Catalytic Converter Cleaning

I have a 2008 Kia Rio, 4 Cyl 1.6L, and recently the check engine light came on and the car started running real rough after getting the timing belt replaced at firestone. I took it back to Firestone and they said that 2 of the cylinders where misfiring and i need to replace the ignition coils and the corresponding spark plugs, but that i also want to get a catalytic converter cleaning or flush or something like that becuase of the unburnt gas that was running into the converter. Is this true? They want to charge me another 100.00 for the cleaning on top of the 300.00 to replace the 2 ignition coils and spark plugs, should i get this done or can i clean it out myself?



Did your engine start “running real rough” immediately after Firestone replaced the timing belt, or did the rough running begin later? If it was right away, the likelihood is that they screwed-up the belt installation by being one or two teeth “off”. This is something that will damage your engine, so if this situation took place the first time that you drove the car after the timing belt job, then you need to take the car to a competent mechanic (clearly, NOT the Firestone guys) immediately, and then bring the bill for the second job to Firestone for reimbursement.

If the rough running started a day or two later, then it is possible that this is merely a coincidence, and that you really do need to replace coils and plugs. However, the two things that make this scenario very questionable are

  1. this is not likely on a 2008 vehicle
  2. “a catalytic converter cleaning or flush or something like that”.
    If they actually told you that they could “clean or flush” your cat converter, I suggest that you never return to this Firestone garage again.

Cleaning or flushing a catalytic converter???
Did they also suggest changing your blinker fluid?
Did they recommend replacing the muffler bearings?

I appreciate you commenting so quickly, thank you. It started about a day or two after we got it back, so it ran fine for a day or so. This is a 2008 i bought new, but it has high mileage as i commute about 120 miles a day, 5 days a week for the past 3 years and we recently went over the 100,000 mile mark. I believe the mechanic is right about the ignition coils, and i can replace those myself along with the spark plugs for half of what Firestone wants, but the mechanic stated that because we are only running on 2 cylinders of a 4 cylinder right now that the gasoline would be running into the 2 that where not working as well and that it is a good idea to have them clean “something out” cause it could ruin the catalytic converter, he said that it would flush all the contaminants out. I have called around to a few different mechanics, mostly mom & pop shops i explained to them the situation the same as i have here and they don’t seem to know what the Firestone guy was talking about cleaning so i am sure i am probably not saying it right. One shop thought maybe he meant to say a muffler flush possibly. Any other ideas on what else would need to be done after replacing the ignition coils and spark plugs? Can i just forget about cleaning the catalytic converter?



It’s not likely they can ‘clean’ the converter. But I’d want a second opinion on this, too many things happening at once. Do you have any other shops in your area? You can use the mechanic finder on this site to find one:

I think, from a pure chemistry standpoint, there probably is a way to burn off excess hydrocarbon contaminants from the platinum catalyst in order to extend the life of the converter and without damaging it. Practically, I have never heard of this, and would want a lot more details before forking over another hundred buck to these guys.

That would be a wonderful thing to clean a catalytic converter, I can’t hep but wonder if they mean the inside or the outside! Enlighten us with details!

The reaction between oxygen and unburned hydrocarbons generates heat; too much hydrocarbon causes the converter to melt down. Speaking theoretically only, I wonder if it would be possible to heat up the converter to operating temperature under an inert atmosphere like argon, and carefully control the oxygen levels so that the hydrocarbon would burn off slowly, keeping the heat build-up under control. It could probably be done in a lab.

On the other hand, one might simply run compressed air through the converter to evaporate the unburned gasoline.

On the other other hand, whatever unburned gas got dumped into the cat was probably burned up right away. Whatever damage there is has already been done, assuming the car is not driven again under the misfires are fixed.

Theory notwithstanding, a commercial, mechanic-provided “converter cleaning” sounds like a hoax until proven otherwise.