Need info on replacing ECU... ecu-noobie here. Thanks!

[keeweechris]

In a last ditch effort to fix some engine issues (fuel consump, eratic idle, jerky accel/deaccel), I need to work out if my ecu is faulty or not.

First up, its a stock JDM 97 WRX ecu, but I can't find much info about it online.

Label says:

2S

22611 AC731

A18-000 D56

Its a 3 plug one.

So, first question: How can I tell if an ECU is faulty?

2nd Q: Seeing there are so many types of wrx ecu's out there, can I replace it with another? Does anyone know if any other ECU's are similar to this one? Similar maps, boosts, etc.

3rd Q: What dies on ECU's? Can I attempt to fix it? Has anyone fixed theirs before? Are there common faults? Dry solder joints, leaky caps, etc?

Thanks for any help guys!

Chris

[gazzy2000]

Hey man,

I had a JDM 97 STI stock,

Had real bad surging etc, i did a heap of stuff to try and fix it and in the end it was an o2 sensor.

Can you tell us what you have tried thus far to try and fix yr issues cause i can suggest a heap of things.

[keeweechris]

 gazzy2000 said:

Hey man,

I had a JDM 97 STI stock,

Had real bad surging etc, i did a heap of stuff to try and fix it and in the end it was an o2 sensor.

Can you tell us what you have tried thus far to try and fix yr issues cause i can suggest a heap of things.

Dude, I've just about tried everything!

First up was the obvious 02 sensor. No difference.

Then cleaned AFM with elec cleaner

Then cleaned and tested IACV

Poured Upper Engine Cleaner through it, absolutely no diff.

Tested Throttle pos sensor

Changed plugs

No fault codes at any stage of this.

I now have laptop connected with EvoScan running, but being a noobie I don't really know how to "read" the readings.

My latest attention is back to the AFM and ECU. As I type, I'm opening the AFM up (purple sticker) to try to resolder the joints. (Seen a post about that somewhere in here)

Also thinking maybe the ecu is dying, so going to try that.

Sick of taking it to mechanics who say its fine and nothing wrong and charge me $200! ;-)

Fuel economy is slowly getting worse, and although power is still there, it surges and jerks on accell and deaccel. Freakin makes me angry to drive it anywhere!

Life is too short for this sort of thing stressing me out. Who's got a doobie?

Thanks for any help.

[subieboy]

 keeweechris']

[quote name='gazzy2000 said:

Hey man,

I had a JDM 97 STI stock,

Had real bad surging etc, i did a heap of stuff to try and fix it and in the end it was an o2 sensor.

Can you tell us what you have tried thus far to try and fix yr issues cause i can suggest a heap of things.

/quote]

Dude, I've just about tried everything!

First up was the obvious 02 sensor. No difference.

Then cleaned AFM with elec cleaner

Then cleaned and tested IACV

Poured Upper Engine Cleaner through it, absolutely no diff.

Tested Throttle pos sensor

Changed plugs

No fault codes at any stage of this.

I now have laptop connected with EvoScan running, but being a noobie I don't really know how to "read" the readings.

My latest attention is back to the AFM and ECU. As I type, I'm opening the AFM up (purple sticker) to try to resolder the joints. (Seen a post about that somewhere in here)

Also thinking maybe the ecu is dying, so going to try that.

Sick of taking it to mechanics who say its fine and nothing wrong and charge me $200! ;-)

Fuel economy is slowly getting worse, and although power is still there, it surges and jerks on accell and deaccel. Freakin makes me angry to drive it anywhere!

Life is too short for this sort of thing stressing me out. Who's got a doobie?

Thanks for any help.

have you checked you Vacuum hoses? especially the ones leading to and from the solenoid and the wastegate actuator...

[keeweechris]

Oh yeah, I've checked some vac hoses, and replaced 2 which were brittle with slight cracks round the ports on the manifold, but not the wastegate ones. Will try that, thanks!

So the solonoid being one of the gadgets behide the airbox?

[gazzy2000]

everytime you change or clean a sensor you MUST reset ECU, hopefully you did that?

Have you tried knock sensor relocation?

[keeweechris]

 gazzy2000 said:

everytime you change or clean a sensor you MUST reset ECU, hopefully you did that?

Have you tried knock sensor relocation?

Well, not religiously, but I have reset it a few times. Both the "disconnect the battery" way, and the "connect black-black and green-green plugs" way.

Nope, havn't tried knock sensor relocation. Easy to do I spose. Will add to the list, cheers :-)

[gazzy2000]

 keeweechris']

[quote name='gazzy2000 said:

everytime you change or clean a sensor you MUST reset ECU, hopefully you did that?

Have you tried knock sensor relocation?

/quote]

Well, not religiously, but I have reset it a few times. Both the "disconnect the battery" way, and the "connect black-black and green-green plugs" way.

Nope, havn't tried knock sensor relocation. Easy to do I spose. Will add to the list, cheers :-)

yip, painful as it is i wud reset it every change you make.

here is that link on knock sensor relocation, i spoke to PBMS about this and they say its all good to do.

Infact in rescent knock sensor troubleshooting i mounted my knock sensor on the manifold on the intercooler bracket and listened with a listening device and it worked fine.

You MUST torque knock sensors at 24nm aswell

http://www.imprezasport.net/forums/index.php?showtopic=785&st=0

[log1call]

If you want to send me a log of the car running I will have a look at your figures and see if there is anything obviously wrong.

To use the evoscan efficiently you really need to go for a test drive with a specific symptom in mind and try to induce it, or, go for a carefully thought out test drive that will test one component(or maybe a couple) at a time.

Just going fr a random drive around town logging won't reveal much generally.

[keeweechris]

 log1call said:

If you want to send me a log of the car running I will have a look at your figures and see if there is anything obviously wrong.

To use the evoscan efficiently you really need to go for a test drive with a specific symptom in mind and try to induce it, or, go for a carefully thought out test drive that will test one component(or maybe a couple) at a time.

Just going fr a random drive around town logging won't reveal much generally.

Sweet Log1call, I was hoping you'd offer!

So tomorrow I'll move the knock sensor, and log a drive around. I'll video it too, so I/you can match up the log timing with the real world... might reveal something. Also, I've discovered that the more sensors you request from the ecu, the longer each "pass" takes. Makes sense. So I'll only log O2, AFM, knock, rpm, and timing. Anything else?

Also, I was thinking about air leaks. Maybe theres some tests I can do to test for leaks? Maybe if I take that collar off from the IC to throttle body, and block it off and pressurize the intake from air filter, and somehow test for a leak? I dunno, just an idea.

Thanks guys, really appreciate the help and idea's. I'll get the f$%ker!

[Swindog]

Checked your fuel filter?

[Guest boostin]

Try cleaning up all earth points with a bit of wet n dry, and CRC them before you put it back together. Basically find any and every wire that is bolted to the block, manifold etc, unbolt it and scrub up the terminal and mounting point, drench it in CRC and bolt it back down.

[log1call]

You should log the TPS, AFM, manifold pressure, revs, load, o2, IPW, ignition timing and knock.

It's more important to get the figures you need to see interacting together, than it is to have really fast updates. You can see how fast they were updating off the second counter. The interaction between systems is more telling than specific numbers are.

Then you need to find a bit of clear road where you can hold it in gear for a while, long enough for a few passes through the parameters in any particular gear. Then you should get into about third and drive with moderate throttle and let the revs build gradually from low revs, then slow down to low revs and floor it and wind it up under about 3/4 throttle and up to about 5000 revs if possible. Then slow down to slow revs and then floor it up to about the 5000 again.

If there is too much traffic and you have to throttle off too often it makes the data hard to read. If you can find a big hill to go up it makes it easier to get the time and load on it.