JLFIII

iTrader: (1)

Okay, so I've got a 98 T/A with the LS1 (and an M6), and I've been having a nagging problem with the car running rough, it has been happening for the past few months. I'll be driving and everything feels fine, the next minute it is running rough, it feels similar to when your going to slow to be in 5th or 6th gear, a bogging and lack of power.

Last week it final threw an SES code and I thought that this was the clue I needed. I got code P0303, a cylinder 3 misfire. I checked the wire and then pulled the plug and while it didn't look too bad and showed no obvious signs of a problem outside of a large gap I changed it out just to eliminate it as a possible problem.

Of course it is still happening...

The only pattern that I can see forming is that it seems to happen mostly when I drive over very bad/chopped up road. The winter here in NYC has wrecked the pavement and it is tearing my car to shreds. Could all the banging (serious banging) around be causing an issue with fuel delivery or something else?

Any insight would be appreciated!

M4N14C

iTrader: (3)

Check your MAF and TB to make sure they're clean. A gunked up MAF will almost always make you run rough.

JLFIII

iTrader: (1)

I'll give those a check this week when the weather warms up... but would a dirty MAF cause intermittent problems like I'm having?

It doesn't happen all the time, that is what has me most baffled!

matt02ws.6

Did you change the wire too. I had a similiar problem with a p0305 code. I went ahead and replaced all the plugs and wires and it has not come back.

JLFIII

iTrader: (1)

No I didn't. When I purchased the car it came with MSD coils and wires, I know they are a little pricier than the run of the mill parts store brand, is there anyway to test the wire itself without swapping in a new one.

And can you get a single MSD wire at your local parts shop?

JLFIII

iTrader: (1)

Could any of these symptoms also point to bad cats? The exhaust looks original from the manifolds to the corsa axelback, and that would mean they have 215k+ miles on them.

LS6427

iTrader: (2)

Sounds like an 02 sensor or both FRONT ones might be acting up from time to time. You might have a frayed or ripped wire and when it gets moisture in it it acts up.

I would first pop that spark plug wire off and trade it with another one.......then have the code cleared. See if the code shows up again but the cylinder you moved that wire to. Of it does, go buy a set of wires from PepBoys for $36.00 and change them all. They are VERY GOOD wires.

A dirty MAF will cause the engine to run crappy at WOT......and it will idle shitty at cold start. But during normal driving a MAF doesn't effect anything. MAFs are used for cold start and WOT. The 02 sensors are responsible for the engine during normal driving after the engine reaches operating temp.

Swap that wire......see if the misfire follows it.

.

Jrclayton

so my 99 firebird was wantng to die after revs and had no power on hills. i drilled 3 holes right in front of the cat and presto it runs like a dream again. i am getting a new one installed saturday. u might try that but first start your car and see if it fees like you have the appropriate exhaust coming out of the tail pipe. you will be able to tell by putting your hand infront of it. trust me you will know if they are not putting the exhaust out. if im right its the cats