Question before I buy a sw2 saturn wagon with p0304 and p0420 codes

[vikasevan]

I like a saturn wagon 1997 sw2 and want to buy but it has check engine light on and it shows two codes P0304 and p0420....

I don't have much access to car to check something major like compression test or leak down test....at the same time I dont want to buy this car if it has some major problems like piston or valve etc...

How do I check whats wrong with it ?

From your experience can you tell what is main reason why it will give these two codes together?

Owner said he recently changed plug and wires but has not changed anything else like ignition control module or ignition coils ...
If its something minor like ignition coils etc...I want to buy but not if something about head or engine ....like I said she wont allow me to check compression etc...

so I have to trust on people on forum and their experience....so please advice.

[OldNuc]

What brand f plugs did he use? Does it idle smoothly when fully warmed up?

If the owner will not let you check it out then walk.

[SL19302]

Originally Posted by vikasevan

I like a saturn wagon 1997 sw2 and want to buy but it has check engine light on and it shows two codes P0304 and p0420....

I don't have much access to car to check something major like compression test or leak down test....at the same time I dont want to buy this car if it has some major problems like piston or valve etc...

How do I check whats wrong with it ?

From your experience can you tell what is main reason why it will give these two codes together?

Owner said he recently changed plug and wires but has not changed anything else like ignition control module or ignition coils ...
If its something minor like ignition coils etc...I want to buy but not if something about head or engine ....like I said she wont allow me to check compression etc...

so I have to trust on people on forum and their experience....so please advice.

The P0304 is a misfire on Cylinder 4 and the P0420 is a Catalytic Converter Inefficiency code, If the lady wont let you take it to a mechanic you trust I would walk away.....

[vikasevan]

Originally Posted by OldNuc

What brand f plugs did he use? Does it idle smoothly when fully warmed up?

If the owner will not let you check it out then walk.

Idle is rough all the time irrelevant fully warmed up or not...
Could not find out about brand of plugs...
but after changing plugs no difference same rough as it was before..

[SL19302]

Most likely a burned exhaust valve on Cylinder 4, And most likely needs a new Catalytic converter from it misfiring on cylinder 4 for who knows how long causing the converter to overheat and get saturated with raw gas.....

[vikasevan]

Originally Posted by SL19302

Most likely a burned exhaust valve on Cylinder 4, And most likely needs a new Catalytic converter from it misfiring on cylinder 4 for who knows how long causing the converter to overheat and get saturated with raw gas.....

That's what am worried about....is there any short cut to verify that? I won't be able to do compression test..



Also is it ppssible that bad cat would cause misfire on cyl
4? Or its always misfire would cause the cat to go bad?

[SL19302]

Im currently working on a 05 Chevy Suburban that had a misfire for 4 months before the owner had the money to fix the bad intake gasket, now that the gasket was replaced and the engines running perfect again the converter has an issue from her driving it that long with a misfire, Usually on these computer controlled vehicals one problem will lead to another and another if not adressed right when the issue occurs, You can ask them how long its been running rough with the misfire and that will give you a good indicator of how long the converters been suffering....

[SL19302]

Originally Posted by vikasevan

Or its always misfire would cause the cat to go bad?

^^^ This is what will cause the converter to go bad thats why in the owners manual it will state that a flashing check engine light you should shut the car off as soon as possible and have the car serviced as soon as possible, A misfire is when one or more of the cylinders are not firing correctly and burning up the air/fuel mixture correctly as a result the unburned air/fuel goes down the exhaust and the converter becomes overwhelmed and cant keep up, The longer it stays that way the worse off the converter is.

[OldNuc]

Originally Posted by vikasevan

That's what am worried about....is there any short cut to verify that? I won't be able to do compression test..



Also is it ppssible that bad cat would cause misfire on cyl
4? Or its always misfire would cause the cat to go bad?

Rough idle + P304 = burned valve on #4. listen art exhaust pipe and you will hear it, 3 good beats and a fart.

[vikasevan]

Originally Posted by OldNuc

Rough idle + P304 = burned valve on #4. listen art exhaust pipe and you will hear it, 3 good beats and a fart.

Thanks...

[Coachvtennis]

Originally Posted by OldNuc

Rough idle + P304 = burned valve on #4. listen art exhaust pipe and you will hear it, 3 good beats and a fart.

How can i fix this Burnt valve myself.....I have sw2 1996, 186000 miles, a bunch of carbon build up from clogged egr still ran it about 1 year. Need to fix now.

[billr]

What is your skill/experience level? The cylinder head has to come off for valve-work or replacement. How much money and effort are you willing to spend? As a wholly DIY project it can be in the $100-200 range to just replace one valve. About 15 hrs. of work to R&R the head, depending on how fast you can work and how good a job you try to do...