Hey MiataTurbo Members, this is my first time tuning an ITB engine and it is running a unusual. We were trying to set the base timing (by following the instructions on Megasquirt manual) but TunerStudio and our wideband is showing 22.4. Car starts up fine but idles at a high rpm (1k-3k). We tried adjusting the timing to see if it would run rich but there was no difference in AFR's. We also tried to add more fuel in the VE tables but the car would only rev higher and still run lean.. I will attach the MSQ.

I'm used to base mapping turbo cars (like my own) or nearly stock miata's but never dealt with ITBs.

1.8 engine in a 1.6 Chassis (1990)
CAS
Maruha ITB
Racing Beat headers, test pipe, and muffler
Toyota Coil on plugs
Innovate MTX-L
IAT sensor
Deatschewerks 200 Fuel pump
NB Red top Injectors

 

We also calibrated the o2 sensor, tps -- also changed the accel settings to 100% TPS, and IAT

 

22.4 is the max setting for the MTX-L. Usually means an error. Or a giant exhaust leak.

Is the sensor in the header?

And plugged in?

Is it all wired correctly?

 

From the ecu, it's the red/blue wire yes?

I recalibrated the o2 sensor and still doing the samething. hm...

 

are all the injectors actually firing?

 

Yes red/blue for signal, as long as your MSPNP2 is configured for reading wideband off the factory pin at 2N. But, that doesn't matter for your situation. All the MTX-L needs is power and ground for the gauge to work properly. Obviously you're getting power, otherwise it would not read anything. It could be a faulty unit. Where are you getting power and ground from?

If it's running at least fairly healthy, I'm sure it's below 22.4, and that would be a sensor error.

 

in my brief experience, you would have a poorly running car if you were that lean. Your sensor or gauge are most definately off. i am assuming MS is showing about the same reading? Is this a brand new wideband unit?

 

Yes, definitely not a misfire and the plugs are wet.
I rewired everything and will be calibrating again.

This is what I have so far: Wideband -> Harness
Power -> Cigarette wire (red/blue)
Ground -> back of head
Yellow -> red/blue from ecu
Brown -> red/blue from ecu
white - wrrapped away

MS is now reading o2 but the gauge still showing 22.4 (weiiiird...) It is idling at 2k rpm and everytime I add fuel in the VE the rpms increase. hm...

I'm starting to think this wideband is defected

 

Why do you have both outputs going to red/blue? Yellow is analog output 1, use that. Brown is unused unless you're sending it to another logger/stock ECU or something. White should be grounded if you're not using it.

 

My mistake, I did not repost my update on time. I actually used the yellow wire and left the brown wrapped away. Isn't white just the dimmer? Anyways, I tried to calibrate the o2 sensor again hoping that would be the problem but failed. Still reads 22.4 (so is megasquirt). hmph. It really seems like it's a faulty sensor.

edit -- grounded the white wire still 22.4

 

Ah, yeah I believe the white wire is just for the dimmer. I just remembered grounding it on mine. Yeah, I'd put in a call to Innovate. Hopefully you bought it new so you can get support.

 

Yes, my friend bought it new. We have a spare wideband. I'm going to try and test that out.