carquote

Sorry for the long post, but I could use some help. I have a 2003 Accord Ex-l v6 6spd that has only 29k miles. A few months ago the car started to hesitate under acceleration and the check engine light came on with codes for random misfires on all 6 cylinders. The exhaust had a strong smell as if the car was running rich and burning fuel and it seemed as if the exhaust tips had more carbon build up on them than normal. Long story short, the dealer changed the spark plugs and re-flashed the ECM and completed the idle learn procedure.

When I left the dealership the CEL was still on and the dealership said they thought there may be bad gas causing the CEL to remain on and the car to still have a rough idle and minor hesitation when the engine was cold. The dealership advised me to run the gas low and fill up got another two to three tanks to try tip purge any possible bad gas. I did so and the rough idle seemed to go away, but the CEL remained on. I went to AutoZone a few times and had the codes pulled and each time it was the same random misfire codes as before. I was advised by the dealership to pull three negative battery cable to reset the ECU and the CEL was off for about 50 miles or so before it cable back on.
This time when I had the code read it was a P0420. The dealership said this code meant my catalytic converter was bad and needed to be replaced and they confirmed this after I brought the car back to them to have it checked. I asked about a possible good will repair since the car is only a few months out of the 8 year federal emissions warranty and well below the covered 80k miles. I think they contacted the district service manager and said they would help me with the repair and charge me around $400. The dealer claims the OEM cat has a lot more precious metal inside than aftermarket direct fit replacements. While I appreciate the substantial discount, I don't feel this part should have failed with such low mileage on it. I contacted American Honda's regional case manager and was told they could not help me since I had already been offered assistance by the district manager by being offered the discounted rate.

At this point I'm unsure what caused the cat to fail so soon, and with the exhaust still having the same odor as before I'm concerned there is still something wrong with the car that may cause a new cat to fail again so prematurely. The service tech alluded to the possible cause being that I drove the car under the previous condition however as soon as the check engine light came on with the random misfires I took the car into them. If driving it with possible bad gas was the cause then I feel the dealership is responsible for advising me to do so and not advising me that damage to the catalytic converter could occur before offering the suggestion. I'd appreciate any input or advice any of you could give. Thanks

MSchu

this is an issue between yourself and the dealer.

BTW, 2003-2011... 8 years. bad petrol or some other fuel additive could indeed have caused premature cat failure. where are you buying your fuel and have you added anything to it such as octane boost?

accidentally run diesel or leaded fuel?

carquote

Thanks for the reply MSchu. If the cat indeed failed because I drove it with the bad gas in it (as I was told to do by the dealership, with no mention of any possible negative side effects), or because while it was left at the dealership for several days they drove it while trying to run the gas down instead of draining the fuel tank, then yes I agree the issue would be with the dealership. The problem is how can I know for sure or more importantly prove that it was caused by this?

I've never added octane booster to the car and I'm positive I filled up with regular unleaded as I always do. I always get gas from reputable gas stations and in driving almost 20 years have never had an issue due to bad gas. I'm extremely careful not to get gas when I see a station receiving a delivery and I never let the gas tank run low in the car. I even try to not fill up on days it rains to avoid getting water in the tank.

I'm still perplexed as to why the exhaust has this strange odor. My understanding of a defective cat is that it often gives off a sulfurous, rotten egg odor which this most certainly isn't. I'm unaware of a defective cat causing any other odors, so my concern now is that the car still has something wrong with it that the dealership didn't catch. The strange thing is that my gas mileage is still really good and hasn't seemed to decrease much if at all.

MSchu

that's a normal smell to be honest, for new converters.

no real way to tell if and why this happened... have all the issues subsided since the implementation of the new converter?

if so, I think you count your blessings and go on from here. looking to the dealer for responsibility post warranty period is a bumpy road, and they did give you good will.

is it possible that someone put something in your fuel tank, maliciously?

carquote

I haven't had the defective cat replaced yet. The smell I'm referring to is with the defective cat still installed.

Other than the CEL with the P0420 code for the bad cat the car is running fine. There might be a bit of loss of acceleration but that might also be in my head since I know a bad cat can cause that.

Since the car has a locking gas door that was never tampered with, I don't believe anything was put in the gas. I've filled up about 5-6 times since I initially left the dealer and the same odor still persists. If it was somehow bad gas, is it possible something is still remaining in the tank after this many fill ups?

MSchu

no... but what can happen is that as the substance burned off, it CLOGGED the cat essentially ruining the cat and making replacement necessary.

this is of course all speculation.

carquote

An ideas on why the exhaust still has a strong fuel/oil odor as if the car is running rich, yet my gas mileage hasn't noticeably decreased? I know a bad cat can cause a sulfurous, rotten egg smell but can it also cause the odor I described, or is this likely an indication that something is still wrong with the car?

wolfy47

sounds like you indeed have a dead cat that was most likely caused by the unburnt fuel from the misfires

the only thing you can really do is replace the cat