Occasional rough idle?
#21
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I've not noticed this problem as much latey, It's still happening, but I'm no longer running stock injectors, they're now (cleaned and flow-tested) 600cc injectors. I don't know if because of the loss in resolution because they're high imp injectors it's masking the problem slightly?
#22
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As for your spikes and dips on the ignition output, that was taken VERY seriously and fixed quick. 029v or later fixes that right up. As for the random minor misfire at idle I'm not sure if I've experienced the same thing you guys have or not-- I do sometimes hear what sounds like a very minor miss at idle that I've never been too concerned about, I don't see evidence of a miss in the AFR datalogs (which would look like a lean spike in the AFR logs due to the unconsumed air in the pipe). At any rate it looks like James is looking into it based on the thread linked at the beginning of this thread. My experience thus far has been A) it doesn't effect my AFR so I'm not sure it's a miss, and B) it really doesn't seem to effect anything. But the bottom like is James is a wiz at this stuff and I'm sure he'll nail it. Definitely go ahead and run 029v or later though to get rid of those spikes and dips...
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Jerry a.k.a. 'FoundSoul'
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'91 Miata BEGi S3 GT2560 w/ MSPNP - 14.1psi - 253whp, 232wtq
'95 Miata n/a
A few other cars....
#23
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Jerry,
I already run 029v, I also had the spikes and I participated in the "Ignition spikes under boost - scary" thread. As for the AFR, whenever the problem appears I do get leaner, from 14.7 to about 16-16.5ish. I'll scope the injector outputs today.
Jim
I already run 029v, I also had the spikes and I participated in the "Ignition spikes under boost - scary" thread. As for the AFR, whenever the problem appears I do get leaner, from 14.7 to about 16-16.5ish. I'll scope the injector outputs today.
Jim
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Cool-- if you get anything useful scoping the ignition I/O I'd suggest posting the traces in that thread on msextra.com- James appears to be watching it pretty closely. At one point I had this going on with my MR2 but I haven't noticed it lately-- I'll see if it is and if so I'll bust out the PicoScope and get some traces for James myself...
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'91 Miata BEGi S3 GT2560 w/ MSPNP - 14.1psi - 253whp, 232wtq
'95 Miata n/a
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Jerry a.k.a. 'FoundSoul'
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'91 Miata BEGi S3 GT2560 w/ MSPNP - 14.1psi - 253whp, 232wtq
'95 Miata n/a
A few other cars....
#25
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I have to bring this thread back up because I had the same problem for the longest time.
I have an MSI Extra High Res running on an Escort with a GTX motor (essentially a BP with lower compression) and GTR turbo pushing 16psi of boost.
Here's the issue with the rough idle. Our motors like to run rich at idle. And I mean 13-12.5:1 rich unless you oscillate from lean to rich. The MS O2 feedback controller is not setup like the factory one and will not oscillate properly causing idle roughness. Don't worry, your gas costs won't go up dramatically if you have a rich idle.
Do not run closed loop with the O2 sensor at idle. Turn on closed loop at 1200-1500rpm
Tune your VE table slightly on the rich side.
Watch your intake air temp/density compensation. MS starts to pull fuel above intake temps of 70F. This can be seen in the gammaE if I remember correctly. As you warm up the car, the sensor heat soaks not being representative of the actual intake temp. MS pulls fuel and you start to have a rough and unpredictable idle. Correct this by doing coolant temperature correction and ADDING fuel when the coolant is hot up to 1500rpm. Do this until the car runs smoothly.
At this point you should never have a rough idle anymore ... I certainly don't anymore. Hoeve, if you need to pass emissions, you have to change things a little or you will fail on idle.
When tuning the MS in general be aware of all its compensations ... little problems drove me nuts until I learned to watch all compensations and then everything became really simple. Hope this helps out.
I have an MSI Extra High Res running on an Escort with a GTX motor (essentially a BP with lower compression) and GTR turbo pushing 16psi of boost.
Here's the issue with the rough idle. Our motors like to run rich at idle. And I mean 13-12.5:1 rich unless you oscillate from lean to rich. The MS O2 feedback controller is not setup like the factory one and will not oscillate properly causing idle roughness. Don't worry, your gas costs won't go up dramatically if you have a rich idle.
Do not run closed loop with the O2 sensor at idle. Turn on closed loop at 1200-1500rpm
Tune your VE table slightly on the rich side.
Watch your intake air temp/density compensation. MS starts to pull fuel above intake temps of 70F. This can be seen in the gammaE if I remember correctly. As you warm up the car, the sensor heat soaks not being representative of the actual intake temp. MS pulls fuel and you start to have a rough and unpredictable idle. Correct this by doing coolant temperature correction and ADDING fuel when the coolant is hot up to 1500rpm. Do this until the car runs smoothly.
At this point you should never have a rough idle anymore ... I certainly don't anymore. Hoeve, if you need to pass emissions, you have to change things a little or you will fail on idle.
When tuning the MS in general be aware of all its compensations ... little problems drove me nuts until I learned to watch all compensations and then everything became really simple. Hope this helps out.
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I agree completely that the BP likes a rich idle. I have had much better results w/ 13.5:1. The thing that kills me, though, is that the stock ECU manages 14.7 and holds the idle rock steady. Last night I started setting up a blended Alpha-N just for idle (<1250rpm). It is rock steady but my tune is still very rough. Alpha-N seems really touchy and a lot less error tolerant.
I've also found I had to enrichen the mixture at intakes temps above 100 F. I see than a lot when I idle for long periods in my garage.
I've also found I had to enrichen the mixture at intakes temps above 100 F. I see than a lot when I idle for long periods in my garage.
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Jim
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Sorry, but you are plain wrong. The rough idle issue is tracked to a firmware bug. Specifically, one of the our injectors is randomly not opened/squirting, same goes for the coils/ignition. It has nothing to do with AFRs. I DO have a perfect 14.6-14.9 AFR at idle and the car runs BEAUTIFULLY. Just like stock, maybe even better at times. Perform a reset and it gets fucked up. Reset again and it propably is ok. Repeat N times within S seconds (with the IAT and CLT not changing more than 3* F) and the results vary tremendously. Its a software bug, not a tuning issue.
Jim
Jim