's like I took off an HT lead as it works fine just melting them.

I honestly don't know where to start as my mechanic doesn't understand electrical issues and the second pin is showing current when it should be ground according to wire diagram.

I never opened up the round connector before and am really worried as you don't find ECUs for 164 3.0 24v these days

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Yes ECUs are hard to come by. If ECU is at fault, then the injector light should (theoretically) come on.
You also said one pin shows current where it should show ground. Then I guess you would have to trace it back.

However, note that checking resistance of electronic devices (or integrated circuits/chips) can damage them. (I guess its because the multi tester sends a current).
So avoid that and better test continuity while the ECU is disconnected. (Pig of a job reaching that but better to be safe).

Do you have the ECU pinout diagram? How many pins are there for injectors? Perhaps if you have the ECU disconnected, you can check for continuity from the designated pin of the ECU (from connector) to the faulty ignition coil. If you don't have continuity where its supposed to have it, you sure have a wiring issue.

I am just telling you what I would do, not that I have figured all out

Best of luck

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Current:: 1996 Alfa Romeo 164 Super V6 24V || 1993 Alfa Romeo 33 1.5IE || 1974 Holden HQ SS || 1972 Volkswagen Beetle || 1997 Nissan Sunny 2.0D (economobile)
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Quote:
Originally Posted by keithhm View Post
Thanks I didn't know that. I checked the wireing and found that Pin 1 was giving ground when it should be giving low voltage. I found that the clip holding the wires was pinching the wires going to the coil. I released it and placed it better and checked the pins and now there is voltage in pin 1. I tried it with a broken coil (The one that started to melt) and started it up. It was misfiring on that cylinder as it was gone but it didn't heat up, yesterday it was heating up again even if it wasn't working so I think I had a short with the ground.

I'll check again with a new coil and see what happens hopefully it's sorted.

Thanks again

Keith

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Great. Let us hopefully hear some good news.

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I wish I knew about the multimeter before, I tested 2 Coil Cables to get the confirmation of the pinout and to compare the one that was melting the coils and a good one.

It started and misfire on the same cylinder hope I didn't do any more damage!

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