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Old 05-09-2011, 03:24 AM   #61
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Quote:
Originally Posted by Savington View Post
?? News to me. The coils on the black car (off-the-shelf TSE COP kit) had no trouble on 100 octane at 240-250kpa and 11.2:1 AFRs - even when I was doing 5th and 6th pulls with 3.63s in the rear end.
I don't know which COPs your kit has, the car I'm talking about had Toyota COPs from a junkyard.
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Old 05-13-2011, 05:01 PM   #62
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From: https://www.miataturbo.net/showthrea...995#post726995

Changed a couple of things before heading to the dyno:
- NGK race plugs (heat range 7)
- pluggen PCV
- breather on VC hot side

Turned out my sprak map was kinda lousy. I removed some timing before to combat the issue, but the curve looked choppy.

Had the boosted 4krpm+ range tuned on the SuperFlow with electronic detcans. Gained over 5 degrees some places. MUCH smoother curve now.

Was never able to reproduce the issue like before (need to find that old graphs where the dip is shown on the dyno). Maybe the ventilation changes made some impact with the new plugs.

Real test will be on the track later this month.
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Old 05-13-2011, 05:03 PM   #63
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Oh, and we did leakdown first; near ZERO leakdown. So the dip stick popping out is the left-turn-oil-issue...
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Old 07-28-2011, 07:45 AM   #64
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So the final verdict was the spark map?
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Old 07-28-2011, 05:52 PM   #65
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So the final verdict was the spark map?
No, not the CAS, not the map, not the fuel, nothing yet...
On the track it's there sometimes...
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Old 07-28-2011, 06:45 PM   #66
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That's a shame, I'm getting the same thing with my DIYPNP. I don't remember ever having revved past 6500rpm without experiencing this.. although I've been short shifting to avoid it most of the time.

Btw, from reading these forums it seems that misfiring should be visible on the AFR trace as a lean spike because of the unburnt O2? I've made my car misfire by bumping up the VE until it goes very rich (at ~2300rpm with no load) and it didn't go lean at all.

I'd discounted a problem with ignition because I didn't see the AFR go lean during the hesitation but now I'm not convinced that it would go lean if there was a misfire.

When my car does this I can't see anything in the logs that look suspicious at all - fuel and spark are consistent, the AFR stays flat. the car doesn't 'buck' as I would expect it to with a mis fire although I don't know whether it would buck at high rpm. It's not hard like the boost cut, it just feels like power drops significantly but smoothly, the return of power above the point is more abrupt than the loss of power.

I had a similar symptom around 5000rpm before I disabled the prediction in the ignition setup, wondering if there's something that causes the MS to get confused around 6500rpm resulting in the ignition being retarded in reality but fine on the logs? not sure that explains why it happens at 6500rpm and not 7000rpm though.

Going to take some time to work this one out I think.
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Old 07-31-2011, 05:40 AM   #67
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My dwell was set to 3ms.

After reading this page...
http://www.diyautotune.com/tech_arti...azda_miata.htm

... I changed it to 5ms today (I have an '89 eunos roadster) thinking that this might help with this issue but instead it killed power between 4-6000 rpm.

Not sure why that is but I set it back to 3ms and the problem disappeared. Might try even lower dwell tomorrow just for the heck of it and see if it revs smoothly to 7000rpm

When it lost power it behaved a lot like what I'm seeing at 6500rpm, but obviously lasted a lot longer. The AFR's looked normal when this happened too.
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Old 07-31-2011, 06:30 AM   #68
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Mine is 3.5 on Toyota COPs (TSE kit)
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Old 07-31-2011, 06:37 PM   #69
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This morning after dropping my girlfriend off at uni I changed the 'Maximum Dwell' from 3ms to 2.5ms. I don't know how to explain it but the car now revs smoothly right up to the redline.

Spookyfish: I read about the changes you made to your ignition, I just thought it was curious that more dwell seems to make my car run worse, this is the opposite of what I've learnt to expect from reading these forums and the megamanual. I don't have the knowledge to explain why decreasing the dwell - to a value that should be well below spec for the 1.6 coils - has improved things for me.

If anyone can explain what is going on here then I'd be keen to know.

Sorry for hijacking your thread too btw, I guess it's entirely possible that we have two completely different problems with the same symptoms... It seems to be that way with cars I've found :\

Is there any risk with running a lower dwell setting? As I understand it the only issue would be a weaker spark and mis firing? but as i just pointed out there's a lot I don't understand here It concerns me a little bit that there is an 'Underdwell protection' option in tunerstudio..

Last edited by giblets; 07-31-2011 at 09:18 PM.
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Old 08-08-2011, 06:50 PM   #70
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I'll be at the track tomorrow and try 2.5ms if the problem appears again.
Yours is OK now @ 2.5?
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Old 08-08-2011, 07:51 PM   #71
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That was at 2.6ms and the hesitation at 6500 was gone but the low end/mid range dropped off.

I now have it at 2.7ms and the 'Maximum Spark Duration' is down to 0.6ms from 1.0ms and it's feeling strong and torquey across the rev range with no hesitation.

To be honest I have no idea what's doing on here because I thought that less dwell = weaker spark and more dwell just meant hotter coils? But I'm happy with how it's running currently.
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Old 08-10-2011, 05:16 AM   #72
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Well, the issue was still there, so I changed the dwell and discharge time. Seemed better until the engine started to make very abnormal noises. Very mechanical sound.
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Old 08-10-2011, 05:34 AM   #73
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That doesn't sound good :\
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Old 08-10-2011, 07:40 AM   #74
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LSx groupbuy!!
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Old 08-10-2011, 07:10 PM   #75
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Quote:
Originally Posted by Spookyfish View Post
Seemed better until the engine started to make very abnormal noises.
So I take it that the blown engine isn't related to adjusting the dwell/spark duration?
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