Started working on my Miata again this last weekend. Haven't touched it in a year. New Job, live in the Bay now...haven't been on the forums in awhile.
It's a 1990, 1.8, NB head, NA manifold, MP62, Track Dog intercooler....running an older Rev MS2.


It's got a couple problems and I'm in over my head. My goal is to tune it, and get it to pass tailpipe emissions as it is. Need to address whatever problems it has, then I'll probably upgrade to EV14s and tune again.
It started right up after sitting a year or more. Last time got a lot straightened out with during a a tuning session with Vlad (18PSI) and a thread on this form. A couple problems still remain.

1. AFR is all over the place bouncing around. I've googled and googled this, and found people with similar issues but never any possible solutions. I've tried two WBO2s...an Innovate LC1 first, then an AEM UEGO. It's currently on the UEGO behaving exactly the same as it always has. It starts, runs and drives...but it's not right. Any thoughts?
2. The fuel pump runs constantly now with the ignition. It never used to do that.
3. The factory tach wont work. I've tried to resister trick, ran a wire from the tach straight to the 1.8 coil pack...nothing. This is last on the list. As I recall it worked about 10 years ago when this was a 1.6/pre blower/pre MS2. I'm pretty sure this ecu has an output for tach.

Does anyone know any shops in the Sacramento or Bay Area that tune? Vlad, if we can figure the bouncing AFRs out here, I may want another tuning session.


Attached is my current tune ripped from the ECU this weekend, and the tune after Vlad worked on it, just in case I changed something stupid. I didn't have the tune file or even tunerstudio on my computer when I connected, so I created a brand new project. Also attached as a data log from a short drive.

Thanks, Thanks and Thanks!

 

Are you referring to the intake manifold?

 

 

boncy wideband: you're talking about on the gauge right?
Bad ground(s) and/or bad signals and/or bad wiring. That may also be the fuel pump culprit

 

Yes, Intake Manifold. I've got a NB head with an NA manifold. Welded a piece of bar stock to the bottom, ported it, and surfaced it.

I'll check the grounds. As I recall when I switched the LC1 to the UEGO I redid the grounds. Where can I begin to look at bad signals?
I'm not running an actual physical AF Ratio gauge, it's the one in TunerStudio that bounces around. This bounce looks/feels a little different than the bounce I've seen from people with bad grounds.

I'm going up to the car this weekend, will check it out and rewire it again.

 

you can also decrease sensitivity in TS if you're sure its not the grounds

 

Checked it out this weekend. I have two ground options for the wideband, one to the factory ground for the ECU that the MS2 uses, and another to the bolts for the factory ECU kick panel/mount. I tried both, same bouncy AFR. I also tried playing with the Lambda Averaging Lag Factor. It was at 65, changed it to 20. No real effect on the bounciness, maybe it's less maybe not.

Still thinking this might be grounds? Next weekend I'll come back and run a new 14g ground straight from the battery to the wideband (and maybe MS2 also), and I'll check the battery to chassis ground, and engine ground too for fun.

Boost on

 

turn off ego correction. if it stop bouncing and pegs lean, you got an exhaust leak

in this log you can clearly see that when ego corr is at 100 the car is lean, then overcorrects, then starts bouncing back and forth

 

The wideband is a sensor and needs to be ground directly to the sensor ground pinout on your MS2; there's only one pinout for that so look up the wire that you need to ground it to.
From what I understand none of your electrical components should ever be grounded directly to your engine battery. The voltage drop across the battery ground causes a lot of problems for sensors.

To get the tach working you need to go into your MS2 and wire the pinout that you want to use as your tach singal from the board itself.
Happy boosting.