Help with building your Speeduino, installing it, getting it to run etc.
#57079
1992 MX5 with Speeduino PNP, GM IAT, vTPS, AEM 30-0300 WB.

Stock everything else.

I've had speeduino running since 2020.
Never had issues with cranking over. Idle runs a little high, but overall it's ok.

However I've had the dreaded hesitation since day 1. I was never able to tune it out. Consequently I've not been able to get a good tune because the hesitation causes so much trouble.

Today I updated the latest firmware + loaded the latest basetune and setup my WB and my vTPS.

I've attached a log I took earlier today, it's short but should have enough data.

Mechanically my car is like any other stock 92. I don't believe I have any vacuum leaks. My throttle looks good.

The hesitation happens when I push the throttle in. I can accelerate very very slowly without any hesitation. But if I try and drive it normally, it will immediately bog down/hesitate. It's as if it's misfiring, but on all cylinders.

This only happens under engine load. In neutral I can rev it to redline real smoothly.

Here's what I've tried:

WUE ON and OFF. No effect.
ASE ON and OFF. No effect.
AE ON and OFF. No effect.
Dwell settings, can't recall, but I messed around quite a bit with no effect.
VE tuning, more fuel.. less fuel.. no effect.
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#57081
I'd start though by turning ego correction off, that's making it inconsistent.
I'd also adjust your IAT correction table, it's taking 15% fuel out at normal operating temps.
Can you point to the times in the log it stumbled?

It goes lean quite a lot - I'd generally add more to your VE table where it goes lean.
#57087
I'll turn off EGO correction.

I'll adjust/calibrate my IAT.

I'll turn off ext baro.

Is my IAT too high and thus it's causing 15% less fuel input??

And by heat soak, do you mean just the IAT is reading too high? I have it mounted inside the intake tube (which is on the hot side of the engine of course).

As for the stumbling/hesitation, on the log it happens wherever you see throttle increase.
#57091
Heat soak is where the iat sensor, is warming up from the heat from the engine and not giving a true reading of the inlet air temperature.
Cause is generally down to sensor location, and airflow. So usually noticed more at prolonged idling. Mostly, it needs to be given consideration when tuning idle. :)
#57095
My first reaction is first that you simply need to spend more time adjusting your tables to your targets. All other fuel add-ons such as AE add to the base fueling in a certain cell. You are close enough that you could use VEA or VEAL for auto-adjusting, if you are smoother and more deliberate with your throttling. You can see in the log screenshot below that it's a mess, mostly from unstable throttle movement.

You can see your stumble in the rpm/s (yellow trace at bottom), and playing the throttle is just adding fuel (see PW and Duty Cycle traces working) to cover for your lean tuning. Tune it so you don't have to do stuff like that. Start tuning from a good idle, and work-up from there. You can't short-cut the tuning process.

To get clear info from logs you need deliberate throttle movement, from one position to another and hold for response. Even the "auto-tune" functions will pause when the throttle is moving. Movement does not have to be slow, just simple and deliberate. Position A to B and hold. Once the base tables are stabilized, then you can work to add useful function with AE, idle control, and such. Until then, you are chasing your tail. ;)

Smooth & deliberate please.jpg
Smooth & deliberate please.jpg (197.48 KiB) Viewed 2048 times
#57627
SOLVED !!

The issue was that the flap in my OEM AFR box was getting stuck. So the engine was being starved of air.

This whole fucking time I've been tuning against an engine that's sucking less air than a ride on lawn mower.
This also explains why I was able to tune my idle without any issues unlike everyone else.

I only checked the AFR flap thingy because I realized the car was struggling to gain RPM while under load. Even tho I had plenty of fuel, spark and timing. That only leaves air as the last culprit.

I've drilled a hole in the airbox and stuck a bolt thru it to jam the flapper open.

I also re-tuned and now it drives amazing.

Later tonight I'll post my current tune because I'd like to get some feedback on it. It is wildly different than the base tune, this is because I messed around with it so much trying to solve this problem.

I like my tune, but I could just as easily start fresh and re-tune pretty quickly now that I've done it a few dozen times.

I have a few questions:
  1. When auto-tuning, should I leave EGO correction ON or OFF?
  • When auto-tuning, should I leave DFCO ON or OFF?
  • When auto-tuning, should I be doing straight & consistent pulls thru each gear? or any specific gear? or should I just be driving around?
  • What is the use case for EGO Correction SIMPLE? I find that the SIMPLE option is terrible and leads to an almost sinusoidal EGO result, while PID is significantly better, it holds my AFR super tight and smooth.
  • In a stock engine, what is preferred for AE, MAP or TPS? I've swapped back and forth and neither one is able to get me back to OEM throttle response when in neutral (just blipping engine)
#58032
Ok lads, attached is my tune and log.

I've been running this tune for over a month and over 2,000kms.

I did several road trips with no issues. One day I was fully loaded with camping gear + thick gf 8-), top down and I spent 3 hours at 4krpm and still averaged 24mpg oh and it was ~30C out.

My best has been 26mpg. Overall daily driving average around 23mpg.

Early in the month I did have a much more aggressive tune with advanced timing, but I dialed it back because my NC broke and I had to make sure my NA would reliably get me to work.

Anyways I'm quite happy with the tune. I know I can extract more power, but as far as stability goes I'm very happy. It cranks, it idles, it accelerates and it gets better mpg than stock.

One thing I want to point out is that my tunes VE Table is set to Multiply VE value by MAP Ratio : Baro. I believe the base tune is different. I found that this option made all my acceleration problems go away.

I have IAT completely disabled. It's just not worth the headache. Heatsoak on the IAT pretty much guarantees that you'll be chasing your tail. Even if you got it right, there's very little gain in performance (as in mpg).

I also keep DFCO ON at all times. This is worth +1 to 2mpg per tank. Also it keeps the engine temps down.

And I keep EGO correction on with PID. I don't know how or why it works well on my car, but it does. If I use SIMPLE it sucks ass. It causes the closed loop feedback to go sinusoidal. PID works great.

Lastly I wired an industrial pressure transmitter and a simple panel meter into the cabin so I can monitor MAP while driving without having tuner studiorunning.

Life is a bit busy these days, I hope to sit down sometime soon and do a complete and simple write up on how to get an NA6 running.

P.s. I love speeduino but I hate TunerStudio with a passion.
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