ECU learning issues

[Legacy777]

Out of curiousity, and you may have mentioned it before, but have you tried a different ECU?

I would try and see what has remained constant throughout this entire troubleshooting process since you are still experiencing problems.

Just as an aside, I'm going to be swapping to the newer style knock sensor found on the WRX's. It's output is a little funky or doesn't seem to work as well with the Link's knock control.

[ericem]

He has swapped over ECU's if I recalled correctly.

[BSOD2600]

Yea, I swapped in the '94 TW ECU in last summer when I first started to look into these problems (w/o the part replacements yet though). They both exhibited the same issues of knocking and the octane factor never staying at 100%.

One day, while searching for knock sensor stuff, I came across BigMoose's Ramblings on Knock Sensors, which has some interesting analysis for various knock sensor types. Looks like our Subaru sensor is a, "non resonant, or flat response sensor" which does the signal processing in the electronics and not with a resonant sensor. Since that's the case, I wonder if Revtronix:
1) has already altered the knocking detection in the Stage 1/2 chip.
2) can alter the knocking detection for something less. Even more ideal would be a user parameter changable with RevScan.

Too bad, Mike/Revtronix has been MIA for weeks...

[Legacy777]

Interesting info on the knock sensor. I'm actually looking at swapping over to a newer knock sensor. I think I've still got a data acquisition setup. If so, I may try and do some testing.

[ericem]

BSOD, Mike told you he can disable the knock sensor and he has done so before just need to watch for audible knock or possibly just wire up a knock lite.

[BSOD2600]

Yea, he has suggested that I disable the knock sensor too. I'm very uncomfortable with doing that though. Would rather fix the knocking issue or manage/tweak it with software. I seem to recall the user tunable chip would have some knock sensor tuning abilities.

Anyways, is it possible something was damaged in the engine from the crash? If so, what could be the problem only while on boost?

[ericem]

Well under boost there is more stress on the motor. Maybe crankcase bearings or something changed the way it was seated on impact? How bad of a impact was it? Your SS didn't come with a motor right?

It sounds like the best option is to disable knock sensing and to wire up a knock lite.

[asc_up]

Lot's of maybes, but: maybe your turbo or the oil and/or coolant lines going to the turbo were slightly damaged, causing it to blow hotter air at higher PSI readings.

[ericem]

I don't think the coolant circulating through the turbo does much of anything under boost, but mostly does good when idling or when the car is shut off. Could be wrong.

[asc_up]

No, you're right about that. My point was that maybe something with the turbo was damaged somewhere along the way and it's now blowing hotter air at any given PSI.

[epicfail]

A user-adjustable knock threshold would be optimal.
Could it be sensor picking up 'piston slap' noise? How many miles does the motor have on it?

[BSOD2600]

For intake temperature, I've been thinking about taking the temperature probe that came with my craftsman multimeter tool and inserting it into the intake post-TMIC right before the throttle body. drive around a bit and see what temps are seen. Obviously only a ghetto temporary solution. Even if I got the data, then what? Since I don't have numbers from when the car was working or anyone else on the forum that I've seen, it doesn't do me much good.

The motor has around 200K, but hard to really say since it's been through a lot of swaps. What I do know, is that this same engine was working great, making ~16 PSI boost, octane factor always at 100%, etc while it was in my TW. Then I wrecked it (sadly) and transplanted the engine and other performance bits into the '94 SS I have today. Ever since the wreck/swap, ECU detects extra knocking, yet I can never audibly hear it.

[RJ93SS]

goodluck with all of this, youve been at it awhile and i hope it all pays off for you. i've def learnt a thing or two.

[BSOD2600]

I finally gave in and relocated the knock sensor up to the bell housing. Within 10 miles of highway driving and partial boost, OF set itself to 100%. Didn't hear any ping/knocking while on boost for the whole drive. Will give it some more time before I increase the boost from ~10 to 15 psi.

Now I wait and see how long this lasts before something internally really breaks...

[ericem]

Hmm, it does have 200k so the who knows. If it works atleast you can enjoy the boost.