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Posted Below in several spots is the saga of trying to correct what was initially a rare, then more frequent TCS error. It happened as the car warmed up. By the time I started to work on it I was able within 100yds to predict when it was going to fail 1.5mi down the road. I had a TechII code of 78390 which indicated an issue with vacuum or safety valve or check valve, or... At the same time I noticed that my 10yr old Aero had suddenly developed a set of really nasty looking vacuum hoses overnight!
I figured the cure just might be a new set of Hose Technique's finest, and replaced all the hoses. When I got done, the car was in a permanent Limp Home Mode. I could not figure out what could possibly have happened to make things much worse. I rechecked all of my routing, the resistance of the TB, valves, triple checked the check valve, checked all of the vacuum connections for the 10th time, blew/sucked on all of the hoses. Still LHM.
I read a bunch of past posts on generic TB problems. I called a bunch of sponsors who sell used Saab parts, no TCS TB. My choice is a new TB from sponsor for $650, rebuilt for $300-400, or try ripping it apart myself. I chose to rip it apart.
There were a number of posts indicating that the TB was fairly straightforward, and of robust build. Not much to go wrong. One person indicated that his failure came from a wire that grounded out on the frame of the TB, others indicated dirt on the stepping pods. I decided to gamble, even though I was risking my potential $100 core charge. My TB is the later version, or a later version with gold contacts. Swedecar says that is the better body. I thought it was worth saving.
Getting the TB off the car is pretty time consuming but not hard. One side is a plastic housing which comes off with 4 bolts, one of which is sealed to let them know someone is messing with it perhaps. The oval shaped pod on top of the TB is a big bag which I unscrewed and set aside.
On the oposite side is a butterfly shaped closure held on by 4 machine screws. Mine were corroded, and I broke two that had to be drilled out and replaced with screws. Under this cover is the connection between the motor and butterfly valve. To remove the motor, I flipped off the connecting rod, removed the three screws holding the motor on, and used a hammer and rod to gently pound the motor out of the throttle body by pounding on the opening in the TB shell which is the top shell of the motor. The motor comes out with the 7 pin connector and a plastic shell with red and black wires attached to pin 1&7, plus 5 more wires. The lever which attaches to the connecting rod slips through the opening in the TB that I pounded on to pop the motor out.
The black wire had been pinched in assembly, and the insulation was worn through over a 5mm section of the wire. It was rubbing on the plastic housing, so don't think it was grounded out, but there was some corrosion or something where it was contacting the plastic housing. I wrapped it in plastic tape, cleaned the housing, checked the other wires, and everything looked fine.
I inspected the rest of the motor and cleaned what I could. The brushes looked new, I moved them around to make sure there was a connection. I cleaned the stator under the brushes with alcohol and q-tip. Then I blasted the motor and housing with air to remove any other debris. Everything looked to be in excellent shape before I began, but figured as long as I was in there I may as well do what I could.
I also carefully cleaned the throttle housing around the butterfly valve. I had cleaned it earlier by spraying TB cleaner into the housing while on the car. There was still some gunk, and it was easy to clean from both sides. I also cleaned the interfaces between the TB and intake manifold. There is an o-ring on the TB, and I coated it with Dow molycoat, a grease.
So, I put it together and it works! Forgive the long report, but something I did fixed my problem, and I'm not really sure what it was. I don't know why replacing the vacuum hoses caused a hard failure vs the intermittant soft failures before. The bare wire is very suspect, but does not explain why the original problem was with a warm up situation. I don't really understand but will take the results. Maybe a combination.
I understand why Anders doesn't mess around with this stuff as he indicated in an '03 post. 3 days, and I'm just hoping that it is a permanent cure. Nevertheless, I think it is and it shows that it may be worth putting forth the effort. I hope I've made it easier for the next person.
posted by 159.116.2...
, Thu, 19 May 2005 08:49:34
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