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  1. #1
    Saab Fan
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    08 Oct 2017
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    Saab(s)
    2007 9-3 2.0T Sport Combi
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    Engine Shudder only when boosting at high speeds

    I've searched endlessly through the threads and can't seem to find anyone with this exact issue. My 2007 9-3 2.0T shudder's/misfires but it only occurs when I am at high speeds 70mph+ and I accelerate pushing my turbo. As soon as it hits the red, the engine starts to shudder. Feels like misfiring but not sure. It's pretty bad so as soon as I feel it, I lay off the pedal and it goes away immediately. So it's definitely engine, and not alignment balance, etc. Shortly afterwards I got the P1312 code. Changes the plugs to the NGK recommended, put new OEM coil packs on cylinder 1 & 2. Problem persists. Tried swapping packs to position 3&4 and cleaned MAS. I'm thinking this is not ignition coil at all. The strangest thing is that the car runs like a dream at lower speeds, even when I floor it, it takes off with no issue. the problem is only at high speed!!!

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  2. #2
    Bruno
    Saab Nut swisssaabist's Avatar
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    18 Nov 2016
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    Saab(s)
    9-5 ARC Wagon 2002 2 t auto engine B205E
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    you must check the fuel pressure regulator, you have certainly a starving of fuel or lack of air..

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  3. #3
    Saab Owner Digger's Avatar
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    28 Oct 2016
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    Saab(s)
    2006 9-3 2.0t SportCombi
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    The WIS has a multi word description for code P1312 that boils down to ping or knock, depending on how long you've been around. When you consider all the things that have caused engines to ping during heavy acceleration, add in a turbo, all the sensors for computer control, then add in age of wires along with miles on the motor and you get a dozen and one things that could cause this problem driving the way you described.

    Fuel pressure can be low, pressure can be good and volume can be low, good volume and pressure doesn't mean that all the injectors are still good enough to fuel all the cylinders equally at high rev and high boost with high torque, because by now your tranny should have down shifted making things even squirrellier. At speeds already over 70, boost reading into the red, the engine itself is making next to no vacuum where even the smallest leak in the right hose could keep your waste gate from working like it should and you could be over boosting. With all the simple stuff in mind it's time to consider how the mechanics are working compared to how the electronics think they are working and what your ION module might be telling your ECM.

    For your car to shudder bad enough for you to pull you foot off the gas and toss a code when you did, the check engine light should have flashed at least once and I wonder why it didn't. If you don't want to risk sending parts of your engine into orbit, you're going to need good assortment of test equipment and maybe even hands on help, because to find this problem every possible cause needs to checked and fixed from fuel pump to rock hard vacuum hose to wire bundles loose from rotting tape need to be replaced or re-wrapped. Then you start testing modules and valves.

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  4. #4
    Saab Fan
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    Saab(s)
    2007 9-3 2.0T Sport Combi
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    Engine Shudder at high speed boost

    Thanks guys. So checked code at Autozone and the only code is P1312 - Position B misfire. Both of you are saying that it could be fuel related. Fuel pump or fuel pressure regulator. Should I therefore stop chasing the ignition coils? Is the test I performed by unplugging teach coil an effective test to determine that they are all actually working? i suppose it could be the wiring harnesses as you mentioned. I looked back through my records and found that I seem to have had this issue way back at 29k miles and they replace the fuel pump and MAS under warranty to fix the issue. Now I'm at 130k. can it be the same thing? I also have the infamous broken fuel gage issue which requires a tank drop to fix, so maybe the fuel pump is a good thing to check. Make sense? Appreciate the help. Purchased new in 2007, this has been the best car I've ever owned which is ironic considering the state of the company.

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  5. #5
    Saab Owner Digger's Avatar
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    2006 9-3 2.0t SportCombi
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    Gas in the tank cools the pump and running with less than half a tank on a regular bases shortens the life of the pump. Fix this problem or not, a working gas gage is a good thing to have and a failing pump could cause this problem. As could a fuel filter that needs to be changed.

    Unplugging coils will tell you if they are working, doesn't tell you how well they are working. With this only happening at speed with hard acceleration, new OEM plugs and coils in place I would put coils on the low end of the things to check and look to fuel and air first.

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  6. #6

    Join Date
    12 Oct 2017
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    NJ
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    Saab(s)
    2006 9-3 2.0T Convertible
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    There are several threads on this (I have been searching because I have been researching the problem because I have it as well).

    From what I have read, P1312 pertains to the Ionization Sensor, plugs and or Coils.

    Here is another thead based on this.

    http://saabworld.net/showthread.php?t=31641

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  7. #7
    Saab Owner Digger's Avatar
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    2006 9-3 2.0t SportCombi
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    Quote Originally Posted by JayMonster View Post
    There are several threads on this (I have been searching because I have been researching the problem because I have it as well).

    From what I have read, P1312 pertains to the Ionization Sensor, plugs and or Coils.

    Here is another thead based on this.

    http://saabworld.net/showthread.php?t=31641
    For the most part P1312 pertains to the plugs, coil packs, wire from the coil packs to the ION module, wire from ION module to the ECM and if you follow the WIS troubleshooting guide it sends you off to read more sections if your answer is NO to fault resolved.

    The WIS is a great resource, but it isn't the be all and end all of Saab service knowledge as the material the WIS sends you on to read expects you to have the knowledge of a an educated and experienced mechanic. I'm by no means any kind of a factory trained mechanic, much less a Saab expert, but under the hood of the 06 Cobalt SS you will find the same engine as our 06 Saab 2.0t's, I've had some practice with Chevy's and a lot of it carries over to Saab. P1312 is also a knock code and unlike working on a late model Chevy, the Tech 2 either doesn't tell you what the Saab engine computer thinks the gasoline octane is, or I haven't found that screen yet and that makes eliminating the ECM and emission system a lot more difficult when the cause isn't one of the usual Saab suspects.

    If your symptoms and situation are identical to the ones listed by the original poster you need to look at all the things that can cause knock on hard acceleration.

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  8. #8

    Join Date
    05 Oct 2017
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    BelgiŰ
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    Saab(s)
    Saab 9-3 2006 2.8 Turbo V6 Hirsch
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    Had this Problem with my 2.8T 2006. Check your boost solÚno´de. Now what fixes the problem completely for me. Put your gap on your spark plugs at 0.8 or 0.7 not the Ngk spec of 1.1.


    Verzonden vanaf mijn iPhone met Tapatalk

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  9. #9
    Saab Fan
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    2007 9-3 2.0T Sport Combi
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    Well it turns out it was the coils after all. Initially, I thought the p1312 code meant a misfire on position 1 or 2 (read that somewhere). so I only ordered 2 new coils and tried them in position 1&2, after that didn't work, I tried them at positions 3&4 and still no luck. So after reading this thread, I figured it must be something else. I took it to a local indie SAAB mechanic thinking fuel issue. They advised that I order another two coils and replace all four before I ask them to do anything on my car. They said that the p1312 code is a random misfire and the plugs or coils are most often the issue. If this didn't fix it the I should bring it back and they would look to test for vacuum leaks and then boost components. Digger is correct that unplugging coils one at a time tells you if they are working but does not tell you how well they are working. So today I replace all 4 coils, took it on the highway, and the issue was fixed. Floored it up to 100mph fast, turbo winding, with not even the slightest shudder. The light cleared itself after a couple of errands later. So this cost me $100 per coil for OEM's. Not bad considering what would have happened if I went to the dealer. I'll probably still take it back to the indie shop to drop the tank and replace the fuel sending unit. If you are in the Pittsburgh area and want an honest Saab shop I recommend Simply Saab.

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  10. #10
    Saab Owner Digger's Avatar
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    2006 9-3 2.0t SportCombi
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    As I can't remember why, I've been looking at this thread to find what made me think that you had already installed 4 new coils and the problem persisted. Near as I can figure I either assumed that when I read you swapped coil positions that you did it methodically to eliminate the weakest two, or in responding later I confused your initial statement with another poster that had replaced all four coils. Either way my apologies to you and JayMonster for adding confusing to a simple repair.

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