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Discussion Starter #1
Hi All,

I just bought a 2007 9-3 Aero 2.8L V6 manual with a busted engine that I will be replacing. Is there any recommended maintenance I should perform while the engine is already out of the car?

I will be switching the turbo for the one on the new engine, and will also replace the serpentine belt. Any sensors, pumps, etc that I should replace as well?

Also, is it worth taking off the cover to check the timing chains? The new engine has 75,000 miles on it.

Thanks for the help!

Isaac
 

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Hi All,

I just bought a 2007 9-3 Aero 2.8L V6 manual with a busted engine that I will be replacing. Is there any recommended maintenance I should perform while the engine is already out of the car?

I will be switching the turbo for the one on the new engine, and will also replace the serpentine belt. Any sensors, pumps, etc that I should replace as well?

Also, is it worth taking off the cover to check the timing chains? The new engine has 75,000 miles on it.

Thanks for the help!

Isaac
Change the timing chains and tensioners. The original chains were not hardened and will stretch, and so getting them done before you install the engine is infinitely easier. And the tensioners are oil driven, so you want to make sure they are 100% functional. So, probably wiser to change them on a motor that is probably a decade or so old.
 

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Oil pressure and oil level sensors! These are both cheap and are also complete pains in the rear to replace when the engine is in the car.
 

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Discussion Starter #5
Hey all, OP here replying 10 months later :rolleyes: Sorry for dropping off the edge of the earth!

Thanks for all the responses! I just thought I'd update the thread to say that I finished the engine swap last summer and my Saab is now running like a dream! Or, at least most of the time... currently working on a mystery misfire that cropped up recently 😄

I'm happy to say that one more "dead" Saab has been restored to the road!
 

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Did you do new plugs and coils when putting the “new” engine in?
 

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Discussion Starter #8
I put in new NGK plugs, but used the coils that came with the replacement engine, figuring they would be easy to replace later if they failed and I had more cash on hand at that point 😁

Here's the thread I created for the misfire problem, if you're interested! 07 Aero injector mystery misfire
 

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There is is a wiring harness/connector at the back of the engine near the atmospheric sensor.
Disconnect the connector and inspect it, attach a photo of both sides of the connector here
 

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Discussion Starter #10
Will do! Would that be the connector for the injector harness? Or the one directly behind/beneath the atmospheric sensor (don't remember what that connector is for...)
 

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Discussion Starter #12
Sounds good. I looked at that connector, and I can't see anything that looks problematic. Here are the pics - I put some dielectric grease on it back in the spring when I was rebuilding the engine...

271339
IMG_1322.JPG
 

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Discussion Starter #13
Also, I got a coil spark tester, and the misfiring cylinder is sparking very well. Since I already replaced the injectors, it seems that this reduces the problem options to either the wiring to the injector in question, or the ECU itself... unless I'm missing something...
 

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Pull the harness to that injector, connect it to one of ur old injectors (i suppose u still have them) and see if the injector fires or not ..
Make sure u do that with ignition off, and erase any faults before starting the car
 

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Discussion Starter #15
Sounds good. I can try that tonight. How do I get the injector to fire without turning the car on?
 

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Discussion Starter #17
Long post here, but I think we're getting close to a diagnosis... I don't have a scan tool, so I started the car to test the injectors. Magically, it did not misfire, so I tested injector #1 (the problem injector) with a screwdriver to the ear - firing perfectly. I compared it to the other injectors - exactly the same.

The car then started misfiring, and I found that injector #1 was no longer firing at all. I unplugged it, plugged another injector in, and that one did not fire either. Then I pulled injector #6 for comparison, plugged in the other injector, and it fired nicely. However, within 30 seconds the computer seemed to realize what was happening, and stopped the injector from firing. This happened several times, with clearing the codes and restarting the car between each time.

I then used a multimeter to test the wiring. With the car running, but the injector NOT firing, I get 14.5 volts on one side of the connector, and 3.5 volts on the other. These measurements were the same at both injector connectors. But because the computer shuts down the injector, I could not test the firing voltage to compare a working one to the problem.

Because the 14.5/3.5 volts are reaching injector #1 no problem, it seems 99% likely to me that the firing signal would also reach the injector, but that the computer is not sending the proper signal.

Is there some way to confirm this? Such as by using a TechII? The only other thing I can think of is to get a more advanced multimeter by which I can test the voltage to the injectors at the wires themselves (something that pierces the wires and will also measure with sufficient accuracy)
 

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Its hard to say what r u expected to see as voltage coming from the ecu without a scope, the other factor is the ecu shutting down the injector due to the misfire.
What if u do the following, start the car until it start misfiring, plug a small amp test light to the injector connector, then quickly turn off the car, erase the fault, restart the car, does the light flash then ??
 

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Discussion Starter #19
I didn't have access to the small amp test light over the weekend, but I did another test that proved that injector #1 is NEVER firing, save for a few completely random times once a week or so.

I found that if I clear the codes, then remove the wires to a good cylinder/coil and to the bad coil/cylinder, then start the engine, the injector for the good one fires for 20 seconds then stops, but the injector for the bad one never fires at all.

In my thinking, this means the injector side has the primary issue, with a misfire being secondary, rather than the computer shutting down the injector secondary to a primary misfire/coil issue (as would be the case if the computer were fine and problem was actually the wiring from the coil falsely communicating a misfire to the computer).

Any thoughts? I'm about ready to attempt a fix on the computer, but don't want to waste money there if the problem might be elsewhere...
 
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