Ive searched and cant find an answer to my problem. I got an 87 rx7 that ive put a jdm s5 turbo engine in. Its street ported has a stock turbo with a bigger compressor wheel 750 secondary injectors 550 primary injectors s4 rotors and rtek 1.7 chip in the ecu. Ive checked timing its seems right the first mark on the pully lines up with the peg on the cover at idle and ive adjusted my tps. Also have no emissions or omp. The problem is i can go past quarter throttle. It chugs and backfires if you snap the throttle and if your driving it falls on its face unless you stay under light throttle. Ive got to granny drive it everywhere and have a hard time with hills. Any input will be greatly appreciated.

 

So it only does this under load? Can you just rev it while parked?

 

No wont let me go over quarter throttle in any condition. Sitting still or driving

 

Recheck your tps

 

Make sure you double butterfly's aren't stuck either

 

Rechecked. Smooth voltage on both and the butterflies are clean and move freely. This has got me stumped

 

and make sure your JDM engine isn't blown.


additionally, now that you'd upgraded the compressor you may need a standalone. a 1.7 chip aint gonna do squat in that respect.

 

I just rebuilt the engine. Why wouldnt it? I cant even get into boost because of the throttle issue.

 

a bigger turbo pushes more air, more air requires more fuel. the airflow meter can't properly correct for the differences in the compressed air volumes.

 

I see. But shouldnt the chip see that and correct accordingly? I figured out its going into limp mode. But i don't know why

 

i see, so you are using all the S5 electrical components. are you also running the 370 ECU or the JDM one that came with it? the chip doesn't compensate for a larger turbo either, just allows you to run more boost more safely on the stock turbo.

 

The JDM one. Which i think may be having an issue with the rtek chip which is causinv it to go into limp mode. But i cant flash any codes because i dont have a cel on the s4 idiot lights. I dont know which wire color to ground at that ecu to make it flash codes on a wired in bulb

 

i dont know why they even let you send in the JDM ECU here in the states(tells me they dont care, just to sell a part), we have known issues with wiring the JDM ECUs into USDM cars since we have no schematics for their wiring. usually i say pitch everything and go with a standalone or get a USDM harness and ECU so you have a wiring diagram to follow if ever needed.

as for if it's an electrical wiring issue, like i have seen on the earlier S4 with the power steering tapping the knock box, i don't know anything about an S5 in an S4 car or how you managed to integrate all the harnesses needed to even get this far.

the s4 doesn't even have a check engine light, so you'd have to build the LED tester or borrow a factory diagnostic tool.

 

I think the S5 JDM ECU has a pin for fuel cut. Check pin 1M of the ECU as it should read close to 0 volts and not 12 volts w/key to on. If it reads 12 volts w/key to on then remove the wire and see if it changes things for the better.

 

Well it came with the harness just had to wire in the body side and coils and the schematics we used were US.

Ill try that pin and see what it does.

 

Did you hook the fuel lines up correctly? JDM engines are backwords from USDM

but in all reality if they were backwords, it shouldn't run at all i believe

 

Not to belabor the point, but pin 1M on the JDM is for fuel cut and there is no wire from an S5 USDM car for fuel cut thus if you have a wire running to pin 1M and it has a voltage value higher than a volt or so then the ECU will interpret that as a sign to cut fuel.

 

i feel like pulling a styx moment after reading satch's post.

 

Your house reno must have gone quite well.

 

constant and ongoing project, working in the attic now so it's probably making me a little nutty.