99 3.8l misfire on 3 and 4 Desperate for help
#1
10-30-2012, 04:21 AM
99 3.8l misfire on 3 and 4 Desperate for help
i have a 99 3.8l....recently it started idling real rough and losing power....hooked a scanner up and it detected a misfire on 3 and 4....i pulled the plug wire for number 3 and there was no change in the running of the car....but when i pulled the wire for 6 the car started runnin worse.....would this be the coil packs or plug/wires? i am stumped any help would be greatly appreciated. thanks to you guys in advance!
#2
10-30-2012, 06:59 AM
So you are trying to trouble shoot the car right? Here are a few things which could be bad.
1. The coil could be bad.
2. The plug wires could be bad, are they original? Have you changed them out?
Z. The ICM which is what the coil sits on could be bad.
I would start with a easy experiment first...
You can check a coils by easily moving the 3-6 coil to the 1-4 coil being very careful to plug the wires on the correct terminal (they are interchangeable, the numbers are there to help guide you), and then put the 1-4 coil where the 3-6 was. Start the car see if its still throwing a code, if it is than its not the coils that are bad.
If you dont have new wires, you can try those next and see if that helps. At this point you are only out like 30 bucks for new wires which you might have needed anyways (JUSTIFICATION to get new wires and plus you get to go to the parts store, HURRAY!!!
).
Then change out the wires, if you still are throwing a misfire, only one thing left...the ICM!
You can get a ICM on ebay relatively cheap but you always take a chance on used parts. My 1997 had the same misfire for #3, changed the coils and the plug wires and it still threw the code. Then I took a spare ICM and threw it on there, sure enough the misrfire went away but the motor was past the point of no return after the lower intake manifold gaskets failed and developed a knock.
If you notice where your coils sit there is a chance some water can leak and drip on your coils causing some issues, but not all the time. I saw that with mine and perhaps it could have been the reason my Camaro was abandonded in Hawaii.
Good luck!
1. The coil could be bad.
2. The plug wires could be bad, are they original? Have you changed them out?
Z. The ICM which is what the coil sits on could be bad.
I would start with a easy experiment first...
You can check a coils by easily moving the 3-6 coil to the 1-4 coil being very careful to plug the wires on the correct terminal (they are interchangeable, the numbers are there to help guide you), and then put the 1-4 coil where the 3-6 was. Start the car see if its still throwing a code, if it is than its not the coils that are bad.
If you dont have new wires, you can try those next and see if that helps. At this point you are only out like 30 bucks for new wires which you might have needed anyways (JUSTIFICATION to get new wires and plus you get to go to the parts store, HURRAY!!!
). Then change out the wires, if you still are throwing a misfire, only one thing left...the ICM!
You can get a ICM on ebay relatively cheap but you always take a chance on used parts. My 1997 had the same misfire for #3, changed the coils and the plug wires and it still threw the code. Then I took a spare ICM and threw it on there, sure enough the misrfire went away but the motor was past the point of no return after the lower intake manifold gaskets failed and developed a knock.
If you notice where your coils sit there is a chance some water can leak and drip on your coils causing some issues, but not all the time. I saw that with mine and perhaps it could have been the reason my Camaro was abandonded in Hawaii.
Good luck!
#4
10-30-2012, 08:52 AM
NEVER pull plug wire on High energy ignition system. That is 80,000 volts looking for a place to go. If you pull the plug wires that 80,000 volts will find a way out of the coil. This causes carbon tracking inside the coil and will cause the coil to fail. It will take a little time for yours but any coil you did this test on will fail over time.
If your plug wires are more then 5 years old you should just replace them. If your sure they are newer then that and they do not have any external damage they may be ok. There is NO good way to test a plug wire. Well you can test on a scope but the cost of the test is greater then the cost of the wires. The reason I say replace the wires is because a bad wire can cause a bad coil, In the below test you may need to swap coils around. If you have a bad wire you can damage other coils besides the bad one you may already have.
Once you know the wires are good, get a spark tester. See if the coils are firing. If one is not firing inspect the plug and swap the coil with one you know work. If the failed spark stays with a given cylinder and does not follow the coil then you may have a bad module.
Most parts stores has testers.
http://www.harborfreight.com/90-inli...ker-69023.html
If your plug wires are more then 5 years old you should just replace them. If your sure they are newer then that and they do not have any external damage they may be ok. There is NO good way to test a plug wire. Well you can test on a scope but the cost of the test is greater then the cost of the wires. The reason I say replace the wires is because a bad wire can cause a bad coil, In the below test you may need to swap coils around. If you have a bad wire you can damage other coils besides the bad one you may already have.
Once you know the wires are good, get a spark tester. See if the coils are firing. If one is not firing inspect the plug and swap the coil with one you know work. If the failed spark stays with a given cylinder and does not follow the coil then you may have a bad module.
Most parts stores has testers.
http://www.harborfreight.com/90-inli...ker-69023.html
Last edited by Gorn; 10-30-2012 at 08:56 AM.
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