Random Idle issues help
 

Stats

04 MSM
upgraded intake/ chargepipe
exhaust
ID 650's

rev built MS2+


hey guys.... so cars been doing pretty good and set for a track day down at Gingerman raceway next week...

but got a funny gremlin thats keeps happening ive tried contacting Rev since he built the ECU but he hasnt gotten back to me since last august.....

the car will randomly Rev surge to 4K RPM and hold there.. than go back to normal and will also rev search ramdonly from 1-2 K RPM...

if i cycle the key on off right away it goes back to normal..

is this maybe a problem with the ECU or settings... im stumped and cant find the issue of course it never happens when i datalog... my tuner doesnt use megasquirt much so hes stumped as well anyone have ideas? greatly apperciated

closed loop idle settings
also the iacv settings

here are some screen shots... anything look out of wack?

idle control is set for pwm closed loop

i appreciate any help!!!

https://www.miataturbo.net/attachmen...ine=1431170321

https://www.miataturbo.net/attachmen...ine=1431170321

https://www.miataturbo.net/attachmen...ine=1431170321

https://www.miataturbo.net/attachmen...ine=1431170321

https://www.miataturbo.net/attachmen...ine=1431170321

https://www.miataturbo.net/attachmen...ine=1431170321

https://www.miataturbo.net/attachmen...ine=1431170321

https://www.miataturbo.net/attachmen...ine=1431170321

https://www.miataturbo.net/attachmen...ine=1431170321

have you tested the idle valve?

As in? Sorry with out it plugged in the car won't idle on cold start I haven't gotten up to temp and unplugged it to see what happen. The car normally does fine but will randomly and doesn't do it every drive but will do the rev to 4k rpm or will randomly rev search out of the blue.. I guess that's what's throwing me is that this is so random...

You need to be saving a datalog of when the problem occurs. That's the only way to nail it down.

Is the problem occurring while you've been idling steady for like 10 minutes? Does it occur when you decelerate to a stop in a neighborhood? Does it occur when you are accelerating quickly through gears?

You need to look at:

TPS %
idle air control duty %
RPM
AFR

If you are seeing idle air duty spiking, and this corresponding to high rpm, it means you have to make adjustments to initial duty table, closed loop gains, or dashpot functionality. If you see TPS % misbehaving, maybe you have the throttle linkage binding or something. If you see AFR bouncing around, then maybe you are going into a lean condition that is causing a surge.

Start narrowing it down.

thats the stupid thing about this issues is ive never been able to catch it during datalogging... its completely random..


yes some times it will occure when we have been driving and come to a complete stop and it will randomly search idle other times ive started it up letting it warm up and than it will randomly rev up to 4 K RPM hold there till i cycle the key and it goes back to normal. its really random. some drives it will do fine and others it will give us idle issues but if you cycle the key it goes away and may or may not come back for that drive. i have a hwy trip down to gingerman this week im going to be tunning on the hwy and also running data log that trip at points i will see if i can catch anything..

i appericate everyones helpfulness!

what kPa do you normally idle at?

Am I right in thinking it's happening after you coast in a high gear like 5th at a very low rpm?

i will start it up tonight and see what KPA it idles at..

i honestly couldnt say it happen always after coasting in high gear 5th or 6th.. it will honestly rev search randomly after warming up, or after driving and coming to a stop, it will spike idle to 4 K RPM randomly durning warm up or even after driving coming to a stop and than will go to 4K RPM. gremilins i tell you. basically got the ECU from REV. set it up did some street tunning of fuel maps, took it to my buddy that mainly uses AEM on his NSX builds but hes tuned with alot of other programs just mainly AEM and hondata stuff. couldnt get it to do the funky idle things when he was around.... go figure.

If it helps, I'm having the exact same problem on a '01 NB8C running MSLabs MS3 Basic using only the base tune (VE has been tuned). No performance modification bar ECU (still stock injectors at the mo).

Only had 4k surge under cold start (very cold start.. car sitting >5 days).
The 2k as far as I've noticed has only occurred during gear change, though I might just be less attentive to that, until I let the clutch out and suddenly lurch in my seat. :)

What won't help however, is I don't have a datalog either. Was waiting to get one to email Reverant...

Nor have I solved my problem.

an initial surge to 4K on startup suggests that the initial idle duty table needs adjusting.


you really need to log these events to see what the MS is actually trying to do.

Mine does the same thing,

04 MSM, all bolt on's stock injectors, and it does the same thing, it only does it on cold start. I haven't had a chance to look into it though. Are you using the base map that REV supplied?

I found the following guides to be pretty useful when working on my idle, although I haven't taken time to really dial it in yet.

1. Tuning Idle
2. Tuning Idle Valve

all that has been done via the basemap, it could use fine tuning, but this issue is beyond the intial setup.

I have a similar issue 04 MSM far from stock though. MS3 from Rev

Here is a few-second-long log of mine doing the same thing (attempting to idle high but hitting fuel cut). When it does this, if I turn off fuel cut it will idle back down to normal after maybe 15-20 seconds.

Mine too does this randomly. MS3 basic, 02 VVT engine in a 95 chassis. Haven't been able to figure it out.

Didn't see that another person had posted a log. Doesn't look too dissimilar to mine, really.

It's particularly obvious where TPS is 0%, as opposed to seeing if VSS is 0, since it still happens when I hit the clutch to change gear. I was actually datalogging to try work out what's going on with cold start at the moment (it's winter here) when I caught this.

If it isn't obvious, I have no clue what the problem actually is. What comes first, the chicken or the egg? AFR is all over the show, but is that a cause or an effect?