IS300, 30-6050, LQ9 Misfire Issues | AEM
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XtremeCoupe
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IS300, 30-6050, LQ9 Misfire Issues

Hello,

Let me preface this by saying that I'm not a professional tuner and I don't claim to be. I have a 2002 IS300 that is equipped with the AEM Series 2 (30-6050). Over the course of the last few months, I have performed several upgrades to the car including an LQ9 coil conversion from Mojo Performance. Using information/settings found on the internet, I was able to get the car up and running with the new coils relatively easily.

 

Here's a quick rundown of what is going on:

- Originally had dwell set to around 3.0ms and was already experiencing misfiring/breakup at around 6000 RPM under vaccum (no load). Pulled dwell back to around 2.5ms and it seemed to fix the issue.

- After a couple test drives, everything seemed to be working pretty well so I took the car over to my dyno to get everything dialed in only to run into more ignition issues. At 10 PSI, I started experiencing misfiring/blowout at around 5500 RPM. I adjusted the RPM-based coil dwell table to pull dwell back to around 2.1ms by around 7000 RPM and it pulled smooth to 7000 RPM.

- Slowly started increasing boost and at 16 PSI, I started experiencing more misfiring/blowout. I didn't feel comfortable pulling dwell back any further, so I decided to tighten up the gap on the spark plugs. The plugs were brand new Denso Iridium IK27 plugs with a stock gap of around .028". I had an extra set of new plugs so I tightened the gap down to around .020" and installed the new plugs. No more misfiring/blowout at 16 PSI.

- Again started increasing boost and ran into another misfire/blowout wall at around 23-24 PSI. At this point I don't feel comfortable lowering the dwell or decreasing the spark plug gap any further so I just decided to call it quits and leave it below 23-24 PSI for now.

 

Some other information:

- The car ran great last year with the stock IS300 ignition system (tuned by a reputable local tuner). I was running up to 28 PSI at .020" gap without any issues (same IK27 spark plugs).

- Ignition has been synced using the Ignition Sync Wizard (and rechecked multiple times).

- The LQ9 coils included with the kit are supposedly "good tested" coils (used).

- Main coil ground is going directly to the cylinder head (as suggested by Mojo).

- The engine harness is a brand new engine harness that was made by Tweak'd Performance.

- The car runs strictly on VP C85 fuel.

- Guys claim to run these LQ9 coils at 3.0ms, stock plug gap, 35+ PSI, on ethanol without any issues so I don't understand what is going on.

 

I stumbled upon this thread on the Megasquirt Support Forums and it has me wondering if I'm fighting a similar issue. It ended up being something with his crank/cam settings (maybe phasing?). I don't know if any of that information translates to any thing useful for the Series 2 AEM but at this point I'm just looking for anything to try. I'm not very knowledgeable when it comes to teeth/phasing/etc so I was hoping someone here might have some experience with LQ9 coils on the IS300 platform.

Here's my current cal file.

Here's a log from a good 21 PSI pull.

Here's a log from a bad 24 PSI pull (misfire).

I'm sure those logs won't have all of the data you need, but I figured I'd post them anyway. I'm open to suggestions if there are specific parameters I should monitor/log for an issue like this.

 

Thanks in advance,

 

AEM_NS
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It's most likely a bug that

It's most likely a bug that you can read about HERE.  You can either move the coil outputs around so that the "roll over" doesn't occur on either Coil 7 or 8 or use coil outputs 5 & 6.  If you decide to switch from Coils 7/8 to Coils 5/6, let me know I can PM you some directions on what to do.  Be advised that it involves opening your EMS to change some jumpers.  

XtremeCoupe
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Joined: 06/23/2017 - 07:38
Thanks for the response. If

Thanks for the response. If you could, please PM me the directions on how to switch to coil outputs 5/6 and I'll give that a shot. Does it require any additional rewiring or is it all done with just the AEM jumpers?

I don't know if it's related at all, but another issue that I've been having since the LQ9 coil swap is that the idle ignition feedback is all over the place. It's almost like the idle ignition feedback is quickly switching itself on/off for whatever reason. As a result, the idle is not very smooth. (Note: I am not running an IACV so I use ignition timing and throttle body adjustments to achieve the desired idle speed)

Here's a log of the idle ignition issue, you can see it happen near the end of the log.

Thanks for your time, it is greatly appreciated.

Kurt
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Joined: 06/04/2014 - 17:17
Set your TPS Min Volts option

Set your TPS Min Volts option a little lower so your Throttle channel value never goes below 0.5 - 1.0 percent.  When Throttle goes to zero, it registers as a tps fault and idle ignition control stops.

AEM_NS
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My first reply was a little

My first reply was a little hurried so let me go into this some more.  Honestly, what you should do first is actually verify that the roll over problem is actually your problem.  Add Ign X Firing Loc (means location) for all coils (1-8) to your workspace and log the channels while running the engine.  Coil 7 or 8 should be very near 0 and you should get a misfire when the timing is at a value where the firing location tries to "roll over" from 0 to 23.999.  Note that this won't be rpm or MAP dependent - this is purely affected by commanded ignition timing so you could make the problem happen by simply typing in an ignition timing value that makes the problem occur while the engine is sitting at idle or slightly revved up.  Once you identify that this is actually the problem, you can then move forward with one of the solutions.

There's a caveat to switching Coils 7 & 8 for 5 & 6.  You will lose Knock 1 and the T3 VSS inputs which are probably being used in this application.  Presuming that you won't want to lose those inputs, I suggest not using Coils 5 & 6 and instead sticking with Coils 7 & 8 but swapping the bad roll over coil output to another coil that isn't rolling over.  Say for example that Coil 8 is the culprit which is for cylinder 6.  Swap the wire from Coil 1 over to Coil 8 and vice versa.  Then, swap the phasing values for both coils in the software.  This will put the roll over on Coil 1 and move the firing location for Coil 8 by 360° and prevent the roll over.  This is honestly and probably your best solution.  Just swap the coil output wires and change the phasing and rock on.  Oh and change the knock sensor assignment.

XtremeCoupe
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Kurt - Thank you! I believe

Kurt - Thank you! I believe this was the issue. I had a feeling it was related to throttle position based on some basic troubleshooting but could not find which parameter(s) were causing it. Thanks again!

XtremeCoupe
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AEM_NS - Thank you for the

AEM_NS - Thank you for the detailed response. I too am a bit skeptical that the "rollover" issue is what I'm fighting since my problems seem to be more RPM / MAP dependent like you mentioned. Regardless, I appreciate the information and will certainly do some further testing to determine if this might be what's happening on my particular setup.

I know there are a lot of variables (wiring, condition of coils, spark plugs, etc.) when it comes to troubleshooting an ignition-based issue like mine but I just mainly wanted to ensure that there wasn't something obviously wrong within my AEM cal that may cause the LQ9 coils to underperform.

• Some information I was able to get from the harness builder concerning the coil wiring: "The main coil power is a 14G into the harness, then 18G to each individual sensor (coil?). The Dedicated grounds are also 18G."

• I have upgraded the factory grounds with -4AWG (and added additional grounds).

• I have tried new spark plugs and even gapped them down to .020" (as stated in original post).

I'm just running out of ideas of stuff to try at this point and feel like I've already wasted too much time and money on the LQ9 coil conversion. If anyone has any other ideas of things to test/try, it would be greatly appreciated. Otherwise, I may just ditch the LQ9 coils and go with smart coils (although with my luck I'll just experience the same issues).

Anyway, thanks again for your time. I will do some testing on the "rollover" theory and let you know what I figure out.

Kurt
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No problem.  There are some

No problem.  There are some unused pins on the header plug of the 6050.  I had a project that needed coil 5 and 6 but I also needed VSS and KS1.  I snipped two unused pins on the back of the header plug and wired to the open pins on JP6 (coil 5) and JP7 (coil 6).  No need to give anything up!

AEM_NS
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I'm not skeptical - it's

I'm not skeptical - it's definitely a bug and it definitely affects applications that use Coils 7 & 8. I just like to verify something before I go in and start making changes.

Kurt - that's a sure fire way to void your warranty!  

XtremeCoupe
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AEM_NS - I just idled the car

AEM_NS - I just idled the car for awhile to verify that Kurt's idle ignition trim fix worked (which it did!), and kept an eye on the firing location of all coils. Coil #8 was around 4.0 teeth at idle (~20 degrees of timing) and dropped down to maybe 3.7 teeth when revving it up a bit (~35 degrees of timing). I feel like it would take a boat load of ignition timing (more than the engine will ever see) in order for Coil #8 to fire at 0 teeth (or maybe I'm misunderstanding the basic concept of this).

Again I'm certainly no expert at all when it comes to this stuff, but if I was in fact experiencing the "rollover" issue, I guess I just don't understand how I was able to temporarily reduce/eliminate the issue by reducing the coil dwell and physical spark plug gap.

Thanks again for the response, you guys have been a great help!

AEM_NS
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It's been a while since I

It's been a while since I tested for this problem but things are starting to come back to me more and more. It's not purely the firing location rolling over that's the problem. The problem actually occurs if the coil is turned on while on one side of zero and then is turned off on the other side of zero.  You need to look at both Ign X Firing Loc and Ign X Charge Loc.  If Charge Loc is in the high 23's and Firing Loc is a little over zero, you'll get bad dwell control and misfires.  I was wrong before - it will be rpm dependent since coil duty will increase with engine speed if commanding the same dwell.  Commanding the same dwell as engine speed increases means that the Ign Charge Loc will have to happen sooner and sooner and could eventually push it to roll over.  

Sorry for the scattered info but now that I've recalled all this and have it posted on the forum, it'll be here to come back to in the future.  

XtremeCoupe
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Ah okay. Thanks again for the

Ah okay. Thanks again for the detailed response. I will do some further testing while monitoring/logging the Ign X Firing Loc and Ign X Charge Loc parameters and see what I can find out.

Thank you!

XtremeCoupe
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Alright so I'm back from the

Alright so I'm back from the dead. I was able to do a little bit of testing with the car this morning and indeed found that IGN 8 Charge Loc rolls over past 24 teeth under some circumstances (mainly higher RPM) while IGN 8 Firing Loc is around 3.5 - 3.6 teeth. This happens just when revving the engine in neutral so obviously timing values are pretty advanced (as opposed to under load).

Anyway, is that the scenario in which the dwell can get funky for coils 7/8? Based on that information, would you suggest swapping coil 1/8 outputs and phasing?

Here's a log with the charge/firing location data (you can see the IGN 8 Charge Loc rollover happening near the end of the log).

Here's my AEMdata template if you'd like to use it (already has all charge/firing location data graphed and rescaled).

As always, I appreciate your time.

AEM_NS
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Yes that's the scenario and

Yes that's the scenario and yes, swapping 1 and 8 would solve it. Physically swap the wires and then swap the coil phasing values too. Be aware of knock sensor assignments if you're running knock.

XtremeCoupe
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Okay, I'll give that a try

Okay, I'll give that a try and see how it goes.

Thanks again for your help! With any luck I'll finally be able to crank up the boost!

XtremeCoupe
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So I swapped the Coil 1 (B13)

So I swapped the Coil 1 (B13) and Coil 8 (A22) outputs on the AEM connectors and also swapped the coil phasing (Coil 1 was 0.000, Coil 8 was 12.000).

Now the car will not even start.

Am I missing something here? Any ideas?

Edit: Was a tuning issue, resolved with some fuel adjustments.

AEM_NS
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You might be over looking

You might be overlooking something not related to the changes you just made. You moved two pins and adjusted two coil phasing values... that in itself won't keep the engine from starting. Even if those cylinder were timed wrong, it'd still start and run on the four other cylinders that didn't change. Do some basic troubleshooting and cover all your bases. Still getting fuel and spark? Timing sync still good?

XtremeCoupe
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You are correct. I swapped

You are correct. I swapped everything back to where it was originally and still had an issue with the car starting. It ended up being tuning-related (although something I have never experienced before). Just my luck I suppose. I just wanted to make sure I wasn't missing something as I didn't want to damage anything.

Anyway I got it fired up and running with Coils 1/8 outputs/phasing swapped and it definitely revs more "freely" in neutral. Before it felt like there was almost a soft limiter around 5000 RPM and additional throttle was required in order to surpass that point. Now it revs smoothly all the way to my RPM limiter.

Off to a great start! Hopefully it responds similarly under load!

Thanks again for your help!

 

AEM_NS
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Glad you got it all sorted

Glad you got it all sorted out. yes

Bluebullet89
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Is there any firmware update or long term solution to this “rollover” problem that doesn’t require swapping pins/phasing etc...? Ever since I bought this 30-6050 box I have had ignition issues in the upper rpm. Been able to tune out some of it between, adding fuel, sequential ignition, new plugs gapped .020, milspec harness, smart coils, lowering dwell, but still get misfire/blowout at 27psi. Is swapping the “rollover coil 7/8” with coil “1”still the best option?   

And another question is no matter whether it’s coil 7 or 8 that has the rollover. Can I swap both of them to coil “1”?

 

Bluebullet89
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Joined: 10/15/2018 - 21:21
 

 

Is there any firmware update or long term solution to this “rollover” problem that doesn’t require swapping pins/phasing etc...? Ever since I bought this 30-6050 box I have had ignition issues in the upper rpm. Been able to tune out some of it between, adding fuel, sequential ignition, new plugs gapped .020, milspec harness, smart coils, lowering dwell, but still get misfire/blowout at 27psi. Is swapping the “rollover coil 7/8” with coil “1”still the best option?   

And another question is no matter whether it’s coil 7 or 8 that has the rollover. Can I swap both of them to coil “1”?