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Old 09-22-2010, 12:32 AM   #1
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Default Accel Enrichment problem

After a few logging and VE analysis/modification cycles with Megalogviewer, I got the MS now tuned reasonably well. AFRs are OK and it runs pretty well too.
The only problem is that it bogs down for half a second or so when you get on the throttle.

The AFR reading when it bogs is pretty low (~9) which leads me to believe that it gets too much accel enrichment. I have found several places where I can configure when to enrich but not by how much, where can I configure this?

It's a 95, naturally aspirated, with 460cc injectors (ready for boost as soon as I have it dialed in naturally aspirated). Req_fuel is set to 7.5 (6.5 would be the correct seeting for these injectors).

I uploaded a log and since I'm a total noob, I'd appreciate some tips regarding what I should do different/better.
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File Type: zip datalog201009212003.zip (49.3 KB, 47 views)
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Old 09-22-2010, 01:39 AM   #2
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You're using TunerStudio, right? (Even if you're not I think this applies, though you should probably go download it).

What are your settings like in the Acceleration Wizard? Have you seen anything related to MAPdot or TPSdot?

You are definitely getting TPS enrichment.
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Old 09-22-2010, 02:32 AM   #3
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I'm using Megatune, I downloaded TunerStudio and the menues look pretty much the same so I figured I'd save the money.
AE trigger is TPSdot, Accel Timer is set to Cycles
Decay AE is set to none

The Accel Wizzard shows some time values depending on the TPC change, is that where you set the amount of enrichment in ms?

I'll try that tomorrow, reducing the times by 30% or so.
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Old 09-22-2010, 09:28 AM   #4
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Tunerstudio is free, the menu system is much more user friendly. in the least, you can open multiple windows and still watch the gauges behind them.
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Old 09-22-2010, 12:35 PM   #5
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These are the settings I used when I was running MS1.

Name:  MS1accel.jpg
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Note that those are absolute injector time values in milliseconds and are not affected by reqfuel. I was running stock 265cc injectors, so for your 460s you need to factor in a multiplier of .58 (which is 265/460). I think you also have to factor in the injector opening time which should be about 1 ms. So for example the 5 ms value I used with 265cc injectors would become:
5 ms - 1 ms opening time = 4 ms of fuel.
4 ms x 0.58 = 2.3 ms
Add back the 1 ms opening time = 3.3 ms
Note that if you simply multiplied by 0.58 without accounting for opening time you'd get 2.9 ms, so it does make a small difference.
If you do the math based on my values it should get you in the ballpark, or at least not be stumbling pig rich every time you hit the go pedal.
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Old 09-23-2010, 08:33 AM   #6
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Don't forget that a lot of the 'stomp the throttle' responsivness is down to the VE table rather than AE.

Stomp the throttle and look at the area of the VE table the engine goes to, if it's too lean add in fuel in that area. AE should be the last bit you touch and if you require massive numbers in there your VE table is incorrect and needs further work.
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Old 09-23-2010, 09:15 AM   #7
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you'll never really get rid of the 'stomp the throttle' delay anyways, even if you try to flood the motor.
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Old 09-23-2010, 09:25 AM   #8
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Dialed it way back to 2.2/1.3/0.8/0.5 (using TunerStudio) and it's much better now.
Throttle response is good fom 2000 RPM and up but from idle, I still get some hesitation.
Part of the reason might be that it likes to idle a bit rich, AFR15 or higher and it idles rough (I increased idle from 850 with the stock ECU to 1000 rpm using the idle screw).
I set the VE to idle around AFR13-14.
Any tweaks to get the idle better (other than sequentia fuel)?
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Old 09-23-2010, 09:51 AM   #9
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I found that 13.5-14.0:1 AFR and 15* of timing is where mine was smoothest on MS-I.
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Old 09-23-2010, 09:55 AM   #10
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I got idle timing at 17 right now, I'll try 15
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Old 09-23-2010, 11:54 AM   #11
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Quote:
Originally Posted by Braineack View Post
you'll never really get rid of the 'stomp the throttle' delay anyways, even if you try to flood the motor.
Quite, there's always some delay, even in a 100% stock car, you can't kid physics aka the length of the intake track.

IRTB's properly tuned will give you that instantaneous response, but it's a lot of $ for not a lot of gain IMO.
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Old 09-23-2010, 11:56 AM   #12
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Lower timing at idle = good IMO. It dampens the engines response which means it idles smoother.

I idle at the OEM timing of 10deg BTDC.
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Old 09-23-2010, 12:20 PM   #13
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I've found ~14deg works best on my engine with AFRs ~15:1 and ~800rpm

I'm parallel though.
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Old 09-23-2010, 12:39 PM   #14
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FWIW, since I went seq. fuel and EAE code, my "stomp the throttle" is way better than my stock 2000 altima and stock 2001 prelude.
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Old 09-24-2010, 04:40 AM   #15
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With seq fuel I have virtually nil TPSdot/MAPdot AE and EAE is off - still not got around to tuning EAE).
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Old 09-24-2010, 07:55 AM   #16
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Quote:
Originally Posted by Braineack View Post
Tunerstudio is free, the menu system is much more user friendly. in the least, you can open multiple windows and still watch the gauges behind them.
Slight tangent, but how long has TS been free? I know it was originally, but last I heard it was officially out of beta and cost $40.
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Old 09-24-2010, 08:11 AM   #17
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The 'light' version has been and always will be free.

It offers the same and more functionallity than MegaTune.

The full fat paid for version offers the VEAL and customisable dashboards etc.
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