Ignition misfire on coil 8 output | AEM
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arknotts
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Ignition misfire on coil 8 output

I'm having an ignition misfire on cylinder #6 on my 1992 Toyota Supra.  I have it hooked up to the coil 8 output on an AEMV2 (model 30-6050). I scoped the output (on wire A22) and it's literally trying to dwell the coil for ~50ms! Where all of the others are about 3-5ms like I'd expect. I've tried many different dwell settings and coil 8 is always acting up. What would cause something like this? Thanks.

AEM_GN
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Joined: 02/18/2014 - 09:55
It could be a few things.

It could be a few things. Open up your Coils/inj tab and make sure it is setup correctly there.

Also open up Display -> Show Options Full List and scroll down to the coils. Make sure they are all setup the same way.

arknotts
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Everything looks OK to me. I

Everything looks OK to me. I actually got it to run OK when I wired up cylinder 6 to fire wasted spark off of the cylinder 1 coil. Here are my settings:

AEM_NS
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[quote=arknotts] What would

Quote:
 What would cause something like this?

There's probably something in your cal that's trying to use the coil output for some other function.  Where'd you get your cal from?

arknotts
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Here is the waveform of coil

Here is the waveform of coil 1 vs coil 8 output:

I got the cal file from the same company I bought the EMS from. It had a basemap for my 1992 Toyota Supra (although initially the cal file was set up to use waste fire on coils 1, 1b, 2, 2b, 3, and 3b). I've since switched to a COP setup and enabled coils 4, 7, and 8 to run the other three. I can't see anything else attached to coil 8, but I may not be looking in the right place. Here is my cal file for your reference. Thanks.

https://dl.dropboxusercontent.com/u/34152173/supra.01V24.cal

 

 

AEM_NS
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I decided to do some testing

I decided to do some testing with this as this is the second time we've heard of this problem and both were with 6050's on MKIII Supras - presumably from the same company.  I've tested across a few different firmware version and a few different cals and it appears that there is a bug with how dwell is handled on coils 7 & 8.  What happens is that the ECU calculates what the dwell should be based on the commanded ignition timing value and the current engine speed.  It basically back tracks and knows if the spark is to occur at X then the coil charge start time occurs at X minus dwell time.  Everything in the system is based on teeth and there are channels that indicate where the coil starts charging and where the coil is fired.  The problem appears to be that coils 7 & 8 do not handle the transition from 0 teeth to 23.999 teeth well.  As the coil charge location goes from about 0.60 teeth to 23.88, the coil output starts doing some funky stuff which is likely what you're seeing.  

There are two ways to fix this.  First, you can change the phasing values for all the coils and your Ignition Sync value in a way that the roll over occurs for one of the first four coils as they don't seem to have this problem.  Basically, instead of phasing values of 0-16-8-20-4-12, you could offset them all equally by some number, say 4, and have 4-20-12-0-8-16 and offset your Ignition Sync to keep the ignition events occurring in the right spot.  Regardless of how you do it, the objective would be to have the roll over NOT occur for coils 7 & 8.

^^^Not a valid fix - see last post.

The second thing you could do is open up the box and move some jumpers around to allow coils 5 & 6 to go to the outside world.  I tested coils 5 & 6 and they also appear to be okay.  

arknotts
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Thanks for the detailed

Thanks for the detailed research and post! Unfortunately I changed the phasing like you said and coil 8 is still behaving very oddly. I did have high hopes for that solution though.

What jumpers do I need to change to enable coils 5 and 6? And what pin are they on the harness?

Also, would upgrading to another firmware help this issue? I'm at V01.24 right now.

Here are my new phasing settings:

...and just to check, my cam and crank signals seem pretty strong (the top one is just cut off a little I should have moved it down a little):

...and lastly here are the jumper settings on my unit:

AEM_NS
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What did you change your

**EDIT** What did you change your phasing values by?  My suggestion of 4 was only an example and not an actual number to use.  You need to keep adjusting the phasing values to make the roll over occur in a different spot.  Also, as I mentioned in my previous post, I tested across multiple firmware versions and this looks to occur universally so no, there isn't a different firmware version that you should try although 2v02 is our latest and greatest that has many enhancements and a number bug fixes unrelated to this problem.

 

DereckR
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Joined: 08/24/2014 - 14:34
How are you seeing the coils

How are you seeing the coils is that in the AEM?

AEM_NS
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It's from an oscilloscope.

It's from an oscilloscope.

Caleditor@pcmca...
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I am runing into the same

I am runing into the same issue. I have moved the phasing twice and it will run for an hour just fine, then the next day it will over heat #6 coil within 2 minutes. Any help would be greatly appreciated.

 

AEM_NS
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Sorry but changing the

Sorry but changing the phasing alone isn't the fix. See this thread for a solution: http://aemelectronics.com/?q=forum/is300-30-6050-lq9-misfire-issues

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