2006 93 2.0T MISFIRE

[Omar21]

I have a 2006 93 2.0T w/ 122k miles. The car stutters only when the turbo boost is at high end. In October 2016 the car misfired for the first time and I had the P1312 code. Since then i replaced the spark plugs and coils. Code went away and the Car ran great! then about a month ago i was on the highway, stepped on the gas to switch lanes and the car stuttered hard and lost power, engine light came on. After that ride the engine light went away but the car misfires from 2nd to 5th gear. I think its the turbo but i dont know where to start.

Please comment...

[Digger]

Start with your code reader and look to see where those misfires are. If your misfires are evenly balanced, that is the number of misfires on all cylinders is in the same numerical range and they only occur at high RPM the cheapest to replace and most likely cause is the crank position sensor "CPS"

Misfires will happen and if you have a few misfires on 3 out of 4 cylinders and a large number on the 4th then you look first to a bad connection and if you don't find one your new coil or plug has applied for early retirement. Misfires on the evens or odd cylinders only is another thing and cylinders next to each other is another and all have different first places to look.

[RoccoH]

Omar21 already read the code, the description of the P1312 code is: "Combustion detection cylinder 1+2, open circuit / short to B+".

So there is either a problem with the combustion of cylinder 1+2 or there is a wiring problem for these two cylinders.

Which spark plugs did you install? only use NGK PFR6T-10G, gapped to 0.9–1.0 mm

[Omar21]

Rocco: I try to only get genuine saab parts. I have the Saab service software and the workshop manual, i use that for parts and i do all the work (that i can) myself. Those are the spark plugs that i used and i set them at 1.0 mm. There was a very small amount of residue as the tips of the plugs so i cleaned the chambers and dried them out. Once i did that, installed the new plugs and 1 new coil the code went away and the car ran great. 3weeks after that it misfired again. i ordered 4 used coils installed them and the car was good again. But about 6 weeks ago it started misfiring when i hit the accelerator and the boost gets to about 3/4 (before the red on then boost gauge), gears 2 to 5. If i accelerate and keep the boost to about 1/2 then the car will reach the speed I want but in much longer time. I'm gonna scan it today and see if any code comes up even if my engine light is off. Also I got a new fuel filter (which i have to install) and I'm pretty sure i need new oxygen sensors too. I dont think the fuel filter will fix it but hopefully its the oxygen sensor. I just hope the turbo is not done.