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alerored04
08-28-2010, 05:25 PM
Three days ago on my way to work I had to stop for gas at a station I rarely use. The tank was almost dry so it was almost 11 gallons that went in. The car ran fine the rest of the 20 miles to work. When I started it to go home at the end of the day I had to tap the gas a little to get it going, this happens from time to time, I don't know why, but this one was bad enough that I noticed the difference. Immediately leaving the parking lot the car had severe hesitation and was bogging significantly below 3k rpm and or 1/2 to 3/4 throttle. After straining to get to 55 it was having minor rpm fluctuations while driving. These were enough to get me to go to 65-70 where it ran better because of the higher rpm range. At the same time it was running a little warmer than usual. But it had not yet shown any CEL codes. Friday before I left the town I work in to drive home I bought and poured in a bottle of isoheet thinking I had got bad gas because the station I filled at didn't seem like they sold alot of 91 octane which I require because of the cam, no fix from that.

That was thursday, it behaved the same to and from work on friday, except when I was a mile or two from home on friday afternoon it finally threw a CEL. I scanned it when I got home and came up with P0404, EGR Flow ckt perf, and P0306 cyl 6 misfire. This morning I bought a new EGR and installed thinking that was the issue. It did not fix it. I got fed up and took it to a shop to get diagnosed thinking it might be a plugged cat, shop immediately ruled that out. He called and said the MAF values looked pretty strange. He said normal was anywhere from 3-5 grams/sec I believe thats the measurement it was in, mine was reading 10-12 g/s. He suggested I needed a new MAF. I borrowed the MAF from my sisters GAGT and went to pick it up. Slapped the working MAF on and drove it home, no change. I am back to thinking it was bad gas and am contemplating doing the fuel filter tomorrow just to see if that is the issue.

Anyone have any clues? I am out of ideas here.

remiljr
08-31-2010, 12:39 AM
pull plug 6 and check it out?

AaronGTR
08-31-2010, 05:02 PM
well, other than telling you 91 octane is not "required" for just a cam, I don't think I'll be able to help much. P0404 isn't even found in my manual so it must be a code they started using in 2001. I can't look up any diagnostic info on it.

alerored04
08-31-2010, 09:15 PM
I took it to a different shop today and he immediately said it was the cat. Unbolted it and she ran perfect. Thats what I get for trusting that other dumbasses opinion.

The tune with my cam makes 91 a good idea. I did not mean that it would preignite without it but I have not tuned for anything else so I don't trust 89 or lower.

Malaclypse
09-01-2010, 07:07 PM
I was gonna say... Catalytic converters are notorious for going bad in these cars.

They'll sometimes set EGR codes because of the back up of exhaust gas forcing the EGR valve open.

AaronGTR
09-02-2010, 05:15 PM
I took it to a different shop today and he immediately said it was the cat. Unbolted it and she ran perfect. Thats what I get for trusting that other dumbasses opinion.

The tune with my cam makes 91 a good idea. I did not mean that it would preignite without it but I have not tuned for anything else so I don't trust 89 or lower.


Well yeah if you are tuned for 91 octane then that's what you need to run of course, but you could tune for 89 or 87 and it would work.


I kinda thought it sounded like a catalytic converter issue myself but didn't say anything since you said it was checked already. Guess they screwed up or didn't know how to check it. One more reason I do most things myself... can't trust anyone else to do it properly.

alerored04
09-02-2010, 09:03 PM
I did not know how to check a cat. I called the shop that checked it and chewed them out, they refunded my money so im ok with their screwup aside from my time wasted. I have to say the car hauls ass now though. It must have been partially plugged for the past 50k. It has never ran this well. It was the original cat and had 172,000 on it. It was well past due.

AaronGTR
09-03-2010, 05:58 PM
Oh yeah, that would definitely wake it up then! :)

sugar ray
09-05-2010, 02:05 AM
My cat went on my 02 when it only had 70k km's (not miles) I did throw the same code and had me stumped. The STEALERSHIP called me with a diagnosis claiming my cat was gone, "installed and replacement will be $700"

You gotta be kidding me??? I asked...."how much do I owe you for the diagnosis?"
That bill was $45 bucks just to tell me the cat was gone and the $700 was to replace it, labor and an ORIGINAL GM CAT. Forget that noise!! Aftermarket cat $140 + $40 install. $180 grand total from a local muffler shop. Yet......$700 at the dealership. We wonder why GM is all but bankrupt. Who can afford to give them business at those prices??

And oh......by the way.....after I got my 02 back from the muffler shop I called the dealership service department to tell them about the price DIFFERENCE and SAVINGS. His response as you would expect, "uh....well....sir.....the difference is now you do NOT have an original GM part on your vehicle" I told em, "you mean the same original part that crapped out at ONLY 70k km's?" He got nervous and asked if there was anything else he could do for me? I finalized things by saying, "ya, next time one of your customers needs a cat converter send them to a muffler shop so they don't have to take out a second mortgage"

That was over 2 years ago and thinking about it STILL bugs me!!:asshat

alerored04
09-05-2010, 10:13 AM
Oh yeah, that would definitely wake it up then! :)

It's nice to finally have the car perform the way i thought it should after all the money I have put into it. Even after the heads, cam and tune I was disappointed with the power, now it's good enough to have me stop thinking about a part out and start eyeing the pacesetter headers for the 3400.

AaronGTR
09-05-2010, 04:57 PM
My cat went on my 02 when it only had 70k km's (not miles) I did throw the same code and had me stumped. The STEALERSHIP called me with a diagnosis claiming my cat was gone, "installed and replacement will be $700"

You gotta be kidding me??? I asked...."how much do I owe you for the diagnosis?"
That bill was $45 bucks just to tell me the cat was gone and the $700 was to replace it, labor and an ORIGINAL GM CAT. Forget that noise!! Aftermarket cat $140 + $40 install. $180 grand total from a local muffler shop. Yet......$700 at the dealership. We wonder why GM is all but bankrupt. Who can afford to give them business at those prices??




Well $700 is a lot of money, but technically there IS a reason for the price difference. Most after market cats are just the cat and have to be welded in and have a flange and O2 sensor bung added on to work etc etc.... the GM one is all one piece ready to install including the entire Downpipe, just like the original part. You are getting a lot more material hence it costs more. Plus many of the aftermarket ones are smaller and less efficient and will set off codes for the rear O2 sensor. You have to make sure you order a cat with a large enough core, were the OEM replacement you already know will work. Not trying to defend the dealership for their price raping people... just remember there is more to it than what you think. ;)