Rotary Engine Mazda RX7 (FD) hesitation issues

Hey Guys, Eric from NZ here

I’m reasonably new to in depth diagnostics, hoping to gain a bit more insight if you guys can chip in.

I am working on a 98 Factory spec twin turbo RX7, I am experiencing a flat spot and hesistation off idle and snap throttle. If I snap the throttle fast it will backfire and engine will bog.

The rpm also surges at when I hold the throttle at about 2000 as if the engine is reving itself

My verus does not connect to it, there is no check engine light in the car. The car is too old to datalog or full fuel trim data. All working off instinct at this stage

Things I have checked so far.

-Engine compression is perfect (not my go to, but being a rotary engine certainly a good approach)

-I have checked rail pressure, idle pressure is to specs, increases on throttle demand, max pressure is a bit low compared to specs but at this stage the fuel pump is able to put out more fuel than our demand is.

-New Plugs, New leads, at idle a visible bright blue spark can be seen as I pull plug boot away and ground my test probe while increasing air gap.

- I have scoped my TPS, no flat spots or drop outs on both bands and adjustment is within spec.

-carried primary current ramp test on the leading coil( the leading coil is a waste spark system that’s does 95% of the work on both rotors)

Here my my findings (attached)
The tail oscillation is a bit different on a few snaps and I have managed to capture it. Not sure if it’s normal?

How can I determine whether this is a rich or lean misfire? When I pulled the plugs they certainly didn’t look too carboned or too white.

If suspecting a fueling issue where would be a logical place to start?

Any advice would be appreciated!

Thanks!
Eric from Rotary hell in NZ

You're gonna have to work with me a bit here. :silly: The only rotary experience I have is from a couple US market RX-8's.

The snap throttle bog and backfire screams lean to me. You won't be able to see a lean condition in the primary current ramp, but you'll likely be able to see it in a primary voltage or secondary voltage trace. If you're interested, it's pretty straightforward to make your own secondary ignition probe:

www.scannerdanner.com/forum/lab-scope-di...need-to-buy-one.html

Is this a speed density or MAF system? If MAF, that'd be my prime suspect.

Thanks Tyler for your reply.

This car uses a map system, I have tested the map sensor with a vacumn/pressure gun . It is within specs. The owner has tried a known good sensor as well. No improvement.

Slightly different ignition circuit to rx8 (individual coils). This system uses a leading that companion and fires both lower plugs , and a trailing coil for each trailing of their respective housings. I have added a schematic for better understanding.

I don’t have a secondary probe, the article above is a little confusing (I don’t think I quite understand how to set up the alligator clamp up to be able to read it) unless you can help me along, happy to try and learn!

I can try pull a primary meanwhile, in theory it should pretty much be a mirror image as the secondary right? What should I be looking for? Is there glitches that I can only catch in a secondary pattern that I won’t be able to capture in a primary voltage pattern?

Thanks
Eric