Four hours into an 8 hour trip to Louisville our 2002 4Runner Limited with 316k miles started running rough. Stopped at the local garage and after replacing the mass air flow sensor, coil and number 4 injector they gave up. We ran the last 4 hours to Louisville on 5 out of 6 cylinders. There we found a great mechanic who found out it was the number 4 plug wire shorting out. The other day the check engine light came on. I’m sorry Scotty I don’t remember the codes but they said it was catalytic converters and that sometimes a car with that many miles will show catalytic converters even if they are ok. The local muffler shop cut the catalytic converter‘s off and shined a flashlight through them and said they looked fine. I have had this old girl since she had 21,000 miles on her. Should I spend the money to replace the catalytic converter’s even though the check engine light may come back on again Scotty? Help, I’m at my wits end.
Thanks
Clarification: Can you get us the exact codes? Go to a place like Autozone or O’reilly’s and they will scan for free.
Yes I will try.
Cutting the cats off and shining a light through them to see if they're clogged is an unnecessary, labor intensive way to determine if a clogged cat is creating too much exhaust back pressure.
The right way is to remove the upstream O2 sensor and use an exhaust back pressure gauge.
Takes a few minutes. Scotty did a video on it a while back.
There's several things that can trip a cat related code. You don't replace expensive cats (or cut them off to take a peek) in response to a cat code
https://www.youtube.com/watch?v=qJTmddbOxMk
First off, I suggest you change your plug wires about every 30k miles just so you don't get that issue. How many miles since you had them changed? Yours is not hard to do, and you can get a good set of NGK or Denso plug wires for about $30.
The mechanic in Louisville replaced them all in March.
Wow that is shocking that they went bad that fast. Do you know what brand they were by chance?
I’m afraid not.