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2000 93 SE Vert Auto : 2001 93 SE Vert Manual
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Discussion Starter #1 (Edited)
I have looked this up and seen quite a few threads, most of which end without ever divulging the issue.

I recently did the PCV update to the She Saab as well as replace the aging and cracking vacuum lines. In doing so I noticed that the brake booster vacuum line assembly was cracked at a one way valve, so I replaced it with a new one (not sure if I did this replacing the vacuum lines or if it was already broken). Note that the car has an automatic transmission, so its has a few bits that are different than my 5 speed.

The car used to start fine when it was cold, but now it stumbles on cold start and throws a P0300 code. I can keep it from throwing a code by giving the engine some gas when it tries to stumble, as if it were a carbureted car. Trouble is I can only do my testing once a day when the car has sat overnight. Once the car gets over the initial startup it runs fine and has plenty of power with no stumbling whatsoever.

I have gone over and over all of the vacuum lines, PCV system and brake vacuum lines as well as looking for any other potential vacuum leak. I also changed the spark plugs to no avail (but I was happy to see that the ones I pulled looked good).

I have not tried a replacement DIC, but will swap this one with the one in my Saab this evening to see if it makes a difference when I start the car tomorrow morning.

Any advice or insights appreciated.

---

Spoiler Alert: I think it was the Crankshaft Position Sensor (CPS)
 

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I can only imagine two things you could have done during that work: Left a vac line unattached or hooked up wrong or wiggled a connector that is marginal (corroded inside). You could try cleaning the DIC connector. Also, did you gap the new plugs to .9mm? That can help.

Other than that, it's time for a DIC swap to see if that's it.
 

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Discussion Starter #3
I changed out the DIC to no avail. The problem seems to be getting worse, so I think that something is failing.

I am beginning to suspect the Coolant Temperature Sensor. From the bits and pieces I have picked up researching generic car rough idle at cold start, the engine temperature sensor is often listed as one of the suspects (I am making an assumption that that would be the coolant temp sensor for a Saab).

When the car is warm the car runs well and pulls strong without hesitation or hiccup. It also idles smoothly when warm, which is one of the generic indications of a bad engine temp sensor.

I pulled the vacuum lines off one at time while the car was running and it seems there is no vacuum leak. There was a little bit of additional roughness when the individual lines were disconnected, but not too bad at idle. I pulled the brake booster vacuum and the car almost cut off, so I am crossing that one off the list.

I am going to replace the Coolant Sensor and if that does not work I am going to have to swallow my pride and take it to the shop to get it diagnosed. It may take a week or so before I get the part.

I have been a bit disappointed and frustrated at the number of threads on this site concerning this issue that did not post their final fix, so I am going to make sure that I post when I get this issue sorted.
 

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What year is the car?
Doubling down on this... if it's a T7 OG 9-3 you can pick up the factory sensor at a GM dealer. Only about $15 last I checked.

That's a quick change part (Pull connector off, deep socket on sensor, remove, stick finger in dike, spin in new sensor, tighten, re-connect. Ten minutes work. If you're not real coordinated or sure of the path, have an assistant stick their finger in the dike when you pull the old one out while you get the new one ready and screw it in.

FWIW, this isn't the normal failure mode for an engine temp sensor... but one never knows.
 

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Discussion Starter #7
So far no luck. However, the situation is getting worse. It used to be that there were issues on cold start, but the car ran strong after a minute or so. Now the car is starting to hiccup at speed and has cut off on me at stop a light. It did not throw any codes, which I thought peculiar. I had to put it in neutral and keep the engine at about 2k rpm at stop lights to make it home.

I am beginning to think its an O2 sensor, but it seems that it would have its own set of code. Even though I used my DIC in this She Saab and it had a rough start, I have not rulled out the DIC.

I am going to replace the fuel filter this weekend to cross it off the list. I would have replaced it last week, but I forgot to order the washers with the rubber inserts. Since I am now the custodian of two Saabs I ended up getting ten each of the large and small washers because they were so cheap - the shipping was more than all the washers.
 

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FWIW, you can reuse the copper ones if that's what's in there. Wet dry sandpaper flat on a flat surface (like a table saw), move the washers, not the paper, keep it flat on the surface. up the grits and finish at 400.
 

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It's not the fuel filter, and it's not the O2 sensor.

What year is the car? What engine? What transmission?
 

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Discussion Starter #10
The car is a 2000 SE Automatic with the HOT engine.

I thought that I had the problem solved, but alas it does not appear so.

When I went to replace the fuel filter I went to relive the pressure on the fuel rail and there was no pressure. I also noticed that there was gas around the valve and that the valve was loose. I tightened it the best I could with a tire valve stem tool, but I don't think it ever bottomed out or got real tight.

I do not see any fuel when I check the valve when the car is idling in the driveway and the car runs much better, especially at idle, but there are still issues on cold start and the car stutters occasionally when I have been coasting and then give it a little gas. The stutters seem more pronounced after a hard acceleration, but they are not predicable and I can not make them happen on demand. The stutters only show up after I have been driving for over 10 minutes. They seems more pronounced and frequent when in sport mode.

No doubt the leaking valve was part of the issue, but there is still a gremlin lurking somewhere in the system.
 

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The system should hold good pressure for many hours after shutdown. That's a function of the fuel pressure regulator and the check valves on the pump. If either has an issue, pressure won't be held. Bad check valves will generally lead to longer cranking but no other side effects. A bad regulator will cause all sorts of havoc, including very rich running and possible catalyst damage. Obviously an external leak will also cause loss of pressure, but those are uncommon.

I would really invest in an OBD2 tool that can show live data. That information is invaluable when you don't have a check engine light to start you out.
 

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Discussion Starter #12
I have an OCD2 tool that works with my iPhone and is capable of viewing live data. What should I be looking for?
 

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Discussion Starter #13
I have an OCD2 tool that works with my iPhone and is capable of viewing live data. What should I be looking for?
 

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I would start with MAP and MAF readings and make sure they make sense. I would also look at O2 sensor 1 to get a sense of what mixture looks like. Between these you should know what sort of issue you're looking at.

Have you physically inspected your spark plugs?
 

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You didn't mention how many miles were on the car, has the fuel pump been changed ? some of what your experiencing sounds fuel related, lack of pressure, stumbling when first starting, the pump itself may be loosing the ability to build pressure. Do you know if it's been changed.?
 

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Pressure check tool used to be a loaner from Autozone AFAIR.
Try turning the ignition to on when cold. Wait one minute. Then start. See if it starts or runs better.
 

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Pressure check tool used to be a loaner from Autozone AFAIR.
Try turning the ignition to on when cold. Wait one minute. Then start. See if it starts or runs better.
I'm curious why you suggest a minute, Bob? AFIK, the fuel pump will activate with the key on, but will shut off after a few seconds with no CPS signal. Waiting an additional ~50+ seconds seems like an opportunity for pressure to potentially bleed off and to cloud the diagnostic process. Or am I missing something?

I would do a key on for five seconds...key off briefly...key on for five seconds...key off...(repeat 2-5 times)...try starting it. This would allow the pump to run for two-five cycles to pressurize the system.
 

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Complicating things more, I think T7 only primes the fuel pump X times over Y seconds. Multiple turns does not result in multiple primes. I think it's something like runs once every 30 or 60 seconds or somesuch.

The process I use:

1. Shut the car down, come back hours later, check fuel pressure (WIS describes this precisely)
2. Turn the key, let the system prime, observe pressure
3. Jumper the fuel pump so it runs, observe pressure
4. Modulate the FPR +/- psi and be sure fuel pressure changes accordingly
 
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