Law

iTrader: (2)

Are the series 6 ('92-'95) ECU's all the same? I have a USDM '95 RX7. Wondering if I can put in any US market factory FD ECU or if it needs to specifically be from a '95. (I think I may have a faulty ECU so I want to hook up another factory ECU to trouble shoot). Thanks in advance.

rx7rcer09

i believe the 95 is slightly different from the 93 and 94 but im not 100% sure. what exactly is the car doing to make you believe that your ECU is dead?

Law

iTrader: (2)

Car is acting like it's in limp mode (fuel cut when throttle seems to be open past narrow range). I am getting a check engine code 45 (charge control solenoid valve). That is the only code I am getting. I tested the solenoid and it's fine (resistance and vacuum/pressure). I checked electrical involving the solenoid and it's fine (continuity from solenoid clip to ECU harness/ECU pin). The final diagnosis from the FSM for a check engine code 45 is to replace the ECU. I'd like to borrow an ECU to see if it changes the way the car is acting but I don't know if it needs to be from a specific year 3rd gen.

rx7rcer09

first thing i would personally do is swap the solenoid, even though it seems to be okay i would start with that, once you can fully rule that out then look for a test ecu. or on a cheaper route checking all your grounding points, i know on these older cars poor grounding could cause some problems.

Law

iTrader: (2)

I checked my solenoid and even though it checked out fine, I replaced it anyway. I've checked all ground points, cleaned and sanded each ground wire in the engine bay, and even sanded down all the contact points (even the area that had the factory paint... I sanded off the paint).

rx7rcer09

well, if the swap fails i would start looking into an ecu. hopefully someone with more knowledge will chime in and answer if there is a difference between the years.

DaleClark

iTrader: (55)

There are some minor differences and there are various versions of the US ECU's, but in general any US ECU will do the trick.

The only weird part is the EGR switch. '93 Cali ECU's checked the EGR switch to make sure the EGR did its thing. All '94s checked that EGR switch. '95 they got rid of EGR so it doesn't check.

If you put an EGR ECU into a car without the EGR switch you'll get a check engine light but the car will drive and operate fine.

Now might be a good time to go ahead and get that PowerFC

Dale

TIICONV89

iTrader: (2)

sorry to hack your post but i got a Q;

Any one knows if a JDM ECU will work on a USDM car?
or what needs to be done to make it work?
some one offered me a reprogramed JDM ECU at a very low price that im thinking about use on my USDM FD if it works.

DaleClark

iTrader: (55)

You have to install a JDM ECU like a PowerFC - cut the 4 wires, etc. But, yes, it will work.

Dale

CloudPump

iTrader: (2)

I believe there are some minor differences between Automatic and Manual ECU's as well.

-Geoff

Law

iTrader: (2)

Thanks for the replies. I have a '95 model. Bone stock except for simplified sequential via removal of the emissions solenoids. My car was running fine and recently kicked into limp mode. I've read that unplugged emissions solenoids should not put the car in limp but I plan on putting resistors on those plugs anyway to see if it's making the ECU act funky. Can anyone (*cough-cough* DALE, RX7 guru) shed any light on the ever elusive 45 (charge control solenoid) check engine code? Is it possible for something else to throw false solenoid check engine codes?

Another thing I plan on checking is the leading and trailing coils.

DaleClark

iTrader: (55)

You have to remember the factory ECU is REALLY dumb, it's simply checking resistance on the wires coming in to it. If the resistance of a circuit is out of spec or open circuit, it will throw a code. Few exceptions, like the oil metering pump, but most things (like the charge control solenoid) is just that simple.

If you're getting a code for that solenoid it's either unplugged or the wiring to it is damaged. Or the solenoid is REALLY bad.

Dale

Law

iTrader: (2)

Thanks for the reply, Dale. I may just need to pick up that pfc. But as far as the the bad wiring and solenoid go, I already checked for continuity and checked the solenoid... it all checked out fine. Will the PFC be a lot more forgiving than the stock ECU when it comes to picking up a slightly out of spec signal? Or will the PFC encounter the same issue as the stock ECU?

DaleClark

iTrader: (55)

The PFC will probably be just the same as a weak signal, but it doesn't throw codes or go into limp mode. The PFC could care less what you have or don't have plugged in.

Dale

Law

iTrader: (2)

I guess my next step will be to purchase the PFC (which I was planning to do prior to this episode). From there, the car should no longer be in limp mode. And then I'll check to see if I have the proper 10-8-10 boost pattern. If I don't have the proper pattern, I'll start trouble shooting my sequential turbo system from there. But at least it'll be driving around. It just won't be boosting properly. Am I correct in this assumption?