1996 Saab 900s NA 2.3 No spark, tried everything...HELP

[Pinnacleranch]

Hello all, I bought this Saab from an owner said it had died on him. At first it started and ran but then would not restart so started replacing the obvious parts called out on various forums. So far and in order replaced are: fuel filter, CPS, fuel pump, coil, immobilizer checked and has already been bypassed, checked all grounds from battery and around engine compartment, cleaned distributer hall sensor, cap and rotor in good shape, checked all fuses, it has gas. So it cranks but has no spark and won't fire. Battery is charged. When key turned on gets a chattering FI relay after 2 seconds and check engine light. This car does not have a DIC. Before I replace the distrubutor to get a new Cam position sensor is there anything else I have missed? FP seems to prime but tested new pump by crossing fuse connections and its ok. If you have suggestions as to what to try next I am at my wits end. Frustrating car!
Thanks for any help.

[Digger]

If this is your distributor http://www.ebay.com/itm/94-95-96-97-...RYgLST&vxp=mtr it's a Bosch and if you have juice from the coil no spark is usually a bad Hall. If you're really adventurous you can tear the distributor down and resolder the connections. Usually isn't always and try that before you spend a couple hundred on a reman, or give a good used one a try.

[Pinnacleranch]

Thanks Digger. I have a reman distributer but have not tried it yet. When you say juice from the coil do you mean hot voltage from or power to the coil? I do not have anything coming from the coil. Could be the cam position sensor I guess. But i feel like it is not likely. Something else I may have overlooked. How do I get at the ECU to check for bad ground or loose connection? I checked for grounds under the intake manifold but only saw one on the end driver's side. Is there others? This car has a conventional distributor and a regular coil, cap and rotor. I meant Normally aspirated (not turbo) in the description but I guess it is a new generation. This seems like a simple car to be so confounding. The ebay picture is what I have.

[Digger]

I mean the sparking hot, make you jump, knock your socks off voltage that comes out of the coil and goes into the top of the distributor. The right angle spuds on the rotor came in when vacuum advance went away, the thing under the rotor is the electronic equivalent of mechanical vacuum advance and points. When mechanical points don't open and close you don't get good spark at the plug, but with power and ground to the coil, you will still have enough juice in the coil to create a visible spark to ground if you pull the wire out of the cap and get the end close to ground. You can also get knocked on your butt while doing this so rig something up to do this or use something with more insulation than your hand to hold this in place. Soget setup, turn the key and take a look. If you have an O Scope I can look at the wire diagram and tell you what to look for, but I can't tell you where it is under the hood.

You have a vintage automobile, a vehicle that is old enough to qualify for special plates in most states and I haven't been under the hood of one of these things for years. If these things hadn't come with Teves brakes way back when, I wouldn't know that these distributors came in about the same time the Teves went away and I wouldn't know that they are usually the problem. You have a good reman distributor, if your coil doesn't ohm to open and you have any kind of spark out the end, but not enough to fire the plugs, your most likely repair is distributor replacement and when you're working without test equipment it's also your best troubleshooting if it doesn't.

[Pinnacleranch]

Yes I thought you meant hot spark. We have tested that and there is nothing from the coil on cranking. It seems to me the items that can shut off spark are ECU detecting fuel supply drop, Fuel pump causing said drop, CPS, Immobilizer, and possibly the Hall sensor in the Distributor. We have changed all except the distrubutor at this point. I have the reman one to put in next but was really hoping to send it back. CPS is pushed all the way in. The way the relay chatters and check engine light comes on with cranking is indicative of loose ground but we can't find one. It really acts like something simple and I was hoping someone would have a similar experience to shed some light on this.

[Digger]

Do you have power to the coil with key on, it should be on when key first turned to on. Was a lot easier to check power at coil before the plug connectors started getting in the way, but you can do it through the back of the plug connect.

If you have power to coil with key on, jump the starter solenoid to crank the engine before auto shutdown circuit drops power to coil and see if pops. You're right, things can shut down spark, but don't forget to check that power to the coil is being supplied for start. If you have power to the coil with key on and don't when key to start, it's whole different problem.

[Pinnacleranch]

Ok that's good information. I will try tomorrow and let you know the result. Thank you for your help. I really appreciate it.

[Digger]

This coil test is from the 900 WIS and if you have a 32 bit or 64 bit Windows 7 Pro operating system that will emulate 32 bit XP, you are going to want to download it if you can and buy if you can't as you will need this and all it's pictures if you don't get spark from the coil. You were hoping that someone with similar experience could shed some light on this and the tech bulletin on 3 circuit breaking for Saab 900 3D/5D and 900 CV MY95-98 from VIN S700999 inclusive, details in 21 short paragraphs the repair of a crank but no start problem caused by oxidized relay contacts. This is something you should do before you replace an engine controller as you might never find the tool you need to check input voltages for the US market, OBD2 compliant Motionic 4.1 ECU which is mounted inside the cab on the RH pillar and accessed by removing the glove box and pulling down the carpet.

Coil test engine will not start:
1, Disconnect the coil high voltage output cable from the distributor and connect it to a test spark plug with a gap of about 10mm. Ground the plug and engage the starter motor. If the plug does not make a spark continue to #2.

2. With the ignition switch in the on position, check that the +15 pin of the ignition coil is supplied with battery voltage (from fuse 17) Also check that pin 1 of the ignition coil is supplied with battery voltage.
If voltage is supplied to the +15 pin and not the pin 1, unplug the connector and check resistance of the ignition coil across the +15 and pin 1 (primary winding) for resistance of .52 to .76 ohms. Also check resistance of secondary winding of 7.2 to 8.2 ohms between pin 1 and the coil high voltage output terminal.
If the ignition coil is OK proceed to #3.

3. Plug in the connector and measure the voltage across pin 1 and the +15 pin. With the ignition key in the on position the voltage should read 0, with the starter motor cranking the voltmeter should be pulsing with a reading of about 4- 6 volts.

NEXT THING --- how the heck do you make sure the immobilizer is actually bypassed and check to see if +15 via fuse 17 is present on pin 58 of the ECU, while the cable is plugged into the ECU. Not going to be easy without the special cable and test box, but it can be done.

[Pinnacleranch]

Ok we have voltage at the coil but 7.5 volts with key on. (Indicates bad ground somewhere perhaps?) but no hot spark. We changed out the distributor for the reman one and taped up the Hall sensor wires where they were fraying. Still no fire. The immobilizer in this car has been taken out not by us, and wires into and out spliced together cleanly, might even be factory. We have not changed anything with it and it did run prior. Will try to download the manual to chase further unless you can suggest what to try next. Check engine light comes on and FI relay chatters on Cranking. Something is interrupting spark. #17 fuse is intact.

If you have access to the teck bulletin with the 21 paragraphs on repairing crank but no start would it be possible for you to post the paragraphs?

[Digger]

Ok we have voltage at the coil but 7.5 volts with key on. (Indicates bad ground somewhere perhaps?) but no hot spark. We changed out the distributor for the reman one and taped up the Hall sensor wires where they were fraying. Still no fire. The immobilizer in this car has been taken out not by us, and wires into and out spliced together cleanly, might even be factory. We have not changed anything with it and it did run prior. Will try to download the manual to chase further unless you can suggest what to try next. Check engine light comes on and FI relay chatters on Cranking. Something is interrupting spark. #17 fuse is intact.

Fuse 17 is intact, but what is your voltage at fuse 17?

The distributor has nothing to do with key on voltage at the coil, wrapping up frayed wire harnesses will prevent a lot of odd problems from occurring when you get the engine running and the car back on the road.

Before we go any farther we need to get some terminology straightened out. A bad ground will give you a voltage potential where you shouldn't have any. A bad contact or connection will not give you the voltage and potential you should have. With auto electrics the best example and most common problems are stranded wire that has wiggled enough at some point to break most of the wire strands. Check this with a volt meter and it will show 12V, check it with a light tester and the mostly broken wire won't carry enough current to light the 12v bulb. Another problem is contact oxidation, bright shinny new copper penny's eventually tarnish with exposure to air, bright shinny copper roofs turn green with exposure the elements. An oxidized contact might carry enough current to light your 12v bulb, but the added resistance of the crusty contact will diminish the supplied voltage and it won't light it bright.

Divide by 2 is the standard common sense method of troubleshooting a complex circuit. If something isn't working at the end, find out if it's working in the middle. 7.5 volts at the coil means this thing isn't working at the end, if it's not working in the middle there's no point in looking at things between the middle and the end.