P0301 code help

[mga111]

I have a 1998 grand am se with a 2.4 twin cam. Yesterday, the engine started sputtering and it won't hardly pull a hill. I checked the plugs,wires, and changed the 2 coils and it is still doing it. Also, you can smell the raw gas out of the exhaust. I ran a compression test in cylinder #1 and it's good(about 122 psi). I am all out of options here. Please help!

[Bjornboy81]

Clogged Cat?

What's the P0301 say?

[rixGAphx]

P0301 = Misfire detected cylinder #1.

Misfire is caused either by poor/no spark, OR by very rich or lean fuel injection preventing firing of the mixture in the cylinder.

The injector can fail (won't open and allow a 'squirt' when the PCM tells it to); OR,
It can be so clogged that it won't let enough or any gas (thus, too Lean); OR,
It can be held OPEN by a microscopic spec of sand, allowing fuel to leak into the intake passage in between 'squirts' (thus, too Rich).

Based on the smell of raw gas out the exhaust, your engine is rich.
You've checked the ignition, but don't rule it out yet. The plug could be broken internally, or the wire could be broken.
Swap both the plug and the wire with another cylinder, and see if the problem follows the plug to the new cylinder.
Or buy a new plug and and wire.

Once you've proven that it's not the Ignition, then you need to replace that Fuel Injector. $75 - $135, depending on brand, source, and quality.

Do it now, before the richness destroys the front O2 sensor, the cat, and the rear O2 sensor. $$$$.
Been there, no fun.

Good luck.
-Rick

[adamD]

pull the cover off,connect plug wires from another car that will reach from the coil pack to plugs (with the cover off). start the car,pull the plug off of #1 and check for spark from the coil pack,hold the wire on top of the spark plug you should hear or see the spark jumping the gap to the plug ... use rubber handled pliers and wear gloves and carefull where u let the spark ground out u could fry the pcm or icm.

[mga111]

Bjornboy81-- The code reads misfire in #1 cylinder.

rixGAphx-- I changed the plug in #1 cylinder and swapped the boot wire with #2. The diagnostic still read P0301. My next was going to be the fuel injector because it's the cheapest. I'm not driving it until I get it fixed. Does anyone think that it could be the O2 sensor. I never had one go bad before so I don't know what it causes. I don't think that is it though. Thanks for all your input guys

Mark

[rixGAphx]

NOT the O2 sensor.

The O2 sensor produces a signal indicating how much O2 (raw, left-over oxygen) comes out of all the cylinders in that bank.
The PCM (Powertrain Control Module, the engine/tranny computer in our cars) interprets the signal, and adjusts the amount of fuel 'squirt' so the air-Fuel Mixture going In the cylinders is optimum.

As an O2 sensor gets older, it sssllloooooowly produces a weaker signal.
And, if one (or more) cylinders is burning VERY rich, the unburned gasoline can start to degrade the O2 sensor's performance very quickly.
To a certain degree, the PCM can adjust for this.
Ultimately, the PCM thinks the O2 sensor just isn't working decently, and it sets a code specifically for this (P0130 thru P0134 are the codes, see http://www.obdii.com/codes.html for the entire list of Generic OBD-II codes).

So, if the O2 sensor was the cause of your current misfire, it's 99.99% certain you would have an O2.
* * *

At this point, I would go for the injector at #1.

Good luck.
-Rick

[adamD]

u have to check 4 spark like i told u.if no spark probably the icm is bad ur problem is only related to cylinder 1 so it cant be the o2s.

[adamD]

oh yeah, if you think its the injector try swapping them from cyl.1 to 2 and see if the miss moves to cyl. 2 code p0302

[mga111]

Hello everyone. I just wanted to let everybody know that I found the problem. It was the plastic coil housing cover that connect the coil packs to the spark plugs. It cost about $45.00. I wanted to thank everyone for their suggestions. They helped me eliminate alot of possibilities.

Mark