Scanner says misfire on cyl 2 and 3

Tiny
BRANDON_R08
  • MEMBER
  • 2004 CADILLAC CTS
  • 3.6L
  • V6
  • RWD
  • AUTOMATIC
  • 167,000 MILES
Had a very slight miss when under moderate acceleration. Ran a scanner and came up with cyl 3 misfire. I replace all the plugs put the car back together, hit the key and the car ran like crap. Would barely run. Also heard something "rattling". I hit the gas and it sounded like a nut or something may have fell into intake but I did not ccompletely take the intake off. I only moved it to the left and right as I needed. Also I did not end up missing any bolts or anything so I do not believe anything fell into my motor. Anyway I tore the car apart 3 more times taking every plug out and finally the knocking stopped. The car how ever is still running aweful. I have 2 coils on order right now hoping it may fix the problem but I'm not so sure. The knocking/rattling sound has me scared because I've heard horror stories about timing problems. I haven't ran my car low on oil. Check it pretty often. Also I don't understand how it could run fine then with new plugs it runs like crap. Also the first time I tore it back down after the miss started I put old plugs back in it still missed something aweful. Please any advice would be amazing. Thanks - Brandon
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Tuesday, August 26th, 2014 AT 1:56 PM

9 Replies

Tiny
HMAC300
  • EXPERT
You may have damaged the coil to plug connector but for a misfire have apro look into it because it can be a sensor screwing up alongwith an injector and many other problems. These are very hard to diagnose why they have a misfire.
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Tuesday, August 26th, 2014 AT 3:23 PM
Tiny
BRANDON_R08
  • MEMBER
Thank you for the reply. I took the car to my local auto parts store and had it scanned again after unplugging the battery all night. 16 codes! The guy said that the computer has to "relearn" or something and he unplugged it before I could write them down. I guess he was in a hurry. I did see the random misfire code along with every cylinder misfiring this time. I did absolutely nothing but put plugs in. I cannot believe the car of my dreams is cropping out on me. I owe about double what it Is worth too. Is there a chance something really bad has happened? I'm calling the car lot where I got it in the morning since the nearest dealership is 50+ miles away. Any thing that you can think of that I should tell them to look at? I'm 99 percent sure I did nothing that could lead to it jumping time or nothing like that. Like I said I check my oil pretty much once a week. All I did was drive home from work which is right at 50 miles and pull into the garage. No noises before changing them. Put it together and cranked her up and bam. I don't understand how I could go from 2 codes to 16 just by unplugging the battery.
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Tuesday, August 26th, 2014 AT 6:28 PM
Tiny
HMAC300
  • EXPERT
1. Don't believe an autoparts guy and then take to any garage they can do just as good a job as dealers. Check your battery for condition including load test autoparts cando for free make sure terminals are clean a weak battery can cause a lot of problem but not he one you are experiencing.
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Tuesday, August 26th, 2014 AT 7:41 PM
Tiny
BRANDON_R08
  • MEMBER
Yea I didn't really think he knew much. I will get it scanned again this evening to see what codes come up and I will post them all. I hope it's not a timing issue. What codes would show if it was something to do with the valves or timing? Also I'm not the original owner. Is there any tsb or recalls my car may qualify for? Is not under warranty either.
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Wednesday, August 27th, 2014 AT 12:00 PM
Tiny
HMAC300
  • EXPERT
There are no codes for valve or timing unless you have low compression which wold give you the misfire code. The only tsb on your car for a misfire code is an aftermarket installed alarm system that will destroy your converter and cause misfires because it'snot circuit borad driven and shuts the fuel on and off and shold be put to starting system. As far as timing the belt shold be replaced as a kit at 60k unless in California then 105k. Normally akit is used so water pump pulleys, tensioner all get replaced at same time. This is an interference engine so if the belt breaks or slips your valves bend. They also have aproblem with crank sensors which are in the timing cover so if they aren't plugged in right they screw up but I don't think that is your problem.
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Wednesday, August 27th, 2014 AT 12:25 PM
Tiny
BRANDON_R08
  • MEMBER
Ok. By what I'm telling you what would you guess is wrong? The whole thing about changing plugs leading to this has me pretty angry with it. Is there a way for someone to check and see if anything is up with the valves?
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Wednesday, August 27th, 2014 AT 1:52 PM
Tiny
HMAC300
  • EXPERT
A compression test. I really thing tht the coil to plug bootsare probably screwed up causing a lot of this but hey ya never know til its 'scanned.
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Wednesday, August 27th, 2014 AT 2:57 PM
Tiny
BRANDON_R08
  • MEMBER
Ok didn't do the compression test because I really don't think it's an internal problem. I went ahead and bought some double platinum autolite plugs and installed those and it still didn't help. Hooked it up to scan for codes and it came up as random misfire and no. 1 2 and 3 cylinders are misfiring. Brand new plugs. They have 10 miles on them now. I gapped them to .050 because that is what the guy told me to do. I'm lost. Taking to the car lot I hot it from to let them check it out. Any info you guys could give me sound be appreciated. The auto parts guy said it could be where I unhooked the battery and it could possibly be a cam or crank sensor. I have no knowledge about these engines other than what I've read over the last 2 months. Thanks again! And we're you recommending that I should do the compression test? Or did you mean that it would tell me if my valves were bent?
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Thursday, August 28th, 2014 AT 7:00 PM
Tiny
HMAC300
  • EXPERT
If the valves are bent a compression test will show it.
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Friday, August 29th, 2014 AT 6:37 AM

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