It never ends. Factory ECU died. Replaced but immobilser ...

devski · Postby **devski** » Wed Oct 26, 2011 9:37 pm

Replaced the ecu but...
The immobiliser kills the engine because the ECU doesnt have the immobilser code.

Its a jap spec ECU with no immobiliser.

Is there any way to remove the factory immobiliser?

93_Clubman · Postby **93_Clubman** » Thu Oct 27, 2011 11:44 am

Lokiel's one of the few that's posted around this issue - see following quote, also in posts by Lokiel in: viewtopic.php?f=75&t=48169&p=606664

Lokiel wrote:Here's the definitive tech manual regarding the MIS (Mazda Immobiliser System): http://www.mazdabg.com/ftp-uploads/MAZDA%20material%20for%20technician/CT-L1007_en.pdf

It describes what's needed when replacing an ECU, immobiliser or keys - stash it away now before it disappears off the "internets".

Not immobiliser specific, but rather ECU & key related, however worth being aware of - see Russellb's post in following:
viewtopic.php?f=81&t=47191&p=592305

devski · Postby **devski** » Thu Oct 27, 2011 2:57 pm

You're a legend.

By the looks of it the immobiliser controls the both the starter relay and also goes out to the ecu.

Now if I have a JDM ecu that doesnt have the immobiliser it shouldn't need the wire going out from the immobiliser to the ecu.

But because the immobiliser controls the starter relay and will only fire the starter if the ecu authenticates the car wont start.

So if I wire the ignition switch straight to the starter relay I should get the car to start?

Correct me if im wrong before I zap myself.

93_Clubman · Postby **93_Clubman** » Thu Oct 27, 2011 3:26 pm

devski wrote:Correct me if im wrong before I zap myself.

Sounds logical, but I'm in no way qualified to make a call on this. However, good luck if you decide to try it.

Steampunk · Postby **Steampunk** » Thu Oct 27, 2011 11:34 pm

I don't understand two issues:
1) how did the ECU "die"?
2) so you are saying the car will start, but then shuts off after a brief moment? I thought immobilisers will not let the starter motor turn at all.

devski · Postby **devski** » Thu Oct 27, 2011 11:46 pm

1red5 wrote:I don't understand two issues:
1) how did the ECU "die"?
2) so you are saying the car will start, but then shuts off after a brief moment? I thought immobilisers will not let the starter motor turn at all.

1) Not sure what actually happened to it. Miss firing, running lean down low, rich up high. Every thing else ruled out.

2) The car starts to begin with then the immobiliser gives the ECU a kill instruction. It also controls the starter relay.

I need to connect the ignition switch straight to the starter relay and remove the communication wire for the immobiliser to the ecu.

If I can find out which wire it comes down I may be able to bypass it. Unfortunately the link above only provides the circuit diagram for the latest revision of the immobiliser and not the one in my car.
And yes its different.

Cheers,
Jamie

93_Clubman · Postby **93_Clubman** » Fri Oct 28, 2011 11:24 am

1red5 wrote:I don't understand two issues:
1) how did the ECU "die"?

Andrew, some background:
viewtopic.php?f=18&t=49166
viewtopic.php?f=29&t=49562

93_Clubman · Postby **93_Clubman** » Fri Oct 28, 2011 11:34 am

devski wrote:If I can find out which wire it comes down I may be able to bypass it. Unfortunately the link above only provides the circuit diagram for the latest revision of the immobiliser and not the one in my car.
And yes its different.

Not sure if these NB8A wiring diagrams cover it or if they're detailed enough:
http://neomiata.com/garage/index.php?pa ... 1997-2000/

NB8A manual:
http://www.mediafire.com/file/y4m5mzymy ... Manual.pdf

Steampunk · Postby **Steampunk** » Fri Oct 28, 2011 3:40 pm

ok cool, well not really, whoever did that service needs to be kicked in balls several times. I just asked because I can't recall the last time an ECU failed.

I'm not trying to be a PITA, and I apologise if I missed reading it, but did you check/replace coil packs, the CAS (as I read these fail on a a regular basis), MAF?

Can you do just one thing for me please (if you haven't done it); I had a issue that appeared suddenly, where the car (Pulsar GTi-R) would not rev past 3,000RPM and didn't like anything more than 1/4 throttle. Symptoms were the same as yours, spluttering, misfiring, and it felt like a 1,000cc engine.

Phoned a friend and he said to unplug the MAF connector, give it a light spray of contact cleaner/WD40 and a gentle clean. Voila! not a sign of the problem for the last 6,000km.

Once you've done it, replace your original ECU and see how she goes.

devski · Postby **devski** » Fri Oct 28, 2011 4:20 pm

You didnt come across in a negative light at all and I dont think trying to help makes you a PITA :lol:

Everything you mentioned has indeed been checked.

I would have sent the ECU off for testing however Mazda wanted more to test it then I could buy a Jap spec ecu for...

I will give your advise a go tonight when I get home from work and let you know how I get on.

Thanks for the tip!

Steampunk · Postby **Steampunk** » Fri Oct 28, 2011 4:25 pm

You're welcome Jamie. Fingers crossed.

93_Clubman · Postby **93_Clubman** » Fri Oct 28, 2011 4:39 pm

1red5 wrote:I just asked because I can't recall the last time an ECU failed.

I can't think of an NB ECU that's failed & been advised on here, although can think of a few NA ECUs that have failed. Guess there would eventually be a first time to read of it happening on an NB.

devski · Postby **devski** » Fri Oct 28, 2011 7:51 pm

Car has deteriorated to the point of being totally un-drivable.

It now rev hunts and has even stalled at idle.

Tried cleaning the connectors for the air flow meter and had no luck.

After trying that I thought i'd leave it entirely disconnected and fire up the car.

Pretty much exactly the same behaviour out of the engine. Connected it back up.

Rarely even acknowledges any throttle now. Pushed the throttle all the way down. No effect. Left it down for 10 seconds and it slowly started to climb in revs.

Went back to idle and it stalled.

My relationship with my MX5 is on rocky terms after the last month!

My mechanic definitely said that the MAF was fine. However when he gave the car back to me it also drove fine. Then started farting a week later.

Its getting all a bit too much for me.

I have a megasquirt coming in 1 month. Hopefully that wont have an issue with the immobiliser and my car will run.

One can only hope.

Steampunk · Postby **Steampunk** » Fri Oct 28, 2011 9:42 pm

Damn. Too optimistic.
Are you buying a MegaSquirt PnP? from DIYAutotune? Regardless, I would send an email to them stating the potential problem with the immobiliser and see what they say.

Another diagnosis, and one that you will not like to hear, is water may have contaminated the wiring loom somewhere and due to capillary action, it crept closer to the ECU, hence the steady deterioration.

google "capillary action faulty ECU"

I never thought it was possible as I've only heard capillary action in plants, permeable materials etc, but the science behind it makes sense.

Has it lived most of its life outdoors? I guess with the cold down your way and it associated air-moisture/condensation levels higher than us on the mainland, it won't take much to have water collecting in many places.