Sounds like a tuning issue.

Honestly it sound exactly like what my sensors do before they start to fail.

Did it ever run correctly or always do this?

It ran fine last Saturday when I got it back from the shop that tuned it. The idle when fans kick on was always an issue. But lately it's been a lot hotter and more humid out lately and that's when I'm noticing this stumble and stalling during several warm starts.

I'm also not too sure if feel too good about the map in general. I'll post up the msq when I get home. But I am a bit fearful to log a pull if the stumbling might be more serious. Maybe it's just spark blow out
(doubtful at a mere 16psi)? Maybe worse?

May have it towed to another tuner in PA. I wish I had time to deal with this, but I need to get it inspected and emissions tested far sooner than I can learn to tune it myself.

Mine has been stumbling under 2500 RPM. Also stalls out when I restart the car and its warm. As soon as I start moving it's fine though. I always thought it was because my IACV isn't being used.

Hmmm.... I have the IACV hooked up but maybe it's going bad and settings are off. I still cant figure out why it just idles so high. MSQ attached if any guru is interested.

I also think my o2 sensor is not reading correctly. I'll recalibrate, but this is the third sensor on the MTX-L after inaccurate readings. Maybe I'll look into a new wideband solution as well.

Engine bay is getting real hot in expected areas by brake booster. Need to figure out some heatshielding or wrap or both.

<p>Output test mode is your friend.</p>

It seems to be working. Just for shuts and giggles I tried switching the iacv frequency from 511Hz to 384Hz and it seem to do well even when the fans kicked on however when the fans came on again the idle shot back up to 2500.

you do not switch frequency of the iacv. you run what it was set up to run by whoever built your MS

I'll change it back :eek:

When I start the vehicle, it idles nicely around 1k RPM but as soon as I touch the throttle, even the slightest blip, it'll bring itself up to 1.5-2k RPM and hold. As soon as fans come on it'll idle up to 3k. I'm wondering if I need to back the idle screw on the throttle body or check the mechanical side of things or if it's really just in the tune. Would a higher output alternator help at all?

I got finicky o2 sensor readings the other day just cruising, minimal load, then it just gave an E8 error (MTX-L). I'll try replacing the sensor to see if that corrects it. The IAT seems to be ok, it'll soak a bit when sitting but temps drop as soon as it's rolling.

I scheduled a retune with another tuner, but ALLLL the way out in Carlisle PA. I hope they'll be able to smooth it out more, it felt like there was some misfiring on full tilt once, so I've just been taking it easy till it's in the hands of someone more competent than myself.

Then I get to worry about adding A/C back in; but with my luck......


Someday this thing will run right. Or be sold. Who knows!

tune.
don't ever touch the screw, leave it in oem position.

The biggest problem with TUNERS is the fact that most of them will only tune the power/go-fast part of your ecu, and the really important day to day stuff they either use canned settings, or settings that "should work", or something like that. Because they can't really tune them, you'd have to actually cold start the car to tune cold start, you'd have to idle it in different temps and idle loads to tune ide, and so on.

And that would take days if not weeks. Not 3-4 hours

That's what I'm afraid of. This has just become my primary car as the backup has a bad coolant system and it's almost not worth putting any money into.

It's just becoming a pain as driving around feels strange when it bounces between idle and vacuum decel so AFR is all over the place. Then idling at a traffic light at 3k, it nearly hits resonance and the car is just loud /old person rant

I just got back from trying to fix some of the warm idle stuff. I got it to where it isn't running pig rich, and the idle stopped hunting. But once those fans kick on, it stalls sometimes. I just reverted some settings back and let it be; confidence shook. I think I've just become a nervous wreck since the last motor bombed, I don't trust myself even if change are made incrementally. I'll try to do this on the weekend when I know I don't need to be anywhere.

Look for vacuum leaks and then work on the IAC and dashpot settings. What is the closed DC value? Screenshot that whole window, if you would.

Here is a good guide on tuning idle on a ms3.

Thanks for the suggestion folks and the link Shuiend. I'm going to have a crack at it again tomorrow. Idle doesn't hunt anymore, the RPM is down by 500. It does have a bit of a lean condition after restart during throttle tip in.

I did a lot of maintenance stuff today, changed the oil, replaced the dipstick oring which was mangled and seeping a bit of oil. Also replaced the suspension so it's not scraping everywhere. Good thing I have frame rails. I have to contact county about fixing the apron to the driveway of my house.

I cancelled the appointment for retune. It does alright and I should really try to learn this shit the hard way after I grow some balls to tinker in ms3 (with an inherent acceptance of catastrophic failure.)

Tomorrow I hobble it down to Rosenthal to see if they'll align it. I hope they'll accomodate custom number. Otherwise, it'll just have to hold me over for another two weeks. The caveat of fun car being daily.

I'm going to try to rework the hotside piping so I can reinstall the A/C compressor once I get some A/C lines to the condensor.

Attached are the idle settings

https://www.miataturbo.net/attachmen...ine=1439086474

https://www.miataturbo.net/attachmen...ine=1439086474

Changed the oil today and noticed some oil seepage at the oil pressure senders. Tightened them down, hopefully that eliminates some of the mystery oil spotting my car has been doing.

I also replaced the wideband with the LSU4.9 version of the MTX-L and used shielded wire. I grounded the shielding to pin 2 on the bottom MS3 connector as the hardware manual shows this as crank sensor shield, but was unused on my unit. I hope this smooths out the signal as mine was jumpy. I figure it was being influenced from being run behind the radio and whatnot.

Got the car aligned as well.

Trying to so some tuning today and just found out that the vvt intake (relative timing) is set to all '0'

Does this mean that vvt has been functionless the entire time? I think I've stepped way to far in over my head now lol. Maybe I will go back to throwing money at a tuner to set this up properly.

Reconnected the catch can on the PCV side after running a check valve all the while. I want to do a compression test just because I'm paranoid about what happened last time. Also finally got the rest of the bits in for AC so as soon as I put the charge piping behind the fender, I'll try reinstalling the compressor and plumbing. Hood vents are off to get powdercoated. Need to keep the car cool.

Circuit breaker that came with the Flyin Miata Airflow kit crapped out which exposed what a poopy idea this shroud is. It does not contain a divider between the fans so if one stops, air is just being pulled from the adjacent space. Either I'll remove it to weld in a thin piece of aluminum with some weather stripping, or if that poses to be a great risk of fan ingestion by fan, I'll ditch it altogether and go for a single big fan. That'll leave more space for an oil cooler somewhere perhaps.

On highway, oil temps are 220-240°F. Thanks 6spd/4.10.