I’m helping a friend install a new (used) TII motor in his ’88 TII. We pulled the old motor out and put the new motor in. Now we are realizing that we should have asked more questions before we spent the weekend doing the hard work.



It appears that the new motor (40k miles) is from a 89-91 TII. From what I have read in this forum, it sounds like we are trying to put a S5 motor in a S4 car. I won’t go into all of the details now, but it is still not running at all after we installed new injectors. I’ve been told that it did idle roughly for a few seconds when I wasn’t there.



Questions: Will the S5 motor work with the S4 ECU? What do we need to do to get it working? Are we better off just pulling the S5 motor out, sending it back, and finding the correct motor?



Any advice would be greatly appreciated!!



Thanks,

Scott

Roanoke, VA

I only have a few minutes to answer.



I would check the timing, make sure the cas in on the right mark. make sure you haven't crossed yoru ignition wires too.



It should work, as long as you don't have any vacuum leaks. Make sure you have the grounds all on.



The only youll have to do is runn premix since the s4 computer can't control that. Is you want to run mecahnial OMP youll have to swap out the front cover and OMP to a s4 and some little parts in the throttle linkage.



I will try to answer more later ith detail but ih ave to get going to work or i'll be late



C

Whats up fellow Va'n?



Well, you can do what turborotor suggested, which is run the premix, and double check everything. Did you guys use the s4 manifolds, etc? Or was the s5 motor a long block with all manifolds, turbo, etc? You really would be better off w/ a S5 ECU and harness, BUT as I have recently learned, to save yourself some headache, get a standalone EMS, like a Haltech or similiar. They are a bit pricey, but will be well worth it..especially if you are planning to really modify the car. Dunno what else to suggest, its always a tough call when swapping different series motors.

Thanks for the feedback.



The S5 block had the intake manifold, turbo, crank angle sensor, and some of the control stuff near the manifold (air control valve, switching actuator).



We used the S4 throttle chamber, fuel system, harnesses, and anything else that looked like it controlled something. In general, we wanted the block and turbo assembly from the new motor to work with all of the old controls. Anything that didn't look like the old motor came off the S5 and we put the parts on from the S4. We even put the S4 oil pan on the S5 motor since the sensors were a bit different. We were told that the new motor was an '88 and we saw the 13B stamp on the block. So we jumped into it. Live and learn!



Good news is that all of the parts from the S4 are useable except the block and turbo. So we can mix and match as needed to get it running. Initial goal is to get it running with stock power. Upgrades may come later.



Being new to this, please explain "premix" and "mech. OMP". At least a hint:)



I just did some searching in the forum and came across a note about getting correct impedance injectors for the ECU. I'll have to check the new injectors.



Thanks again. I'm glad to see so many active technical forums for RX7. That says a lot about the car and the owners!



- Scott

One more question just to be sure: How do I confirm that the new motor really is an S5?



- Scott

S4 engines have a mechanical oil metering pump (Mech OMP) while the S5 is electronic. The difference is the location where the pump bolts onto the block...there's not the same!. The pump injects oil into the chambers to lubricate the seals and if no oil is sent when the engine runs, it wont last a day



premix is when you add oil into your gas in order to bypass the oil pump (whichever it is) and is probably what your friend will need to do.





DO NOT RUN YOUR ENGINE WITHOUT AN OIL PUMP OR PREMIX



call your friend asap

I'm learning a lot.



Without knowing why at the time, we did swap the front engine cover and install the old mechanical OMP on the new motor. This includes the throttle linkage and misc. hardware. So I'm guessing that will do the trick without any special mods to premix.



Also, our new injectors are for the '88, so that should be compatible with the CPU.



An aftermarket ECU is out of the question for now, so we will have to make it work with the '88 ECU. I know that the S5 is supposed to be a higher compression motor than the S4. Should we expect it to run normal with the '88 ECU and all of the '88 fuel, air and emissions controls?



We may have more questions if we have an opportunity to look at the motor sometime tomorrow.



Thanks again!

- Scott

Hey guys,



I am the frustrated owner of the 88 t2 Scott was asking about. Thanks for all the input so far. I read the part about distinguishing between the s4 and the s5 block. The replacement (advertised as an 88) appears to have the metering pump in the exact same location, and be identical to the one we removed, and it has a mechanical linkage going up to the top of the motor and connecting with the other stock linkage.

The mechanic who tried to fix it after we couldn't get it to run says he thinks we have the wrong motor based on the advice of some other Mazda tech he was checking with for help. He got it to run roughly for about 5 seconds at a time before switching injectors. After replacing injectors, he said it ran good, he checked the compression, and said it was good. After a while he said it just cut off, and wouldn't re-start.

If in fact the metering pumps are the same on both motors, is it possible that it is the correct motor, and the tech was mistaken? If so, what are your recomendations to get it going. Any possible causes for this behavior? Is there any type of serial# or something to reference to get the actual year model for the motor?

I look forward to any and all recomendations you may have, including any good rotary mechanics in Roanoke VA or the surrounding area who may be able to get it running.

Thanks!



Allan

I'm located in the central VA area, close to Fredericksburg, and the only real rotary shops in Va are in Manassas. Rotary Performance and Peter Farrell SuperCars. However, Rotary Performance is who helped me w/ my setup...and well...I'm not pleased with the results and money I spent w/ them...



Are you still using the stock fan for the radiator? What about the pulleys?

ok i think you guys should just send that engine to me. I dont think that its gonna work so just pm me for the address!