It's always something...strange interruption of drive in specific circumstances (Saab C900 content)

This is punishment for not driving my Saab 900S for a couple months. I had a locked up rear caliper, but that's now been addressed and the car rolls freely and stops normally. Drove it yesterday to pick up a load of stuff for the dump this morning. On the drive back I felt a jolt in the driveline a couple of times, always starting out from a stop, and always with the nose pointed uphill (that happens a lot here - nothing is flat). At first I thought it was a miss, but the more it happened the more it seems like something in the driveline. Did it again this morning, same circumstances: first or second gear, nose up, on the gas.

When it happens it feels as if someone just snapped a giant clamp on the flywheel (or slammed on the brakes - I don't want to suggest that it's necessarily an engine issue) and the engine wants to stop turning, suddenly. If you continue to push it will stall. Lift off, engine returns to idle, and then you can accelerate normally (unless you're still pointing uphill). Worst instance was yesterday evening, when I had to rev the engine and dump the clutch to get going on a particularly steep hill. There's no clutch slipping, no loss of power, no indication of a problem in normal driving, including under heavy throttle.

I was under the front end not long ago and inspected everything visually and saw nothing awry. The problem appeared suddenly, so obviously I have to get in there again and see if anything's changed, but there was no indication of an issue earlier. I already checked the connectors at the MAF, ICV, and throttle position sensor - all seemed fine, nothing loose or corroded. Any brilliant ideas as to what's going on would be most welcome.

Sounds secondary ignition-ey or fuel pickup-ey to me.

I had those exact symptoms on my Saab 9-3. I know it's a completely different drive train. It was a bad coil. Not sure if that helps or not. 

As far as the coil, this is a traditional coil and distributor setup, not the coil pack on the 9-3 (I had a 9-5 years ago, so I'm well-versed in the joys of later Saab coil packs). I'll have to check for excess heat and look at the connections and resistance at the coil. Plugs and wires, cap and rotor are only a few years old, and good stuff, not cheap parts store crap. I definitely considered fuel, and it could be the pump I suppose, but the tank is nearly full, and I had no such issue when it was down to a quarter a few days ago.

There are two fuel pumps on '89s - maybe the smaller prepump is failing? [edit]But on nonturbos there's only one pump, so nvm.[/edit] 

The only other thing I can think of is a bad front motor mount, but I think you sorted that at some point. (Distributor whacks the hood when you boot it and the engine lifts up.)

Motor mount is totally solid. I will have to investigate the fuel pump arrangement - it's one of the few bits of this car I haven't had occasion to dig into yet.

So of course I decided to start looking at stuff after dinner. I pulled the coil to test it. Connectors were a bit dirty, but showed clean metal where the washers contact them. Cleaned everything anyway. Primary circuit spec is 0.5-0.9ohms - coil tested at 1.2, so that's problematic. Secondary circuit spec is 7200-8200; tested at the high end of the range at 8100. Put it all back together and now it won't start. And it started raining heavily while I was working outside. No good deed goes unpunished.

This car is a non-turbo and has the EZK ignition system. My wires, however, don't match the wiring diagrams at all. I have the ignition amplifer mounted to the coil bracket. The amplifier has a four-wire connector coming in and two wires - red and blue - coming out to the coil. There is a single black wire that runs to the body of the distributor from the other coil terminal. I could swear the red and blue were on the + terminal and the black on the - when I pulled it out, but could that possibly be backwards?

Right now I just want to get it started so I can move it; I can replace the coil later and see if that solves the initial problem. No matter what, I'm not dealing with it until tomorrow. I'm soaked and annoyed.

Since this stupid thing kept me awake until 0200 trying to figure out what I did wrong, I went back and checked my work first thing this morning. Turns out working in the pouring rain isn't ideal for keeping one focused on things. Since the wiring diagrams were less than helpful (Saab seems to have made a lot of little changes to the ignition system in this period), I checked the witness marks on the coil to make sure I had it in the proper orientation. I then looked at the wiring lengths and sorted out that I needed red and black on the + and blue on the -. Once I did that it started right up. So now I can get back to trying to figure out the initial problem, unless cleaning up the terminals on the coil somehow magically fixed it.

Well, that doesn't sound like much fun. 

Also, I was wrong about your car's pump system earlier - it's got only one. 

In reply to procainestart :

It wasn't the happiest time I ever spent working on a car. I'm just glad I didn't fry anything with my carelessness.

Thanks for the heads-up about the fuel pumps. It would have made me nuts if I couldn't find the second pump.

I had a 91 900s that did that.  It would randomly lose power and need a lot of foot dancing on the throttle to keep it running. After a dozen or so seconds, it would pick up and drive normally again.  

I haven't had a chance to test-drive it since messing with the coil wiring - maybe later today.

In reply to mad_machine (Forum Supporter) :

Do you recall if the problem you had was only when accelerating from a halt, and only when pointed uphill?

02Pilot said:

I haven't had a chance to test-drive it since messing with the coil wiring - maybe later today.

In reply to mad_machine (Forum Supporter) :

Do you recall if the problem you had was only when accelerating from a halt, and only when pointed uphill?

very few hills at this end of the state.  It would always happen at random times too, no rhyme or reason and I never did discover why.  

If this car uses the same rubber fuel pump mounting as a late 99 hatchback pull the pump up out of the tank and look for floating pieces of pump mount in the tank. I saw one of those cars drop the pump into the tank due to the mount rotting away. This was in 1984, when the car was only a few years old.

I believe the later cars use a different style of mount, but I'll have to check to confirm.

TurnerX19 said:

If this car uses the same rubber fuel pump mounting as a late 99 hatchback pull the pump up out of the tank and look for floating pieces of pump mount in the tank. I saw one of those cars drop the pump into the tank due to the mount rotting away. This was in 1984, when the car was only a few years old.

It does not, thankfully. These later ones went to a plastic collar that threads on, IIRC.  Any luck yet, Pilot?

In reply to Powar :

Not yet. I was away last week, and now it's too damn hot to risk getting stuck somewhere in a car without functional air conditioning. Once it cools off I'll continue the troubleshooting process.

So it's finally cooled off and I had a little time, so I test drove the car to see if I could replicate the problem. Short answer: nope. Either cleaning the coil connections solved it, or (more likely) the coil being slightly out of spec is causing issues when it gets hot. Checking the Saab forums I see a fair number of people with similar resistance specs on their coils, some with issues, some not. I'm thinking I should just replace the coil, but of course no one stocks the OE part. I suppose if I want to do it, I'll have to use a generic part - suggestions for what's good would be helpful. I think the OEM is Bosch, but the label's gone.

Next up is to check fuel pressure. I would have done it now, but the engine is hot, and I don't feel like scalding my forearms unnecessarily.

I don't know for sure and I'm far from my 89T for a while, but it may be that the wiring harness has everything you need to convert it to the standard coil and separate ignition control module (both Bosch parts). The module on turbos is normally bolted to the inner fender, left side, and the coil is bolted to the rad crossmember, right in the middle. It's been a few years, but if memory serves, the nonturbo standalone module has the same plug as the Turbo but different pinouts; in addition, you would need to get a wire from the EZK to the module. Also from memory, the turbo and nonturbo modules are different. The connector has ~5-6 pins. 

This is a long-winded way of saying that the more common parts are more likely to be available and converting might be simpler. 

Assuming, of course, it's your coil/module. I'm wondering, too, if the CPS might be failing or the wiring is messed up and moving around when the car is on a hill. 

I'm not discounting anything, but I inspected the CPS wiring carefully when I had it apart to do the front main seal a couple years ago, and it was totally fine. I really hope that's not it, as those sensors seem to be getting scarce. I'm inclined to think the coil itself may be the problem, but again, that may just be wishful thinking. I'm goiing to drive it some more when I have the time and see if I can pin it down more closely.

Updating this. Wanted to get the Saab running for the first time in months, so I took a booster box, hooked it up, and the car fired right up. Moved it from its semi-remote parking place to the main driveway with no issues. Left it running while I checked tire pressures and such; charging voltage was good according to the gauge. After running for about 15 minutes it just died and would not restart. Pulled a plug and there's definitely fuel, so it's a spark issue. Coil was not hot to the touch, and the hood was open on a ~60degF day, so I don't think it's a heat issue. Tried to restart with the engine fully cold - still nothing. I'm left with thinking it's the coil, the Hall sensor, or the ignition booster next to the coil (89 non-turbo 900S w/ EZK). Testing will commence when time permits, but any thoughts about this latest failure mode are welcome.

If the tach needle bounces a little while cranking, then the ignition control module and the Hall sensor are working, which would leave the coil.

If the CPS is dead, and finding another is hard, I have read about people using a distributor from a pre-CPS NA or any Turbo car, which has the Hall sensor inside it, and grafting in a connector to it; manually set timing per Bentley for NA with Hall sensor in distributor. The LH2.4 distributors have a more robust plug than LH2.2 -- I'm getting old, but I'm pretty sure '88+  is the first year for LH2.4. Don't plug a vacuum line into the retard/advance capsule on a Turbo distributor, but do not remove the capsule, either (it holds the Hall sensor in place).

BTW, you can run the starter from under the hood, at the six-pin round "TSI" socket on the fuse block. Pull the fuel pump fuse first, put it in neutral. :-)

From a Saab tech on Saabnet:

   1 is +30 (steady power)
   2 is ground
   3 is starter engagement
   4 is +15 (switched power)
   5 is RPM signal
   6 is not used

   So you can supply power from pin 1 to 4 and have the ignition turn on and then also jumpstart the car by supplying power from pin 1 to 3.
  
   Be careful though since the cooling fans and a couple of other things WILL NOT run when ignition is turned on through that socket using pin 1 and 4. You are
   actually backfeeding power toward ignition switch +15 by doing that.

Not the same vehicle, but a 1999 Jeep XJ.  Would have occasional hard starts, then nothing.  Checked the usual suspects, fuel, spark, etc.  Replaced a crank sensor, and cam sensor.  Turned out to be a hairline crack on the coil, had spark when tested, but not enough to  start it.  I'd say give the coil another look.  Good luck.

Rainy day here, but I figured I could at least go out and crank the engine to see if the tach moved - sure enough, it bounces a tiny bit when the ignition is turned on, and a bit when it's turned off, so I guess the Hall sensor and ignition module are good, so now it's time to buy a coil. The OE Bosch seems NLA, so I'm thinking I'll opt for the MSD Blaster 2 or the Accel Super Stock Breakerless - both seem to meet the 0.7ohm primary resistance spec, and are as close as I can find to the secondary spec. Any reason to buy one over the other, or something else?

I just wasted a big chunk of the weekend by misdiagnosing a no-start issue with my 9-5. I was pondering your 900 no-start trouble while flailing under the 9-5, and it occurred to me that the advice I gave earlier isn't applicable to your car because it's got EZK. Electrical stuff is a bit mysterious to me, but my thought was, the CPS is sending a signal directly to the EZK, which, in turn, sends it to the tach, so you see the bounce. On Turbos, the ignition control module is involved with sending the signal to the tach, but I'm looking at a wiring diagram and that's not how it works for EZK. My apologies for passing along bad info.

So, before concluding that the coil is the problem, maybe confirm that the signal to the control module from the EZK isn't making it, or it is, but the module isn't passing it to the coil. Also, I have no idea where the ground for the integrated control module is located, but maybe the connection is loose or corroded.

I've misplaced my Bentley manual, but there should be a diagnostic section in there. If you don't have a Bentley, lmk and I'll look for mine. Meanwhile, the wiring diagram (but, curiously, no detailed diagnostic info) is here (actual page 88): https://drive.google.com/file/d/1q_IFS63FRFAlL1KdSjtpGNZBJyezWztG/view