How did 2 new AEM smart coils blew up

This section is dedicated to discussion of DTA engine control units such as the DTA E48 EXP, P8 Pro, DTA S40, S60, S80, and S100, as well as all things ECU related.
maxiice
Posts: 67
Joined: Sat Apr 13, 2013 5:16 pm
ECU Model: S80 Pro
Firmware Version: 63

How did 2 new AEM smart coils blew up

Post by maxiice »

I just installed 8 new AEM smart coils, and i did it with much care
They all have each solid ground in battery
And they all have ground in their cylinder bank
They have their own 20 amp fuse
Dwell is 3ms
Ecu is set to external coil amps
Motor has been running a couple of hours with this coils and running fine.

The first coil burned up with only ignition on, and the other one another day, under cranking. Battery is strong.

I see 2 outcomes, i have received some cheep china AEM copies, or the ecu is not sending correct signals
aem_tandspole.jpg
aem_tandspole.jpg (10.97 KiB) Viewed 571 times
MarcoV6T
Posts: 101
Joined: Tue Jul 26, 2011 12:20 pm
ECU Model: S80 Pro
Firmware Version: 58

Re: How did 2 new AEM smart coils blew up

Post by MarcoV6T »

The S80 and amplified coils are not the best combo in my humble opinion.

Firstly, on your coils its stated TTL trigger, means they need a 5V signal, and if I'm not mistaken, the S80 output's a 12V signal(amplified coils checked), through a pull-up resistor on the coil drivers.

I had an S80pro myself in the past with amplified coils on plug, and what the ECU does when using the 'amplified coils' option, is that it inverses the signal to the coil drivers(output), meaning that at rest the drivers are 'ON' and because they switch to ground, the output is ~0V, thus no trigger.

When they need to trigger, the respective coil drivers are switched 'OFF', meaning the coil drivers are 'floating', but because of the pull-up resistor the output goes 'HIGH' or in the case of the DTA +12V(although not 100% sure, could be a pull-up to 5V, I guess Alex can tell you), and triggers your amplified coil.

The problem I had with this 'procedure', is that each time you switch on the ECU, the coil output with their pull-up resistors hard wired to +12V, goes first 'HIGH' a fraction off a second, the time the CPU starts up, reads the map settings, then turns 'ON' all coil drivers to switch to outputs to ground...

So what I had was that all coils fired each time a turned on the ECU, and one day I had a leaky injector, and boom went my plastic intake manifold...

To avoid that problem of coils firing each time you switch on the ECU, I used the fuel pump output to switch my power relay for the coils +12V supply. In doing so, the ECU has time to switch 'ON' the coil drivers, before it turns on the fuel pump output, and no sparking anymore when turning on the ECU.

I also connected my external Lambda sensor to this +12V supply, so it doesn't heat up the sensor when the engine is not running...

Cheers,
Marc.
stevieturbo
Posts: 3362
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: How did 2 new AEM smart coils blew up

Post by stevieturbo »

I ran LS coils for a very long time with the "12v" trigger without issue. Cannot comment on whether the IGN1A will be happy with that though. I do use them on my own car but with a different ecu and I trigger them at 5.5v

If in doubt, scope the signals from the ecu to see what they are doing.
Alex DTA
Posts: 1562
Joined: Fri Feb 28, 2014 1:03 pm
ECU Model: S40 Pro
Distributor: DTA
Firmware Version: 79

Re: How did 2 new AEM smart coils blew up

Post by Alex DTA »

The pull up is to 12V.

We have not had any issues with any amplified coils running this way. We have plenty of IGN1A (our recommended coil for methanol) running on our ECUs with no problem.

As Marco says, you do need to wire the power supply to the coils through the fuel pump relay due to the start up issue.

If only two coils have failed, it's more likely you have dodgy coils.
maxiice
Posts: 67
Joined: Sat Apr 13, 2013 5:16 pm
ECU Model: S80 Pro
Firmware Version: 63

Re: How did 2 new AEM smart coils blew up

Post by maxiice »

Ok thanks you all :) you are great

MarcoV6T : cheers
Yes i have had that boom too, I just open throttle wide open before turning on ignition, But i will rewire it later on.
I have had TFSI coils for years, and not blown any

stevieturbo : Thanks yes i will source a scope if more blows up. And yes one blew up when motor was not running.

Alex: Thanks yes lets hope it was bad coils, but 2 of 8 ?? I believed AIM was quality
stevieturbo
Posts: 3362
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: How did 2 new AEM smart coils blew up

Post by stevieturbo »

AEM is just a sticker, as are all the other brand names who put their name onto these coils.

As to how many are the real thing these days....who really knows.

I know Lance at Pantera EFI was one of the designers, they are originally Mercury Marine coils but have become massively popular in the car scene in the last handful of years.
And I believe there are also some higher power versions of them too, although quite a bit more expensive.

But you would hope when a big name has their sticker on it, they would be from a reputable source....

All the ones I have used have had AEM stickers too....mainly as most sellers seemed to be selling them.
maxiice
Posts: 67
Joined: Sat Apr 13, 2013 5:16 pm
ECU Model: S80 Pro
Firmware Version: 63

Re: How did 2 new AEM smart coils blew up

Post by maxiice »

Did some testing today, Just turned on the ignition, and right away 3 more coils started to heat up, and 3 remain cold. the heat sink got up to about 60 degrees in 10 sek, before i cut the power.
So i swapped the coils, and the good cold coils, remain cold, so it must be the coils, that are bad. Now 5 of 8 coils gone bad.
I tested the wiring where the coils was hot, and the trigger signal is grounded, and it was so also where the coils did not heat up.

So i guess the trigger signal stays grounded until it is suppose to fire a spark?
maxiice
Posts: 67
Joined: Sat Apr 13, 2013 5:16 pm
ECU Model: S80 Pro
Firmware Version: 63

Re: How did 2 new AEM smart coils blew up

Post by maxiice »

As i await some answers i am considering going oldscool with dumb coils and 2x bosch 4 channel igniter.

This is some info i fount about wiring up the igniter :

This module requires the ECU to
determine coil dwell time.
The coil charge starts as the Ignition
Output from the ECU goes high.
The coil spark event happens when
the Ignition Output from the ECU
goes low.
This Ignition Module needs good
heat sinking using heat sink paste.
Suggested Charge Times
1.2mS to 1.8mS - Small coil on plug coils
3.0mS - Normal large coils------------------

So how does this play out when my trigger signal is grounded all the time its not sending spark signal? Will the same happen?

I
stevieturbo
Posts: 3362
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: How did 2 new AEM smart coils blew up

Post by stevieturbo »

maxiice wrote: Sun May 22, 2022 2:51 pm Did some testing today, Just turned on the ignition, and right away 3 more coils started to heat up, and 3 remain cold. the heat sink got up to about 60 degrees in 10 sek, before i cut the power.
So i swapped the coils, and the good cold coils, remain cold, so it must be the coils, that are bad. Now 5 of 8 coils gone bad.
I tested the wiring where the coils was hot, and the trigger signal is grounded, and it was so also where the coils did not heat up.

So i guess the trigger signal stays grounded until it is suppose to fire a spark?
Modern coils with internal amplifiers will charge, draw current when a "Hi" voltage is applied....by that I mean 5v, although in the case of DTA it may be near 12v.

Upon removal of the 5v, the coil will fire. Sitting idle with the coil trigger line at 0v, the coils will be doing nothing, they will not be drawing any current
A scope and current clamp is very handy here for monitoring.

Or even a current clamp linked to the ecu and logged as fast as possible like 1000hz might get you a picture.

If for whatever reason this voltage was high for an extended period...yes it could burn them out. And given they will usually run in the 2-4ms region, an extended period need not be very long.

Although that's some serious heat, very quickly. Although I don't think I've ever powered on one of the coils for 10 seconds to test to see what happens.

Where were the coils sourced from ? Where they in correct AEM boxes etc ?
stevieturbo
Posts: 3362
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: How did 2 new AEM smart coils blew up

Post by stevieturbo »

And if you're intending to use "dumb" inductive coils....DTA can run these directly. There is no need for an external ignitor
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