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Discussion Starter #1 (Edited)
i just went through the typical "no start" scenario and i'm 99% sure my problem is a dead ECU. i have an '89 900 Turbo

weeklong story short:
  1. good fuel pressure to the injectors
  2. jumping pins #20 and #21 with relays in and ECU out runs fuel pump and gives power to injectors
  3. grounding pin #18 fires all injectors with #20 & #21 grounded, relays in, and ECU out
  4. with voltmeter across pins #1 and #17 there is AC voltage of 4.2 while cranking.
  5. there is a spark at the plugs when cranking
  6. with relays and ECU connected, and pins #20 & #21 grounded (ran ground through back of connector. the car will not start. i had heard that even with a bad ECU it might run if those pins were grounded. not sure if this was true or not.
i've made other voltmeter checks and i'm probably forgetting something, but i'm pretty confident the ECU is bad.


there was a similar post by saab89 that has talked about ECU's. so hopefully i'm not repeating any questions that have already been answered. but i still have a couple questions and you guys know your shiite :) :
  1. i'm wondering if it is certain that an ECU from a '90-'93 900 turbo will work ?? e.g.,0 280 000 948 (or 582). the bentley mentions other years as having 29-pin connectors. i'm wondering if there's a chance that it won't match up.
  2. is there any way to possibly rig the wiring so that the car can be driven ?? i'm presently stranded and it's a little tough
  3. if / when i change the ECU should i also buy new relays ?? are they the possible cause ?? and if needed, can i buy them from somewhere like eeuroparts.com or should i pay twice the amount and go to the dealer ??
  4. is there any way to check the ECU or potentially fix the ECU. i have access to an oscilloscope, VM, etc.
any thoughts would be greatly appreciated. as for now i'm searching ebay and also have found an '89 ECU at a salvage place where they are asking $125. i would like to find a different year, if it will definitely work, since the '89 seems to be the weakest link.


thanks a lot for your time.


- james
 

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Sounds that the ignition signal from the hall effect transmitter in the distributor is missing. Fuel pump will not run without this signal, and there will be no spark. Easiest would be to try a distributor from a working car. A NA dizzie(not EZK) would also work on zero to moderate boost.
 

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Discussion Starter #3
thanks for the reply.


i do have a spark at the plugs. and the AC Voltage between pins #1 and #17 is there (4.2 Vac).
 

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Discussion Starter #5
89turbo said:
i just found a 582 should have it near the end of the week i will let you know if my problems go away

thanks. let me know. hopefully it will fire up.

did you happen to get this one off of ebay ($81) :)

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1,1&item=7973746935

i wasn't sure i needed one at the time but i almost bid on it. small world if it's the same ECU. also, good thing we didn't try and outbid each other. ha.

there's another ECU up there but i'm not sure i can trust the seller. he hasn't returned any of 3 emails i've sent and there's a few complaints about how long it takes him to ship parts and also of shipping the wrong item.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1,1&item=7974286015



in any event, good luck with yours
 

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I'm ready to replace my ECU as well. I finally got it on the road and all kinds of weird things are happening.

-when starting cold it won't idle worth a damn for about a minute
-when it goes it hesitates terribly and awful sluggish off the line
-check engine keeps coming on and going off. car seems to run fine when cruising.
-turbo boost on gauge wont go past 12 oclock which is about the middle of the orange

I've replaced the AMM with a known good one, no difference. I've cleaned the AIC to no avail. I've tuned it up. no difference. 93 octane gas. no difference. checked hoses. none leaking. There isn't too much left. Its gotta be the ECU.

I was wondering if the Bosch pn. 0 280 000 586 would work in my 89 900 turbo. its supposedly out of a 9000 but i'm told it will work in my 900.

Thanks
 
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