Been searching ither threads and forums and I feel it is still unique. Other day it's in second or third or after it warms up it goes away...so on.
it doesn't matter if sat all night, cold, warms up, leave (-) terminal off all night. It just won't boost.

I have rechecked vac lines, seem good. The y pipe boot doesn't exist as it just bolts together. Tighten down any worm clamps i could find.

 

Following the videos I posted above might be hard. Perhaps find another source to explain the proper placement of the jumper wire and the LED lamp leads.

Rather than a potato in the exhaust, a plugged up cat may be a cause. It don't know how you check for that, as it is difficult to shine a light through the FD cat due to the bend in the pipe.

Coils can show spark, but the spark could be weak. New coils can be expensive but there are usually used sets of three available on Buyee (or here) for $100. You can test them before installing.

The set of coils pictured above was such a used set, which we swapped in for good measure; and it seemed to be part of the solution; Augmented by a new coil harness.

 

"Smoke tests" can usually be done for cheap, and may show vacuum leaks that a visual inspection can miss. Expect some leaking around the throttle axles as well as the turbo flap actuator axles. This might be considered normal on an older car.

Open up the ecu to see if there is any damage to the motherboards, or any bent pins (don't bend any yourself).

Check to see if there is any damage to your harnesses as they pass through the firewalL. People fishing wires through shared openings may cause hard-to-see damage.

 

Ill rig something to smoke test. Sounds dumb to ask but from where do I blow the smoke? I grt it has to come the intake side.... That's about it That's about it.

 

You might enquire at a local shop if they have the proper equipment.

Or you could visit an automotive retail store and look at what they have for sale.

I would not recommend a DIY effort as you see on you tube.

 

Remove the coupling between the intake elbow and intercooler when it's idling at 600 and see if it revs up at all, you can also take it for a short drive with the coupling out and see if it responds any differently. You're doing that to rule out an intake restriction.
I think redbul is on the right track about the car going into limp mode though.

 

alright. update. I may have done too much but...
Took out everything I initially removed, removed elbow and reseat the wires to coils and plugs. went over vac lines to ensure i hadn't pulled anything loose. went over all the grounds and loosen then tighten back.
I did this all while the pos and neg were removed from the battery.
Car drove fine on the way home. Parked. Shut off. Took for a drive in neighborhood...same issue back again.

So yes...something is putting it into limp mode I believe as well. Let the car get warm. Turn to On...not no codes. So now stuck again...

 

@Molotovman I didn't remove the coupler and try this yet...just seeing this morning and will see if it is an intake restriction.

Cat seems okay, it is a high flow cat, and discon O2 sensor in case that was giving a bad reading or it is going bad but the same issue.

 

@Kilito Racing this is my issue. OMP, as suggested? Seems it requires a bit of time (mostly) to replace.

 

I am back to the potato theory, but this time, I suspect a neighbour.


I wonder if you disconnect the electrical plugs from a few solenoids (don't break anything) if you will see codes? This might confirm you are doing the code check correctly.

(There is no CEL light on JDM, as I think we have established that. Just checking that you are not expecting a CEL light to be blinking. There is an engine overhead lamp, instead of the CEL light. Its symbol looks something like a CEL light symbol)

ECU might be expecting feedback from the O2 sensor. Check the code list in the FSM.

 

I am not expecting a CEL yeah...odd they dont have one but all too familiar with the fact. lol.

So 02 sensor connected/disconnected same. no CEL codes that I can tell....but have not tried any solenoids. Further update...when it starts bucking (limp mode, I presume), I can toggle the key really quick Start>On>Start and the car drives completely normal. Assuming this is "bypassing" limp mode. However....I have to do this every 2 or 3 times driving. Other than it all drives like normal once I trick the ECU. TBH not sure if I am doing any damage. If it is infact the OMP sending a bag signal or no signal...I do premix. About 8-10 oz per tank.

Should I be good to continue this until I can actually get the time to replace the OMP? Or at least further diag if it is the connector, harness lead, or something? I am not 100% where the OMP is located but I can see the pwr lines and the clearish oil tubes and follow them with my hand.

 

The on-and off thing works, until it doesn't.

Try to run the codes again.

Changing out the OMP is a bit PIA. But how about checking the connectivity at the connector.

 

Things the ecu looks at to set the injectors. Includes o2 sensor.

There is where the OMP is.

 

I suggest unplugging a sensor that you know for sure will throw a code just to make sure you are reading the codes correctly (or at least make 100% sure you in fact don't have any codes stored).

Would limp mode even affect the idle?

What would have the effect of lowering the idle (but not effecting the quality of the idle?) and hurting drivability under boost intermittently depending on how hot the car is?

 

I'm surprised anyone would own one of these cars in 2025 without installing a wideband O2 gauge. It's been known that rotary engines have smaller margin for error, the stock ECU didn't always run safely with airflow modifications, the stock fuel system didn't leave much headroom, and many of the components and harnesses are pushing 30 years old by now. Aftermarket ECU with engine protections and fuel pressure monitoring sounds like an even better plan, and would still cost less than an engine rebuild.

 

My understanding that, in certain situtations, when the ecu is not getting a signal it wants, it will assume a range, and run the engine accordingly. For instance, making the idle fluctuate within a range. I'd have to review to find which situations cause this, but perhaps a bum MAP sensor or TPS or O2 sensor, or.....

(Check that the filter for the MAP sensor is aligned in the correct direction.)

As scotty305 suggests, I tried for a year to get my stock set-up to work and although I managed to get the stock set up to run well, my efforts ended in a failed engine (a shop connected my coils wrongly when changing the plugs ).

Upon rebuild, the main tuner shop here refused to try to reconstitute a stock set-up (for anybody) , and I switched to a Power FC.

That was nine years, and 50,000 km ago. I do miss the sequential turbos, but running reliably has been a treat.

 

INB4

 

Perhaps borrow a TPS that is known to be good, and swap it in.

(Use a small ratchet with a Phillips head to remove the machine screws and take care not to drop the screws or strip the screw head.)

I have heard that TPS can test OK, only to go out of range when the engine gets hot.

New TPS can cost $400, but working used ones can be found for $100.

 

https://buyee.jp/item/yahoo/auction/...n_DirectSearch

 

Awesome. Soon as i have funds and the time. I will tackle the OMP check and see about a temp TPS.

In other news. For some reason air con blows out vents and heat out defrost...at the same time. Blend door actuator? I'll check forum but any quick insight/links appreciate

 

Ohh...and now hood latch cable just broke when trying to pop the hood and check coolant level lol...

 

You can run a rod along under the front edge of the hood and force the latch open. It surprisingly does not take much practice. If you can try it on someone else car with the hood open, first. Remember you'd come at it from the opposite as LHD.

New cables run about $60 on Buyee,

 

So after much testing, guessing, and ruling out by A/B...continual limp mode seems to be caused by the OMP. Will need to source one and more importantly find someone to install. Will grab the wideband 02 and am looking into a simplified non sequential, PFC or Microtech and air pump delete. Would it be okay to actually delete and cap the OMP at this time as well? Just have to heavy premix I assume and monitor. Mind you this is my daily, grocery getter, etc. Track and drift days are done with...for now.

 

Did you actually read the codes, or are you just guessing?
Don't try to modify your way out of a problem.

 

S8 had an upgraded OMP, "Mikuni" brand. Replacement with a good used could be about $400.

Many people delete the OMP and commit to "pre-mix" religiously.