It's Alive-now have idle questions

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twelvexs
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It's Alive-now have idle questions

Post by twelvexs »

Hello.

Thanks to those who replied to a couple items I asked about. I was able to get my engine running (new build, new to MS3x, never used EFI before), warmed up, broken in, and operational fully under MS3x control! Fixed timing is dead on, little hard to start, but I think I can handle that from the reading here I'm doing.

My next goal is to get my engine to idle. Reading the documentation and searching posts here I 'think' these are the steps to shoot for:

1) I'm running full sequential, so in my SD AFR table, set the BINs around the idle area to 14.7 AFR (as mentioned in documentation)
2) My TB has a PWM IAC valve. Use it and set for Open-loop warmup. It's clear not to use Closed Loop at this time, get that.
3) Idle advance settings to OFF since this refers to closed loop operation
3) Get the engine up to operating temp (above ~160F) to get out of ASE/WUE areas

Target idle speed is 800-1000 RPM if possible. Manual transmission, so can tolerate some variance there.

If the above are the correct steps, here's my questions/confusion

1a) Currently the throttle blades are CLOSED (set screw not opening them) and TPS calibrated to 0% at that position. DO I open them slightly, say 1/32"-1/16" to give engine some air flow or rely totally on the PWM idle valve here for the bypass air needed?
2a) I can hold a steady engine speed of ~1500 RPM with a fairly steady throttle. If I use the set screw as in 1a above, should I go for somewhere around that RPM as a starting point to start tuning? Once stable, use the set screw to CLOSE the blades in an attempt to hit the target idle? If not, how will the PWM IAC do this? Am I missing a setting?
3a) In either case of 1a/2a, should I at this point start adjusting my SD VE table around the idle area up/down using the AFR sensor readings as the point to shoot for with the amount added/subtracted to those BINs? Should the include AFRtarget setting be used here?
4a) Is there a way to 'average' or 'dampen' the AFR readings? I come from the land of embedded MCUs so here, I'd look to use some sort of 'n' tap IIR or simple running average filter to give me more stable reading. Am I on base here, or as I approach a good idle AFR, I'll see the readings begin to settle in more of a steady state condition?
5a) Once I get this on track (idle-wise), if I'm using the set screw to crack the blades, how can closed loop perform idle control if the blades are held open a fixed amount? This may be outside the scope of the questions at hand, but I'm open to thoughts/suggestions.

Sorry, I know there's lots of questions embedded here. If I need to seperate these into different posts, gently let me know and I'll do so.

In any event, hope this makes some sense to anyone who can help. I did do a good bit of searching/reading and don't seem to be able to conclusivally answer my questions here. I come from the land of carbs, so maybe this question is obvious to others, but I'l gladly take it on the chin if the answer is clear and I'm off base.

Also, my MSQ is attached if there is data there that would be relavent to know.

Thanks in advance for any help!
1990 Mustang LX, 347, 10.87:1, SCAT, Mahle, RHS Pro Action 200CC/58cc (txs Boyette's Automotive), Comp XFI236HR-14, I-236/E-248 @ .050 w/ .579 lift, Super Victor EFI, GZ Sportsman Pump, LS2 CNP, 1-5/8" -> 1-3/4" step headers, MS3x

It ain't the biggest, nor the baddest, but it's mine!!
Matt Cramer
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Re: It's Alive-now have idle questions

Post by Matt Cramer »

Please also post a data log of what's happening.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
DaveEFI
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Re: It's Alive-now have idle questions

Post by DaveEFI »

All engines are different, but I'd say that most older ones won't be happy to idle at 14.7:1 AFR. Something more like 13.5 - 14:1 would be where I'd start. Once you have a reliable steady idle, you can lean it off to find the best compromise.
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twelvexs
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Posts: 26
Joined: Fri Jul 03, 2015 7:39 pm
Location: Durham, NC

Re: It's Alive-now have idle questions

Post by twelvexs »

@Matt,

Hi. Sorry, should have been more clear reading this back now. I'm going to work on the idle in a couple days while on vacation, I was reading and making notes on questions I had regarding idle tuning to improve my understanding of the process.

I guess my main question boils down to: should I depend solely on the IAC for air, or perform idle tuning with the throttle plates craked open as in a carb's setup for open loop idleing?

If I run into issues, for sure I'll return with a data log.

Thanks!

@DaveEFI

Thanks for the tip and good point there. I'm attempting to follow the manual and pointers at diyautotune, which is where I referenced the 14.7 for my setup. However I do tend to agree that most older engines do like a fatter idle.

For sure, probably a safer place to start!
1990 Mustang LX, 347, 10.87:1, SCAT, Mahle, RHS Pro Action 200CC/58cc (txs Boyette's Automotive), Comp XFI236HR-14, I-236/E-248 @ .050 w/ .579 lift, Super Victor EFI, GZ Sportsman Pump, LS2 CNP, 1-5/8" -> 1-3/4" step headers, MS3x

It ain't the biggest, nor the baddest, but it's mine!!
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