95RedM

Hey guys, this problem seems to have begun when I installed the LS2 truck coils. These are genuine D585 pulled off a Chevy Tahoe. I Was able to open my plug gap from .019 to .030 at 21psi without blowout. But I noticed that when I would do a WOT pull, TS would freeze and whatever datalog I was recording would stop right then. I have to close and reopen it to plug the laptop back in.

At first there was no apparent running condition accompanied by this, it seemed isolated to TunerStudio. The car ran smooth with no hiccups and pulled hard. Fast forward about 2 months and now I started to get a very violent miss during WOT pulls in 3rd and 4th gear. 5th doesn’t seem to do it and 2nd also doesn’t really do it unless I get 2nd to hook, which is rare. So it seems load is a factor. This is a hard, abrupt miss during a WOT pull. I can go into boost and even hit full boost at partial throttle and this doesn’t happen: only at WOT.

TS doesn’t freeze at partial throttle either, even at full boost (240ish KPA) but at WOT it freezes between 160-220kpa. Never the same spot in the load range, seems to be right around the peak torque range. No it’s not boost cut or a weird cell in the middle of the map at 2° or anything like that. I’ve checked and rechecked, replaced all the coils, changed plugs, updated TS today, changed firmware on my SpeedyEFI, I switched the ground for the coils to the intake manifold instead of sending the ground to the ECU, thinking maybe a factory ground wire was compromised or that the coils were sending too much noise to the ECU and turning off the USB port
on my laptop. Problem still remains. I cleaned the PPF ground and checked the ECU ground by the TB.

This violent jerk is the type of thing that would damage an engine, damage a bearing or blow up a piston I think. I’m running e85 but still, violent changing of ignition events during WOT at 350hp is no bueno. Any ideas or questions or advice is very, very much appreciated.

SpartanSV

https://www.msextra.com/forums/viewt...?f=131&t=48931
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​​​​​​If current in the primary winding goes over 8.5 amps the coil will fire. I'm only guessing though. If you include your tune and a log when asking questions like this we wouldn't have to guess.
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95RedM

i just wasn’t sure what’s the best way to post up the tune and a log. What’s the preferred method to posting tune/datalog on here? It’s also worth noting that it’s almost impossible to pick up the miss on datalog because the screen freezes and the datalog ends before it picks it up. But I’ll post what I have

thebeerbaron

iTrader: (1)

Are you logging voltage anywhere? Are you controlling the alternator from your ECU? In other words, any chance this is a voltage drop at the ECU due to ??

95RedM

Voltage logs normal, dwell logs normal. I can literally hit max boost at 85% throttle and have no hiccups. When I floor it the laptop freezes. TunerStudio will either stop comms with the ECU and say “offline” or freeze all the gauges and fuel map (and stop comms with the ECU). Im gonna redo the coil subharness and then bypass the existing wires that go to the ECU. I’m also going to do address the major grounds a little more then just checking that the bolts are tight and the contacts are clean.

Newaza

Might be some noise in the 5v circuit. I ran those exact same coils briefly and had ts lock up on me a couple times too while testing those yukon coils, whereas it was not an issue with the stock 99 coils. You may have to run the capacitors on the 12v power and the 5v signal as suggested in the megasquirt instructions. I only ran a capacitor on the 12v power as I also do on the stock 99 coils, but I didnt run any on the signal side, so I suspect those signal capacitors may be needed with some ecu's that dont have much internal filtering. You may also look into the routing of you wires to the throttle position sensor to see if picking up noise and may have to re-route or shield the 5 volt signal and return to tps sensor.
I personally didn't find the d585 coils to be enough of a benefit over what i was doing with the stock coils set up to be worth any extra effort to do more testing in regards to adding those signal caps, so I just put back on the stock 99 coils. I did buy some ign1a coils from Pat though to test. Just waiting on those to show up and will see how they do. However for me the stock 99 coils work ok at a very narrow gap when using solid plug leads. The main issue is the narrow gap and fact that plugs dont last very long before they start missfiring. New plugs always fixes that, but only for a time as I'm pushing them really hard... I'm hoping the ign1a coils will allow a little more gap and have plugs last a little longer.

95RedM

You have no idea what a relief it is to hear someone else have this same issue. I have tried for weeks to find out more about this from people since I couldn’t find anything online but nobody has been very helpful. I will look into the capacitor thing you’re talking about, do you have a link maybe for where that info is? It cost me a total of $10 to switch to D585 coils. I pulled off a bunch from the junkyard and built by own mounting plate, using existing bolts and nuts and reusing the OEM connectors and wire from an old Miata harness I had laying around. The $10 is the nice braided loom/wrap and shrink tubing I used. Even then 10.5mm plug wires I got for free from an LS motor. I opened my gap up from 0.019 to 0.030 successfully at 350whp on e85. At 0.033 I was getting blowout on the LS coils, so 0.030 is fine by me.

im going to upload a datalog and my tune to google drive and link that here, hopefully it works.

sonofthehill

iTrader: (1)

So, no experience with the GM coils, but the IGN1A's are nice and seem to be able to take some abuse. I think that Andy has had decent luck with the stock coils dwelled around 5ms. I don't really see any improvement running a gap bigger than .020. Dang, I am drunk now and not sure that's right. Anyway, I don't run any capacitors or anything with my crappy ms2pnp, just can't dwell more because wasted spark.

Newaza

here is a link.
Megasquirt Sequencer Coils

Yours will be the lower example. Going by the connector in the lower example I wired all the d's to heavy 12v power through a relay and incorporated a capacitor. I wired the c's to there respective trigger wires at the ecu. All the b's were wired together through a heavy ground to the head. All the a's were also wired together to a separate heavy ground wire on the head. Wired like that I had the ecu lock up a few times on me too. If I were to do it again I would add a capacitor on each coil between b and c and run the b's to an ecu ground and spliced close to the ecu to act as a signal ground. Dont know if that will fix the issue or not as I didnt test that, I just switched back to what worked for me.

On my 99 coils I use a capacitor on the 12v power that is incorporated in the harness of many models of miatas from the factory. I use solid copper plug leads, and gap plugs at .014-.015 to run up to 37psi on e85. Plugs dont seem to last long like that though. I have tested gapping all the way down to .011-.012. Plugs lasted longer and would allow more boost but was getting an occasional miss at idle gapped that low. Also very small gaps produces a small initial flame kernel which requires a little more timing to get the power back that you have from a slightly larger gap. You may want to lower your gap some though, .030 is a pretty wide gap on a boosted car with suppression leads.

95RedM

Thanks for that detailed response. I just got some new pigtails in for the LS coils and I ordered a new ECU and wiring harness. I’ll be going to full sequential injection and ignition and follow that wiring example you posted, but tomorrow I’ll try reducing the gap. I had seen some people running very large gaps with the LS coils. At .033 I was getting blowout at 21psi on e85. At .030 I got no blowout at that point, and even up to 24psi. One friend told me try tapping the plugs down to 0.020 and unplug the TPS and see if it still happens. So I’m going to try that tomorrow and see what happens.

I definitely have a miss that’s coming from somewhere tho, I’m now seeing it even on normal driving and at idle. Miss at idle is barely noticeable and in normal driving in boost I’m seeing the miss: in datalog the rpm jumps around erratically when this happens. Maybe the signal wire to the ECU is damaged and is shorting to ground causing the miss, and at high rpm the vibration exacerbates it or the increased amperage.

Newaza

What ecu are you going with?
Was it ever running cleanly for you with those coils and fresh plugs? Have you tried new plugs again too just to see? At .030 plugs may not go long before getting missfires, even though the plugs may still look good when you take them out. E85 doesnt seem to color the plugs nearly as much as normal fuel. Gapping down should help them go longer, at least that's what I found for my setup.
You may also try wiring the ground wire from the b terminals on the coils to one of the grounds at the ecu by splicing in very close to the ecu. That may help your issue enough without adding the caps. I am just quessing though as I never tested that, I just took them off and went back to what worked for me.
Yeah, i've seen some wide gap used with those coils too. They were used on some vehicles with up to .060 from the factory, but no way you are doing that on a power adder vehicle. The more cylinder pressure and mixture density the lower the gap as i'm sure you already know.
When you unplug your tps you may want to go through your tune to see what all uses the tps signal and make adjustments. I dont know your setup but for example on my setup I'm using o2 correction below 60% tps and closed loop idle below 3% tps. I use map for accel enrichment but you may be using tps based enrichment.
I know you are on speeduino but i dont know which board. Im on the fishdog from speedyefi which use a wtmtronics designed ua4c board. It has 4 common grounds but unfortunately no dedicated signal ground. I am using one of those 4 common grounds to act as a signal ground.
Good luck with this and let us know what you find.

95RedM

Yeah I just switched from the SpeedyEFI PNP to a fishdog kit with an 8ft harness. Should be here in a week or so. I enjoy this ECU, and it’s cheap so it works for me. The car ran perfectly fine for 2 months on these coils and only just recently started missing. I brought the plugs down to .025 before leaving today and it appeared to miss the same as before. Rpm goes up and down VVVV like that when it misses on the datalog. Miss is getting more and more apparent. When they ran great it was on 6 month old plugs with .030 gap. Now I have brand new plugs and still missing, gapped down to .025 and still missing. I just swapped in a new(used) set of D585 a couple days ago and the car ran great that day. Now it’s missing again in boost. Something is frying my coils. I’ll post my settings. I have dwell turned down to be in the low 3s right now as an attempt to address this issue. But it all goes back to wiring because I had a very faint miss when I first bought the car, on stock everything and a totally diff engine. It would lightly miss at idle and hiccup on partial throttle accel. Never on WOT. I replaced everything that contributes to combustion events, including the entire engine and still does the exact same thing. So it has to be wiring

Newaza

Their latest fishdogs are now supplied with ua4c vc3 boards by wtmtronics. It is supposed to be more tolerant of voltage spikes and noise than the prior boards so it may help. However that is also the board i have in the car now and was getting some ts lockups on those yukon coils. Hopefully rewiring will fix your issue. When you rewire I would consider wiring with the caps on the coils and taking the signal grounds back to the ecu. On the harness they are supplying you the crank and cam wires will be shielded, but I would also route them as far away from the coils and plug wires as practical. When I wired mine I also got some extra shielded wire to shield the tps and temp sensor wires. Also ran an additional VERY heavy power and ground from the battery to engine, Used star grounding on the engine for everything but the sensors. Ran sensor grounds to the ecu. May have been overkill, but thats what I did.
You may want to ****** up an extra cam and crank sensor too if you never changed those. I always keep a spare of those.