1994 Fd rx7 adaptronic modular afr issue?

Hey guys I was wondering if someone could point me in the right direction on a weird issue. This is my first rotary I’ve tuned so I’m learning as I go, but basically it doesn’t seem to like to run happily unless it’s quite rich.

As an example it won’t hold a steady idle and begins popping like it’s lean if I lean out the idle to anything more than say 13.2-13.5 as well as not holding a consistent afr at idle. It hunts almost a half a point at idle.

While low load cruising it has a bit of a hesitation/misfire and likes to drive around the low 13’s and if I lean it out any more it pops.

under boost it’s totally fine, Afr stays consistent and drops down into the low 11’s and high 10’s and stays rock solid with no hesitation or popping.

Am I missing something simple here? I have a couple local tuners stumped too.

hello, important things on a rotor are the injectors and making sure they flow the same you may be reading rich but it certainly sounds like one rotor is running lean if not both. I'm not sure what AFR gauge you are using but it would be a very good idea to check the 12v and ground are both in very good condition if it is wired into the ECU then check the ECU and the unit share the same power and ground voltages. this will stop any offset between the two units. also, check the tps spans nice and linear. watch the acceleration enrichment also to make sure it goes a little richer when active and is not active when not needed

Regards Ross

Injector phasing can make them more fussy too if not right. If it is ported it will probably sound happiest at idle around 12.7 petrol scale. It's pretty normal. Likewise for temperature management people generally run them richer than most water cooled piston equivalents, you can bow apex seals or cook turbines if you aim for aggressive afrs.

I think Ross is onto it, it seems like one rotor is leaner than the other but I’m having a tough time differentiating. Is there a test I can use to check? That would explain the car being happier the richer I run it.

I had the primary injectors cleaned and flow tested and the secondaries are brand new.

Can you run a dual channel egt?

Have you tried fuel trimming one rotor relative to the other?

The modular allows oscilloscope function doesn't it? Can you do a crank signal trace to see if one rotor has a consistently better crank acceleration?

I have bungs for egt in my manifold I just have to get some sensors and install them.

I had considered trying a fuel trim on each rotor separately but wasn’t sure how to go about that.

there is an oscilloscope function I can definitely check the crank acceleration with.

Im pretty new to tuning and tuning rotaries in general so I haven’t really tried a whole lot yet as I’m a bit lost. I think I’ll get the sensors first and try to figure out how to do a fuel trim on each bank/rotor. I think that is the problem if I’m being honest. My guess is the engine is maybe ported and isn’t quite equal?

They brap if they are ported and you have some timing in them, it's completely normal and as I said they like to be well rich of stoic. It's probably worth watching some start up videos of ported motors on YouTube to compare to yours before you get too carried away on idle. If there are significant differences in exhaust temp once you start to load it I would be more worried about fueling differences.

Oh I know about the brap im not overly concerned about that I’m just more concerned about the popping while cruising and the afr being so inconsistent at idle. I guess maybe with them being a bit lopey maybe I’m being unrealistic in my idle afr targets but should it hunt from say 12.5-13.2? It idles fairly consistently as far as rpm and my closed loop idle control is only doing about 2-3% work. If that’s just how it is going to idle at for afr then that’s how it is I can live with that answer.

I would like to sort out the cruise misfire/popping so will check egt while cruising still

If you are getting the miss on idle you will get lean readings. If the port isn't massive you can try retarding timing and giving it more air to see if it flattens out. If you can get it steady the afr should then ready pretty constant.

You may have to try something similar with cruise at low rpm for it to be smooth too.

Okay I’ll give that a go thanks! I took a couple videos tonight of what it’s doing if anyone would like to see it. I’ll start bringing the idle timing back and go from there

while cruising go to the cylinder trims and add 10 percent fuel to the front rotor and see if it helps if it doesn't take it out and try the back rotor if that helps my advice is to either fit duel lambda or egt sensors to then add a 3d map of fuel trim if you cant find a actual mechanical reason for it running that way

regards Ross

I haven’t been able to find if there is a way to trim fuel by rotor on Eugene so I’ve sent an email to adaptronic tech support. Maybe I’m missing it but I checked the manual and looked on Google. I’m sure there is I just didn’t see it. I think I’ll jack the back end of the car up and hold it in that area and play with the fueling and timing. It does it under no load as well, so I should be able to replicate it and not worry about driving the car. I’m sure it’s something minor as if if I load the car up with more throttle it revs right through that area fine.

Those idle numbers are completely reasonable, I shoot for ~13:1ish and settle on wherever the engine likes it. Depending on how aggressive the porting/overlap is you'll also get mixture fluctuations that are far more active/volatile than your standard piston engine.

That said, if you feel like you're running into a flow differential issue, please take care of that first.

As a quick update I was able to remove 2% fuel from the front rotor and it really calmed the idle down. It has a slight brap so there is some fluctuations but the car now idles between 12.6 and 12.8 and my target is 12.8. It doesn’t like idling much leaner so likely that’s what I can get with the porting.

I was able to get the car cruising without backfiring/hesitating but it will only cruise fairly rich ie. 12-low 13 before stumbling slightly. Obviously not the best for gas mileage but if that is how it will be then so be it. Didn’t buy a rotary for the gas mileage. I’m going to finish engine break in and revisit the cruising afr tune.

compression tested last night and on used housings and new RA super seals it’s already up to 100psi on all faces

Hello, good news on the results so far can you post your ignition leading and trailing map, the stumble you get now in light cruise maybe requiring a bit more ignition timing in that area only, but I would be mindful of where it is now before adding anything.

Absolutely I can. I’m at work and don’t have my laptop currently but I believe I’m around 20-24 degrees in vacuum at 1500-2500 rpm in the cruising area

Okay heres the link for the file I've been working off of, keep in mind it is nowhere near completed of course. I had a "rotary tuner" remotely tuning the car and this is mostly what he has done, my experience with him has basically brought me to learn how to do it myself.

I was able to get the car to drive without misfiring albeit rich. At about 1800-3000rpm and -6 to -12inhg the car is sluggish and then once you either rev through that or give it more throttle the sluggishness goes away and the car revs cleanly and closer to target afrs. Is the timing to conservative in that area? I looked at a few other maps and it doesn't seem to be too far off, but perhaps it could be advanced a bit more and pick up some extra torque.

Well complete bone headed move by me but I should have checked this earlier. The file I was working off of was given to me by a tuner. I verified timing on the original adaptronic map at factory 5 degrees. For whatever reason this file was at -1....I was watching one of Andres webinars and he said something that got me thinking so I checked if the base timing was 5 degrees and it wasn’t. Not sure why he ever changed it but I switched it back and verified with the timing light and the car is night and day.

cruises at 13.7 with no popping or hesitation. I think now I can continue to dial in the afr. Idle still brapping a bit but that may have more to do with the porting than anything.

Good you found it before too long.

well done