Engine code P030X, can't get past 2500 rpm

[knowledge8069]

Quick background of my ride:

2000 GS Coupe
Automatic Transmission
2.4L LD9
GM Supercharger Kit
109,000 miles
Amsoil 25,000 mile drain synthetic oil since 16,000 miles on car

Parts serviced: both front wheel bearing sets, both window regulators, brakes, calipers, tires (normal stuff), no drive train issues yet

My car threw a code last night after a 40 mile drive. Everything was fine until I got to a stop sign, idling, and noticed the car was jerking back and forth. "trac off" light came on. Brought it to Autozone the same night, they read OBD-II code P0301, which is "cylinder 1 misfire."

Bought new spark plugs (Rapidfire #8 which is current AC Delco equivalent for plugs that come with s/c kit) and new plug boots. Gapped the plugs at .050 as GM s/c kit instructions state. Installed parts and the jerking stopped. Thought it was fixed, started the test drive.. Got to about 4000 rpm before the car bogged down. I was unable to get it past 4000 and after getting there it got worse to where I couldn't get above 2500. Will only do about 30 mph. Limped it home, went out this morning and bought an ignition coil housing. Installed that, no effect. Tried putting some clean gas into the tank, thinking it was bad gas. That did nothing. Now the indicator lights are "service engine soon" and "trac off" which goes on and off at will. The "service engine soon" light will sometimes flash, other times not.

Looking at the code description, these are possible problems:

A code P030X may mean that one or more of the following has happened

• Faulty spark plugs or wires
• Faulty coil (pack)
• Faulty oxygen sensor(s)
• Faulty fuel injector(s)
• Burned exhaust valve
• Faulty catalytic converter(s)
• Stuck/blocked EGR valve / passages
• Faulty camshaft position sensor
• Defective computer

There has been a rattle for a few months coming from the catalytic converter. Sounds like a piece loose inside when I put my ear up to it. Since it's fairly expensive ($350) to get the preassembled exhaust system I've put it off.

Do you all have any ideas? I'm broke right now after 7 years of school, so I have limited means. Trying not to buy unnecessary parts if possible. It seems to me that the engine is being choked out at higher rpm.. It's smooth as normal up to around 3000 rpm, then it chokes and gets worse. Any help you can offer would be greatly appeciated. Thanks in advance.

[[ion] C2]

Cut off the cat! Have a pipe welded in place of it. My cat clogged up a year after being supercharged.

By the way you can get a new cat for $60 and have it welded on at Midas on the cheap. That "direct fit" bullshit is... bullshit. Exhaust is custom.

[Nate's Alero]

P030x - Misfire on Cylinder x Detected

The Crankshaft Position (CKP) sensor is the primary input to determine if misfire is occurring. Engine misfire is detected by monitoring crankshaft speed variations between cylinders. If a crankshaft deceleration occurs during a combustion or power stroke, the control module will compare this change in crankshaft speed to the previous cylinder. If the crankshaft speed change is more than a maximum allowable speed, the misfire is detected. Misfire may occur in a specific cylinder or in all cylinders randomly.

When an engine is misfiring, brief decelerations in crankshaft rotational speed will be detected by the CKP. The control module determines which cylinder has misfired based upon the Camshaft Position (CMP) sensor input. Misfire data is stored for each cylinder in separate accumulators. After 100 combustion events, the misfire totals are compared to a calibrated maximum number. If the misfire is excessive, this Diagnostic Trouble Code (DTC) will set.

[widbyj]

Remove the cat to test... if the RPMs come back up you are holding the problem.

[Kilroy]

Not sure what the code P030X means, but if you get the code P90X, it's the car's way of telling you that you are out of shape.

[[ion] C2]

P0301
P0302
P0303
P0304

All misfire codes, common knowledge in DTCs.

[Kilroy]

Originally Posted by Kilroy

Not sure what the code P030X means, but if you get the code P90X, it's the car's way of telling you that you are out of shape.

Originally Posted by [ion] C2

P0301
P0302
P0303
P0304

All misfire codes, common knowledge in DTCs.

Ion......dude........you see that thing zooming over your head?? It was the joke from my previous post!!!

[knowledge8069]

Update: Definitely was the cat! Works perfectly after replacement. The old one was in bad shape.. It was obstructing the airflow and causing the engine to choke. Just to be sure I went in for a tune-up and had the fuel delivery and ignition systems checked. Everything was ok.

Bottom-line: If this happens to your car, unbolt the exhaust assembly (only three nuts on bottom of engine) and pull it away from the block. Then try driving your car as normal. NOTE: It will be extremely loud when driving it this way, but don't worry no damage is being done. If the car works with the exhaust pulled away, then you may have a plugged catalytic converter. =)

Thanks for the help all.

[[ion] C2]

Yup. One reason no cat on my car anymore. No more chance of clogging.

[alerogls001]

But I thought a car without a cat would fail emissions....

[alerogls001]

Originally Posted by Kilroy

Not sure what the code P030X means, but if you get the code P90X, it's the car's way of telling you that you are out of shape.

I got it. the exercise videos!!!

[[ion] C2]

Of course, if you had emissions testing.

[a.graham52]

Originally Posted by knowledge8069

Update: Definitely was the cat! Works perfectly after replacement. The old one was in bad shape.. It was obstructing the airflow and causing the engine to choke. Just to be sure I went in for a tune-up and had the fuel delivery and ignition systems checked. Everything was ok.

Bottom-line: If this happens to your car, unbolt the exhaust assembly (only three nuts on bottom of engine) and pull it away from the block. Then try driving your car as normal. NOTE: It will be extremely loud when driving it this way, but don't worry no damage is being done. If the car works with the exhaust pulled away, then you may have a plugged catalytic converter. =)

Thanks for the help all.

pulling the O2 sensor in the manifold is usualy easier. A LOT of the time (atleast in the east coast) you dont want to mess with exhaust bolts unless you feel like replacing that can of worms with a nother can of worms.

[alerogls001]

Originally Posted by [ion] C2

Of course, if you had emissions testing.

Well guess some of u have it easy- had to replace mine in April so I would pass it.

[a.graham52]

for future refference. when the SES light flashes... thats your car begging for mercy. in reality it means there is a catylist-damaging-missfire, and raw fuel is being introduced into the cat.

[Kilroy]

Originally Posted by alerogls001

I got it. the exercise videos!!!

FINALLY, SOMEONE DID!!!

[alerogls001]

Sorry, I couldnt just let your joke wilt there.... lol