The Jensenator is coming along slowly, I'm getting the bugs worked out. There's a big one right now, though. It's running a non-turbo 1990 RX7 13B, called an S5. I am using a hybrid fuel injection system with an S4 (1986-1988) ECM and a S5 (1989-1991) air flow meter. That's a common and well documented swap. I did all that so I could run a mechanical oil metering pump and ditch the S5 electronic oil metering pump which has some bad habits. S4 and S5 share all the same sensors except for the MAF and MAP, I am using the S4 MAP. I am using a MSD fuel pump with the stock pulsation damper and pressure regulator.
The first motor made good power etc but smoked heavily on decel. I don't have time to build a motor so I grabbed another used one which I heard run before buying. It's in the car now and has nowhere near the 'Puff the Magic Dragon' attributes of the first motor.
At the last AX I ran with the old motor, it was super easy to flood. I put that down to a combination of really hot weather and the painfully obvious oil consumption, but with the 'new' motor it's every bit as bad. I mean the plugs come out with a big drop of wet fuel on them, not just black carbon. And it takes only about 2 or 3 minutes of running to get them this wet. It also idles like crap. Whatever is happening affects both rotors as all 4 plugs come out soaked.
I'm planning to jump into this with both feet over the next couple of days, I plan to ohm all the sensors and compare to specs, test the fuel pressure, recheck the harness to be absolutely positive nothing is crossed, etc.
Can anybody recommend anything else I should check? Have any ideas?
In reply to Jensenman:
Rotaries run rich in general. I'll assume you're using the proper impedence stock 550cc injectors, they're clean and have been flow tested.
You're letting it get good and hot and not shutting it off before it reaches regular operating temp, right?
Your AFM isn't sticking open is it? It should move back and forth with no real effort at all.
Is your TPS is adjusted properly? (I'll also assume you're using an S4 TPS since you're using an S4 ECU)
Have you checked your compression? Rotaries will run with bad compression, they just won't run well.
Also, all of the crappy vac lines under the hood get old and brittle. Vacuum problems can cause weird things to happen, poor idle being among the common problems.
Also, a buddy of mine from the local Mazda club moved down to the Chuck. I won't speak for him, but there is a club down there, too. If you get stuck, someone local might be able to diagnose it on the cheap.
Are the injectors leaky? Sounds like leaky injectors and the fuel pump overpowering the fpr to me. Possibly bad coolant sensor causing you to run in cold start all the time as well. (BTW-same problems that plagued our challenge miata)
In reply to MrJoshua:
Good call on the cold start- bad thermowax might be to blame, too. The cold start in my car is long gone.
Coolant temp sensor, fuel pressure regulator, 02 sensor, MAF sensor is kinda the order I look at things when I've got a rich situation. Certainly not rotary specific- just efi specific.
Also- Does it have a separate cold start injector? Probably not, being that new, but they can stick open, or be wired wrong.
I'm leaning toward leaky injectors or overpowering fuel pressure as well. Stoopid question: if the fuel pump is just plain overloading the injectors and FPR, is it possible to install a second FPR to bring the pressure down without killing the flow? Reason I ask, rotaries need a lot of fuel flow.
Jman-bout to send you a PM.
In reply to Wonkothesane:
And a different impedance for the s4 injectors themselves (at least on the Turbo cars). Stupid VIN split.
My understanding:
Early S4 = low impedance, square connector, center tab
Late S4 = high impedance, square connector, offset tab
s5 (all) = high impedance, oval connector
I'm running the S5 injectors with the S4 ECU, both from NA cars. The ECU was from (IIRC) an '87. I would have to snake under the dash to look, but IIRC it's an N352 unit.
Tonight's results: all the sensors tested within spec, including the MAF. The fuel pressure is ~39 PSI, it varies as normal with vacuum. I pulled the injectors, wired them to the 'logs' and pressure tested, after 10 minutes at ~40 PSI no leaks. I pinched off the return line and spiked the pressure to ~80 PSI, still no leaks.
Late S4 and all S5 injectors are high impedance, right? My research shows 1986 used one style of injector (probably the low impedance), '87 and '88 used a different type (probably high impedance) with a connector similar to the 1986 pieces, and '89 -up used high impedance as well.
I'm starting to run out of idears. 
A couple of the RX7 guys say the 87.5 to 88 injectors, even though high impedance, are a different impedance than the 89-up stuff. So here's my dumb question: how do I test injector impedance?
In reply to Jensenman:
If they have an offset tab, they are most likely high impedance. If the tab is in the center, they are most likely low. They are the exact same part number, and if somebody put in aftermarket injectors the only real way to test them is with a multimeter, like Wonko said.
Okay, impedance is merely another term for resistance. The spec for the 1988 injectors is 12-16 ohms, the 1989-up is the same. These fall right in the range, around 13-14 ohms for all. According to that rotaryresurrection page the high impedance injectors can be used with a ECU originally set up for low impedance injectors with no mods since it actually works with a ~13 ohm load, but if using LI injectors with any of the ECUs you have to use the resistor pack or otherwise fix it so it 'sees' that same ~13 ohms. So now I'm back where I started. This is a real head scratcher.
One more thing: on the original motor, I disconnected the 6PI actuators and left the tubes in place but turned them so the port was open all the time. On this motor, I removed the 6PI tubes completely. Again that's well documented, when this is done it will idle somewhat rougher and lose some bottom end but make up for it over ~3500 or so.
Hey J, how about try running it with the secondary injectors unplugged. Then try with the primaries unplugged. That might tell you if it is getting fuel from the secondaries below the threshold rpm. As much fuel as you are getting I swear I thing the secondaries are flowing when they aren't supposed to.
T, that's on the list of tests yet to come. It's all ripped apart at the moment, I'm going to put it all back together very carefully, looking for vacuum leaks etc and once reassembled use my 'noid' light to be sure the secondaries aren't jumping into the fight too early. I checked that when I first put this turd together and it was working correctly then, that doesn't mean it's working correctly now of course.
The only way to unplug the primaries is to remove the intake. 
You got a pair of wire cutters don't you. 
Call me tomorrow if you're working on it. I'll try to get out of the house for a couple of hours.
Still battling this sonofabitch. I verified the AFM is working by unplugging it while the engine was running, it nearly died and straightened out when I plugged it back in. I have two sets of plugs and I do believe they are both fouled beyond the regeneration capability of glass beading and carb cleaner. No one has plugs, I'll get some on Monday and try, try again. Dammit.
What are you running on the ignition?Is it OE stuff or aftermarket? Is it a combination of OE stuff like the injection? Is the base timing and dwell set properly for the new injection system?
Basics, patience and zen-like thinking shall get you through this, my son...chill a bit and the answers will come.
I know Brett_Murphy already asked you this, but do you know what TPS you are using? My turbo FC is running an FD3S UIM and TPS, but it is wired incorrectly to talk to the S5 ECU. It has a 2000rpm-ish idle and the engine will stall if I don't keep the revs above 2000rpm when clutching out or between shifts- not easy on a OS Giken semi-racing clutch. I already know how to wire it correctly, I just need to get around to it.
Maybe you have something similar going on. I found this wiring list on RX7Club. Hope it helps:
Series 4 TPS
-Orange - (+5V)
-Green/Red - Signal (Narrow range)
-Black/Red - Ground
Series 5 TPS
- (2) Brown/Black - Ground
-Green/Red - Signal (Narrow range)
- (2) Brown/White - (5V+)
-Black/Green - Signal (Full range)
The ground and VREF wires are doubled in the harness in this particular build, because the car has two TPS units.
All the ignition stuff is stock S4/S5 RX7 bits, they use the same coils and igniters. Base timing SHOULD be correct, it's hard to know for sure right now because while checking that Saturday morning my old timing light took a dump. I'm going to borrow a good Snap On piece from work on Monday.
I'm using an S4 TPS, I verified yesterday that it shows~1k ohms at idle. Or what passes for idle. After yanking everything apart and putting it back together, it's developed something new: it won't idle. It misfires badly and pops and bangs from the exhaust, then will clear up and run great for a few seconds, then back to popping and banging again. That's consistent with fouled plugs even though they have been cleaned thoroughly and that's how I could always tell when Stinky or the Abomination needed plugs. I have 2 sets, both have been cleaned a few times but still the same problem. No one around here has plugs so I ordered some that should be here tomorrow (Monday). I was able to get the engine warmed up enough so that the thermowax allowed the throttle plates to close to the idle position, that's where I verified the TPS reading. It was at ~850K ohms before, not far off.
One other thing: the car I got the engine from sat for a good while, the guy kept ATF in the motor (keeps the rotor side seals soft). When I pulled the trailing plugs yesterday, they had what looks like oil, rather than fuel, on them with no odor, which tells me oil. I thought I had cleaned the chambers completely, maybe not. The trick to that is to pull the plugs, disconnect the coils, then spray carb cleaner in the leading plug hole as the engine is spinning over. Then let it sit for a day or so and spin it some more, finally put the plugs back in and light it off.
This is going to keep me busy for a while, obviously.
Brett_Murphy wrote:
Rotaries run rich in general.
No, they don't. Rotaries are quite happy at air/fuel ratios that would have a reciprocating engine leak its pistons out the exhaust pipe.
They just don't burn it all.
Jensenman, are you sure you aren't dealing with an ignition problem?
For gits and shiggles I would put new plugs in all around and make sure something is not wonky in the ignition. Check your grounds on the coil, module and from engine to chassis.
New plugs go in tomorrow night. Knurled, as far as I can tell I'm not dealing with ignition. Reason I say that, the tach continues to work and if there's something flinky with the ignition generally the tach will drop to zero. When trying to start the engine, it will start but runs as if the idle is set way too low. Sometimes I wonder if there isn't something really weird going on with the ECM. The only thing that makes me think that's not the case is the other motor ran great with these electronics, it just smoked.
RX7's of that era had real trouble with broken solder joints in pretty much any system with a circuit board. Easily fixed at home. Might be worth cracking the ECU case to take a look.
