I've swapped a TurboII engine (S5) into my 1990 RX7 Convertible. Most of the work done by myself. In all, I've installed a complete JDM 13BT engine, transmission and drivetrain. I also swapped in the N370 AFM, a N374 ECU, N370 boost sensor, US-Spec engine (emissions) wiring harness, Accelorator cable, and a front-mounted intercooler....but for some reason it doesn't want to run.
Everything appears to be physically good, but when and if it turns over, only the rear rotor ignites. We checked compression, the spark plugs/wires, fuel injectors, they're all good, pretty sure wiring is good.... So, if there are any Rotary/Rx7/Wankel/13B Gurus who might know what's wrong...., any help in completing the swap would be very much appreciated!!

 

i know you said you checks plugs and wires......did you check the coils? Did you ground everything properly?

nice FC BTW.......post more pics......My next project will prolly be a turbo vert........


more details pertaining to the problem will yield more replies.

 

are you sure that your front rotor is getting fuel? Does your front spark plug have fuel on it? You have a TII pump in it right, just incase you do get the front running you'll have enough fuel? I wound first check and make sure the injectors are giving you fuel. Switch front injector clip with the rear and see if the front rotor runs instead of the rear. Simplest thing you can do at the moment I think.

 

Re-check every single ground, make sure they are clean and there is absolutely no sign of corrosion(all nice and shiny connections- a wire brush or scotchbrite helps a lot) and re-check the fuel pump, the filter, and the pressure at the rail. If you have another set of coils try those and re-check all of the coil wiring. If there are any questionable connections- factory or repairs- check for continuity across the connection.

Just out of curiosity have you checked for compression? Did you replace the sparkplugs when you put the engine in? If so, are you certian they are the right ones? As mentioned above does the sparkplug have fuel on it? If it does, and the fuel has soaked the ceramic you are better off replacing all the plugs again, after you have checked that you have proper fuel pressure and the injector is not stuck open.

The issue with imported engines is they have frequently sat for some time and you can have corrosion issues in many unsuspected places- plug wire ends, ground straps are common and easily checked, injectors that have sat with fuel in them can be gummed up or corroded or simply stuck open from trash, and of course all wiring connections are suspect until cleaned with contact cleaner etc.

 

might have a bad leading coil if your getting no spark on the front rotor.

 

On a JDM engine the fuel from the filter goes to the rear feed pipe on the engine, not the front pipe as on a USA version.

Both LEAD plugs fire at the same time. You can't have one lead spark and the other not speak unless the sparkplug wire is arcing to gnd.

How in the world would one know only the rear rotor is working?

 

Nice car - where in Texas are you? I just did the turbo vert swap and I've been ironing bugs out of mine too. Listen to Hailers (and thank you Hailers btw).

For sure - with that JDM engine, swap the fuel lines on where they go to the rails. Seriously.

 

How come the fuel lines have to be swapped on a JDM compared to a US domestic ?
Does that mean the line for the charcoal canister is different also ?

 

assuming so.

 

hmm thats weird. because when i did my jspec on my TII a while back i went off the us fuel lines and it worked fine

 

The fuel pressure regulator is on the opposite rail on a JDM. Take a peek under the manifold and see.

 

Because the hard fuel lines are routed different on the JDM vs USA Engine

The ide is, that the line that returns fuel to the fuel tank should be the one that comes from the FPR.

So. Find the FPR and follow it to where the fuel lines connect to the engine and make sure you don't connect it to the line off the fuel filter.

 

try a us spec ecu... or even your stock ecu... if it's a 5 spd stock... i had a problem with my n374, the car wouldn't fire, threw my stock ecu in (n/a s5 coupe) and it fired up... ran it a couple days until i could find a stock us spec tII ecu, which i'm currently running....

just a thought...

 

Madrx7racer - Yes Checked coils, they're all good...Thx!! more pics to come soon

gerbraldy-Fuel pump... no, i know a better fuel pump would mean more power, but is it necessary to get the car to run?... on that note, who makes the best aftermarket (prefferably plug & play) fuel pump

Hailers - the way we found out only the rear chamber was working was by pulling spark plug wires. With all 4 attatched it turned over. With just the rear ones attatched, it turned over [sounded exactly the same (tone, volume etc.) as with all 4 wires in it] Then we tried it with just the front 2 wires and it wouldn't turn over. coils are good, wires are good, pretty sure sparkplugs are good...i could swap front and rear plugs to check that...

D Walker - I'm gonna double check my grounds with an ohmmeter...but they seem good to me...we did a compression test it's all good

chaosseven - exactly which fuel lines do I swap, where? (pics, a diagram or walktrough - anything along those lines would be helpful)....I'm near Austin

Thank ya'll so much for your suggestions! Keep em coming!!!

 

Swap the inlet and outlet fuel lines (the rubber lines coming from the fuel filter and the one returning to the tank).

Should be the same two fuel lines you hooked up when you installed the engine.

The idea is that the fuel pressure regulator is the last thing the fuel flows through before returning to the tank. The rail with the fuel pressure regularor is the one with the vacuum line attached to it - it goes to the line returning to the tank. The other one is fed with the line from the fuel filter.

On MY jspec engine, even after swapping the lines so that they were correct I couldn't get it to start either. I gave it a squirt if PB Blaster in both rotor housings to lubricate the seals and it started right up. I know everyone says ATF but there are lots of horror stories about it out there.

 

That's a MUCH better explanation than I tried to give.

 

I swapped the fuel lines.....didn't work.....
So, since i still had the spark plugs from the original motor, I swapped those in and found a ground wire that wasn't connected.
She starts right up now!!! (Both rotors roaring).
It doesn't want to idle, but i think that's mostly due to a lack of exhaust (no back pressure, exhaust comes by friday).
I drove it around the block with little problem (tho the neighbors prob didn't like it, I got a good thrill)
Thanx for all ya'lls help!!
If I need more, I know just where to come!!

BTW - heres a few more (teaser) pics -
The first one is a sensor or ground of some sort that I found while doing clean-up...I found another one already installed just like it under my hood right behind the driver's side strut tower (does the car have 2 of them or do I have an extra?
The Second pic is my dash...like the rotor?
Third is a slamming angle pic (ok, so the paint needs touched up a bit...so what)!!

So what do ya'll think...not too shabby for my first engine swap and 2 months of work, eh?

 

So Everything U Used Is U.s Spec Except The Ecu...jdm Ecu??

 

That looks like the ground under the UIM for the injectors... I was gonna tell you to check that but looks like you already found it...

 

Engine, Transmission and ECU are JDM.
Everything else - Wire Harness, AFM, Driveshaft, Boost sensor, Alternator, A/C compressor.....is U.S. Spec

 

exhaust would have nothing to do with it. Back pressure only helps in producing less horse power.

It's not runing right because it needs more fine tuning.

 

That first picture is a condenser for the oil pressure sensor. The oil pressure sensor wire has a wire that is spliced to it and has a connector that mates with that condenser. Ther is another condenser just like it under the trai coil assy and that one is connected to the supply voltage wire to the coils.

That is NOT the ground for the ECU that is located under the intake, on top of the rear ROTOR HOUSING. That ground has a ring ternimal and has two wires in the ternimal. Both black.

 

good now i know that i dont need that thing anymore seeing i dont use the stock oil pressure gauge.

 

Very nice car

 

HAILERS - Awesome! thx! That explains why my oil pressure gauge isn't working.....lol