I just finished putting a new engine in my 90 Turbo II but I am having problems with it. The engine is a JDM S4 but my car is an S5. It is running everything S4 except the injectors, TB, and wiring harness. The engine fired right up very well and runs fine. But when you step on the gas more then a little bit, the engine tries to stall out, but never really does. It just drops rpm and then sits at a low rpm and jumps up and down every couple seconds. Then, when you let off the gas it goes back to running like normal. Check engine light is on but I haven't gotten the code out of it yet.

 

I am also not running an air pump. I don't have a block off plate, just the ACV with the vacuum fittings capped off.

 

if it's an S5 ECU, I think it's in limp mode. You should probably get an S4 ECU and try to make it work. I'd recommend going to a full EMS though...you're probably going to have a hard time making the S4 engine function properly in the S5...

 

Why would it have gone into limp mode? Does an S4 ECU plug in and work in/with an S5 car and harness?

 

Would go into limp mode because something is not right and its basically a failsafe feature to prevent the engine from blowing up.

The problems could be many different things, I would do an error code test to see what is wrong if not you could be guessing and never know.

 

I have been trying to get the codes out of it but I have not found anywhere that will tell me how to get the codes out without having a scanner. Anyone know how to get them out?

 

You actually have to make a test light that connects to a spot on the wiring harness that will light up and according to the amount of times it lights and/or pauses etc it will be a certain code.

I dont know much about this but I know this is how you scan for codes on the rx7, because there is no obd scanner hoookup on our rx7s.

These links tell you how to do all the work to get the codes

86-88 - http://fc3spro.com/TECH/HOWTO/ERRORC...KI/zerror.html

89-91 - http://fc3spro.com/TECH/HOWTO/ERRORC...KI/kerror.html

 

So...I got the codes pulled out finally. You don't need to make a test light for mine. Just have to ground the single green connector that is found taped up to the diagnosis connector. Anyways, heres my list:

# 20 - Metering Oil Pump (MOP) position sensor - Basic Fuel Inj and fixed timing
# 25 - Solenoid, Pressure Regulator Control
# 26 - MOP (Step Motor)
# 30 - Solenoid, Split Air Valve
# 31 - Solenoid, Relief Valve
# 32 - Solenoid, Switch Valve
# 33 - Solenoid, Port Air Valve
# 42 - Solenoid, Turbo Precontrol

I would assume that my problem would be with # 20 because it is under the Code - Input Device - Fail-safe operation mode heading. I am running a mechanical omp or mop. Anyone know of anyway to trick the computer into thinking it is there? Maybe if I plug in the electrical omp and tied it off to the side it might do the trick? Any input would be helpful.

And for those of you who read this thread and say WTF is he doing putting that engine in an S5 car, its cause I am planning on rebuilding the original engine so this one is just temporary so I can drive the car (I bought the car a year ago and its just been sitting ever since).

 

Fixed - I just plugged in the original omp and threw it off to the side of the engine bay. Car runs great now. Too bad it just snowed and I have summer tires.

 

Was pretty sure that was what your problem was (the omp), thats one thing that makes the s4 1986-1988 model better because the mechanical omp never caused this problem from not being tied into the ecu.

 

Ive gone series 5 eng in a series 4 car,with series 4 harness,so I know where your coming from only in reverse,glad that fixed it you still have to have some codes though? need to check service manual,to see if your solenoids are properly connected assuming you are running emissions. at least hook up #25 properly as it will save ya gas and help idle all aroung hot and cold.

 

. so I guess ya changed the front cover and waterpump over also?

 

I'm not running any emissions so thats why all the codes. FPR is just hooked up to manifold vacuum. And no I didn't switch front covers. Just plugged in the electrical omp so the computer would get out of fail safe mode.