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No start! Eating computers??


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18 replies to this topic

#1 Prospeeder

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Posted 03 August 2006 - 01:10 AM

Well Try as i will, we cannot get this freaking 87-88 Subaru XT turbo to run!!! I put new intake gaskets and an oil cap and made sure there we NO vacuum leaks, and it started! YAY! Ran fine for like 2 minutes then sputterd and died. WTF....thought maybe it ran out of gas, so we put some in it, and it wont even FIRE now! We looked at the ECU, it was freaking hot as hell and the metal box looked discolord, it fried its THIRD computer! Why!!!! Heres the story

He had a new motor put in, and it ran great, the turbo blew and he happend injured himself around that time. SO he asked his friend to put a new turbo in, simple right? No his friend proceeds to tear the entire top end of the motor off and put iy back half assed, we put it back the way it should, but found he maybe screwed with some electrical stuff, mabye somekind of relay. Im not quite sure. The guys calling the guy to find out, and hes gonna get another ECU for it and check some relays and electrical stuff to find out whats frying the damn thing. Its not getting ANY spark now. Theres no Check engine light on the dash ever not even with the key to the ON position.
The owner whos helping me fix it is an Electrical Engineer and mechanic, so he knows his stuff, but this is getting rediculous! 3 ECUs its eaten up. One you put it in, no spark, another no fuel pump running, and the 3rd (one just fried) does the no spark. The 3rd one we had worked great up untill it was running then died, now it has no spark, but the fuel pump works.

#2 NorthWet

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Posted 03 August 2006 - 01:38 AM

Did someone bypass the dropping resistors for the injectors?

#3 Prospeeder

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Posted 03 August 2006 - 02:09 PM

its possible, where is it?

#4 NorthWet

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Posted 03 August 2006 - 02:48 PM

Right strut tower; an aluminum-clad "tootsie-roll"-shape (the large kind not the little bite-sized things) with a many-wired (5? 6?) pigtail and connector on its bottom. Remember, just because it may still be present and connected doesn't mean that it wasn't removed from the circuit. Other possibilities exist for shorted control lines.

#5 Prospeeder

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Posted 04 August 2006 - 01:13 PM

so fit thats not thier is can fry the computers and what else?

#6 NorthWet

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Posted 04 August 2006 - 01:29 PM

I am *suspecting* that it could fry the ECU. The dropping resistor limits the amount of current that the injectors draw and that the ECU's switching transistors have to handle. Bypass the resistors and the power that the transistors have to switch increases dramatically, potentially causing the transistors to oveheat and blow.

#7 Prospeeder

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Posted 04 August 2006 - 01:49 PM

makes sense, the ECU box was majorly hot after having it run, ill havce to check it out, anything else anything wants to add please do, i want this car

#8 NorthWet

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Posted 04 August 2006 - 03:36 PM

makes sense, the ECU box was majorly hot after having it run, ill havce to check it out, anything else anything wants to add please do, i want this car

PLEASE!!! I am not an expert on this problem by any means. Wealth-of-experience will trump my basic electronics/mechanics any day. :)

#9 Cougar

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Posted 05 August 2006 - 02:35 AM

I agree with Northwet about the dropping resistors. You are going to have to get a wiring diagram, if you don't have one already, to check things out. Another problem may be is a circuit has been changed and power is being applied to a part of the ECU that it shouldn't be going to. I would check each lead of the ECU plugs while the ECU is disconnected and the ignition is ON. Measure the voltage of each lead and then the resistance of any leads that don't have any voltage on them. You will need to look over the wiring diagram to see if the measurements seem to be correct or not.

Another thing you can do is to try and trace the damaged ECU circuit from inside the ECU. By locating the current path that was damaged it will show you which external lead you need to trace and find the problem.

#10 Prospeeder

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Posted 05 August 2006 - 03:28 AM

wow talk about time consuming! Im hoping its just that resistor! I have the entire 88 Service manual downloaded for the XT, mines an 88 according to the registration but the build dates 87/02

#11 mikeshoup

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Posted 05 August 2006 - 10:36 AM

wow talk about time consuming! Im hoping its just that resistor! I have the entire 88 Service manual downloaded for the XT, mines an 88 according to the registration but the build dates 87/02

Your's is an 87.5. The 88 Manual doesn't cover Spider Turbos. They only cover the Spider N/A and the ER27. Try and find an 87 XT Manual...

#12 Cougar

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Posted 05 August 2006 - 11:42 AM

Hopefully the ECUs are close to the same if you have a manual for a different model. The quickest way to find the trouble would be to check which circuit(s) was damaged in the ECU and back track the wiring from the plug pin(s) tied to that circuit(s). Using the manual as your guide, it's really not too difficult.

#13 Prospeeder

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Posted 05 August 2006 - 01:37 PM

Well its the one i found here that i downloaded, unless you have a Manual for a 87 aroundhere i could download. By Spider you mean the instake runners right? So the ECU HAS to be from an 85-87.5 SUbaru XT Turbo or what?

#14 mikeshoup

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Posted 05 August 2006 - 04:34 PM

Well its the one i found here that i downloaded, unless you have a Manual for a 87 aroundhere i could download. By Spider you mean the instake runners right? So the ECU HAS to be from an 85-87.5 SUbaru XT Turbo or what?

By spider, I mean it has the new fancy shmancy intake manifold on it. TB points toward the firewall, and has 4 runners that look like spider legs (sort of...). That's an 87.5. I'm not entirely sure what ECUs are compatible with it though.

85-86 definitely are not compatible. Seems to me early 87 (non-spider, tb points toward the sky, but has hotwire maf and optical disty) aren't either. Probably could use the non-XT 88+ Turbo ECU. To be completely sure though, you'd probably have to get an 87.5 XT Turbo ECU. (XT Turbos never made it in the US past 87.5)

#15 Prospeeder

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Posted 05 August 2006 - 04:45 PM

Oh.....really now, so an 87.5+ EA82-T ECU should work then?

#16 mikeshoup

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Posted 05 August 2006 - 04:49 PM

Oh.....really now, so an 87.5+ EA82-T ECU should work then?

87.5 XT Turbo, definitely. I dunno if the spider intake has anything special on it that prevents non-XT ECUs from working though.

#17 Prospeeder

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Posted 05 August 2006 - 06:07 PM

Ok I went and looked, i cannot find the Dropping resitor, mabye some one could get me a picture? My friend also found out the guy switched the relays for the ignition and fuel pump around

#18 Prospeeder

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Posted 09 August 2006 - 01:40 AM

Ummm he just told me he remembers hes using a NON Turbo ECU for the car............uhh that could explain alot

#19 Prospeeder

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Posted 13 August 2006 - 12:25 AM

Ok, Im in need of an 87.5+ ECU from a Spider intake Turbo car, Im hoping some1 just needs to get rid of crap and i just pay shipping, but im looking for it cheap, because if this doesnt solve it im not getting it, ill fix my pontiac with the money i saved and drive it. But i really do want this car, Theres also some 85 Subaru GL-10 Turbo Sedan for sale, but it needs its timing belts, wich they already started and its missing its grill, and the side ribbing is rivited on and the trunk dont close....and has 265k on it but they want 400 freaking dollars for it!




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