Spark blowout?
 

The car was happy with its boost level @ around 17psi until I did a pretty hard pull throughout all the gears. Now I'm facing this issue where if I go full throttle, seems like I'm getting spark blowout. Feels like it's hitting a soft rev limiter but still going through the revs.

Blow out seems to happen around 5k~ feels like the blow out stops and then starts again while going through the rpm. If I go half throttle I don't get blow out and feel fine at lower boost levels.

Could someone point me in the direction of what I should be looking at to diagnose the car? Could a bad vacuum line cause this? Thanks!

What's on the car (These only have about 2k miles on them):
FlowForce LS Truck coils
DW 200 Fuel Pump
DW 700cc Injectors
High flow rail
Adjustable fuel rail


what I have done so far:
Replaced fuel filter
Replaced spark plugs (ngk 4644 bkr7e) gapped at 0.25, but previous plugs were running at .35 (brisk plugs)

Do you have the coils wired sequentially or are they wasted spark?

Wasted

kind of stumped, my LS coils are relatively new, so I kind of doubt these are the culprit. I'll try to lower the gap once I get home to .020 and see if that makes any difference.

Could I be leaning out? Cuz it only happens at WOT, if I ease into it, she'll boost around 10psi. But around 5-6k WOT is when it breaks up. Even on wastegate (10psi) WOT, it breaks up.

I found your problem. You are using a fixed dwell of 6. You need to use it referencing a table and use the table that either Nigel provides on his website or what miataturbo has in older threads. I think those threads had content from Andrew at Trackspeed engineering.

https://goflowforce.com/ls-coil-instructions

Scroll down for your info.
LS coils are known to self ignite at dwell around higher than 5 under load.

Awesome! I'll try it out when i get home.

But why is that the car boosted fine previously? Now after 1kish miles its having issues.


Edit: also I thought I entered most of the settings given from flowforce. I'll double check

wut

My dwell settings were all reset. I know I changed them as soon as I got the kit installed.

wut

I attached another log after I added back my dwell settings, and it breaks up a lot less now, but still does at around 6k

looks like when it breaks up, my AFRs jump around 12.9/13.1 from 11-12.

I'm running an SCG-1 boost controller with AFR cut at 13. I don't know exactly how it cuts but seems like it cuts around there.

Could too of a small gap cause a blowout as well? Previous plugs were running at .035, thinking somehow my dwell settings got reset?


https://cimg7.ibsrv.net/gimg/www.mia...9f72a5b939.png

Edit:

Just bought another set of LS2 coils. Flow forces coils are refurbished, so I'm thinking they probably pooped out. Hopefully that will fix the issue.

A few things I want to clarify:
Because the spark blows out at around 6k, is that why AFRs shoot up around 13 and kind of leaning out? I can't see the fuel pump/injectors not being able to supply fuel as during the whole pull, it stabilizes around 11 and low 12s and only goes up to 13 only when it breaks up.

Don't think the plugs are at fault either cause first set was running fine at .035, second set running at 0.25 still same issues. Havent tried gapping to .020 yet tho. What led up to this was going through the gears pretty hard, top of 4th I noticed it break up. Maybe the coils decided to give up then?

Haven't seen much threads about LS coils going bad though.

Made some edits in MSPaint, in the thicker colored lines.

Red: your MAP signal should be flatter
White: your RPM signal should be smoother
Green: Your lower boost levels are a little lean, specifically 3600-4200, 128-180kpa, none of those boost levels dips below 12:1.
Yellow: I didn't mark anything, but above 5500rpm, your AFR is creeping up, as high as 13.4:1 at 180kpa (that's slightly lean for a naturally aspirated car btw), yet your VE is trending down...

I'm leaning towards red, or your map signal, being the problem. It should be a smooth signal, I doubt your turbo is doing what the datalog shows, however without a duty cycle log from your boost controller, I can't tell you that for sure. Regardless, your tune isn't set up correctly for higher boost levels, although it's difficult to tune with significant swings in boost.

Your afr target is barely lean for my tastes, I generally target more like 11.6, you're targeting 11.8. But although I may do a dyno pull for science, I would want a boost controller to cut at anything above 12.5, maybe even 12. Definitely no where near the 13s.



https://cimg6.ibsrv.net/gimg/www.mia...a9c53536fb.jpg

I cleaned up my tune a little, i posted another data log in my previous post, afrs seems more stable

In the previous datalog the breakup was pretty bad, now it only happens at 6k in my recent datalog which cause my afr to spike to 13.1.

https://cimg2.ibsrv.net/gimg/www.mia...40403e0ce0.png


For some reason, my ts afr gauge wasn't reading properly as if my settings were tweaked, fixed it, but still breaks up at like 5.9k. Did this pull at wastegate (10psi) with spark plugs gapped at 0.025.

You might try the attached tune in the mean time, I fattened up a lot of the lower boost and upper rpm cells. It needs it.

Also, your efr should have near zero creep, you're going from 10psi to a peak of 15. You might try taking some wastegate preload out. But first, make sure your boost controller isn't trying to increase boost for some reason.

If this doesn't help, you may still be having issues with the coils, but there is such a thing as lean misfires, I'm not sure at what point they happen in boost, as I've never stayed in it above 12.5:1

Fuel map wise its the same, there was just issues with my ignition settings. I'll try it out after work.

Thanks!

I think what's happening is my boost controller activates at 10psi, and then I have it set so it boost cuts at roughly 16psi, which is why it creeps up to 15~.

In the meantime I'll run wastegate pressure, and probably invest in a turbosmart wastegate, then run spring pressures and disable my boost controller entirely.

Where are you getting your coils from? Every LS coil I have purchased from a parts store has given me weird problems. I will only run OEM ones I pull off chevy trucks in the junk yard.

The ones on the car currently are from flowforce, refurbished. Just purchased a set of acdelco d585 ls2 coils, hoping that'll fix my issue. Anyone have experience using these? Supposedly they are OE for GM.

Where I live i don't have the access to junkyards to salvage :(

From where?

eBay, link

FIXED THE BREAK UP

ok so, tried out your map and also gapped the plugs to 0.20ish also went around the car just moving vacuum lines around like I knew what I was doing. Fiddled with ground connectors to make sure things were tight and etc. Also, I checked the timing, everything looked good, but my ignition timing was almost off by like 2 degrees. Could this of caused the issue? If so I think my belt might be loose or something cuz I thought I had it dialed in prior.

So in short. I don't really know what fixed the breakup. The car feels pretty much how it felt before the breakup. So I guess I have spare d585's now. Should I try to go back to a wider spark gap or leave the spark plugs in atm? Don't really know the benefits or downsides of running a small/big gap.

I don't really wanna run any more than 17psi, so I'll try to fix that.


I like your map a lot more than my previous one, but towards redline I notice it's starting to become very rich in the 9s.

As for boost creep, I need to figure that out, even with the boost controller off, it still spikes to 17psi. with it on, sometimes it'll hold 16 where I currently have it set, but then sometimes it'll spike up especially at WOT.. Will check preload once car cools off.

https://cimg1.ibsrv.net/gimg/www.mia...2485d5df4c.png

Disconnect your boost controller. It is not working.

You can take 8-10% of fuel out from 5500 to 7000 at 220kpa. (multiply those cells by .92 or .90(.92 is safer!)), however I'd be hesitant to do anything in the lower RPMs because your map is all over the place.

Also for your rev limiter, you're cutting fuel, I'd recommend cutting spark only. Turn your hysteresis down to 100 too. That'll increase your rev limit by 100rpm, so if you still want to rev to 7000 only, change your limit to 7100.

Notice at the end of the above log you're at 100% throttle, 19 degrees timing, 17psi, and 12.5:1 AFR.

Your RPM signal is still not looking great, here's an example of what your boost curve should look like, and how smooth I expect the RPM trace to be:


https://cimg3.ibsrv.net/gimg/www.mia...2d4f805a1a.jpg

What could be causing the rpm signal to so jumpy? Could a bumpy road cause this type of reading? If so roads aren't really the best here.

also I'm running a SCG-1 boost controller/afr guage.

current settings are,, wastegate duty cycle 25%, gain 0%, boost cut 16psi @100%
I'm not entirely to sure if I have the lines hooked up correctly.

Ignore the messy wiring, plan on cleaning that up once I have everything dialed in.

Also if I wanted to disconnect the BC, just take the line from the compressor straight to the wastegate, correct?
https://cimg4.ibsrv.net/gimg/www.mia...63adee9977.jpg
https://cimg7.ibsrv.net/gimg/www.mia...3a4f135c11.jpg
https://cimg3.ibsrv.net/gimg/www.mia...9397222baa.png

Yes that is what you'd do to remove the boost controller, and yes you have it hooked up correctly. Although I'd love to see you ditch the hose clamp and put a small zip tie on all four of those connections.

I would suggest hooking the compressor directly to the wastegate, and doing a pull. Get your base line boost level functioning first, then you know it's right, and any other boost issues is a boost controller problem, not a wastegate problem.

Edit: what is your spring pressure set to in the SCG-1? Reading the instructions, that's based off your base wastegate pressure, and if its not right you'll boost spike, which may be what you're experiencing, along with the duty cycle being too high.