1990 cold and warm Idle Control at 3000 rpm, why?
 

Hello all,

First off, if this has been covered i apologise, i have searched and found nothing at all.

Connected my MS2PNP to my 1.6 1990 Eunos, no leaks in the VAC pipes at all, started up first time (wicked!) and then bang, straight up to 3000 rpm. No matter what i changed in the idle control setting, warm up enrichment etc, it stayed right up there. Only time it lowered was when i changed the timing drasticly (not ideal at all) but even when warm, 3000 rpm.

BUT.... i disconnected the ICV pipe from the intake and blocked it up, spot on. Idles at a lovely 850-900 rpm (once warmed up) and timing was base set here with a gun to be sorted. Obveiously from cold it runs like a bag of poo till its warmed up and then i have zero issues, but i cant sit there for 10 minutes with my foot on the gas every morning to drive it to work.

So, my question is why when the ICV is plumbed in, does it sky rocket to 3000 rpm? Am i being a total numpty and missing something very simple here?

Fueling is spot on, timing is spot on, the enrichment was from a base map for my engine and has been edited so it idles slightly from cold without me touching the throttle. Forgot to add, i dont have a VTPS either.

Clearly im missing something very easy, and if so, im an idiot but i have never used Tuner Studio before so still learning things.

Help please :(

I think you are being a "numpty"

Do you know about the "Output test mode -Idle valve" menu? I'd hook it back up right, then play with sending fixed values. My Miata only responds to 35-80%...

Hello mate,

Yeah never knew that existed! although i still have issues.

What ICV should i chose? Stepper, pmw... im lost here and the PMW on closed loop brings up a whole load of stuff!! Doesnt help that i had a 100% blank MS2PNP with not even a base map for my car, base i uploaded was for a 1996.

On PMW closed loop the ICV clicks constantly, dont know if this is an issue but meh...

More testing later, its just a pest as once the cars been started for about 2-3 minutes, it takes forever to cool back down... grrr lol

Will post up my findings

tune.


/thread.

If it clicks, it's working. You are hearing Pulse Width Modulation. Longer cycles have longer 12V duty cycles. Your duty cycle is not wide enough to completely suspend the valve in middle of travel, so it clicks against a hard limit. You need to find the PWM duty % values that actually affect your idle speed, otherwise the valve does weird shit bouncing off that limit, like stalling the car. Closed loop idle has a min and max DC value setting. You should probably use warmup idle control (open loop) till you know what you are doing.

We do not have stepper motor driven IAC valves.

You can find a base map online, it just takes some searching.

I would/am tuning it, but i want to get the thing started properly with the ICV attached as its currently sitting on my driveway till the end of the month (clutch fitting) so loads of time to play about.

Cheers fella, i went to the output test area and it had a 10 in the lower box as the two upper ones were grey'd out. I pressed the test button and the duty went to around 35-40%. im using PMW open loop and changing the HZ in the idle control menu helps.

Im using 124hz at the moment which seems to idle nicely, but again, the car gets up top temp so quick its a daily test to see if what i have changed works.

I have looked for a base map, but the base map i got from DIY Autotune had the ICV set to off :/

meh, i shall have more of a play, now i know what the clicking is, i can now do more testing.

If you fancy taking a screen shot of your idle settings mate, i wont be offended hahaha! Appreciate the help :)

That was a mistake on the initial release of the 1.3 firmware. The current maps here should have that fixed:

MegaSquirtPNP by DIYAutoTune.com

These are my settings, or something close, hope you get her fixed. Those new basemaps should help

https://www.miataturbo.net/attachmen...ine=1410798082

You my friend, are a legend! I shall give that a try later i think once im in from work. Very much appriciated matey :)

I shall re download the base map from DIY Auto tune and see what that looks like in tuner studio also, i have the latest firmware so shall download the 3.3.1a map. If its very different, ill transfer the changes over as my map runs lovely at the mo driving around off boost, so dont wanna destroy that as its driveable in its current state, just doesn't cold start or idle with the ICV attached.

Thanks again chaps, i shall post my findings later :)

An MSPNP needs the idle output set to inverted - just a quirk of the idle circuit in the MSPNP.