turcity

I purchased a MagasquirtPNP for my 94 miata. It ran fine off of the stock ecu but I am on a quest for more power. After installing the megasquirt as per DIYautotunes instructions, loading the base maps, and setting the base timing, the car will not idle below 2000 when warm. When its cold it will start around 1500-1600 rpms but them climbs as the engine heats up. I have the idle settings set to PWM open loop because it was recommended in the instructions to get that about where I want it then fine tune it in closed loop. I am trying to do all the research i can to solve this but no luck. I have checked and looked everywhere for vacuum leaks and haven't found one but i do not expect there to be one considering i only touched the vacuum line on the intake manifold. I have adjusted the idle screw on the throttle body but that does not do much. With it all the way screwed in the idle is still about 2000. I have attached a datalog of my idle.
Ps. Im new to the forums so correct me if im doing anything wrong.

curly

iTrader: (25)

Warm up the car, unplug the iac, and use the idle screw to adjust the idle to 750. Never touch that screw again.

Then dont touch the car for 24 hours. Start it, and go to idle valve test mode, and as it warms up see what idle duty the car wants and at what temperatures. Set these points as your warm up curve. Once you tweak this for a few weeks every day, you can use it to tune your closed loop settings.

i should mention, a cold car should idle around 1500, and warm at 850-950 depending on vibration.

turcity

Thanks for the response! When I unplug the IAC,the connector under the throttle body, the call just stalls. How do i maneuver through TunerStudio to adjust this valve?

curly

iTrader: (25)

Under test mode, click on idle valve. Or go to idle warm up duty/steps, and start taking 5-10% out until it idles and warms up well.

Rasta420

There is also a Idle Control min and max setup we used...

Tuning Idle Valve - Ms2 - Guides: Forced induction - MX5Nutz Forum

We also had a massive air leak at the injector seal where it meets the intake manifold, fixing this helped the car from idling at 1500 constantly, never found anything about this when searching so just pointing out could be an obscure place if it is air leak.

turcity

Due to school and work i do not get much time to work on it. But i found that the idle valve setting was suppose to be "Inverted" instead of "Normal" then using idle warm up duty/steps i was able to get a good idle around 1000ish. But the only issue i cannot seem to work out is a little bit of roughness (feels like a miss or stumbling of the engine) when cranking just before it starts and once it does start it revs up to 1500-2000 depending on the temperature outside then drops back down to normal after a few seconds. Also is mid 13s a good AFR for idle? Thanks

Rasta420

no, 13 afr is rich, "stoich" is 14.7 or 100% VE. I am running after warmup 15 - 15.5 afr's, if your referring to 13 afr during warmup on a cold day, say below 50* F then I would supply a different answer

turcity

I was under the impression since my car is batch fire, you need a higher afr to keep each cylinder around 14.7. I read this here, https://www.diyautotune.com/support/...ng-megasquirt/ under "Correct Fueling." Although i do have a good enough idle, when the car starts its odd how it revs up to 2000rpms for a few seconds, any ideas what settings control that?

ramensoop

iTrader: (1)

you need to look at cranking pulse, ASE, and idle control for the revs after start up.

idle probly in the 13s if you're running batch, 14s or maybe higher with sequential...or more simply just listen to the engine, if its happy in the 13s leave it alone. lower your idle cells and see what happens, if it doesn't like it then raise it back up.

Rasta420

I am assuming:
1. you have set base idle as previously mentioned in this thread
2. you have set the idle valve up in tuner studio and performed the min max setup link I sent
3. you have performed the steps ramensoop suggested as they are very relevant and valid to your original issue
4. you have set req_fuel, all other pre-requisites to starting as outlined in the manual

when you start it and it runs up to 2000 rpm, is this a cold engine, on a cold day, what are the exact conditions as they are also very relevant to how the engine runs when starting up. When I start mine on a cold day 15-1700 is normal, when I start it up on a warm day 800-1000 is normal.

I run idle (fully warmed up) 900, afr's 15-15.5, I am chasing to some degree fuel economy in the idle/cruise cells, all below 80kpa, for the boost cells and WOT cells (with load) I want anywhere from 13.6 - 11.6 afr's depending on what the spark advance is, air temp, and which cell it is on the table. I also only use 93 octane which is readily available in illinois (e85 is next for us)

turcity

Next cold morning I'll log the start up and post it. But yes I followed the guide and both Ramen and your tips and they got me where I'm sitting at now which is acceptable. Need more work on cold starts but Im waiting for chilly mornings to mess with those settings. Its seems very happy mid 13s at idle so I'll probably leave it go or lean it out a bit. The only setting I have not touched are the Idle Cranking Duty/Steps. I bet that's were the high idle for a few seconds is comming from. Thanks again
Jon

ramensoop

iTrader: (1)

also check your crank to run taper setting