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MS3 Basic 6000 rpm backfire and check engine light

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Old 04-08-2016, 07:00 PM
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Originally Posted by midpack
Composite logger is under the Diagnostics and High Speed Loggers tab
I swear I don't have that tab. MS3 Basic.
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Old 04-08-2016, 07:13 PM
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Originally Posted by poormxdad
Pat,

Your tune made the dropoff and Check Engine light come on at about 4000.

Since I can't seem to figure out how to make a composite log, I made a log with the SD card I have hooked up to the MS. Not sure if it will help. This should be from Pat's tune.

Thanks,
Hmm, well that didn't work! Don't use that then, go back to your original tune. I don't use a MS2 anymore, but I remember having to mess with filtering when I had one. I don't know all the differences, but MS3 doesn't have a filtering tab as best as I can tell. I suppose the different input hardware negates the need for it, but not 100% on that.

The fact it made it worse is odd, maybe try less filtering?

Again, I don't know just something to try. I highly agree that logging it via composite logger, which is inside TunerStudio, is the best approach.
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Old 04-08-2016, 07:42 PM
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Attached Thumbnails MS3 Basic 6000 rpm backfire and check engine light-80-aiuljuv_d5ce398d3edfe26c4aca20e422c71ef011f4bc82.png  
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Old 04-08-2016, 07:51 PM
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I'm a big dumbhead...
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Old 04-08-2016, 08:18 PM
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Jeez... I pulled my head out of my *** and here's the file
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2016-04-08_20.20.24.csv (369.2 KB, 86 views)

Last edited by poormxdad; 04-08-2016 at 08:35 PM.
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Old 04-08-2016, 08:49 PM
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I thought I'd recap.

No tuning problems but I need a retune due to changes to the intake piping.
Retune going great, then a backfire at 6000 rpm and check engine light.
Next run up on the dyno produces the same backfire and check engine light.
Tuner reloads the tune I drove in with, and the next run has same backfire and light.
We both assume hardware, like crank/cam position sensor.
Car runs great otherwise.
I replace crank position sensor. No change.
I replace cam position sensor. No change.
Pat's tune moves the drop off down to about 4000 rpm.
We confirm I don't really know what I'm doing.
There's not enough beer...
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Old 04-09-2016, 04:41 AM
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Firmware version?
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Old 04-09-2016, 07:30 AM
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MS3 Release 1.2.0 2012228 23:46 GMT
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Old 04-09-2016, 09:43 AM
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Is it possible there is something in play now due to the increase in boost that was in already in the tune that wasn't in play before?
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Old 04-09-2016, 09:59 AM
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are you making more than 11psi of boost?

sounds like youre just simply hitting your boost cut limiter at 6K.
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Old 04-09-2016, 10:04 AM
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Max boost went from 7 to 9 psi, and I'm cracking through 7 at 6000 rpm now.

This is what the Rev Limiter page looks like.
Attached Thumbnails MS3 Basic 6000 rpm backfire and check engine light-revlimiter.jpg  

Last edited by poormxdad; 04-09-2016 at 10:16 AM.
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Old 04-09-2016, 10:16 AM
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your boost cut is set to 180kPa. Increase that to 200 and see what happens. Since you make boost linearly, the MS might think youre going to pass 180kPa and cut you, makes sense given your rotrex and consistent rpm where it cuts.
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Old 04-09-2016, 10:17 AM
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Yes. Isn't that ~26 psi.
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Old 04-09-2016, 10:33 AM
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no. 180kpa is 11psi.
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Old 04-09-2016, 11:14 AM
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Originally Posted by poormxdad
Yes. Isn't that ~26 psi.
This might help you for future reference; MegaSquirt<sup>®</sup> and Turbocharging
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Old 04-09-2016, 11:34 AM
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I set 200 kPa. No change.
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Old 04-09-2016, 11:56 AM
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Given the change in Pat's tune, I turned off Noise Filtering. She rev'ed to ~6800, then did the same thing. I took a composite log.
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2016-04-09_11.37.40.csv (274.1 KB, 87 views)
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Old 04-09-2016, 12:14 PM
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Originally Posted by bahurd
This might help you for future reference; MegaSquirt<sup>®</sup> and Turbocharging
Very nice. Thanks.
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Old 04-09-2016, 12:17 PM
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Is that a composite log of the issue happening? We need a composite log of the rev and shutdown.
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Old 04-09-2016, 12:22 PM
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Originally Posted by aidandj
Is that a composite log of the issue happening? We need a composite log of the rev and shutdown.
Is it not? I pulled over, started the log, did the pull to where the dropoff occurs, then pulled over and stopped the log.

The car doesn't completely shut off. It acts like it hits a rev limiter, but the check engine light comes on. The previous composite log was done the same way, but the dropoff occurred at 6000 instead of 6800.
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