Project Dumpster Fire - The Madness Continues

"Akio Ohtori - RIP Oppo" (akioohtori) 09/21/2017 at 11:28 • Filed to: Project Dumpster Fire

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I can feel the finish line getting closer. Or at least I think I can. It might just be gas. Or gas fumes.

I apologize for the lack of pictures on this update. I’ve had a bit of the “red mist” on this project. And very dirty hands. And I keep leaving my phone weird places. Must be gas fumes….

After my last update, user !!!error: Indecipherable SUB-paragraph formatting!!! my sluggish operation could be a faulty wastegate. Having done 0 work to the turbo system, I was also inclined to believe this. I was gradually warming up to the idea of the problem being exhaust related, so the wastegate fits too.

That said, the first thing I checked was timing. Unfortunately, one consequence of sitting so long is I couldn’t actually read any of the markings on flywheel. A wire brush and some contact cleaner (while the engine was running) solved this. I hit it with the timing light and was pretty much spot on. Only off by about 3 degrees. Unlikely to be the problem.

Next up was to check the wastegate. I stated the car and revved it and didn’t see any action from it, but that didn’t really prove anything. What I DID see is small bubbles in the WD40 I sprayed in the actuator arm. Possible further signs of a clogged exhaust? Well let’s keep going. I disconnected the wastegate from the APC solenoid and blew 10PSI of air in there. The actuator extended, no problem. Ok… next up…

Following the instructions in the Bentley, I checked the APC solenoid. Though I’ll be the first to admit I have very little idea what it is actually doing, it DID seem to be working as per the instructions. Next.

Now I needed to either remove the CAT or the O2 sensor to see if that helped. Neither sounded appealing, but I opted to try the cat first as I didn’t really want to bypass the turbo yada yada yada…

With the exception of one bolt, the whole process was pretty easy. I mean… I got a lot of PBBlaster and rust in my eyes… but that is par for the course. The (surprisingly heavy) cat came tumbling down, introducing me to another fun problem: with the center pipe now unsupported the whole back half of the exhaust is hanging down. Great.

After a couple of failed attempts to fix the hanging exhaust, I decided to inspect the cat. I’d been putting this off because I knew it would be fine. Because that is how my life works. Guess what? Yeah… pretty much perfect looking despite being from 1996. That said, I’ve never actually seen the inside of a cat before this… so meh?

After trying to completely remove the back half of the exhaust which is both in surprisingly good shape and very well put together, I gave up and decided to wire the exhaust to the heat shield hanger bolts using bailing wire.

Now… on to the test drive.

It was… underwhelming. And overwhelming. The din of a turbo four running straight from the headers is… substantial. Mostly I’ve never heard a turbo so clearly in a passenger car. Whoosh! That said, the performance wasn’t good. The engine still felt like it was holding back and really didn’t want to rev… and that is when things get weird.

After conceding defeat and not wishing to irk the neighbors more than I already do, I decided to cut short the unsatisfying test drive. In the driveway, I knew I needed to regroup and reassess possible fault conditions. Make lists. Think things through. Don’t just start fucking with shit.

Instead I started fucking with shit.

Out of irritation and anger I leaned out the mix and headed back out. It felt… better? Ok, how about a little leaner. Better? Leaner? Better. Leaner? Ok now the engine really wants to die… but it strangely backfiring on deceleration… maybe bring the ratio back up a bit.

So the question is now: did the removing the exhaust change anything? Was it just the mix that fixed it? Or did I just finally work through all the bad gas that was stuck in the lines, fuel accumulator, and pre-pump chamber? How much fuel could that be? Should I just replace the exhaust anyway (it is in REALLY good condition).

I don’t know the answers to these questions. I do know that the car is now drivable, if loud, and that feels… really odd. Like… REALLY odd.

Doggo for your time.

traitor joe > Akio Ohtori - RIP Oppo 09/21/2017 at 11:59

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When you say you leaned out the mix, how were you doing that? Anyway if you were running rich maybe your engine was just never getting to closed loop. Check the upstream O2 sensor? They can also get stuck at a certain reading causing unnecessary fuel trim adjustments.

Other than that I don’t know what system your car uses but you might want to check on the MAF or whatever kind of airflow sensor it has.

Akio Ohtori - RIP Oppo > traitor joe 09/21/2017 at 12:10

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Saab 8-valve engines use Bosch K-Jet, aka CIS. The O2 sensor (of which there is only one) only controls a single, auxiliary injector (there are 5 total injectors, the extra is for o2 and cold start) and is only responsible for fine tuning the AF ratio. Early CIS didn’t have any O2 sensors... so there is that. It is all a little primitive and very bonkers.

A/F ratio is adjusted via a mix screw on the air plate. Without an exhaust gas analyzer or wide-band O2 sensor I’m kinda just tuning by ear. IIRC you can take some readings from the stock O2 sensor to figure out if you’re running lean or rich and that is likely in my future.

traitor joe > Akio Ohtori - RIP Oppo 09/21/2017 at 12:50

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Sounds like you need to fly in some sort of Swedish witch doctor. Only other thing I can add is maybe something to do with your fuel pressure or an injector stuck open. You can pretty easily perform a (rudimentary) test on an O2 sensor with a multimeter. In fact, I’d probably be sticking a multimeter on anything with wires. Coolant temp sensor, TPS.. Good luck!!

Urambo Tauro > Akio Ohtori - RIP Oppo 09/21/2017 at 16:50

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Guess what? My brother just bought a 900 S, and I’ll be helping him wrench on it. I’m new to Saabs, so I guess I’ll be checking out your older posts with renewed interest!

Akio Ohtori - RIP Oppo > Urambo Tauro 09/21/2017 at 17:26

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That’ll be a fun project! What year?

Urambo Tauro > Akio Ohtori - RIP Oppo 09/21/2017 at 17:43

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’91. He’s pretty stoked.

Akio Ohtori - RIP Oppo > Urambo Tauro 09/21/2017 at 18:05

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Awesome! Read my stuff with a grain of salt then, most of my problems have been related to CIS/ K-Jet, which is exclusive to the 8-valve engines. Yours will have something more modern and less hateful.

Urambo Tauro > Akio Ohtori - RIP Oppo 09/21/2017 at 18:14

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Ah, well that’s a relief. The very first thing to be addressed (after transporting the car via trailer) will be fuel delivery. It only runs on starting fluid at the moment. (Poor thing hasn’t been driven in about a decade.)

Akio Ohtori - RIP Oppo > Urambo Tauro 09/21/2017 at 18:26

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Yikes! Yeah, mine has been off the road since 2004. I think it was overkill, but we ended up replacing pretty much every inch of the fuel system up to the distributor (tank, pumps, lines, filters, distributor). Chances are you can get away with draining the tank and probably throwing in a new pump.

Best investment for both of you is to buy a Bentley manual. It is essentially abridged version of the (very large) factory service manuals.

Also the Classic Saab 900 group on Facebook is a phenomenal resource.