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Old 06-20-2014, 01:15 AM   #1
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Question MS3 Basic burble-pop on lift

So my MS2E turned off the injectors when I was lifted and coasting. Cool.

My brand new MS3 does the same thing, except that after they turn off, it goes full lean, and then all of the sudden my WBO2 shows like 11 for a split second, I get a burble and/or pop, then it goes full lean again.

I heard on top gear that a car mfg was doing this (BMW i believe?) by design to get that pop, just wondering if this is normal for the MS.

My MS2 would burble sometimes, just from pulling fuel off the cylinder walls, but it never registered on the WB which is what has me confused. This time around it's happening long enough to register on the wideband _every time_ i lift. Googling gets me a lot of people saying to pull timing. I don't think that's it.

MS3 built by rev
almost completely basemap (ran VEAL for a while today)
3" catless midpipe built by 18psi (?)
3" enthuza XR turbo
GT2554R
460cc injectors

PS: Assuming there's nothing wrong, and this is fine to be happening/by design, I love it love it love it.
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Old 06-20-2014, 01:46 AM   #2
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make sure your overrun cut is on
also make sure your eae enrichments are proper

that's not "normal" unless you like that sort of thing.
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Old 06-20-2014, 02:56 AM   #3
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I noticed the same behaviour when I swapped to MS3 from the DIYPNP, on the MS2/DIYPNP the overrun fuelcut activates and the AFR immediately goes to fuel lean and stays there, with the MS3 and the exact same settings it's like Mlev described - fuelcut activates - AFR goes full lean - swings back to full rich for a split second - goes full lean again.

This is with AE only (no EAE - never git around tuning that), the same settings for decel fuel amount etc.

I noticed that some years ago, when I swapped to MS3, but never cared to look deeper into it.
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Old 06-20-2014, 08:54 AM   #4
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If you like the burbles/pops then intentionally tune the overrun areas to be lean i.e. 15:1 or leaner, you also want to really retard the timing in the same area.

If you like obnoxious bangs, then tune the area to be stupid rich (9:1+)
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Old 06-20-2014, 09:20 AM   #5
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tune.
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Old 06-20-2014, 09:22 AM   #6
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Quote:
Originally Posted by Braineack View Post
tune.
/word

But where does the difference between MS2 and MS3 come from?
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Old 06-20-2014, 09:25 AM   #7
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Quote:
Originally Posted by Zaphod View Post
But where does the difference between MS2 and MS3 come from?
extra parameters in overrun that one should tune...
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Old 06-20-2014, 09:28 AM   #8
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Good to know, thanks all. I'll look more into it--it's not something I had to deal with at all on my MS2 so I never learned much about it.

I love that sound though. :(
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Old 06-20-2014, 09:29 AM   #9
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MS3 (depending on firmware version obviously) has a 'softer' entry into ORFC, IIRC it cuts individual cylinders and leans them out rather than cutting the lot all at once.

Would probably explain the extra air in the exhaust causing the pops/burbles (pushed though from the 'cut' cylinders).
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Old 06-20-2014, 10:08 AM   #10
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Ah o.k. that does make sense... Thanks!
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Old 06-20-2014, 10:40 AM   #11
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It just seems weird to me that it knows to cut, and then it comes back in, and then it cuts again. But there's no lurch at all when it happens, like there is when you're kinda riding the RPM limit of the fuel cut.

Also had a weird rubbing/buzzing sound coming from under the car, but it seemed like it was only under load. Not sure if it's a small exhaust leak out that stupid *** slip-joint-clamp thing on the DP or what, but it was very hard to hear clearly as my new exhaust is slightly on the loud side under load now.

Just as long as it's a rubbing from under the car and not my compressor wheel rubbbing again... ><

Need to climb under her again today, poke around a bit, and then get back to tuning. Woo!
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Old 06-20-2014, 10:56 AM   #12
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are your MS2 overrun/rev limiter settings exactly the same as your new MS3 ones?
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Old 06-20-2014, 10:59 AM   #13
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Not sure. I got the car running and coolant burped and timing set and all that at 11pm and had to work at 6am, I literally just drove it around a 1/4 mile loop and noticed that it was doing the stuff in the OP every single time I lifted, and figured I'd ask since my MS2 didn't do it.

I don't have my MS2E anymore, but I should be able to dig into the old MSQs and check it out. I'll do that after work.

To be clear, this is not when I hit the limiter, this is when I'm cruising at 3k RPM and then lift. Pretty sure we're all on the same page there, just want to make sure.
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Old 06-20-2014, 11:18 AM   #14
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You have MS3. Just enable anti-lag, problem solved.
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Old 06-20-2014, 03:11 PM   #15
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There is a delay before overrun cut-off kicks in. Maybe thats it. To fix it, possibly lower the delay and auto-tune the very bottom row of fuel map.

I have overrun enabled after 1-2 seconds and overrun row is static 10* timing. The 10* pleases my inner ricer. If you set the bottom row timing to not retard like that, then it won't make any noises.
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Old 06-20-2014, 04:49 PM   #16
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Was wondering the same thing. Didn't have enough experience to know if the readings were real or some sort of artifact. Mine have no burbling, just the lean / rich / lean thing. I will look into the anti lag. I kept thinking I needed more worke on the low kPa rows of the VE table, but it is good on steady state
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Old 06-20-2014, 04:54 PM   #17
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Quote:
Originally Posted by DNMakinson View Post
Was wondering the same thing. Didn't have enough experience to know if the readings were real or some sort of artifact. Mine have no burbling, just the lean / rich / lean thing. I will look into the anti lag. I kept thinking I needed more worke on the low kPa rows of the VE table, but it is good on steady state
The anti-lag reference was a joke, don't actually go playing with those settings (I mean, unless you want to...)

Anti-lag cuts spark, retards timing, and sends unspent fuel in the exhaust, and it ignites when it hits the manifold, causing backpressure, and allowing the turbo to stay spooled when you aren't accelerating. This creates LOUD burples pops and bangs, like what you'd hear from rally cars.

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Old 06-20-2014, 05:31 PM   #18
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Quote:
Originally Posted by Schuyler View Post
The anti-lag reference was a joke, don't actually go playing with those settings (I mean, unless you want to...)

Anti-lag cuts spark, retards timing, and sends unspent fuel in the exhaust, and it ignites when it hits the manifold, causing backpressure, and allowing the turbo to stay spooled when you aren't accelerating. This creates LOUD burples pops and bangs, like what you'd hear from rally cars.

How bad is anti-lag for everything if you don't actually launch with it? I'm sure it's death to the clutch and tranny, but will it eff up your turbo/engine, too?

There's a group of ricers that meet every friday and saturday night, and I kinda want to drive out there and do a two-step just to see their faces.
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Old 06-20-2014, 05:40 PM   #19
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It's pretty hard on the turbo and exhaust... Generates a ton of heat.

You can just use a 2-step to play with ricers, don't really need anti-lag.
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Old 06-20-2014, 06:20 PM   #20
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I had mis-read your post and thought you had said, " turn anti-lag OFF". So I checked my settings and indeed it was off. Yes, I have no reason whatsoever to play in that arena.
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