4th cylinder misfire

[nlikens]

My check engine light recently started blinking so I took it to advanced auto to have the code read. It told me I had a 4th cylinder misfire so I assumed maybe changing the plugs out would fix the problem...I never got around to putting the plugs in but the very next day I was unable to get the truck over 30 miles an hour. After having it towed the shop, I was told two of my four catalytic converters were bad and the other two were about to go and the repair would cost $1805! Needless to say I was not going to pay 730 a piece for the cats so I took my truck home and now I am stuck here with this dilemma. I called the shop back and asked as to why the cats were so expensive after shopping around and I was told to "be very careful" when buying new cats because there obviously no good if there that cheap. I still firmly believe that this guy is trying to rip me off and he also took out the 02 sensor so it would "run better". although it does run now it sounds like complete ****. What is my best and cheapest option for this fix?

 

[nlikens]

Update:
Took it to Meineke hoping to get a different and more honest insight as to what my problem may be. I was told the same thing that the other place told me. All four of my cats are bad and they "could not determine what the problem is until the cats are replaced". According to meineke I have the california cats which is why they are so expensive and if I were to put any other ones on that my check engine light would remain on. Is this true or am I just being scammed? HELP!!!

 

[RomeovilleIL]

You need to go back and address the misfire problem. I wouldnt say the cat diagnosis from the muffler shop is wrong, but the fact you got misfire codes instead of oxygen sensor codes tells me your missing cylinder probably stopped firing entirely. A dead cylinder will absolutely run like garbage. Replace the plugs. Be sure to test the wire with the miss to check voltage is getting to the sparkplug. If needed replace the wires or coilpack should they test faulty. Chances are very good you will return to previous drivability.

Removing the O2 sensors leaves holes in the exhaust so sounding like crap makes perfect sense. Where did he put your sensors? Are they tied up somewhere or were they removed completely - a set of O2's is a couple hundred dollars so get them back if he took them off.

Direct OEM replacemnt CA cats are expensive. There are a bunch of aftermarket exhaust options you can find with a search in the forums which cost much less and work fine with your truck. But before you go there, fix the original problem. Driving with a misfire will cause damage to your cats from the unburned fuel moving down the exhaust.

 

[RomeovilleIL]

As an aside, the muffler shops wont fix anything else to put you back on the road without first replacing the catalytic converters because it would violate emission laws.

 

[nlikens]

I am not sure what they did with the O2 sensors. I will have to call them and find out I didn't realize they were that much. Ill replace the spark plugs today and see where that gets me.

On a side note, (I know this isn't legal but..) how would the truck run if i were to cut the cats off and weld straight pipes on?

 

[nlikens]

Ok so I changed the spark plugs, still showing a misfire. I also have two other codes one stating Bank 1 is lean and another stating Bank 2 is rich.

 

[RomeovilleIL]

It will certainly run rich if that cylinder is not burning the fuel. Did you check that the spark plug on cylinder #4 is firing? What did the old plug look like? Since it was missing I would expect a lot of carbon buildup but was there any damage or other indicator of why the miss was happening? A lack of spark generally boils down to the plug, the wire, or the coil pack. You need to test each piece. The coil pack and wires are fairly easy to test by swapping locations and seeing if the missfire moves.

If the spark is good but still missing and running rich, the likely issue is a non-pulsing fuel injector which dumps too much fuel. Using a piece of hose or a mechanics stethescope you should be able to hear each injector pulsing (sounds like a tick). A stuck one makes a faint hiss. Often tapping with a plastic screwdriver handle can get them temporarily unstuck.

 

[nlikens]

I did check the plugs and its not firing, but I checked them right after replacing so it's not the plug. I guess my next test will be to switch out the wires and I'm crossing my fingers that will fix the problem. Also when my truck was idling the other day it was making an intermittent tick noise, not sure if that has anything to do with the fuel injectors.

 

[RomeovilleIL]

Well, you are getting close. With no spark the possibilities are the wire and the coil pack. Getting a new set of wires will be 50/50 chance of solving the problem. I would try swapping a wire from one of the other cylinders first to see if the coil is sending electricity through before buying parts, although new wires to go with new plugs is not a bad thing. A replacement coil costs $80 retail and isnt too difficult to install.

 

[gingerbredman00]

I have the exact same issue with cylinder 8.
Oreilly's said it would be $50 for new plug wires.
I'll try switching them around later.

 

[RomeovilleIL]

When I advised the swap the plug wires, I meant to pull the wire from a known good cylinder off the plug and the coil and swap it to the missing position, then hook the questionable wire to the one you just unhooked and see if the misfire moved. For example, in this case take the wire off of your missing #8 and the corresponding opposite side #4. Rehook the lines using the opposing wires and see if #4 starts missing. If so, the wire is the problem & and new set is in order. If the miss stays on the original #8 then you know the problem is your coil. Considering $50 for a set of wires on the V8 and $45 for 1 V8 coil, I'd prefer to find the issue and only spend $$ once.

** V8 uses 2 coils that control 4 plugs each. The V6 has just one coil that covers all 6 plugs. On the V6 I would swap #4 with #1 wires since they are close to same length and the movement of the missfire to the opposite side of the engine should be pretty apparent without having to go back to a shop if you dont have a code reader at home.

 

[nlikens]

I swapped the two wires next to each other but when I pulled them off the coil I was getting a spark from all of them? Needless to say I found a white cinged mark on the #4 wire and it ended up splitting so I will need some new wires regardless. Not sure if that was new or had been there as that might have been the problem the whole time.

 

[RomeovilleIL]

Sounds like you found the problem. Does the truck run better now that all cylinders are firing?