No codes. Misfires. Lacks power sometimes. IM GOING CRAZY.

Jay89

New Member
Dec 17, 2011
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I have an 89 mustang 5.0. Ive been having misfire issues and cant figure it out. It feels like its always misfirring but I have noticed that depending on the weather is how it will run. Usually in decent, not too cold or too hot weather it runs smooth and doesnt feel like it lacks power but other times it runs very rough and lacks alot of power. I jumped for codes with a test light and i used a scanner and i did not get any flashes. Abyone have any idea? Plugs are new, wires are new. And if any of you have any idea on why my starter still stays engaged even with the key out of the ignition, It would really help. New starter, new solenoid. Im hoping i didnt get myself into a big mess buying this car. Thank you
 
Check out the thread below. Thanks to jrichker I found out my ECM is bad.

http://www.stangnet.com/mustang-forums/threads/engine-miss-what-am-i-missing.850431/

You said you weren't getting any flashes. It's my understanding you should get at least 11 or 111 to show system pass. If your not getting anything you might want to run the tests on the wiring and ECM from that link. It's worth at least checking out to make sure and then go from there.
 
What is the timing set at?

As for the starter problem, I would check the ignition switch and make sure it doesn't have a short in it.
I havent checked with a timing light yet. I was thinking maybe the map sensor since it feels like it might be affected by weather change. When its running "smooth", it feels like its running on 7 cylinders and when its rough it feels like its running on 5. I figured it might be the ignition switch but as a "test", i pulled out the switch when the starter stayed engaged and it still stayed engaged. But regardless im going to get the switch cause the one i have looks iffy.
 
Yeah I had a switch that seemed fine and when I went to change the lock cylinder in the car it just fell apart in pieces as I was working on the lock cylinder.

I would definitely follow that link and check the ECU as well.
 
Check out the thread below. Thanks to jrichker I found out my ECM is bad.

http://www.stangnet.com/mustang-forums/threads/engine-miss-what-am-i-missing.850431/

You said you weren't getting any flashes. It's my understanding you should get at least 11 or 111 to show system pass. If your not getting anything you might want to run the tests on the wiring and ECM from that link. It's worth at least checking out to make sure and then go from there.
Awesome. Thank you. Im gonna go ahead and do those tests. Hopefully I get results.