# megasquirt - coil suggestions for 16v turbo



## chadr (Feb 12, 2000)

A couple years ago at the dyno my car misfired as the boost was turned up more than 10 psi. The guys at the shop suggested to gap the plugs at .022 which did stop the misfire. Lately the car has a misfire (or at least that is what I suspect) under load at times. The coil is stock, plugs look good and are still at .022, cap and rotor look good still. I am thinking the coil may be getting weaker but thats just a guess. It is a stock coil from my 90 16v so it could be getting old. 

I bumped the charge time up from 3.0 to 3.2 in MS today and wasn't able to make the misfire happen again in the short amount of testing I did. 

I was thinking of just getting a new/used stronger coil. Suggestions? I see people mention the ls1 coils frequently. Any specific one to look for? Will the stock wire from the coil to the cap work or will I need a new wire?


----------



## ps2375 (Aug 13, 2003)

I think the LS coil is a COP setup. My car isn't boosted, but when I changed from a stock canister coil to the ABA style coil, I did notice an improvement at low rpm and heavy load. You should be able to find them easy, and it is said to be bad, that is just the ignitor portion at the bottom of the coil and can removed and bypassed as it sounds like you are not using an ICM and are driving the coil directly.


----------



## jmaddocks (Jan 31, 2004)

I had the same problem. MSD Blaster coil fixed it, and I was good to about 22 psi. 

Incidentally, once I started hitting ~26 psi, I started having misfires under boost again. Relayed a wire off the battery to the coil, but that didn't completely fix it. The misfires went away when I went with NGK 'race' plugs with no resistors (don't know the part # off the top of my head). 

Bottom line, I'd try a new coil first. :beer:

Jason 

Sent from my Barnes & Noble Nook Tablet using Tapatalk 2


----------



## chadr (Feb 12, 2000)

Thanks for the feedback. I just got my current meter for my scope yesterday and ran some tests this afternoon. I had the coil dwell set at 3 for years based on suggested settings then I bumped it up to 3.2 recently but it looks like 5 is the right number now... perhaps the coil needs a longer charge as it gets older? 

Graphs are shown with setting of 5ms, 6ms, and 8ms in megasquirt. Previously I had it set at 3.2ms which wasn't allowing it to charge fully. 8 was way too much but I wanted to see where it tapered off. 6ms is about 1ms too much, and 5ms looks about perfect.

Notice the setting of 5ms in megasquirt only appears as a 4ms charge on the scope.

https://plus.google.com/photos/102391619278461274652/albums/5848270381627640737?banner=pwa


----------



## need_a_VR6 (May 19, 1999)

That is a big dwell needed for a stock coil. My bench test on the round Bosch ones shows best dwell between 3.2-3.5ms at 14.2v. 

I would double check your voltage at the coil and your battery correction factor.


----------



## chadr (Feb 12, 2000)

need_a_VR6 said:


> That is a big dwell needed for a stock coil. My bench test on the round Bosch ones shows best dwell between 3.2-3.5ms at 14.2v.
> 
> I would double check your voltage at the coil and your battery correction factor.


Will do. I looked at tunerstudio and couldn't find where the battery correction factor was set for the coil charge.

I found these in the msq by searching for "batt":


```
0.14
0.2
```
Since .14 is for the injectors I guess .2 has to be for the coil charge time. MS reads about 14v at idle and the 5ms dwell is for 12v, so I'd expect 4.6ms after the correction factor. I'll have to test the coil voltage to see what is really going on.


----------



## ValveCoverGasket (Mar 20, 2002)

depending on which plugs youre running (if theyre cheap enough to just go grab a new set) you might just try another set too... you didnt mention how long ago you went through the tuning/gaping, it could just be time to toss some new plugs in.

ive had good luck with mallory coils :beer:


----------



## SirSpectre (Mar 20, 2011)

I'm running COP on my 16v using honda 2.3L pencil coils. Ran directly from MS3x. No trouble at all. Ran great.


----------



## GTIspirit (Dec 13, 2002)

SirSpectre said:


> I'm running COP on my 16v using honda 2.3L pencil coils. Ran directly from MS3x. No trouble at all. Ran great.


Which year and model has these Honda 2.3L pencil coils that you mention? Some more info to find these on Rock Auto would be greatly appreciated! Got any pictures of how they fit and sit on top of the valve cover?


----------



## weeblebiker (Apr 3, 2003)

SirSpectre said:


> I'm running COP on my 16v using honda 2.3L pencil coils. Ran directly from MS3x. No trouble at all. Ran great.


Make/ year for the coils and a pic please, getting ready to go cop and want to see all the options. 
To the op: since coil operating principle is current based having to set the dwell that high indicates a increased resistance somewhere between alternator+,coil, igniter,and alternator-


----------



## chadr (Feb 12, 2000)

I bought an msd blaster coil earlier this year and decided to install it today. I figured the stock coil was weak or going bad since it was misfiring on occasion. The coil was the original one I'm sure but it was leaking fluid and had a long crack that spread nearly from the positive to the negative posts. After putting the msd blaster in there I checked the dwell again with the current scope and made sure it wasn't going flat on the graph. I think it ended up at 4.0ms which was about 90% of the current peak. I'll see how the car feels these next few days and may try more boost. I'm only at 8 or 9 psi... nothing extreme.


----------



## weeblebiker (Apr 3, 2003)

A cracked and leaking coil is most likely shorted somewhere inside


----------



## SirSpectre (Mar 20, 2011)

Coils from a 2002 Honda Accord. No idea on the part number. I have a brand new set in box if you're interested. They normally run $50 a pop. I"ll give a deal.


----------



## chadr (Feb 12, 2000)

The msd coil has added lots of power over the aging stock coil. Maybe a new stock vw coil would have performed the same? Don't know, but my old coil has been holding back the power for a long time because it feels way stronger now. It really pulls strong all the way to the rev limit and has more torque throughout the range. I'm happy to have spent the $30 on the used msd coil and wire from a fellow vortexer for such an improvement.


----------



## weeblebiker (Apr 3, 2003)

the max energy is set mostly by the spark gap. The em field in the coil WILL collapse regardless of how high the voltage in the secondary has to reach to allow it to collapse. 

the bigger the gap the higher the voltage needed to spark and relieve the em field. 

The limiting factor is voltage leaking somewhere before the gap; breakdown between the wires in the coil (what you probably experienced), through the spark plug wire insulation to ground, through the connector boots to the head,etc, and corona discharge around the plug wires.

a oe coil would most likely have given the same result given the rest of the ignition system is relatively stock (cable lengths, distributor,etc) 

that said increasing the plug gap arbitrarily is a really bad idea. you WANT the weakest breakdown point to be the sparkplug gap. otherwise the energy will break out at the weakest point somewhere else.

an ideal ignition system has a resonance balance between the primary and secondary circuits, screwing with changing plug wire resistances and swapping to different coil ratios and race plugs will change the RLC resonance and actually decrease max energy transfer.


----------



## chadr (Feb 12, 2000)

Just wanted to update the post as I think my misfires are solved. I found a bad connection from the air intake temp sensor to the meqasquirt efi that was leading to a constant rich condition. It began as an intermittent problem that was related to humidity. When the connection fully broke open this caused lots of misfiring under load and difficulty starting since it was providing so much extra fuel.

As far as the coil I found msd blaster oil filled version and the msd high vibration coil (8222 - epoxy filled) perform better than the stock coil did. I did adjust the dwell on all coils I used to charge just until the current began to flatten out. The epoxy filled coil is meant to be mounted in any position where the oil filled one is supposed to be mounted upright. In my 16v the stock position is mounted horizontal so the 8222 is what I'm sticking with.


----------



## weeblebiker (Apr 3, 2003)

glad to here you got it figured out, intermittent gremlins are the worst.

I switched to VAG cops using the latest drive circuit based on the tc4427 ic. jbperf has a a 4 channel add on board to give ability to run 4 channel ignition of any style and fuel. 

apparently my last rendition of my system was experiencing misfires also, hence the research in to ignition theory.


Thank you for updating!!!!!:wave:


----------



## chadr (Feb 12, 2000)

The msd high vibration coil quit on me the other day so I had to get a tow home 2 miles. Luckily I was close to home. I relocated the coil mount to the driver side fender well so the coil could be mounted vertical. Went back to the msd blaster oil filled version and its running fine again. I checked the current on the scope again just to be safe and it is no where near going flat so it can't be over charging that killed it. I don't know the history of the dead coil as I bought it used so maybe it lived a hard life already.


----------



## chadr (Feb 12, 2000)

I wonder if the 280 ms charge time I found during cranking is causing damage to the coil. I posted about this on the ms forums a while back but didn't get much of a response.


----------



## weeblebiker (Apr 3, 2003)

depending on how much time you spend cranking, but yah, that's long enough to be toasting the coil.


----------

