WHAT'S THE MOST LIKELY CAUSE OF A 1996 SAAB 900

Hi,

What is the engine size of this motor? Can you tell if it has a distributor? These vehicle's were equipped with two type of ignition systems, Motronic and Trionic - Trionic was distributorless and had common failures in the Ignition Module (Cassette) and CKP (crankshaft position sensor). In any case the engine's diagnostic system needs to be accessed with a factory level scan tool in order to retrieve any related information to the failure.

-Rip

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2 liter turbo, direct ignition, code PO 300" random multiple cylinder misfire". The problem is very intermittent. Will start fine 1/2 of the time.

This code is 90% of the time related to the Ignition Casette. Unfortunalty, it correctly diagnosed thru a factory level scan tool, and costs approx. $500.00 for just the part. You may want to locate a used one, and install it yourself, it's very simple, just (4) torx bolts hold it down. The diagnosis and repair at a quality facility, can run approximatly $800 in labor and parts. I've found these used on various websites for around $150, but they are hard to come by. Also, keep an eye on eBay.

-Rip

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IS "COIL PACK" THE SAME AS THE CASSETTE YOU MENTION?BTW I REALLY APPRECIATE YOUR TIME.

It is the same, but on this system it is correctly called Ignition Module or Cassette, because it incorporates both (4) coil packs and the Ignition Module itself in one Solid state design. Also, when the Cassetts completely fails it will have a distinct electrical burn smell, for now it is considered a intermittent failure.

-Rip

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would a bad cassette produce a code PO 300 for RANDOM MULTIPLE CYLINCER MISFIRE or a problem in 1 or 2 cylinders? Could that code indicate a probable fuel problem.do you have anyway to look it up?

Yes the Ignition Casette will produce this code. More commonly the P0300 (Random Cylinder Missfire ) is attributed to the Ignition System, but on occation, when a fuel system malfunction is so severe, it can also set this code. The Trionic computer control monitors the engine's performance via various sensors, when the engine revolutions are no longer within parameter of preset values, the computer can set this code. But only if it cannot distinguish which cylinders are missfiring. If it can distinguish, it will set that cylinders related code. For example, if cylinder #1 was missfiring due to a bad spark plug, fuel injector, or Cassette; it will set a code P0301, if it notices #2 missfiring it will set P0302, and so forth. If more than one cylinder missfires, it cannot distinguish the revolutions correctly, and therefore set P0300. Although this concern could also be attributed to a fuel problem, what leads me to believe it is more ignition related is the backfiring. In order for the fuel system to cause a backfire situation, it would have to take away just the right amount of fuel to cause a very lean condition with the mixture. This could only be a fault in the computer itself, which is very uncommon. And from my experience most fuel pumps on these, will completely go out, rather than restrict fuel flow intermittently. So, this is why I believe your problem lies in the Ignition Cassette, it directly controls what cylinders will fire, and when. If the Cassette fails, it will send spark to the wrong cylinders at the wrong time and cause a backfire condition. This condition can be tested, but only at a facility equipped with a factory level scan tool, which can trigger the Ignition Cassette, and then the spark Kv (kilovolts) can be monitored on an Oscilliscope, if the Cassette is faulty, there will be a noticable Kv drop.

-Rip

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It certainly sound like you know this car, so i will go with your suggestion. Thank you

Your welcome, let me know your outcome and if you need further assisstance. Thanks for the accept.

-Rip

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good call on the ignition module! found a used one online for $125. woks great now except that i have a brand new problem with the clutch, how do i request you specifically for an answer?

We can still work on this post if you'd like. Good job on locating a used one, I just can't bare spending the amount on new ones... What's the problem with the clutch?

-Rip

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Great, good to talk to you again.
the clutch cable was replaced about 10 000 ago but even though it needs to be adjusted, meaning with the engine running the gears won't go in. How do you adjust the clutch on the car?

But with the engine off, and if put into gear and cranked the gear will engage? (car will move forward)

-Rip

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yes. but even with the clutch pedal all the way in, the car will lurch forward a bit when i crank because the clutch doesn't disengage totally

Alright, can you give me until tommorw morning? I believe this is a self-adjusting clutch, and if it is trully cable operated than there is a mechanism inside the cable which will fail and cause the cable to fully extend. This may be due to a defective cable, or in some cases the cable becomes damaged during installation. I need to check my references tomorrow morning and i'll get back with you with an answer. Thanks,

-Rip

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will do .thank you

Good morning, thanks for waiting. The clutch cable is self-adjusting, below is the factory information and diagram. If you had the cable replaced about 10k mikes ago, I would have it looked at first, for possibly being defective. If your working on it yourself, try pulling the cable at the clutch lever, see if there is excessive play.

-Rip

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good morning,
i took the car back to the place that installed the cable and pointed out to them where the cable sleeve is split open on about 2 inches at the dampener, causing the whole cable assembly to distend. their answer was that i could need a new clutch, then i said there was no sign of the clutch going bad ( grabs just fine, doesn't slip, jerk, the pedal did'nt get hard or soft) then they said that the cable must be encountering too much tension and i possibly need new trow-out bearings, and then they said that they would replace the cable even though it's unlikely it was defective...does any of this make any sense?

No, i've never had a worn clutch cause a cable to break. If there was a jammed lever or throw out bearing, I could possibly see it happening but the vehicle would not be drivable. Ask them if the cable is factory, often aftermarket cables are inferrior. And if this shop does not specialize in Saab vehicles, there may be a good possibility it was damaged upon installation. These vehicles need patience to work on.

-Rip

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would the cable wait 6 months to go bad?

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