After a three plus month hiatus (dead 1990 GSX with a collection of issues, including defunct ECU) I today finally got it fully back together again, insured it, and went for a shakedown run.

It went pretty well except for the interior right front A-pillar trim again popping loose and rattling, but more significantly, there was no sign of my turbo :(! I tried several times to get the turbo gauge into the plus zone, but all it ever reported was normal aspiration.

I suppose something could indeed have gone wrong with my turbo (frozen turbine maybe? Though I've kept the oil in pretty good shape!), but I'm wondering if the replacement rebuilt ECU could have anything to do with it? In the past, I've always been aware of when the turbo needle swung into the boost range (generally moderated the throttle to keep it from going there), but it simply wouldn't even BEGIN to go there tonight.

Anybody know if this could indeed be an ECU issue? (Or is it definitely a turbine issue?)

Thanks -- Trevor

Stop looking at the gauge open your window and floor the motha fuc@#er.

Do you hear the turbo spooling?

If yes your crap gauge is dead and is a good excuse to get something that actually reads the turbo instead of what the ECU thinks the turbo is doing and a sh itty job at that too.

Is jumpy or stuttering or slow? The car**

The car feels normal, no engine misbehaviors, but although it accelerates nicely through the gears when I choose to, there's no real sense of press back into the seats. Hitting the throttle in a lower gear pulls well, but I'm not at all convinced the turbo is active. I really don't know what sound should be present when the turbo spools, so I guess that's a test for another run. (Actually, the car feels great :)!)

PS. So you're suggesting it may be behaving correctly, but the rebuilt ECU may not be interpreting it correctly? If so, then maybe! I deliberately kicked it on a relatively little used road tonight and it moved out quite spryly, but I'm just not getting the sense of pull that I was expecting.

Get a boost gauge.. A real boost gauge.

Try this

http://www.deftracing.com/prosport_gauges/..._white_52mm.htm

It sounds like it's just time for you to get a new boost gauge

I was thinking, the readings on my boost gauge seemed distinctly lower than typical. Is it possible the ECU boost display is taking the full turbo range and adjusting it back into what is cosidered the normally aspirated range?

The stock boost gauge isn't accurate at all it's more of a rough estimate of boost. Just get an aftermarket boost gauge and hook it up and it'll be fine.

Get an autometer boost gauge...never let anyone i know down + is the next mod i'm getting :thumbsup:

You may have a non turbo model ecu. Thats why your stupid boost meter is not working. Do you have any open air filter??? if not you are not going to hear you turbo boosting or spinning. You may also have a bad BCS.

The intake is completely stock (air filter in a can), as is everything else under the hood. Not sure what BCS stands for, what it actually does, or where it is -- boost control system?

I AM suspicious of the rebuilt ECU (though I did specify turbo AWD.) I gather if the ECU is non-turbo the engine would still behave properly? Just the display would be wrong?

I'm guessing the first thing is to verify whether or not the air pressure is being boosted. If not, I'm guessing either the turbine is frozen or the BCS(?) has failed(?).

Are there any particular symptoms I should notice if either of those were a problem?

Jesus, Listen bro, the stock gauges on any car are dumb people switchs. Once the parameters that are set at the factory are exceeded the gauges or lights react. Even your Engine Temp gauge. Every gauge in your car reads what the ECU THINKS is happening.

If your really concerned your turbo is messed up, pull the intake off and spin the turbine wheel. it should spin mostly freely. It shouldn't move in and out or side to side. If it checks out, put it all together and build a pressure tester, then pressurize your intake system if it doesn't leak. Your good and like I said your ECU is not sending the correct signal to your gauge...

Get a Mechanical one from Autometer or from the link I sent you.

Im going prosport because they have been proven more accurate then DEFI gauges. Plus the one I am getting has a Peak hold and warning function which means its gonna scream at me when I over boost so I can try and avoid killing my engine.

For $50 shipped You can have a mechanical gauge and pod. And then you have the peace at mind that you actually have a TRUE boost reading.

If you had the non turbo ECU your car would drive horrible the fuel maps are different just to list one difference.

The difference between the turbo and non turbos are pretty large.

OK -- I just took it to run some local errands and there were a few opportunities for it to show a little turbo (as in acceleration, not gauge) and there was absolutely nothing. If I punch it in a lower gear, most of the pedal travel does nothing, it just feels like normal aspiration.

So, I'm guessing the ECU can't shut down the turbo, so what can? Since the normally aspirated behavior does indeed feel completely normal, I'm guessing the turbine itself is not acting as an obstruction. So whats the BCS all about? I believe the ECU was killed by overvoltage on the battery line, could that also have killed the BCS?

Please understand, I'm not fussing over the gauge, I'm fussing over whether or not I''m getting boost -- and at this point I'm satisfied I'm not. There IS a problem. Now I just need to identify what!

If the BCS is another electronic controller, then it is probably also susceptible to over-voltage damage, and so that would be a prime suspect. Since I know zero about what the beast is and what it does, it's a little difficult to pursue that far. I tried a search for "turbo BCS" and came up empty handed.

So, it sounds like I probably have the right ECU -- thanks :)! If there was a BCS problem, would it show up in the ECU error codes?

Check your turbo, refer to previous post.

That's next on the agenda, just waiting for the engine to cool again after taking it out to make sure the cruise control still functions (separate controller) -- it does!

No luck so far identifying a separate boost controller (BCS?) in my manuals, and so I'm inclined to think that's just part of the ECU functionality on these machines. The only other controller I've identified so far is the cruise control -- hence my test trip :)!

LOL..!! :thumbsup:

No the car WILL not run horrible. I have try it and its fine. The difference is some of the pins on the non turbo ecu don't have, the pines and read out like the turbo version. i have a couple of ECU as back up and one of them end up as a non turbo ECU.

The you have the early car like me. Do you have that little vacuum port thingy on top of the air can ??? try to unplug it and see what happen. In my case, on why my car didn't boost is that bad part.

Got a turbine report! I could only get a couple fingers into that central intake (too many obstacles), but they definitely couldn't budge the turbine -- either direction. So, given the ECU and BCS are apparently one and the same, the turbine was my next logical culprit, and sure enough. Looks like the car is going to have to go down again :(!

Just called Mitsubishi service and asked the cost of repairing a frozen 1990 GSX turbine. They're supposed to be calling me back with a ball park number -- hope it's before they close today!

I understand 1989 was the first year for the Eclipse, and 1990 was the first year for the GSX, so yes, mine is definitely early :), however, it doesn't have the original air can -- it picked up a driver's side nose to passenger side back of front fender clip in 2002 as a result of accident damage (very slow speed nose crunch with an impact offset a little to the right.) The bumper helped not at all :(!

The replacement can has a fitting on the top that I don't recall my original having, so I'm guessing that's the location, but I don't have one.

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Just got word dealer repair would cost about $2100 and includes a replacement turbo unit -- apparently $1500 for that alone. I asked, but it appeared rebuild wasn't considered a viable option. Sounds like I need to find a more affordable solution :(.