Couple of ignition coil related questions

[Rozsko]

Hey guys,

I am revisiting my idle misfire situation and have a few questions on coils and HT leads.

1) In the help file there are two Subaru COP coils mentioned, FK0186 and FK0140 with 5ms and 3ms Dwell times. Are these numbers meant to be set for the normal operating system voltage and increased/decreased if voltage is lower/higher?

2) In the same setup diagram, there is a suppressor capacitor specified. What could be the effect if this capacitor is not added?

3) I just figured one of my coils is an FK0334, and the rest are FK0186. I found conflicting information about the Dwell time for FK0334, so wanted to ask if anyone knows whether this is 3ms or 5ms?

4) As I was looking into alternate coil options, I saw Dwell times specified for different voltages, but not considering RPM. In the V10 Subaru basemap though, the control table is Battery voltage and RPM based and the value tapers off as RPM increases. Is that to prevent overheating? Maybe I am not thinking this trough properly, but at 7k RPM, 1 cycle takes about 18ms, so the time itself should be plenty to use higher Dwell.

5) For IGN1A coils (I seems to like the one MSD makes), is there any special considerations or settings that need to be implemented or any major reasons against this option at all?

6) Regarding HT Leads, in PCLink help, it is mentioned it should not be spiral would nor inductive. Tried to do some research, but pretty much everything I found was spiral wound (unless solid core), with varying resistance. So is there any recommended brand or specific type that should be used? So far I found Magnecor R-100 or KV85 to be the closest to your recommendations, but even these are spiral would as per my understanding (unless spiral woulding means something different).

Thanks a lot

 

 

[Adamw]

Your misfire is probably unrelated to ignition energy if it is at idle.  Cylinder pressure is very low at idle so doesnt take much spark energy to start combustion.  You would typically see ignition energy related issues at higher loads.  

1. Yes.  
2. The suppressor provides a short ground loop path for the spark to return to the coil, this reduces emi.  This Adaptronic video explains the concept quite well, watch from about the 8:00 mark:  https://youtu.be/ZTDsm6b69Lk
3. Again, unlikely to be sensitive to dwell at idle - you can give it more as a test.   
4. VE and hence cylinder pressure drops away after peak torque, so since you need less ignition energy you can drop dwell back at higher RPM to give the coil more cooling time.  Electronics lifetime is greatly influenced by their average and peak temperature.
5. Not in your case.  Probably overkill, but they are good coils, originally designed for a mercury two stroke as a CDI replacement so provide good energy at even short dwell times.  They do have 3 isolated grounds, one is meant to go to the head, 1 to sensor ground and one to battery ground so that can make wiring a little more involved to do it right.  Having said that I have seen many people just ground them all to the same lug and get away with it too.  
6. OEM style carbon core leads are still the best by far for emi supression.  Spiral wound often have quite low resistance and generally arent as good.  You would typically see trigger related issues if there was an emi issue.  

[Rozsko]

11 hours ago, Adamw said:

Your misfire is probably unrelated to ignition energy if it is at idle.  Cylinder pressure is very low at idle so doesnt take much spark energy to start combustion.  You would typically see ignition energy related issues at higher loads.  

1. Yes.  
2. The suppressor provides a short ground loop path for the spark to return to the coil, this reduces emi.  This Adaptronic video explains the concept quite well, watch from about the 8:00 mark:  https://youtu.be/ZTDsm6b69Lk
3. Again, unlikely to be sensitive to dwell at idle - you can give it more as a test.   
4. VE and hence cylinder pressure drops away after peak torque, so since you need less ignition energy you can drop dwell back at higher RPM to give the coil more cooling time.  Electronics lifetime is greatly influenced by their average and peak temperature.
5. Not in your case.  Probably overkill, but they are good coils, originally designed for a mercury two stroke as a CDI replacement so provide good energy at even short dwell times.  They do have 3 isolated grounds, one is meant to go to the head, 1 to sensor ground and one to battery ground so that can make wiring a little more involved to do it right.  Having said that I have seen many people just ground them all to the same lug and get away with it too.  
6. OEM style carbon core leads are still the best by far for emi supression.  Spiral wound often have quite low resistance and generally arent as good.  You would typically see trigger related issues if there was an emi issue.  

Thanks Adam.

On the suppressor capacitor, as per Andy it is meant to be used for the old two pin coils, where the +12V is the common connection for the primary and secondary winding. So does this mean the Subaru COP coils are the same internally even thought they are 3 pin coils?

And one more thing on the IGN1A wiring. So on the 107X G4X, the ground pin from the coils go do D26 on the ECU which is a normal ground. So the sensor ground pin from the IGN1A then should really be hooked up to the sensor ground pin on the ECU (if I want to go by the book), right?

[Adamw]

57 minutes ago, Rozsko said:

On the suppressor capacitor, as per Andy it is meant to be used for the old two pin coils, where the +12V is the common connection for the primary and secondary winding. So does this mean the Subaru COP coils are the same internally even thought they are 3 pin coils?

Yes, the 3 pins on the coil are 12V supply to the primary winding, ground for the ignitor (effectively the ignitor connects to the other end of the primary winding), and the ignitor trigger.  The negative side of the secondary winding is still connected to the 12V pin, just like in an old 2 pin coil.

 

1 hour ago, Rozsko said:

And one more thing on the IGN1A wiring. So on the 107X G4X, the ground pin from the coils go do D26 on the ECU which is a normal ground. So the sensor ground pin from the IGN1A then should really be hooked up to the sensor ground pin on the ECU (if I want to go by the book), right?

Yep.

[Rozsko]

ok, great, thanks very much

[Rozsko]

One more question on the wiring of Subaru coils if you don't mind.

The ground pin of the coils should be connected back to D26 of the ECU, or is it better to ground them on the block/cylinder head?

Thanks,

Béla

[Adamw]

Factory they went to D6 & D26.  This is just the high current ground for the ignitors, so engine block/head would be fine too.  

[kaptainballistik]

Bear with me here... What Heads do you have, and what spark plugs?

 

[Rozsko]

1 hour ago, kaptainballistik said:

Bear with me here... What Heads do you have, and what spark plugs?

 

Not sure exactly what you mean on the heads, but this is an ej257 block so the heads are aluminum and single avcs. The spark plugs are Denso ikh24.

[kaptainballistik]

Ahh, Switch to the Copper core Plugs until you get it tuned, Even the short copper plugs meant for the early heads work ok.

How much Carbon fouling do you have?

[Rozsko]

On 3/1/2022 at 12:34 AM, kaptainballistik said:

Ahh, Switch to the Copper core Plugs until you get it tuned, Even the short copper plugs meant for the early heads work ok.

How much Carbon fouling do you have?

Well, I tried quite a few different plugs by now, so trying one more won't hurt.

I have some carbon build up on the plugs, but I would not consider it excessive.

[kaptainballistik]

The key is the colour of the ceramic, and if there is a ring of carbon around the electrode.. and how much carbon is down the plug grove.the "non-copper plugs are hopeless unless you have a really good tune. In my STI's original spec it would always start on 3 cylinders with  the :"non copper" plugs. 

On the other hand, Some people have Zero issues! (My Road WRX probably "needed" plugs 20K ago and its still ok.  

I think its the combustion chamber design that the issue......

[Rozsko]

34 minutes ago, kaptainballistik said:

The key is the colour of the ceramic, and if there is a ring of carbon around the electrode.. and how much carbon is down the plug grove.the "non-copper plugs are hopeless unless you have a really good tune. In my STI's original spec it would always start on 3 cylinders with  the :"non copper" plugs. 

On the other hand, Some people have Zero issues! (My Road WRX probably "needed" plugs 20K ago and its still ok.  

I think its the combustion chamber design that the issue......

#2 plug: https://1drv.ms/u/s!Ale4oyMCOgLThYUWUDxroZFmBDD8Vw https://1drv.ms/u/s!Ale4oyMCOgLThYUXY_WWmTxAJ698UQ

#4 plug: https://1drv.ms/u/s!Ale4oyMCOgLThYUQpI7fegORN_sdKA https://1drv.ms/u/s!Ale4oyMCOgLThYURIlcVEgwUjvk2iA

Now that looking back the pics, #4 is worse then #2.

[kaptainballistik]

Yeah, plug 4 looks a bit Shady!

Running slightly tighter gaps?

 

[Rozsko]

On 3/2/2022 at 10:19 PM, kaptainballistik said:

Yeah, plug 4 looks a bit Shady!

Running slightly tighter gaps?

 

At idle, tighter gaps should not be required I assume.

What is interesting though is that EGT is about 80-100C less in#4 then in the rest of the cylinders, which leads me to either severe misfire or some sealing issues with the cylinder. (Individual fuel correction in #4 did not have any good result. No matter if I added or removed fuel, EGT decreased even further, though I was expecting it to rise when leaning it out.)

So I did some in cylinder pressure testing and the cranking compression is exactly 10 bars both in #2 and #4. The running idle pressure waveforms again look exactly the same in #2 and #4 and there is only a little difference between the two in peak pressure.

The ignition waveforms look horrible though and it is worse in #4, but I don't think it is electrical, since I swapped the cables between #2 and #4 (and changed the firing order accordingly) and nothing changed.

Also swapped injectors between #2 and #4, again no difference.

So, every test I do is not unveiling any problem, yet there seems to be something wrong with #4.

I recently replaced both cam sensor and the crank sensor and again no change. Crank sensor signal is nice as it can be (all peaks are above 5V or under -5V), and cam signals are as weird as they can be with Subaru.

[kaptainballistik]

I'm actually struggling with something similar ATM.. Comp on 2-4 is  the same, but 2 tends to foul. The STD excuse always seems to be the Subaru coils are Bleh. Which I don't agree with!

In your case, its known for Subaru's to run a bit hotter ( The coolant is hotter there) on 4, so I would first look at adjusting the correction for Cyl 4. 

[Rozsko]

6 hours ago, kaptainballistik said:

I'm actually struggling with something similar ATM.. Comp on 2-4 is  the same, but 2 tends to foul. The STD excuse always seems to be the Subaru coils are Bleh. Which I don't agree with!

In your case, its known for Subaru's to run a bit hotter ( The coolant is hotter there) on 4, so I would first look at adjusting the correction for Cyl 4. 

When you say adjusting the correction, what do you mean? AFR? Because I already tried that, but the EGT decreased even further, no matter if I enriched or leaned out the mixture.

The other thing I wanted to ask is about the normal spark plugs. Do you have any particular partnumber to try? I looked up NGK, Denso and Champion as well, but the first two have only standard heat range plugs, the latter one have colder but only with three ground electrodes.

[kaptainballistik]

I'll have a look for the box!