CEL woes....again....

[6G72Galant]

Ok. So I was finally able to get the new o2 sensors installed. And away went my System too Rich codes. But the Random/Multiple cylinder misfire code still remains. Funny thing is, I didnt get the Rand/Mult. cyl. misfire code until I replaced the Mass Air Flow sensor. So I'm guessing that the sensor is defective. Any other suggestions?

[pinoyesv6]

what code is this you're pulling?

[RedLine DOHC]

reset your ecu and retest. then post the codes if any.

[6G72Galant]

Forgot to write the codes down. Ill pull them again tomorrow and post. Im pretty sure it was P 0300. But Ill double check.

But I know theres 2 codes....

Random/Multiple cylinder misfire detected
Random/Multiple cylinder misfire detected [PENDING]

[RedGalant2k1]

Replacing the MAF won't ever cause a random misfire code on its own. Now, if something was damaged in the install of the MAF (spark plug wire, or any ignition wire) that would give you cause to suspect that. But I suspect it is a coincidental thing.

[6G72Galant]

Replacing the MAF won't ever cause a random misfire code on its own. Now, if something was damaged in the install of the MAF (spark plug wire, or any ignition wire) that would give you cause to suspect that. But I suspect it is a coincidental thing.

Well, Ive never replaced my spark plug wires. But again, I didnt get the Random/Mult. cylinder misfire until AFTER replacing the MAF sensor. Before I replaced the MAF sensor, I was getting "System too Lean" on bank 1 and bank 2 (i believe, ill have to double check my older threads). Anyhow, both of those codes were gone after replacing the clearly rusted MAF sensor. Thats when the "Random/Mult cylinder" misfire code arrived. Ive replaced the MAF sensor, o2 sensors, and spark plugs. Ill do the plug wires some time this week. But I dont know if thats going to solve the problem. And Ive never touched any ignition components, other than the spark plugs. Again, I didnt get the Rand/Mult cylinder misfire until AFTER replacing the MAF sensor.

[6G72Galant]

Ok, I was able to pull the codes. I thought I took care of the o2 Sensor code, but apparently not.

Ive got 4 codes

P0172 System too rich Bank 1
P0172 System too rich Bank 1 [Pending]
P0300 Random/Multiple misfire detected
P0300 Random/Multiple misfire detected [Pending]

I'm clueless as to why I'm throwing a P0172. I just replaced that o2 Sensor, and that code went away, however it returned. That P0300 didn't come about until I replaced the MAF sensor. So I'm going to replace the "new" MAF sensor, with the one that was previously installed. And if the P0300 does go away, then I'm assuming I need to buy another MAF sensor. Any ideas about that P0172? I've never replaced my cat converters. And I have been smelling a rotten egg smell in the cabin when traveling uphill. But I've read from several sources that the rotten egg smell means that the cat converter is doing what it's supposed to be doing. However, when you begin smelling that rotten egg smell, it means you either have an exhaust leak, or your cat converter is clogged. I really don't want to replace those cat converters. My Galant has 3 of them. 2 of them are about $700, and the last one is about $1000.

[SPD_FRK]

And I have been smelling a rotten egg smell in the cabin when traveling uphill. But I've read from several sources that the rotten egg smell means that the cat converter is doing what it's supposed to be doing. However, when you begin smelling that rotten egg smell, it means you either have an exhaust leak, or your cat converter is clogged. I really don't want to replace those cat converters. My Galant has 3 of them. 2 of them are about $700, and the last one is about $1000.

From what I know, and have been taught, the rotten egg smell is a clear indicator of a failed catalytic converter. It is likely plugged and causing severed amounts of back pressure which could be reasonable cause for a random misfire code and a too rich fuel condition. If you can get away with a high flow replacement cat, do that (Summit Racing has some very inexpensive ones), or for the time being possibly fab a cat-delete pipe and see if the condition is gone...

[6G72Galant]

From what I know, and have been taught, the rotten egg smell is a clear indicator of a failed catalytic converter. It is likely plugged and causing severed amounts of back pressure which could be reasonable cause for a random misfire code and a too rich fuel condition. If you can get away with a high flow replacement cat, do that (Summit Racing has some very inexpensive ones), or for the time being possibly fab a cat-delete pipe and see if the condition is gone...

I've always heard that the rotten egg smell is an indicator for a failed cat converter. But then I came across several websites claiming that the smell is from the converter becoming clogged. Ive also read that if you were to bang on the converter with a rubber hammer, theres a chance that you might be able to free some of the debris clogging the converter.

I was talking to my friend at Advance Auto, and he suggested the high-flow replacement cat too. But I have the 03 Galant, therefore I have 3 cat converters. Anyone have experience in using an aftermarket high-flow cat?

[SPD_FRK]

You will have to remove the cats and bang on them, or use a steel rod to punch through the material left/clogged inside of it. lot of people do that if they can get away with the emission portion (ie dont have to get testing done in there area).

The only suggestion I will make about the high flow cats is this...Summit lists their's based on vehicle weights, pick one that is close to your GVW, or even one that is for a vehicle weight about 1000lbs heavier.