[HAHAV8]

Its funny you mention it happening when the you hit the gas. I think I may have a another clue. There could be something going on with the wiring for the gas pedal. Also Id check your DBW as well. Get that vaccum leak checked out to.

[fourseasonsandles]

Some updated info from our local forum. Not a lot of updates, but some ideas we are going to try.

Originally Posted by Shag-e

I wonder if you can find another 06 STi willing to swap ECUs for just a short test.. you would have to fully remove the accessport and reinstall on the borrowed, but it could rule out some things.

I dont think you can just swap ECUs. The ECU is also married to that car by its VIN. I learned this when I needed a new ECU this winter. They told me that when they put the new ECU in the car they had to marry it with the VIN so the imobolizer and the ECU could "get along" and the car would start.

I know the old ECU that came out of my car, Cobb was able to revive it. I sold it to a kid that needed one and he tried to just plug and play. The car wouldnt start. He had to go to the dealer and have them marry it to his car. I never heard from him again, so I can only assume that it worked.

It's a good idea, but Im not sure Innovative is capable of such a swap. I could be wrong though.

Originally Posted by Shag-e

i wasn't sure what was involved... sucks that you would have to jump through that many hoops...

hopefully a fix can be found quickly... it will probably be a combo of a vaccum leak and a bad ground..

Originally Posted by subaru

I realize an International Truck is quite different but a common problem they have with the DBW is the Accelerator Pedal Position Sensor on the Pedal.

They have the same symptoms, Check engine light throwing a code and putting in limp mode, causing very low boost and eventually no throttle control at all. The sensor's resistance is always within what the manual says is normal but thanks to fleets having the same trucks, I was able to swap the pedal for the "trial-and-error" method.

I realize that by now the APP sensor has probably been ruled out, but I've been following this thread and keep thinking of it.

Originally Posted by Innovative Tuning

I have another 06 STI ECU here and it's out of the car because we put an AEM EMS in the car, but the dealer has told us the car will not start because a code in the immobilizer and the ECU must match or the car will not start.

We may have to test that theory. Your call Aaron.

What user subaru just said is the type of issue I'm afraid this may be. Everything tested fine (within factory service manual specs) electrically when the car left, but it still failed after hours of driving. We don't like to charge customers for parts they may not need, but replacing things like the accelerator pedal primary and backup position sensors may have to end up being part of this process. That will be Aaron's call since he'd be paying for it.

I do have an extra STI DBW throttle body assembly which we can install for testing, but I don't have extras of the rest of the system so if it comes down to just trying things, we'd try a different throttle body first. I still have my worries that the throttle body was damaged during the initial overboost and backfire. When the car overboosts it fuel cuts all cylinders via a hard cut, but there will be a burn of remaining fuel in the cylinders since the coils continue to fire. In Aaron's case that final burn will also include methanol since while the meth kit sees boost in its control range it will spray methanol. This all happens in an instant, but the plastic gears etc. in the throttle body may have been damaged when it happened. Unfortunately the DBW system seems to work and then not work randomly so it's not acting like a part that's simply and mechanically broken.

We'll put the new after MAF hose on first and go from there.

I am game for whatever needs to be done to sort the issue out. If you guys want to go trial and error with the ECU and other parts, I say have at it. Im going on vacation, leaving on July 19, so I have my fingers crossed it will be done before then, so we shall see.

Only thing I ask, I dont know how much it costs to replace items like the DBW, APP and backup position sensors. If you can PM me on parts as we might need them, that would be helpful in knowing what I am getting into.

On a side note, My girlfriend and I played the lottery on Friday.. sadly we did not win.. Man that was $1 wasted!

Originally Posted by funkymonkey1002

Could it be something as simple as a gasket (ie intake manifold) being damaged? or something like the tgv's being damaged?

[fourseasonsandles]

Got a PM, they are putting the new MAF hose on today and will continue to troubleshoot. I dont have any other updates yet.

[Mexitr0n]

I really hope this gets resolved, what an F'ing pain/mystery.

[fourseasonsandles]

Thanks.. and yeah, you are telling me..

I also suspect something electrical. They are full of gremlins. The mechanical problems always seem to surface rather quickly, but the electrical are the crazy ones. Shorts etc..

[fourseasonsandles]

Originally Posted by Innovative Tuning

Because the code is rather vague and because Subaru's FSM diagnostic procedure has us check a number of things which all test within spec now, we have no formal procedure to diagnose this issue. The car passes every test in the manual for that code. The only reason we looked for leaks as part of fixing this issue is that was Cobb's recommendation.


We put the MAF hose on today. The stock one did have a big hole in it and the car's AFRs and fuel trims are all whacked out now that the leak is gone.

BTW...it turns out that another 06 STI here has a bad DBW throttle unit, but we think his was damaged when he ported it himself.

This is just getting crazy.. it passes all the tests, but still throws the code

Edit: I dont think I worded that very well, so here is an edit version.

I checked the car for leaks prior to this whole mess happening. My boost leak tester was plugged into the MAF hose on the side where the APS CAI connects. There was definitely 100% no leaks out of the MAF tube as I would have noticed right away when the air started flowing. After I was done searching for leaks, I put it all back together and can only assume this is when I somehow managed to put a hole in the MAF tube. I did not find this hole again until I was searching for issues when the car died on me the very first time in Rochester.

This leads me to believe that the tune would not be effected, as it was tuned with a leak free MAF tube. This is why I think a reset of the computer might fix that issue unless there is something I am missing or unaware of.

That stinks on the other 06.. Having the same code or just a broken DBW?

I meant to ask you too, you mention a backfire in post# 44. I dont recall any backfire unless that is something I wouldnt be able to tell. I think I hit fuel cut or a possible boost cut if there is such a thing, when on the highway and was overboosting, but when it happened, the car just bucked fwd very quickly. I didnt hear any "pop" or any other noise. Just curious on what you meant by that.

[fourseasonsandles]

Update

Originally Posted by Innovative Tuning

We put that maf hose on and the CEL went off right after we started the car with that on. I didn't reset the ecu or reload the map. It hasn't done anything wrong yet.

If the MAF hose turns out to be the issue, I am going to feel like an asshole for not fixing the hole in the first place. I have a feeling that things cant be that simple though.

Perhaps I am wrong and that's why I took the car to Innovative in the first place.

Keep your fingers crossed that this is the only issue..

[fourseasonsandles]

Alright, who didnt cross their fingers?!

Originally Posted by Innovative Tuning

The car just freaked out finally...as usual with no warning. I think it's time to get into this further. The DBW throttle assembly is 499 and I'm having Jay get pricing on the pedal position sensors so we know where the costs lie. I'm still thinking this is going to be an ECU issue, but because electrically things are checking out it's hard to narrow "blame" to a certain component.

[fourseasonsandles]

Just got off the phone with Mike too.

Time for some Trial and error stuff. Our best guesses so far is that either the DBW TB is bad/broken, the Pedal and sensor assembly or the ECU. The throttle body was apparently stuck when the car first came in with the issue so he recommended that we start there.

Parts will be in on Tuesday and they will see what happens. We are replacing parts one at a time since they are special order parts and I wont be able to return them to the dealer. DBW is $499.00 and that is going in first.

If that doesnt work, most likely move on to the pedal and sensor assembly at $138.00 and last would be the ECU. I may be able to get my old ECU back from when I had a different/unrelated issue. But I would rather do that as a last resort.

I guess electronically, everything is checking out and within spec, but the problem still pops up without warning and appears to be randomly. As things check out electronically, I guess that is why the ECU would be a last resort.

[fourseasonsandles]

Back from vacation and a small update.

Originally Posted by Innovative Tuning

We got the pedal Tuesday, but the throttle body just showed (thur) up so we'll put that in tomorrow morning (Fri) and go from there. Apparently it was on backorder for a few days...

No news yet if the parts worked or not yet as the shop is closed on the weekend.