# 2005 Saab 9-2X (Aero) misfiring (Saabaru) **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** saab, 9-2x\ **Created:** [August 7, 2015, 6:18pm UTC](https://community.cartalk.com/t/2005-saab-9-2x-aero-misfiring-saabaru/90837 "2015-08-07T18:18:43Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![NicoleV](https://avatars.discourse-cdn.com/v4/letter/n/c68b51/32.png) [@NicoleV](https://community.cartalk.com/u/NicoleV)\ **Post date:** [August 7, 2015, 6:18pm UTC](https://community.cartalk.com/t/2005-saab-9-2x-aero-misfiring-saabaru/90837/1 "2015-08-07T18:18:43Z")
My 9-2 is misfiring on cylinders 2 and 4. At first we suspected a timing issue but that doesn’t appear to be the case. My mechanic is looking at it but can’t seem to locate the problem… so far: - replaced old spark plugs - checked the coils (moved them to see if the misfiring followed the coils–it did not) - checked the timing belt (all good) - compression is good - fuel coming in is rich He’s dropping the exhaust today to check things from that end… A faulty mass airflow sensor wouldn’t effect specific cylinders would it? and we’d see a degradation in the fuel richness right? Any other ideas? ---
**Author:** ![insightful](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/insightful/32/2732_2.png) [@insightful](https://community.cartalk.com/u/insightful)\ **Post date:** [August 8, 2015, 12:27am UTC](https://community.cartalk.com/t/2005-saab-9-2x-aero-misfiring-saabaru/90837/2 "2015-08-08T00:27:29Z")
Can you feel the misfire? Losing power? While accelerating? Cruising? Cold engine? Hot engine? ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [August 8, 2015, 3:58am UTC](https://community.cartalk.com/t/2005-saab-9-2x-aero-misfiring-saabaru/90837/3 "2015-08-08T03:58:48Z")
Well, a cylinder will fire correctly provided it has 1. spark, 2. at the right time, 3. compression, 4. fuel and air of the correct mixture, and 5. a way to rid the spent exhaust gasses from the cylinder. So it seems you are on the right track. Has the shop visually verified you have a good spark at the spark plugs on 2 & 4? My first suspicion remains something wrong with the coil system. Are you certain when you moved the coil packs, that was done correctly? By this I mean, was this the first time the person who moved the coils around has done that job before? If you weren’t getting a good spark on 2 & 4, that would explain a “rich” mixture symptom. The gas wouldn’t get burned, so it would come out the tailpipe. Another idea, no gas is being injected on 2 & 4, so the other cylinder might get an extra dose of gas, producing a rich symptom. Have you verified the injectors on those cylinders are getting pulsed? A faulty ECM, ECM connector, or igniter, grounding, or other wiring problem could cause this. Was any work done on this vehicle just prior to this starting? A couple other random thoughts. Have the wires to the spark plugs been replaced? Try looking at the engine running in the dark, see if you notice any signs of visual sparks jumping around. ---
**Author:** ![NicoleV](https://avatars.discourse-cdn.com/v4/letter/n/c68b51/32.png) [@NicoleV](https://community.cartalk.com/u/NicoleV)\ **Post date:** [August 13, 2015, 6:14pm UTC](https://community.cartalk.com/t/2005-saab-9-2x-aero-misfiring-saabaru/90837/4 "2015-08-13T18:14:07Z")
well, they rechecked the coils and that was the problem–got two new coils and the engine purrs just like it should! Thank you! ---
**Author:** ![knfenimore](https://avatars.discourse-cdn.com/v4/letter/k/9fc348/32.png) [@knfenimore](https://community.cartalk.com/u/knfenimore)\ **Post date:** [August 13, 2015, 6:36pm UTC](https://community.cartalk.com/t/2005-saab-9-2x-aero-misfiring-saabaru/90837/5 "2015-08-13T18:36:01Z")
Thanks for letting us know. ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [August 13, 2015, 9:20pm UTC](https://community.cartalk.com/t/2005-saab-9-2x-aero-misfiring-saabaru/90837/6 "2015-08-13T21:20:18Z")
How often, if ever, have the spark plugs been changed? Coils usually fail due to one of several reasons. Aged high miles spark plugs. Moisture entering the plug boots; made worse by high miles plugs.