ECM 2005 Honda Element

My 2005 Honda Element AWD, is having some issues that may or may not be related to the ECM. The check engine light was on and at speeds above 55mph it would have intermittent shifting issues when attempting to accelerate. I took it to my mechanic and he said it was the alternator and replaced it. The next day the light came on again. This time the ECM indicated that cylinder #2 was misfiring. We replaced all the spark plugs. The next day the light is on again. The shifting problem is unresolved. Two other issues: 1) the A/C evaporation hose cannot be cleaned out and water drips into the passenger compartment. 2) the passenger side seat belt occassionally locks and will not release. I mention these only because the ECM on this car is located behind the glove box where A/C condensation drains into the cabin. Any thoughts?

Sure, it could be a damaged ECM, but on a 2005 Honda, that is expen$ive, and requires programming due to the security system. A junkyard ECM won’t work, and even on a 1990s car with no immobilizer, you still run the risk that the used ECM could be defective or have an older software revision than the one you have.

The only way the ECM could be at fault for this misfire/poor engine performance would be if it is failing to pulse the fuel injector or failing to fire the spark plug for one or more cylinders. You can actually test for this, and should also have checked the fuel pressure at rest, and while running. You should also perform a compression test and leak-down test to see if this is really an engine mechanical problem.

You may be lucky, and this might be a defective fuel pump, fuel injector, or spark pack, rather than a costly ECM or engine problem.

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Based on my experience with my Corolla, my first thought on reading that you had a misfire was a bad coil. Granted, I am not a mechanic but I’m puzzled by the decision to replace the alternator. My advice is to find another mechanic before you spend any more money.

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It could also be that you can have a fatal case of 16 Year Old Car Syndrome.

Meaning, none of the issues could be related, and all the issues you’re describing could just be older parts nearing the end of their useful lives.

Probably not what you want to hear, but I wanted to point it out.

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Suggest to focus on the misfire problem.

  • Double check battery & alternator are working correctly.
  • Compression test.
  • Check no 2 coil for proper operation. Not sure? Replace it.
  • Make sure no 2 fuel injector is getting pulsed correctly, fuel pressure ok.
  • Are there any diagnostic codes indicating the cat may be failing?

Once you have the misfire problem repaired, if you still have transmission problems you’ll have to find a shop that has the equipment required to read Honda transmission codes.

The A/C drain tube clog is correctable. But it may take some time, and therefore could be somewhat expensive. It has to be done, so may as well ask the shop to do what it takes to fix it. Shops usually fix that problem using compressed air.