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Here's the full story ... Posted by Kevin K [Email]  (#374) [Profile/Gallery]
(more from Kevin K) on Mon, 16 Jul 2001 17:32:07
In Reply to: Start up Drivablity Kevin K ?, James, Mon, 16 Jul 2001 13:14:02 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I've sent this to a few interested independents, and might send it in to NINES for new C900 sections. Read quick, I will not likely be at the bb for the next week or 2 if you have any q's....
Cold Driveaway, Lambda Lock-out, 8V CIS
On lambda/O2 Saabs thru M83, the lambda system can kick in too soon after a cold weather cold start, and undo the richness provided by the CPR. This can be observed by monitoring the modulating valve, which will fall toward '0' as lambda kicks in too soon. Loss of power, ie bog, results due to lack of cold running enrichment.
OEM SYSTEMS
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-> M79-81 have a simple lambda system. No lambda lock-out. No decel valve. No easy cure.
-> M82-83 is an upgraded lambda system, but still no lambda lock-out (this ecu is likely common to all later CIS models). The t-stat housing switch (white top) is open cold, and effects the various cold-start-valve operations (ie, steady flow when cold, or pulsed flow when hot). This switch is also in the M79-81.
-> M84 has simplified relay box, and is the first attempt at lambda lock-out. For lambda lock-out, a ground path for pin 1X of the decel relay is provided, thru a diode, thru the thermal-time (t-t) switch. This holds the mod-valve at 60%, as occurs during warm decel, by grounding ecu pin #12. Lock-out is kept until coolant reaches 110F, and lambda control is then enabled. But ... if starter is cranked for 10 sec or more, the t-t-switch goes to high resistance, and no lock-out occurs, unless t-t-switch temp drops and closes again.
The 'open-cold', white headed switch on M83 is replaced by a 'cold-closed' black headed switch (at same t-stat location) that opens at 77F. Oddly, this new switch is now in series with the t-t-switch that opens at 110F to shut down all/most cold start valve activity. So start valve cold operation is reduced, due to the black 77 degF switch (the 82-83 had start valve functioning to a max of 110F).
-> M85-88 finally provided the proper lock-out by an added thermal switch, now located at the manifold (where earlier model t-t-switches had been). This provides a ground path for decel pin 1x, for coolant up to 77F. The red headed switch on the t-stat hsg opens at 110F, and is in series with the t-t-switch, similar to M84. This switch is completely redundent to the t-t-switch, and is not really needed afaik.
Saab TSB Kits
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Saab issued at least 2 'cold driveaway' kits. A major change was the addition of a new switch, dedicated to locking out the lambda control by grounding ecu pin #12, as occurs in M85-88.
Kit 88-18-015 was for M84. Per TSB copied at Townsend's site, t-t switch moves to t-stat, and black headed switch moves to manifold. A new switch 75-34-910 is added to a plugged hole in t-stat housing, and is wired in series with t-t switch, as black one was before. I think this had a large dia thread, and opened at 110F. The black 77F manifold switch now connects directly to pin 1x on decel valve, and to a ground. A diode/wire is removed from 1x, isolating this lambda lock-out path from the t-t switch. This kit basically retro's the M85-88 system, and was not to be used on earlier years, per TSB.
Kit 85-46-921 was available for M82-83 . No details were available, but someone noted a switch was added to his M83 t-stat housing long ago by dealer. My 83T had an extra hole in the t-stat housing, tapped for 17mm and plugged. (note the later red and black headed switches are 14mm thread)
Kits and 17mm t-stat switch are no longer available from Saab.
Fixes for Today
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For M82/83, install a later, used t-stat housing with extra hole for 14mm red switch. These may come with the red thermo switch installed. Provide a local ground, and run a wire to relay box, and splice into yellow/red wire to pin x1 on the decel relay. I have done this on my 83T, and mod valve stays at 60% until gage just touches green. It is wonderful to have smooth, cold drive-away for first time in 15 years. No effect on cold start valve funtions.
For M84, if recall was not done, only black switch and gage sensor will be at t-stat. Simplest fix is to disconnect leads to black switch, and jump leads together (remember, this switch is redundent to the t-t switch). Then replace black switch with a red one for longest lock-out, and wire as per M82/83 fix above, except just remove the diode link, and connect new wire to short yellow/red wire off decel pin 1x, as in the SB. Swapping the other 2 switch locations, per SB, is not really worth it. This method allows existing t-stat housing to be used, which may have the useless 17mm tapped hole like my 83 did.
, Mon, 16 Jul 2001 17:32:07 <-- Viewing This Message
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