Hi all,

A little more than a year ago I installed a MsPnP2 on my 94 NA. I spent a good bit working out idle issues, AC loading, and general spark/fuel table mapping. Lots of autotuning as well.

The car saw track days, AutoX, and general hooning around. Never any issues. Made great NA power.

Well, about a month ago I noticed on the way home from work one day that my AFR was bouncing around a lot more than usual. I figured it might be due to the change in temps and humidity, since I had not autotuned since winter. As soon as I got home, I nabbed the laptop and took it around the block. Bam, cells corrected and issue gone.

Well, today the issue has come back and I am starting to think it may be a sensor issue or something, IDK...

Which is why I am posting here:

What could have happened to cause erradic AFRs after the unit had been installed so long ago and used so much? Fuel injector? Pinched map line?



I'll admit, I am no pro tuner. But I am a quick learner and always ready to get my hands dirty. Where would you guys start troubleshooting?

Thanks so much for reading
Bai

(cats)

 

Datalog when this happens. Post it here.
It will help us help you.

 

<p>Lesson 1: Always post a tune and log</p><p>Lesson 2: Make sure the tune you upload&nbsp;isn't named &quot;CurrentTune&quot;</p>

 

That + turn off EGO correction and see how "good" your tune really is before you start replacing/diagnosing stuff

 

If you turn off EGO and the car behaves normally, except for fluctuating AFRs, look towards the O2 sensor. They do have a lifespan.

 

have you re-calibrated your WB since install (not all require thins but you should look into it)

 

Is a little over a year typical?

 

Well I was a fcking idiot.

I tried changing the idle tune, but I think I screwed up a lot more. The car won't start now.

I made some adjustments. Drove for some ice cream. Came back to the car, scrapped the autotune adjustments and loaded the tune from the controller. Went to start and nothing. Gave me an error about idle up pin. Found out the AC idle up pin had changed from its original value. I never touched it.

What kind of megasquirt mindfuckery is this? This happened late last night and I work all day, but later I will update the controller with the correct idle up pin and pray to the miata gods for forgiveness. I will post my tune and a log at that point.

Any other suggestions until I am able to do so?

 

 

MS doesnt just make changes...

 

Lol well I am glad to hear it isn't a common issue. Not claiming it changed anything on its own, I probably goofed up and changed a setting I should not have. I tried restoring to a previous point in the tune, but no luck.

I think what happened is that my settings got mixed with the stock MM9495 settings. But.. It cranked up the first time when I initially installed this... Why the issue now?

We really wont know until I post the tune and log, but I have a feeling I blew the coils

 

Are there any settings I should try to confirm? Cranking pulse width, req fuel, etc.

I know some of these settings differ from car to car but it would help to know if I am WAY off.

Hopefully correcting the idle up pin was all that needed to happen and I will drive away gleeful and full of ice cream

 

Update:

Reverted to a tune I had back in Feb. Car started right up. Very busy with work but will compare the old tune to the new tune to see exactly what I f'ed up.

Anyways, attached is a log of the recovered tune while driving home as well as the tune itself. Enjoy!

 

Well I looked it over and my MAT is all over the place. Could this be an IAT sensor on the fritz?

A more experienced glance at my log would be appreciated. ;~P

 

The MAT has gone well past "on the fritz" and straight into complete lunacy. Weirdly, it's not doing this off the throttle. Check to be sure the MAT wires aren't near spark plug wires.

 

Yea at idle MAT is fine. Wtf right? I'll double check wiring but I think the sensor may need replacement. Thanks for checking out my log

I am admittedly a noob but am trying my best to learn

 

Back with good news. The issue has been resolved.

The intermittent fluctuating MAT temps seen by the MS was caused by a short in the wiring I missed upon my initial inspection. The nick would sometimes make contact with the frame of the vehicle, throwing off the readings of the IAT sensor, and who knows what else!

Hey,

I moved it away from anything conductive, taped it up, and all of my issues have gone away. Solid MAT temps though I believe I am getting heat soaked readings. I'll have to relocate my IAT bung but for now the car is running as it should. Thanks for the help, Matt!