Hello all, I am experiencing some possible spark problems with my car that I need help with.

First a short list of some of the mods and then I'll describe the situation:
-1.8 bored to 1.9
-E85
-EFR6258 turbo
-ID1050x injectors
-LS coils
-MSD wires
-NKG R5671A-7 (currently installed)
-BMW ZF5 Tranny
-Getrag Diff

Okay, so the problem is what feels like a soft limiter coming on when I get into boost. It feels like a misfire like spark blow out. Which I have had in the past when one of my previous coils took a dip. I wish I could tell you what boost level it comes on at but it has changed. I dyno'd in the fall at 330whp 330wtq with 22psi of boost. This year the car started to break up around 18psi. Throughout my testing and diagnosing the "break up" has occurred at 18psi, 11psi, and 7psi. I have not been able to pinpoint what could be causing the change in what pressure it occurs at. I could take the car out and it breaks up at 18psi every pull and then the next time I take the car out it might be happening at 11psi every pull. I took it to the track a month ago with my boost controller unplugged (11psi spring) and the car made it through the day without a hiccup.

I have since been trying to diagnose the problem by:
Tried other coils (with another set of authentic used GM coils)
Made up new spark plug wires (was MSD wires before, and replaced with MSD wires)
New spark plugs gapped at .020" (the car dyno'd running NGK BKR7E gapped at .027", now I'm trying R5671A-7 because I was hoping the lack of an internal resistor would help)
Took my injectors out and cleaned them
Checked my fuel pressure during the breakup to verify that my fuel pump sock and or fuel filter was not clogged
Checked existing engine grounds and added a new one just in case
Ran dedicated 12v wires from the battery up to the coils (thinking a possible worn wire could be causing too much resistance to supply the coils)

I'd appreciate anything to look into!
Cory

 

BKR8EIX, .016" gap, report back.

 

I will give those a try.
Do the 8 heat range survive street driving? I would find this fix weird with the old plugs working for a short time and then these new ones not at all.

 

My heat range 9 ngk plugs survive just fine. The BKR7E's need to be changed frequently with high power applications in my experience.

 

Can you post your dwell settings and/or the tune you're running?

 

I gave those plugs a try last night and no luck. They might be a little bit "better" because now it looks like my boost is reaching 20psi before this interruption is occurring. It feels like the same thing is happening though with a "soft limiter", it even resembles the sound. Got any other ideas?
I will post a screenshot of my dwell settings, tune, and try to get a data log with going through at least one gear this evening but open to any suggestions on what to look for.

 

How much spark advance when it's breaking up? Not enough timing can also cause this. On E85, you can run plenty of timing so shouldn't be an issue.

 

Sorry for the LATE response. I had a wedding out of state.
Attached is the tune I'm running.
My timing should be good but I'm questioning my dwell settings now.

Thoughts on that?

 

Has this car actually been tuned? Do you have a datalog of the breakup? What are the AFR's looking like when it occurs? The fuel map looks really smooth like it hasn't been touched and the AFR target doesn't change after 150 KPA. Doesn't have to be an issue, but I'm curious what AFRs you're hitting.

Dwell settings seem reasonable, although I don't see any reason not to use a dwell table. Flowforce has instructions/settings they recommend that might be a bit better, but I doubt that's your issue. Any reason you're using a 4g63 spark mode?

 

-Yes, I took the car to Pure Tuning in Toledo Ohio for tuning (on a dyno). If the idle/really low load looks funky its because I messed with it.
-Attached you will find the log where I did two wide open pulls. I THINK it was 2nd gear and 3rd gear but regardless of the gear the break up was happening around 18psi. My boost controller is set around 23psi.
-I believe I was around 12.2 air to fuel, but it may have been + or - a point or two. The AFR target probably doesn't change after 150kpa because I believe he was going off the gauge and adjusting the fuel table in tandem with no regards to the target table. Now that you mention it though I should probably adjust that target table in case I turn the AFR/EGO control on.
-Some of this tune came from when I was running MS-II, I think the dwell table settings came from that. I will update the tune to run flowforce's recommendation dwell settings and table and report back after runs tonight.
-I remember when I was setting up the base tune it had 4G63 for the spark mode and it worked. Is there be another mode I should be using?
-I ran dedicated ground and 12v wires to the coil harness last night to eliminate the possibility of a fault there.


Aside from the dwell settings I will be messing with tonight, I am open to any other ideas.
Also attached you'll find the dyno sheet cause I thought it had AFR on it but sadly does not.

 

Based on that log I'd start by looking at your fuel map. You're dipping down to 10.7 AFR midway through the pull which is right around where the car seems to break up.

 

If the spark was cutting out I would experience rich correct? I understand what you're saying but unless something happened with the tune over the winter I cant think of a reason fueling would be different from last year after dynoing.

 

In theory I would think so. I'm just saying I think the car is running so rich that it's stumbling. IE I think your problem is the car getting too much fuel, not an issue with spark.

I did think your MAT fuel correction seemed a bit aggressive. That could affect how the car runs seasonally. What time of year was the car dyno'd?

 

I don't have the software on this machine to look at a tune, but what timing are you running when it cuts out?

O2 sensors measure Oxygen. If it misfires, a lot of oxygen will go by the sensor and it will report a lean condition.

What coils, batch or sequential, what dwell?

 

Just for anyone else who doesn't have megalogviewer handy. Pat, these are LS Coils. Dwell is static at 3.5 but voltage correction is pulling it between 3.6-3.8.

Seems like a lot of timing to me, but I have no experience on E85.

I scratch what I said about MAT correction previously. Sounds like this was tuned in the fall so I'd assume colder temps and even more fuel.

 

Try pulling 10% fuel, add 4 degrees timing, see if it pulls clean.

 

Add 4 degrees? Pat you must like timing a lot Meanwhile I'm just crying over here on 91 octane.

Not my car, I'm just commenting since I'm curious about what's going on.

 

Well, I've run 28° @ 15 PSI on E85, and 28° @ 31 psi on Methanol. So yeah, I guess I do like timing.

 

No joke I run like 8 degrees at 15 PSI. Flex fuel is the next thing on the list. Very jealous of your timing maps.

 

Don't LS coils have a discharge problem when over dwelled? I have found voltage dwell settings just lead to slow cranking issues. If you increase dwell when voltage drops, you are just sending extra power to the coils when you crank the starter, and spark barely matters. We need fat dwell during full power, not idle and cranking.

Also, I would listen to what Pat has to say since he has been doing this more than twice as long as the rest of us in this thread.