# Misfiring Alero

**URL:** <https://community.cartalk.com/t/misfiring-alero/50310>\
**Category:** Maintenance/Repairs\
**Tags:** alero, oldsmobile, misfire\
**Created:** [June 14, 2010, 3:02pm UTC](https://community.cartalk.com/t/misfiring-alero/50310 "2010-06-14T15:02:47Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![gmhudson52](https://avatars.discourse-cdn.com/v4/letter/g/d9b06d/32.png) [@gmhudson52](https://community.cartalk.com/u/gmhudson52)\
**Post date:** [June 14, 2010, 3:02pm UTC](https://community.cartalk.com/t/misfiring-alero/50310/1 "2010-06-14T15:02:47Z")

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I have a 1999 Olds Alero 2.4 that is driving me nuts (a short trip). It is misfiring on 2 cylinders but does not generate any error codes. I have replaced the plugs, boots, coil housing and coils, and a different ICM has been tried. The fuel filter has been replaced. Injectors have been swapped around, but it still misfires on the same two cylinders.  
  
 Both the repair shop and I am at a loss for what to try next. Any suggestions?

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**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\
**Post date:** [June 14, 2010, 3:08pm UTC](https://community.cartalk.com/t/misfiring-alero/50310/2 "2010-06-14T15:08:42Z")

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Are the two misfiring cylinders adjacent to one another? If so, have a leak down test performed on those cylinders. A leaking head gasket can cause a misfire in two adjacent cylinders.

Tester

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**Author:** ![gmhudson52](https://avatars.discourse-cdn.com/v4/letter/g/d9b06d/32.png) [@gmhudson52](https://community.cartalk.com/u/gmhudson52)\
**Post date:** [June 14, 2010, 8:06pm UTC](https://community.cartalk.com/t/misfiring-alero/50310/3 "2010-06-14T20:06:46Z")

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According to my mechanic (who is outstanding, by the way) it is missing on cylinders 1 and 4, opposite ends of the block, which is what makes this thing so baffling.

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**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\
**Post date:** [June 14, 2010, 8:32pm UTC](https://community.cartalk.com/t/misfiring-alero/50310/4 "2010-06-14T20:32:18Z")

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I would still do a leak down test on all the cylinders. If cylinders 1 and 4 have low compression it’ll cause a misfire in those cylinders.

Besides, a leak down test is one of the first things that are performed to make sure there’s nothing wrong with the engine mechanically to cause a misfire in any of the cylinders.

Tester