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Hello, I have an '84 12a motor in my RX7. I was driving to work this morning and doing about 60mph in 5th, down shifted to 4th, and then my RPMs dropped to zero and I lost all power. I managed to safely get if off the road, however, it's still sitting there and I want to use it on a more regular basis. I tried to restart it, but to no avail! Where should I start? Is this a common issue? I know the carb needs tuned, but I'm just starting to get into the mechanical side of the house. Thanks in advanced!
Need more info. Check for good fuel pressure to the carb and then check for spark at the plugs. Most likely something simple. Check all your fuses/fusible links too.
I was going to check spark once I get out of work. I know that driving it through town ~30-40mph sometimes when I hit the gas it will "bog down" and take 8-10 seconds to accelerate and pick up the speed. That's all I have right now. Drove it 5-6 times, this is the first time it died. It's new to me. :/ thought about doing a swap for a 13b turbo or a 20b turbo. Easier and more reliable in the long run?
I hope I just lost spark and am hoping new plugs fix that. Would anyone know if a 93' or newer engine would be a relatively easy swap? I'm look at engine/transmission combos for like, $2k.
I wouldn't do a '93 engine again. I've done one in a friend's car; it's a lot of work (not so much mechanical, but really more in wiring an ECU, plus tuning it). But I have to say my modded Nikki setup in my car is a lot better. More power, easier to work on, honestly easier to tune (imagine a carb being easier to tune than EFI), and just plain cooler. You can even see the top of my engine! No ugly EFI intake manifolds in the way.
Something else that I find interesting is his setup had a decently sized intercooler while mine does not have one yet. We both tried the same S5 turbo. Both had full 3" exhaust systems. His was streetported. Mine is only 74 ported which is smaller than a streetport. Mine makes more power on less boost. Go figure.
So in the end I can not recommend a '93 engine. Stick with the 12A for now. Look up and read about mods on this forum. Ask questions. Get answers. And good luck getting your car up and running again. It's probably something simple like a fuel pump or some minor electrical thing.
My only concern with buying a Nikki carb and everything, is that it's the original engine, and if I blow out a seal or something, I'm in a worse predicament I think. I would have thought a newer engine would be more readily available for parts and work. I live in Idaho and no one here knows about rotary engines... So I'd be doing a lot of work myself. I can tear apart my jet ski and put it together, and have some mechanical skill, but I'd have thought a 13b or 20b engine would give me more power and as cheap as I can get one, better in the long run. As far as the electrical part, can't most systems be bypassed?
If you go with a more modern rotary, they are EFI, which brings with it the need for a computer
and all the complexities that brings. Thats what everyone is trying to say here. You probably
have some minor issue that caused your failure I bet. These things are butt simple for the most
part. Make sure you have the three magics working:
1. Compression
2. Fuel
3. Spark
I suspect spark or fuel in this case. You will need to get a little jiggy with it to see whats up.
Newer is not better in this case, trust us on that.
You guys rock I definitely am all for keeping it the easy and inexpensive route. I downloaded the manuals listed on here and printed them out. A lot of paper, but if it keeps me on the road it's worth it! I'll be back tonight or tomorrow with more questions I'm sure! Thanks guys!
So, I pulled the spark plugs, I only have fire from 2... One in each combustion chamber, so I'm getting 2 mis-fires. Is that a new ignition coil? Where would be the cheapest place to pick one up? Also, on the oil fill tube, there is a nipple leading off to the front of my engine, with a hose attached, but it doesn't go anywhere.... Do I need it? Where does it go? And can I just cap it off? (See picture)
Looks like a Frankenstein motor. That nipple should face to the rear of the engine.
So which 2 fire the top plugs or the bottom? Leading is the bottom and trailing are the top
plugs. May just be a bad ignitor. You can switch the ignitors to see. No trailing fire will not keep
it from running but no leading and weak trailing will make it run very poorly for sure.
Yea... I know. They added a bigger alternator. But, that doesn't bother me. Where should the hose on the oil filler connect? Anywhere? It's the trailing plugs. Both.
The bottom plugs, leading ones, are firing. The trailing ones are not. What would you be looking at replacing if it was yours? Also, I know that there are different plugs for leading and trailing, however, everywhere I look, they just use the same plugs for the lead and trail... Will that work or do I need specific ones? I checked the ohms on the wires, the lead had resistance of 460-480 and trail only had resistance of 358. Could it be the wires?
The bottom plugs, leading ones, are firing. The trailing ones are not. What would you be looking at replacing if it was yours? Also, I know that there are different plugs for leading and trailing, however, everywhere I look, they just use the same plugs for the lead and trail... Will that work or do I need specific ones? I checked the ohms on the wires, the lead had resistance of 460-480 and trail only had resistance of 358. Could it be the wires?
Honestly, I doubt it. The aftermarket carb and painted engine tell me your issues are probably in the setup itself.
That carb is probably not tuned correctly, which explains your odd bogs. Sound to me like it flooded on you when you were driving down the road, which is normal for a junk carb.
BTW, 1979-85 rx7 used the same heat range ON ALL SPARK PLUGS.
there is no leading/trailing heat range split with this ignition system.
You should pull both of the blade connectors off of your igntion coils and crank the engine with the bottom spark plugs out. My guess is that shes full of fuel. Lots of gunk will probably come out of the plug holes.
After you "de-flood" the engine, chances are that it will turn over, but i'd also be willing to bed that it will flood again shortly thereafter.
I already pulls dthe plugs and deflooded the engine. The carb is Weber. Is there a carb out there that works well, besides the Nikki that costs $400!?!? I'm on a budget here, but am willing to buy quality, just $400 is a lot and will take a month or so to get to. I was reading another thread about someone's tac dying, and it was due to a bad trail coil.... Did I mention that my tac died on me when this happened yesterday? Here are more engine pictures.
You are probably fighting a dead trailing coil and a carb thats tuned too rich. That weber can be
made to work ok but it will require some tuning which may involve buying different jets but you
may get lucky just adjusting the mixture. Read up on DCOE weber carbs and search on here for
the same. I'm sure answers will show up.
I agree with t.g. Farrell , it definitely sounds like you have a bad trailing coil.one of the wires goes to your tach.but it also looks like somebody messed with the wiring. I would look at getting a nikki carb, there is a lot of info on here on tuning and modding them.and they were designed for the rotary engine. I have a Holley on my half bridgeport engine, and I can't stand it. The nikki can be made to outperform any other carb for this engine. But this is just my opinion.
I'm looking at new coils, but I can't fine them anywhere. Rock auto has some same as advanced auto, O'Reillys and Amazon, but they are all like, ohh, 9-10 inches long, where as the stock ones are maybe 4?
As for ignition, to get you off the road, you can move the trailing wires down onto the leading plugs. Just note that the timing will still be at the trailing 15 to 20 degrees ATDC so you will overheat your exhaust pretty quickly like this. If you have a 10mm wrench or socket available, you could loosen the dizzy hold down nut/bolt and rotated the dizzy housing a little. It's best to use a timing light for this so you don't turn it too far. You want the leading mark to move back to the indicator pin on the front cover at idle (disconnect vac advance if you still use it, and block the hose leading back to the intake to prevent a vacuum leak). A little movement goes a long way as the dizzy spins half speed compared to the eccentric shaft so turn it slowly and watch the mark move.
That's a quick and dirty way to get your engine back up and running if you ever have a dead leading ignitor and no replacements handy. The engine requires the plugs in the L position to spark. The trailing position is mainly for emissions and it won't want to run right on trailing plugs only, like wankel=awesome said.
I'm looking at new coils, but I can't fine them anywhere. Rock auto has some same as advanced auto, O'Reillys and Amazon, but they are all like, ohh, 9-10 inches long, where as the stock ones are maybe 4?
Ask on the forum's for sale section for Diamond brand OEM RX-7 coils that fit 1981 to '85. Make a WTB thread.
01-05-16, 10:44 AM
I definitely am all for keeping it the easy and inexpensive route. I downloaded the manuals listed on here and printed them out. A lot of paper, but if it keeps me on the road it's worth it! I'll be back tonight or tomorrow with more questions I'm sure! Thanks guys!
