okay, my car is a...freak, in one word...
(read here: https://www.rx7club.com/showthread.p...hreadid=303392)

so i was trying to adjust a few things today (TPS, etc.) and it hit me that not only is it screwed up that i have s4 parts and an s4 engine in my s5 chassis, but that the ECU, based on the wiring harness, is still the s5 ECU :eek
i was thinking, how is that even working? anyways, i noticed ever since i got it that the check engine light was disconnected/burnt out. so i checked, and yes it was disconnected. so i plugged it back in, then started up the car. no surprise the engine light came on...now i was like "okay, that makes sense". now what doesn't is that as soon as i start driving it becomes intermitent. it goes off and on, randomly, but it almost seems speed or RPM dependent. i don't know, it's just plain weird.
do you guys think this is just the fact that i have an s4 engine working with the s5 ECU (like...it's going WTF), or is something actually wrong. and why the hell does is go on and off...

like i said, i am basing this on the fact that the whole wiring harness is s5...plus i got things like TWO TPSs.

oh yeah, the BAC is not connected

BTW, in spite of this, the car runs great....

 

does it only come on during somewhat hard accelleration?

 

no, the light is only on constantly if i am at a IDLE.

otherwise, like when i am driving, it is intermittent and random, or just OFF...seems to be on more at slower speeds

 

The engine makes no difference, only the input and output devices connected to the ECU. If one of those devices is faulty or missing, then you'll get a "Check Engine" light and an error code. Have you read the error code(s) yet?

 

i will be reading the codes sometime this week...i'm too cheap to go buy one of those code checkers, and too lazy to check it with a 'ghetto' setup (if that even works)...but my friend should be giving me one sometime this week

i know the engine makes no difference, but right now there are probably input and outputs that just aren't connected...i mean, i the S4 powerplant only has 1 TPS, but like i said, for some reason i have 2 just like an s5. also, the BAC valve is not connected...i guess the S5 ECU doesn't need this? the car runs great like i said, but if i am at idle and apply brakes or something electrical quickly, the idle drops (misfires i think) for an instant. shouldn't the BAC be handling this?

oh yeah, i took a drive again, and now the check engine light only comes on if the RPMs drop quickly (such as in neutral, if you give it gas and let go)...even then it only comes on around 1500 RPM or so...also (if it means anything), when you let go of the gas like that in neutral, it will drop a little below idle (to like 500 RPM), and then go back to 750...

 

S5's don't use a code checker like S4's do. You ground the Initial Set Coupler and watch the CEL flash the codes.
So if you have an S5 dual-TPS, an S5 harness and an S5 ECU, just connect it all up.
Yes it does.
Yes it should.
That's when the ECU uses the BAC valve, so that's probably why the CEL is flashing. It's recognising that the BAC valve is ot working when it should.

 

The idle will drop a little even with everything working under a sudden electrical surge since the stock fc altenater blows

 

That's got nothing to do with the capacity of the alternator; it's simply the engine responding to the higher electrical load.

 

hmm...so you can just use the CEL to give you the codes? i thought the S5 FSM says to hook up a self-diagnosis checker?

 

if you read the book they give you 2 ways to do it. you can hook up the tester or ground the initial set coupler and watch the check engine light flash

 

That's the big-dollar diagnostic tool the Mazda techs use. Good luck getting one of those...

 

okay, cool. i will check out the FSM more throughly and see if i can get that done tommorow...BTW, the CEL now might as well be completely random on my car...

 

okay, i got error codes! assuming i read these right:

12: throttle sensor (full range)

13: pressure sensor (intake manifold pressure)

17: feedback system

18: throttle sensor (narrow range)

34: solenoid valve (bypass air control)

40: auxilary port valve


so...WTF?

 

you need to hook up or replace the following

tps, pressure sensor (its on the passenger side shock tower), idle control valve (bac) and the solenoid for the 6 ports

 

No OMP code? Does your S4 engine still have it's mechanical OMP on it, or does it have the S5 one hooked up?

 

my solenoids have to be hooked up? if you mean the 5 and 6 port solenoids, i just checked one the other day (by putting grease on the rod and then driving...), and it was working fine.

i went to check my MOP yesterday and from what i can tell it is a mechanical S4 pump. why isn't the ECU throwing a code for it?

 

i can understand the codes it is throwing for the sensors, but someone want to explain 17, 34, and 40?

oh yeah, i was actually talking to Aaron Cake at the ottawa rx-7 meet, and he was amazed at how the S5 ECU wasn't throwing a code for the mechanical OMP...