Saab 900 Idle Issues

Dana began to report another strange issue with my 900. She was driving it over the winter as her Cirrus was in serious need of work; because I work on all of our vehicles, and due to the lack of a garage, we downsized for a bit. Dana would make an excellent race car driver; she is sensitive to car performance, and she is correct, so far, 100% of the time that a problem exists. Then it is up to me to diagnose, and treat. It is our arrangement, and it works. In the end, that is- there have been some arguments over the course of this deal- and I will admit they are usually over me not really wanting to do the work. Well that stuff stops as soon as you get THE call: "stranded.... tow truck on the way.... I missed my concert solo." Blurgh.

Being “armed to the tee,” as my father likes to put it, is the essential first step. Never go into battle unprepared or under-armed. And guess what that means: one can never have too many weapons when lives are at stake. So if your boss will let you, ask to splurge majorly on highest quality tools in highest quantity she lets you afford. (Don't argue about the she [or he] part, you know it is true. And if it is not true for you now, my friend, it will be true one day.)

Think you have enough tools? You're Wrong. Go out and buy some more. Then go online and find some weird highly-specialized gadgets and buy those too. Keep them organized in nice tool boxes, and hide your precious weaponry inside your house (this is guaranteed to start an argument however you must hold your ground) and not outside in a shed. And lock 'em up. Never leave them in an unlocked car or truck, like I did. Especially if you live in a “safe” area. Unless you feel like buying a new set.

OKAY-NOW. So back to the strange problem. The 900 would drop out RPMs when at a stop after highway driving. It would barely idle, however she would let you get back on the road after some hesitation. It was a bit scary. After a bit of research into my trusty Saab Manual I found that this was known officially as “limp mode” and that it probably had to do with throttle body components. My toyota truck was notorious for throttle body issues, so it wasn't a surprise. Step one, according to the book, was to clean AIC valve. So I spent one of my mornings doing that. It was a little gummy in there after 104k miles, then I had the dilemma of what to clean it with and whether to leave it clean-dry or clean-lubed. I'm not going to answer that. Send me an email or leave a comment and I'll personally send you the answer. What is your opinion? Why?

Step 2 was to test the Throttle Position Sensor (TPS.) I just tested the one on my girlfriend's Cirrus (oh yeah winter is over- now it is summer) and hers was way out of range. The test for the bosch TPS was a little different than hers; it was a continuity test rather than voltage (I had to insert small straightened paperclips like syringes into her test harness!) so it is EASY with a proper multimeter. It is a good idea to disconnect power to battery & wear safety goggles or glasses before attempting any work on a vehicle. Simply test ohms between terminals 1 and 3 with engine off & wiring disconnected. My omegas were out of range, by 100-200 ohms, and inconsistently out of range. I would open the throttle and I would get different base numbers each time I returned to closed position. Hmmmmmmm. So I checked prices on a TPS and decided to get one. I also had to order a coolant hose as another pin-hole leak formed. The date on the hoses indicated they where 19 years old. So I ordered that too.

I swapped out the upper coolant hose (sensor manifold to head- the shorter hose) and took a peak at the TPS job. I could find no way to get my T15 driver in there without removing the throttle body. Well I had to get back to my house-sitting job to check on the doggies so I decided to limp it over there so I would have more time to work on this thing. After loading the back seat and my trunk with tools, “armed to the tee,” I headed over. Hmmmm- cleaning the AIC valve seemed to have helped, however the 900 did not see highway speeds on the way so it is not over yet. After relaxing for 5 minutes and focusing my mind, I went out to spray some pantherpiss on the 3 throttle body bolts and the back of the TPS (just a drop) to make life a little easier. Then I went into a meditative guru state, and saw something:

The Promised Tool:

Use a ¼ inch box-end along with a T-15 bit and a bit of electrical tape. Remove the two AIR (no clamps) hoses from the top of the throttle body (DO NOT REMOVE THE RIGID COOLANT HOSE!) and one will be granted enough access to use your chosen tool to remove the TPS.

The Promised Tool Manufacture List:

Check OHMS

Manual OPEN condition to check OHMS (use your hand, yo!)

When I put everything back together and started the car, there was hesitation on punching the throttle. Blurgh. Looks like another meditative state is in order to see into the top end. Clogged injectors? Plug gaps off? Something deeper? I pulled plug #1 just to see; it wasn't perfect, however it wasn't fouled either- the business surfaces were very clean. The outer surfaces had a bit of brown deposit. I gapped them myself last time I did a tune up.......was it 5 years ago already!? Not my daily driver by the way- I used to bike to work, and now I work from home. So over 5 years she's seen very little mileage; until she met Dana.

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