ECU Compatibility - SaabCentral Forums
*
Home Saab Pictures Saab Classifieds Saab Dealer Listings Saab Forum Saab Forum


Go Back   SaabCentral Forums > Saab C900, 1979-1993 & '94 Convertible (C=classic) > C900 Workshop

C900 Workshop Classic 900 (1979-1993 & '94 Convertible) Technical Forum.

SaabCentral.com is the premier Saab All Forum on the internet. Registered Users do not see the above ads.
Reply
 
Thread Tools Display Modes
  #1  
Old 8th August 2006
li Arc's Avatar
li Arc li Arc is offline
Saab Lunatic
 
Join Date: Jul 2006                                                
Location: Calgary, AB, Canada
My Saabs: '85 900 T16 Sedan
Posts: 2,186
Garage
Default ECU Compatibility

Hello all,

My car has been having starting and idling problems for a while. It is a 1985 900T 16V, and I have been slowly restoring it to the best of my ability (which isn't much of it).

Recently I (think I) fixed the high idling problem I had before, which I could not originally fix using the usual methods (checking for vacuum leaks, AIC, AMM, lambda sensor, etc.), but I finally lowered it by a screw on the throttle body that seemed to control idling speed (and no, it is not the one that stops the throttle butterfly valve): since this screw seemed like it has not moved in 20 years, I'm not sure if that was the source of the problem, but at least my high idling problem is gone (comments on this?).

This led me to too-low-idling when the car is cold and difficulty starting (although I have always had difficulty starting, esp. in the cold: this is the major problem with the car I need to nip in the bud). As I understand it, the only elements involved in this particular problem (unable to consistently maintain 800rpm idle) is the AIC, perhaps the NTC, and the ECU. Cold start difficulties may be attributed to a cold start valve, but it doesn't much help when the spot where a cold start valve would normally be is just a non-openning on the throttle body (I also don't know where the thermo-time switch is). I have tried two different AICs that open and close the valve properly when connected to a computer power supply (12V), but that will not react when plugged into the car. I thought it might have been the wiring, so I took a multi-meter to it, and obtained the following (interesting) information that is inconsistent with the information provided on this page:

Saabnet LH Info

LH2.2 pin 3 (throttle position switch) -> AIC pin 1 (connector pin /w no protrusions in the housing)
LH2.2 pin 10 (AIC valve output 6-11V @ idle) -> AIC pin 2 (centre connector pin)
LH2.2 pin 12 (throttle position switch wide open) -> AIC pin 3 (connector pin /w slanted protrusion in the housing)

It looked like there was no discontinuity in the wiring, but, to me, the pins seem connected wrong! I'm not sure...at any rate, since the wiring was okay, I assumed that this is how it left the factory, so I wasn't about to argue (comments on this?). This left the ECU. Happy at narrowing down the problem, I set off in search of a working ECU.

After several weeks of visits to the local junk yard, I was unable to find anything useful (two Jetronic systems from 84 900S cars that were both carborated), until today when I arrived to find two 86' 9000 16V's. They both used the 0 280 000 531 LH2.2 systems, whereas (I think) the 85 900T 16V uses a 0 280 000 515 (or 521). So, after a long winded speech, here is my question: will I be able to swap in a 531 LH2.2 ECU in to replace my 515 (or 521) LH2.2 ECU?

Thanks in advance!

li Arc

Last edited by li Arc; 8th August 2006 at 01:35 AM.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 8th August 2006
Jim Mesthene's Avatar
Jim Mesthene Jim Mesthene is offline
Saabista
 
Join Date: Feb 2006                                                
Location: Waltham, MA
My Saabs: Wife's 9-3
Posts: 12,538
Default

You can use any 25 pin Turbo ECU. You can use a N/A for testing if you need to.
Within the same type LH (2.2, 2.2.4 etc.), you can always substitute a later model ECU, sometimes just for improved diagnostic capability.
Turbo ECUs may have enrichment circuits; you can use them in N/A cars, but not the other way around.
Reply With Quote Quick reply to this message
  #3  
Old 22nd August 2006
Jeremy's Avatar
Jeremy Jeremy is offline
Senior Member
 
Join Date: Aug 2001                                                
Location: Syracuse NY USA
My Saabs: 89 900 Turbo 3DR
Posts: 154
Default

Does that mean I could use an '88 turbo jetronic ECU on my '89 Turbo?

Edit: I think i just remembered something, the 88 turbo is a LH 2.2 and my 89 turbo is a LH 2.4? or am I remembering wrong?

Last edited by Jeremy; 22nd August 2006 at 01:25 PM. Reason: Remembered something...
Reply With Quote Quick reply to this message
 
  #4  
Old 24th August 2006
RM '92 SPG's Avatar
RM '92 SPG RM '92 SPG is offline
Saab Lunatic
 
Join Date: Oct 2002                                                
Location: Calgary, Canada
My Saabs: 1992 900T 3dr
Posts: 1,309
Default

Quote:
Originally Posted by Jeremy
Does that mean I could use an '88 turbo jetronic ECU on my '89 Turbo?

Edit: I think i just remembered something, the 88 turbo is a LH 2.2 and my 89 turbo is a LH 2.4? or am I remembering wrong?

That's right, '89 is the first year of 2.4 if I remember correctly!

-Rob
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the SaabCentral Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in


Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 11:25 PM.



Powered by vBulletin® Copyright ©2000 - 2019, vBulletin Solutions, Inc.

top of page | sitemap | email us



copyright © 2003 - 2011 saabcentral.com, All rights reserved http://www.whiter.co.uk - valid xhtml - valid css
SaabCentral is an independently run website and is not affiliated in any way to Saab Automobile AB.

vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
 

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.