Miata Turbo Forum - Boost cars, acquire cats. - MSPnP2 AF tuning help please

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MSPnP2 AF tuning help please

A little backstory to start things off; 1994 1.8L with a home built chinese turbo setup which was running very well on an original Link ECU with RC550 injectors making 12psi boost. The car would occasionally stall after about 5-10 mins of run time, and usually after smacking the ECU it would fire up, but has now died entirely. Unable to find replacement parts, I'm now part of the MS family.

Current setup; homebrew chinese turbo setup (similar to MKturbo), MSPnP2, factory injectors (RC550 removed for diag purposes), turbo base map modified with injector values, ignition trigger offset, TPS values, Innovate wideband with brand new sensor, GM IAT

The car will idle at full lean (22.4) (checked for vacuum leaks), but when I go for a drive, it flips between full rich (7.4) and full lean, without ever really getting anywhere near stoich. I'm pulling my hair out on this one as even small adjustment to req_fuel either have no effect, or swing the idle from full lean to full rich.

I've attached current tune and a quick data log while going around the block (lots of engine braking for speed bumps)

Did you route the innovate to the MS? That sounds like narrowband behavior.

Yes. The behavior doesn't change with EGO control on or off.

The AFR reading has nothing to do with EGO being turned on or off. Did you physically disconnect the narrowband sensor from the ECU harness and connect the innovate to that wire running to the MS?

Yes. There is no narrowband installed on the car, and the wideband 5V output is connected to the MS. The AF display on the MS matches the wideband gauge display.

Quote:

Originally Posted by nikc (Post 1497290)

The AF display on the MS matches the wideband gauge display.

Your wideband gauge display shows the same 7.5-22.3 abrupt swings?

Quote:

Originally Posted by SpartanSV (Post 1497295)

Your wideband gauge display shows the same 7.5-22.3 abrupt swings?

Yup, they are in sync nearly perfectly (maybe .2 difference)

Those numbers can't be accurate. What model is it? Can it be calibrated?

https://cimg5.ibsrv.net/gimg/www.mia...af50bf27be.png

You have a problem here. It's not your main problem, but it's a problem.

Quote:

Originally Posted by SpartanSV (Post 1497301)

https://cimg5.ibsrv.net/gimg/www.mia...af50bf27be.png

You have a problem here. It's not your main problem, but it's a problem.

I recalibrated my wideband again, and adjusted this to 1800 which lowered the calculated req_fuel to 11.9 and tweaking the injector dead time blindly to 1.650 helped a lot.

I then test drove the car, and after analyzing the data logs (https://www.miataturbo.net/ecus-tuni...ad-time-56061/) came up with a value of 1.72 (meaning my guess was pretty good).

I am still running into a very strange intermittent electrical issue as shown in the video I took. I would guess it’s a bad ground, bad relay or something of those sorts as you can hear one relay clicking, then another as the CEL flashes. Thoughts?

I have removed an aftermarket alarm which had some questionable wiring, and the car is running much better now. I am still having an issue where fuel will randomly drop out; sometimes at idle, sometimes while cruising. I managed to catch a log while idling - it seems that dutycycle/PW drops to 0 - but what could be causing this behavior?