bulldogzxz

Hi guys so I got my manual transmission 2005 rx-8 a couple weeks ago and i took it to my mechanic and he said it needs a new ECU. Im not overly engine savvy and I dont really know what im looking for. Does anyone know what ECU would be good to get?

dannobre

iTrader: (3)

What makes him think that? Does it run? Give us a bit more info.

Stock car needs a stock ecu. And it needs to be fully programmed with either a dealer iDS or a pass through device with the proper software and the correct vehicle calibration. It isn't something a usual mechanic can do. It needs "as build" data from Mazda Tech as well.
It's not something that you can just plug in a used ECU and be good to go

bulldogzxz

So i got it with a check engine light on the guy had it looked at and they thought it was a valve stuck open.... turns out it was the actuator locked up and apparently that ruined my ECU. (Had trouble getting it started after he replaced the actuator and he took it back for a second look and he said the ECU needed replaced due to the actuator)

This mechanic does dyno tuning and stuff so i assume he can do this as well or do i need to take it to a mazda dealer?

dannobre

iTrader: (3)

I doubt that it needs an ECU...and it isn't easy or cheap to replace it...likely was the APV valve that was stuck? Or the SSV? Before I went down that road I would make sure that that is really the issue.

But...I haven't seen the car either so take that with a grain of salt.

Just because he can dyno tune doesn't mean he has the equipment or expertise to replace the ECU. It took the dealer tech I use for that kind of stuff close to 3 hours to get mine to work and he is a good Mazda Tech..it is a complex procedure and often won't work the way Mazda says it needs to be done.

bulldogzxz

the guy who owned it before me got it looked at a national tire and battery and they thought it was a solenoid valve or the intake manifold valve but who knows if they are right.Then my current mechanic said it was the actuator so yeah.... So would you suggest i take it to a mazda dealer to get it looked at to determine if it is the ECU or something else?

bulldogzxz

The car currently has trouble starting I turn the key and hear it trying but it takes about 4 seconds to get it to start if i can get it to start.... the check engine light comes on too... Also is it safe to drive it if it is the ECU?

Loki

iTrader: (1)

It is definitely not the ECU. Visiting Mazda might be a good idea, it could be as simple as having the spark plug wires mixed up, or it could be the SSV valve in the intake. It would REALLY help us help you if we knew what code the check engine light was showing.

bulldogzxz

So i talked to the mechanic again they replaced the APV motor(i think this is the actuator thats what it says on my bill) that goes into the PCM which apparently it shorted the PCM and thats why i need a new one. Also the code is P2010.... it was something with the wiring into the PCM from that intake motor

bulldogzxz

After further discussion with my mechanic he said the only thing that the PCM is going to do is make me not pass my emissions inspection. He said the reason it was not wanting to start was probably due to the compression in my engine starting to fail because of the apex seals........

Loki

iTrader: (1)

Is that a guess? Because you're saying the car starts (although with difficulty), which means the ECU is doing its job. It's very possible the APV and/or the SSV need to be addressed, but I'd suggest bringing it to someone who has worked on RX8s in the past. Otherwise the mechanic might be learning about them for the first time at your expense.

Also ECUs are expensive, almost never break, and you can't just replace them, the ECU and the immobiliser need to be reprogrammed , which needs Mazda.

Loki

iTrader: (1)

Go somewhere else. You're wasting time with this guy. His train of thought makes no sense. That doesn't mean your compression is not low, it could be, and there is a test for that which can only be performed at Mazda or a rotary shop anyway.

dannobre

iTrader: (3)

I still don't see how he has determined that the ECU is bad. Just because it throws a code?

Figure out what is causing the code before you change the ECU ( about $500+) and find out it likely isn't the issue.

If you reset the ECU how soon does the code pop up? What are the codes? Is there any freeze frame data associated with the codes?

Has he checked the wiring? It is much more likely that there is a wiring fault than an ECU fault. The APV motor wiring is really close to the hot exhaust manifold

bulldogzxz

He said he went through looked at the wiring to the ECU and when the APV motor was jammed it shorted the ECU because it got locked up or something so thats why they had to replace the APV motor..... the code is P2010... when i went to the shop they showed me the ECU so its seems like they sort of know what they are talking about?

Loki

iTrader: (1)

Willing to bet $500+ on them knowing what they're on about?

dannobre

iTrader: (3)

dannobre

iTrader: (3)

Read the FSM pages. Personally I would make sure the wiring is checked properly before I would entertain changing the ECU.

ECU failure are fairly rare..APV motor sticking is really common....and if they shorted out the ECU there would be many cases of ECU failure due to that....and I have never seen one

bulldogzxz

I scheduled an appointment at my local mazda dealer to have them check the wiring from the APV to ECU and if its not that the ECU and compression. Thank you guys for your help hopefully it turns out to be the wiring

New Yorker

Taking this to Mazda is a good idea. However, rather than have them "check the wiring," might be smarter to simply tell them to diagnose the problem. That's what mechanics are trained to do. You certainly could mention that your guys thinks it's the wiring and ECU, but let them figure it out; might well be something else causing the problem.