Losing Spark/Tach at 5000rpm under load - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 06-27-2009, 09:33 PM   #21
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Yeah, I think I could handle the setup, but getting it to work would surely be the hard part.

I finally got a chance to peruse my datalogs...and they're showing up as resets! Check record 304 (just before 50sec) in the one below. I was also expecting to see the abnormally high rpm spikes, and they're not anywhere to be seen, so I may have a different problem.
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Losing Spark/Tach at 5000rpm under load-reset.jpg  
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File Type: xls summer4.xls (1.61 MB, 58 views)
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Old 06-29-2009, 12:26 PM   #22
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Looks like you have major battery voltage noise issues. Check your wiring grounds.
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Old 06-29-2009, 08:14 PM   #23
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Quote:
Originally Posted by Matt Cramer View Post
Looks like you have major battery voltage noise issues. Check your wiring grounds.
Wow...I'm going to kick myself if that's it. I had upgraded my grounds a few months back and it fixed a lot of issues. I guess I had just shut that out as a possibility. I guess something happened...maybe I should check the grommet where it goes through the firewall.

Thanks for the advice Matt.
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Old 07-09-2009, 02:57 PM   #24
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Ever solve your issue?
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Old 07-09-2009, 02:59 PM   #25
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Pulled my grounds out again over the weekend...need to go get a big lug as I want to solder EVERY ground that is there (5 wire) onto ONE lug to see if the multiple lugs were giving me noise.
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Old 09-12-2009, 08:16 PM   #26
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Any updates?
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Old 09-12-2009, 09:17 PM   #27
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Quote:
Originally Posted by Latch View Post
Any updates?
I was just thinking the other day I needed to update this thread...glad you reminded me.


So far the re-done grounds seem the be holding up.

I also put in some DIY urethane motor mounts...and a beefier engine ground.

My theory is the motor was moving just enough under high rpm torque to tug and shear the OEM driver's side engine ground...which was killing my reference voltage as Matt stated.

I've yet to take a log as I've been fairly busy with school...but it pulls all the way to redline now.
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Old 09-29-2009, 12:04 PM   #28
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Nevermind...still having the problem.

I am reflashing as we speak.

I've redone grounds...replaced ignitor, plugs, and coils...no dice.
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Old 09-30-2009, 02:09 PM   #29
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Okay...I reflashed yesterday...and the car runs better.

The resets had seemed to be load related, and apparently MS wouldn't let the Duty Cycle exceed a certain amount. I'm convinced it's some kind of grounding problem, but had checked, cleaned, and beefed up every ground I could find.

It seems to have gone away int he reflash...but I've yet to turn the boost back up to confirm this. It seems happy below 10psi...but would cut out like crazy after that.




NEW PROBLEM:

Now I'm getting serious duty cycle spikes. I will post .msq and pics when I am done with class...but I can describe.

The pulse width and duty cycle both jump up for a split second, causing AFRs to dip down to 9-10:1. This mainly happens in vacuum (10-20in on boost gauge), and below 4500rpm...basically when I'm cruising in 4th or 5th.

It's violent enough to feel...about like a brisk headwind hitting the car..and causes shifter to move. Really feels like I'm losing spark at the same time...but not sure.


I have:

Reflashed

Replaced ignitor

Replaced coils

Replaced/cleaned grounds



And am still seeing this.

I'm sure Matt hit the nail on the head...and that this is all related to crazy battery voltage. I've seen other datalogs where folks had generally stable battV...and mine has a shitton of noise. I haven't the slightest as to why this is happening. I've checked grounds...do I need to check ECU power?


Any and all input appreciated.
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Losing Spark/Tach at 5000rpm under load-pulse-width-spikes-batt-v.jpg  

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Old 09-30-2009, 03:06 PM   #30
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Put a screen capture in previous post.

Here is that .msq and datalog.
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File Type: msq final.msq (35.3 KB, 57 views)
File Type: xls sep097.xls (1.95 MB, 51 views)
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Old 09-30-2009, 03:24 PM   #31
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Do I need a large cap on the 12V in?

Scott...did you build this thing with one?



When will my ***** drop Dad?
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Old 09-30-2009, 05:59 PM   #32
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Duty cycle spikes are usually your acceleration enrichment.
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Old 09-30-2009, 06:02 PM   #33
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I've noticed that in a few more recent logs today...so I turned it down.

Any other way to keep it from kicking in so violently at cruise?

I'd like to think I'm pretty steady with the pedal...maybe just truly poor settings. The problem did kind of creep up though.
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Old 09-30-2009, 06:04 PM   #34
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Current settings are:

2.9-25.5(v/s) giving 1.0-4.5(ms)
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Old 10-16-2009, 06:24 PM   #35
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ALL PROBLEMS FIXED!

Posting solutions for posterity.


RESETS:

The beefier grounds may have helped, but a reflash cured them once and for all.

RICH AFR SPIKES:

Continued to adjust accel enrichments, and they don't perceptibly kick in during cruise anymore without looking at the datalog. Their slope is much lower on the datalog, and the AFR doesn't move more than 0.75 when it happens, unlike the 2-3 full points as before. I don't wish to lower AE anymore as it seems it would lose it's effectiveness.

SPARK CUTOUT:

One word.....COPS.

Apparently I was blowing out the spark pretty bad, even when gapped at 0.023". This made me hate life...and now I am better. Big difference in power (about half the kick in the butt as full 2.5" exhaust with straight-thru muffler) and MUCH smoother.
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Old 10-16-2009, 06:44 PM   #36
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Could you describe the symptoms of spark cut out? We you getting misfires?
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Old 10-16-2009, 06:53 PM   #37
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Pretty bad misfires. I could feel it during hard acceleration. This combined with the poor grounding and some firmware corruption would make it stop accelerating for a half second right around peak torque.
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Old 04-21-2010, 01:35 AM   #38
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Let me just say THANK YOU for closing this thread! Usually problems go unresolved and searching is just like walking down a hallway of doors with nothing but disappointment on the other sides.
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Old 04-21-2010, 05:13 PM   #39
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dammit this **** is like 6 months old, nm.
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Old 04-21-2010, 07:26 PM   #40
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I'm just awesome like that.
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