Dialing in idle (Stock 1.6 w/ DIYPnP)
 

Hi,

First of all, I would like to apologize in advance for any cringing that occurs while you read this. I am a noob to all of this.

Ok, so just for clarification, I will provide the whole story of my build in as much detail as possible. So, I have a stock 1991 miata that is bone stock besides a "high flow intake" from Racingbeat. I am planning on going turbo in the future and the most logical first step seemed like installing a standalone ecu. I bought and built a DIYPnP. All the solders were good and it powered up on the first try. At first my car wouldn't start on the base tune. Upon investigation I found out that I somehow forgot to jumper the connections for the injectors. So, after that was fixed, I had a properly working DIYPnP with the base tune for a 90-93 miata. I installed an Innovate MTX-L wideband and powered the stock ecu from it, using the narrowband output. Next, I put the megasquirt back into the car. Everything worked as normal and I started the car up. It started after about 2 seconds of cranking, but it kicked and sputtered and sounded very bad. Come to find out, I had forgotten to set the EGO type to narrowband. After I fixed that, I started it back up (Note: The idle control was still set to "Warmup only"). This time still took about 2 seconds to start. When it first started it sputtered for a few seconds (Loads of un-burned fuel in the cylinders that were missing previously) and then smoothed out. However, it was idling at about 1750 rpms and as it warmed up it rose to about 2000-2100. Afr started in the high 9's and rose to about 13.5:1 at 180 degrees. I tried changing to closed loop idle. When I started it back up, it kicked and sputtered how it did before. Rpms were around 5-600 and fluctuating a lot. It sounded like it was only running on 2 cyl and it was smoking badly out of the exhaust. When I reverted back to open loop, I had the same results. At this point, I decided I would put the stock ecu back in and seek help. When I started it back up on the stock ecu, it missed for a few seconds and then started idling correctly. There was a lot of un-burnt fuel left in the cylinders, and afterword there was a lot of water in the exhaust.

Extra details : I had tried setting the tps (stock) to 0 and unplugging it. Also tried editing the pwm %'s. Neither of these seemed to make any difference in idle.

Thank you in advance for the help, tune file will be included. Attachment 151764

You need to check the ignition timing is correct

1. Why the hell would you get a wideband and use it as a narrowband?

2. Did you set the base timing? This should be done before anything else. I had issues getting the car started and running until my timing was close.

3. Read stuff

Also, all of your sensors need to be calibrated. Your computer only sees a voltage range. You have to tell it what that means.

Yes, the base timing is correct. Also, it is on narrowband output because I need to be able to quickly switch back to stock until i get things running better on the megasquirt.

Coolant temp is correct, rpms are correct. For the throttle it was the same voltage no matter how far depressed it was (stock tps) so i set closed throttle at 1020 and WOT at 1021. Then I unplugged the tps. Besides this as far as I know all of the gauges are correct. Thanks

UPDATE
 

UPDATE : Upon further reading, I believe if I can get it back to the high idle, that was smooth, I can edit the CLTvsPWMduty% table to get my idle lower. If someone can verify that this may work that would be great. Thanks

you're using open loop...

if you cant hold your idle valve open to a static position, and maintain a stable idle speed, then you have other issues.

The idle speed is pretty stable (doesn't fluctuate noticably), I just need to get the idle speed lower. What I found so far is that, to lower idle, you lower the idle duty. (Note: Im talking about when it idled at 2000 ish here, not the sputtery 2 cyl idle that spat smoke) My plan is to restart with the base tune (So I can get back to the non-horrible idle), and go from there making small adjustments 1 at a time. Thanks and Sorry for any confusion

you literally have a table that says "at this clt temp, open the valve this much"

that's it.

so if you want to lower the idle speed, lower the duty cycle in that table until you get the RPM you want. But remember base on ambient conditions, that RPM might move 500-1000RPM.


otherwise, if you spent the 10 minutes to tune closed loop, all youd have to do is move your RPM target to the desired RPM.

I would like to tune the closed loop but I seem to be too much of an idiot. I have also read that if you can get a good idle out of open loop that you might as well leave it open because it will be easier that way. Ive been trying to read up on idle tuning as much as possible but it seems that everyone kind-of has their own settings that work for them. I guess ill just have to experiment more and see what works for my car. Thanks

Closed loop idle isn't as hard as people would have you believe.
Getting it to work 90% of the time in 90% of conditions is pretty easy.
Getting it perfect is what people can struggle with.
This should help you:
Mega Miata: Basic idle settings

You need to wire in your wideband to tune your engine.
If you can build a DIYPnP, I'm sure its not beyond you to modify your car's wiring harness so you can switch between your O2 controller's wideband and narrowband outputs when changing ECUs.

Tuning the Acceleration Enrichment is probably the easiest part though, so at least you have that to look forward to

My wideband is an LC2 so all you have to do it plug it into your computer and program it but for some reason it wont read the serial on my computer. That is why I have been keeping it narrowband for now. Thanks for the help

So, I followed the steps in the article, but changed a few to match my car (1.6) and tried to start it up. It sputtered a little and died. I don't know where to go from here. Im totally lost. Try less fuel? Wideband reads 10s while cranking.

Don't try to tune idle settings until the engine is at normal operating temperature and your VE table values and ignition timing have been validated.

Load in the standard map from DIY Autotune
You can download from this link:
https://www.diyautotune.com/diypnp/a...93-16b6-mt.zip

Choose the one for 240cc injectors and load it into your MS

Make sure your ignition is set correctly using a timing light and the method below:
https://www.diyautotune.com/tech_art...ing_how_to.htm

Read all the articles here:
https://www.diyautotune.com/tech_art...h_articles.htm

and here:
Megasquirt2_Setting_Up-3.4

Dialing in idle (Stock 1.6 w/ DIYPnP)
 

You should never use open loop idle. Whatever you're reading, stop.

Loading random tunes and basemaps is also stupid.

Once the car warms up does it idle ok? Do you have a log of a warm idle and some around town driving?