The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support ExtremePSI
Please Support ExtremePSI

2G Spark blow out

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

jed344

Supporting VIP
1,190
298
Jan 10, 2008
Waterville, Iowa
Mods list is up to date. I was battling spark blow out last year. Put a ARC2 on the car and it got better, Added second ground to head, Brand new ngk wires, Br8es at .017 gap. Still hitting spark blow out around 28psi, For reference 28psi is around 57lb/min on my car. My only thought could be coil packs are weak? would weak coil packs even with a CDI box still cause this issues? I am confident its spark blow out feels just like it, car shows zero knock, but will show a split second lean spike in log showing fuel was not ignited correctly in cylinder.
 
I think you're well within the limits of the stock ignition coils, even without the ARC2. If you have a DSM friend with a spare coil pack laying around or willing to let you swap theirs onto your car for testing that would be a fairly quick and easy test. If you don't have that option though, here are a few thoughts I have.
- You mentioned brand new wires but NGK wires are only 7mm and not much better than factory, unfortunately. They may function well enough on a t28/16g setup but you're well passed that. You've got a solid build so you should be running the best plug wires you can get, I always recommend upgrading to the Magnacor 8.5mm (KV85) wires - PN# 45257. Their 2020 catelog lists them for $136.40 but you might find them a bit cheaper from a vendor.
- Assuming the BR8ES spark plugs were also new, I'd suggest moving to a BR8EIX plug. It seems the E85 setups I've tuned seem to respond better to the EIX's and can take advantage of a wider plug gap, usually ~0.025".
Not sure if that helps because I hate recommending people throw money at a problem without knowing it will fix it.
 
I have heard about trying those plugs. I’m going to give them a shot. I do have some msd 8mm wires laying around aswell. I switched to ngk 1g wires for extra length. Sadly it’s not easy swapping the coil packs as they are mounted on a custom bracket to the block under my intake manifold. I have considered building a coil on plug set up for it. But without the ability to run sequential spark I’m unsure if I want to.
 
Last edited:
Alright. I’m gonna start poking into these threads to help people with what I have found on a couple DSM coils and I think a lot of other DSMers are going to be struggling with, but may be unaware.
I’ve found that the plastic / polymer on our DSM coils have issues with voltage breakdown.

Voltage breakdown is the point at which a normal insulator becomes electrically conductive.

I don’t know if it’s due to age or the high stress we’re subjecting the coils to under our modifications for higher airflow under boost (which increases the required voltage to jump the gap). Idk. Bottom line is the coil pack is no longer able to contain the electrical pressure and it arcs out to nearby grounds instead of jumping your gaps.

I don’t think anything smaller than a 0.018 or really a 0.020 gap is worth it. You still need a gap to deliver energy to the mixture. Anything smaller than that is too small imho.


Anyway. A way to test your coil packs I’ve found many don’t know about is using an air gap tool to ‘stress’ (not 100% sure if that’s the right word but that’s what I’m going with) test the coils and checking for arcing.
I’ve found on some of the coil packs that I tested there were:
A) those that consistently arced out to nearby ground at idle —> BAD coil
B) those that consistently arced out to nearby ground at a simulated 15,000-20,000 volts —> Again, BAD coil. This is the one that won’t show issues until under boost.
C) Those that occasionally arc out to nearby ground @ a simulated 35,000-40,000 volts. —> I’ve found these to be good coils.
When looking at stock like / aftermarket replacement options for the Mitsubishi coil packs, I’ve found manufacturers listing numbers from 35,000-38,000 volts and I’m gonna say this is the Max voltage anyone should simulate on their DSM coils. I went to 40,000 and I would get them to arc out to nearby ground relatively consistently but when backed down to 35,000 it would do it inconsistently and I consider an air gap simulating 35,000 volts to be a good test.

I’m going to upload 2 pictures of the two tools I’m used to using. I like the one that’s in the plastic / glass tube, but I’ve found a lot of places are no longer selling that one and they’re now selling what looks like a cheaper one.
 
Last edited:
Here’s a few of the ones I’d use / I like to use. ONLY BUY THE ONES THAT HAVE THE NUMBERS ON THEM giving you a reference for the voltage necessary to jump the gap.
I don’t like the ones that connect to the spark plug as I like to eliminate that as a variable. That and I don’t want the spark plug’s gap included in the test.

So the way you use it is pretty self explanatory. One end goes into the spark plug wire, other end goes to ground. Adjust the tool so the air gap between the two electrodes simulates the voltage you want to test at. The tool will usually have markings for 10, 15, 20, 30, 35, and/or 40 thousand volts.
Once you have it connected, either disable your fuel system or proceed with caution knowing your gonna be putting fuel into the cylinder you’re testing w/o ignition. I recommend disabling the fuel system for the test.
Have a friend or family member crank the car for you while you observe the spark jumping the gap. Specifically pay attention to the coil pack and all of its nearby surfaces that the electricity can jump to for ground. At 35,000+ volts you’re probably going to see the electricity jumping from the coil to a nearby ground, especially the part of the coil that’s bolting to your bracket (including the aluminum ones —> Aluminum IS a conductor. Generally @ 70?%-75?% to that of copper? Something like that).
Any coils that are arcing out at voltages less than 20,000 volts are garbage. I’d say anything less than 25,000 too but I haven’t tested a coil personally that was arcing at 25,000. I’m going to say this would be a bad one as well though. The ones I’ve found to be good do not arc much at 30k+


EDIT: While I was testing a friends car for misfires under boost I used the above method(s). I also checked most of the components for ignition as well.
The coils, plug wires, etc.
Anyone suffering from misfires under boost should verify their equipment. I’ve uploaded a picture from my ‘95-‘96 manual listing the specs for the coils and wires.
Note that I’ve found cheap multimeters incapable of accurately checking the low resistance Mitsubishi lists for the DSM coils. One multimeter will read 1.5ohms (BAD coil), another will read 0.9-1.0ohms (GOOD coil). I recommend either spending a couple bucks on a known good / reliable multimeter (Fluke), or straight up buying an ohmeter.
 

Attachments

  • BFFF5F75-C788-42A3-9DDF-D9AC2606DB2F.jpeg
    BFFF5F75-C788-42A3-9DDF-D9AC2606DB2F.jpeg
    26.5 KB · Views: 93
  • A24C4707-3B46-4891-96C8-E608381BA06E.jpeg
    A24C4707-3B46-4891-96C8-E608381BA06E.jpeg
    37 KB · Views: 92
  • A184C6EA-CF33-4F0E-AF36-CE6474BE95FB.jpeg
    A184C6EA-CF33-4F0E-AF36-CE6474BE95FB.jpeg
    7.7 KB · Views: 79
  • 38F0B840-8B5E-40F8-A8EF-0F320C14A161.jpeg
    38F0B840-8B5E-40F8-A8EF-0F320C14A161.jpeg
    1.7 MB · Views: 85
Last edited:
I will most likely buy this to test them. I do have a good multimeter that was few hundred from MAC. I just am running out of ideas and open to trying what ever as there is no reason I should be having this issues and I suspect it is a coil issue.
 
Update. The stock coils are out of spec, I checked all used coils I have laying around and they are over .7-.9 spec. I cant even find OEM coils anymore. I am running out of ideas other then building a COP for the car, witch I am aware of running this in a NON parallel set up cuts the coil ability in half. What is the power guys have made with a COP wired for waste spark with a ARC 2?
 
I have coils I can actually sell you now if need be? Feel free to message me.

If you’re okay with spending some money on the best setup currently available on the market (R35 coils), get ahold of Platinum Racing Products and tell them I referred you and you need a setup for your engine.
I was speaking to Herman.

Kevin Jewer ran “a crappy old COP setup with 300m coils, and an old MSD CDI box.”
If any of this helps. Sorry to hear about your coils man but I’m SOO glad you found your issue! :)
 
Found some more old OEM coils laying around. One of them tested .7 other one .4? Never seen lower then spec before. Makes me wonder if these would work. Most likely just call the local junk yards and get some 300M coils and go that route.
 
Last edited:
Placed order for stuff I need to build a 300m coil on plug set up. Being I already have a ARC-2 it should work well enough for now. My car is more then capable of putting down 700+whp and decided instead of issues with finding coils in future I would just go this route. Thanks for the responses.
 
No? Not sure how that was deduced.

You pull your plug wire off the spark plug, inserting a tool instead, then grounding it.
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top