exhaust gasket issue, donut gasket

do you know when the coils/plugs/wires were last replaced?...

Sorry, i'm a little unfamiliar with the 'IACV'...what part are you talking about exactly? The throttle body has a throttle position sensor, and a EGR control solenoid/valve positioned underneath it...If there is an additional sensor there, i never noticed...but its been a while, so forgive me haha...

Have you messed with the MAF or IAT sensors in the air box? Some guys ended up with p0300's after attempting to clean those...as residues from certain cleaning products caused them to fail...

I wish i could be more help, im just naming off things it may be thats all...

Installshield 2 said:

do you know when the coils/plugs/wires were last replaced?...

Sorry, i'm a little unfamiliar with the 'IACV'...what part are you talking about exactly? The throttle body has a throttle position sensor, and a EGR control solenoid/valve positioned underneath it...If there is an additional sensor there, i never noticed...but its been a while, so forgive me haha...

Have you messed with the MAF or IAT sensors in the air box? Some guys ended up with p0300's after attempting to clean those...as residues from certain cleaning products caused them to fail...

I wish i could be more help, im just naming off things it may be thats all...

Click to expand...

Coils/wires and plugs were changed less than 10,000 miles ago.

IACV is the Idle Air Control Valve and is attached to the top of the throttle body. It has a cylinderical black section that controls the valve.

I cleaned the MAF sensor a couple weeks ago with MAF cleaner. Then, I dabbed a chocolate donut directly on the sensor to dry off any residual fluid.

Just kidding. But, I did spend the extra couple bucks to get MAF cleaner. I don't know what the difference between that and other cleaners but a YouTube dude recommended MAF cleaner and not other cleaners.

oh ok, i do remember that now...just haven't had to mess with mine yet...Its usually the EGR valve that can get clogged, did you clean that too?

No, I didn't clean the EGR. I had cleaned it maybe 40,000 miles ago. I didn't think I would need to reclean it.

So, I go out to check if there is a leaky vacuum line or leak around the throttle body by spraying carb cleaner around those areas. The car starts up without a problem and idles smoother. I spray carb cleaner around the vacuum lines and the throttle body-to-engine area and don't notice a difference.

Anyway, I have a state inspection to do this month. I don't know if it will be passable even if it idles smoothly, which I would hope for.

...What all of this adds up to is a little thing mechanics call "misfire." A misfire will result from anything less than perfect combustion, and that's obviously the case when your valves aren't opening on time. Many engine problems can cause a single-cylinder misfire, but a belt that has jumped a tooth will cause every cylinder to misfire. At some point, the engine will misfire so badly that it either won't run or won't start. Difficult starting, combined with a loss of power, heavy engine vibration as a result of misfire and raw fuel spewing from the engine are the most classic signs of an engine which has jumped timing...
http://www.ehow.com/info_12229263_would-happen-timing-belt-slipped.html

So, I am getting my timing belt replaced today at the dealership. The symptoms sound related to my problem. Difficulty starting, loss of power, and heavy engine vibration. So I think the misfires cause my P0300 code. It's been over 80,000 since I had the timing belt last changed.

So, I got the timing belt replaced. It doesn't shake heavily when at idle anymore. It still has trouble starting sometimes and the idle is a bit smoother but still changes rather than staying steady. I've already cleaned out the IACV so my next step is to replace the fuel filter and fuel strainer. I've never changed it and I read that a dirty filter can lower fuel pressure thus cause rough idle/hard starts. I've put in this STP stuff that is similar to Seafoam into the gas tank and I'm not sure if that cleaned the injectors, which is also related to rough running.

I bought a new catalytic converter. Magnaflow direct-fit version.
Well, it took awhile to cut off the old nuts. I wasn't going to fight the rust as the rubber hangers kept on flexing while I was trying to crank off the nuts.
I eventually got the new catalytic converter and gasket installed and all was smooth until I had to hook up the cat to the J-pipe. The bolts did not line up. I then recall someone else having that same issue. Having worked on the fuel filter replacement earlier, I was starting to freeze and decided to work on that the next day. I wasn't going to get the flange rewelded.
I lined up the new cat to the J-pipe and made some markings on the J-pipe's flange. The Bosal J-pipe that I had replaced a couple weeks ago had a thick flange compared to the OEM cast flange. Anyway, that took a couple grinding tips but I grinded both bolt holes and eventually got it bolted up. PITA. Sound issue is resolved. No air or water escapes the gasket.
I only got a picture of pre-install.


The old catalytic converter wasn't that much heavier than the new one so there's no weight savings. The stainless steel piping is nice and shiny, flange welds and hangar welds are nice (not super neat).

FYI: Magnaflow includes two bolts that hook up to the J-pipe side. The bolts didn't come with nuts so I got them, they are M10-1.25