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1998 ETC
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Discussion Starter #1
Hello my name is Thomas and new to this forum.

We have a 98 ETC 4.6 with less then 70K. Just about a week ago I lost power and noticed a misfire. So i went out and got new plugs and replaces those, and still had the same issue I also checked for vacuum leaks with a can of carb cleaner and none. So I pulled up the codes and had P0300 and P1381 and the both are to do with misfire. I also noticed when there is a heavy load on the car it will backfire threw the intake.
What are the chances if i replace the plug wires that it will fix my problem? Or is there something else wrong? Please help!!

Thanks in advance!
Thomas
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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6,738 Posts
Most common cause of mis fire is a faulty coil pack. Thru on board diagnostics, you can isolate which cyl is misfiring swap the coil to another cyl and if the miss moves to that cyl, assume that coil pack needs replaced.
 

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1998 ETC
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5 Posts
Discussion Starter #4
Most common cause of mis fire is a faulty coil pack. Thru on board diagnostics, you can isolate which cyl is misfiring swap the coil to another cyl and if the miss moves to that cyl, assume that coil pack needs replaced.

Would i need a scanner to isolate the cyl or could i go about this using the off + heat button?

I am not very smart when it comes to the new V8's and computers. This is the only car of ours the has a computer and OBD II. So sorry if i sound dumb because i am when it comes to stuff like is on a newer car.

Thanks again!

Thomas
 

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1998 ETC
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Discussion Starter #5
So i reset the codes and took it for a drive the service engine soon light came on within 1 mile. Then I noticed it blinking at me as to say HEY STUPID.. So i drove the car about 100miles. Reset it another time and this time it let me drive 26 miles then came on again and blinked more.. I some how got some power back but its when im going about 35mph and a punch it, it will pick up. Its just from like 0-30mph that it is rough. Also when i was on the freeway i noticed that i would leave my foot in 1 place and it seemed to be picking up speed by it self.(not sure if that makes since)

ANYTHING WILL HELP!

THANKS IN ADVANCE

THOMAS
 

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94 Eldorado, and a 99 ETC
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I would bet that your wires are bad, like Ranger said. A/C Delco seems to last longer on caddies than any of the other brands.

You don't need to go into diagnostics mode to isolate the cylinder (in fact OBD-II doesn't have that feature. Only with a good scan tool). Just pull the spark plug wires one by one (with the engine running). Put each one back before moving on to the next one. What you're looking for is the one that causes the Least amount of change in how the engine is running. If the engine runs rougher with that cylinder unplugged then that cylinder was working fine. The rear bank may be a little more difficult to do without getting zapped.
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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That also works to determine which coil is faulty. The light will continue to come back until the problem is solved. Might be worth an hours diagnostic time with a shop to isolate the cause, then you can decide if the repair is something you can do.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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If you decide to change plug wires, make sure they are connected to the proper coil towers as shown. Critical in order to avoid a nagging miss.
 

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1998 ETC
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Discussion Starter #9
VERY COOL! Thank all of you guys for the feed back I did pull the wires before replacing the plugs and I dont remember which ones acted up. Ill recheck it and yes I got zapped 2 times when checked the rear bank.

I also did noticed today that it is rich on start up and idle.

Thanks

Thomas
 

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Super Moderator
2010 DTS
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87,580 Posts
Moving old wires around can cause them to break down and start to misfire. Several years ago I took my perfectly running '97 in for a fuel rail recall. They have to pull the front bank wires and move them out of the way to replace the fuel rail. Almost immediately after that I developed a misfire, but was not sure if it was that or a bad trans (see "Stutter, Engine or Trans?). After replacing the plugs and swapping coils one by one with a known good one, the only thing left was the wires or ICM. I replaced the wires and she ran like she did from the showroom.
 
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