P0302 - Misfire cylinder #2

barch97 · Post by **barch97** » Sun Jan 25, 2009 7:49 am

Mrs. Barch's '01 Blazer flashed this one feverishly the other day about ten minutes after start up on a cold morning. It idled rough and ran even rougher. So, I parked it in the driveway and she took my CC to work.

It's at just under 73,000 miles. So, I figured it was probably a bad spark plug wire or distributor cap and if not, it's due for ignition tune up anyway.

Yesterday morning I replaced the cap, rotor and wires. The old cap and rotor were visibly worn but not terribly so and all six points appeared to be worn equally. The wires weren't in terribly bad shape. Much better than I recall my CC wires being when I replaced them.

It started a lot easier than it has in a while. Barely tapped the key and it turned right over but still idling very rough and SES light was back after a minute or two. Although this time not flashing. So, I went ahead and changed the spark plugs also. As with the cap, all six were worn about the same. It still idles very rough but the SES light has not come back on yet. Clearly there is something terribly wrong.

My next suspect is the fuel injectors but I'm not sure what to do about it. I really expected the issue to have been solved by the overdue tune up.

Any ideas?

04crewvt · Post by **04crewvt** » Sun Jan 25, 2009 7:55 am

Fuel injector would be a good place to start, how about swapping one from another cylinder and seeing if the code follows the injector. If not, a pressure check on the fuel regulator might be in order as well as a compression test. Check to see if the distributor has come loose, a slight misalignment may cause this as well. When was the last time you changed the fuel filter and or run injector cleaner through the lines?

barch97 · Post by **barch97** » Sun Jan 25, 2009 7:57 am

04crewvt wrote:When was the last time you changed the fuel filter and or run injector cleaner through the lines?

I was afraid someone would ask that.

04crewvt · Post by **04crewvt** » Sun Jan 25, 2009 8:03 am

15K religiously on the filter makes 4.3's happy campers and I try to run injector cleaners every 3k I f you haven't done that I would start there.

barch97 · Post by **barch97** » Sun Jan 25, 2009 8:30 am

It's been quite a while for both and she's been running low octane gas what with the prices and all. I'm off to the parts store.

Thanks for the pointers

Post by **HenryJ** » Sun Jan 25, 2009 9:05 am

04crewvt wrote:Fuel injector would be a good place to start, how about swapping one from another cylinder and seeing if the code follows the injector. If not, a pressure check on the fuel regulator might be in order

Neither of these is an option for us. Our injection system is a spider and you can't just swap legs. The fuel pressure regulator is internal to the intake manifold. Tests can be done to detect a failing regulator, but not directly like most others.

I would suggest checking the throttle bore for carbon deposits. The hole in the blade may be plugging. Also clean the IAC valve and seat. Checking and cleaning the EGR valve is another good idea, but it is a different failure code. It can contribute to the excessive intake deposits and carbon on the throttle bore.

I would hope this is an easy fix.

The fuel related problems sound like a good place to start. fuel pressure checks would be a good idea. that will diagnose a plugging fuel filter, bad fuel pump, injector, or regulator.

04crewvt · Post by **04crewvt** » Sun Jan 25, 2009 9:10 am

Didn't know when the switch over occurred since this is on his 01. I was hoping it would not be the spider since my regulator was bad in my 04 before all the other problems arose.

F9K9 · Post by **F9K9** » Sun Jan 25, 2009 9:15 am

HenryJ wrote:...............I would suggest checking the throttle bore for carbon deposits. The hole in the blade may be plugging. Also clean the IAC valve and seat. Checking and cleaning the EGR valve is another good idea, but it is a different failure code. It can contribute to the excessive intake deposits and carbon on the throttle bore....................

This is a cheap fix. I had the exact problem after I installed a new starter in another rig. Wouldn't idle and it was rough once it run. Since I unhooked the battery it had to relearn where to idle. I was told that cleaning the throttle plate would make the process quicker. Sure enough it was.

My CC had a bad habit of dying on me when I used the battery cut off switch. Cleaning the TB cure it.

barch97 · Post by **barch97** » Sun Jan 25, 2009 9:47 am

Well, it wasn't the fuel injector.

When I got down underneath to replace the fuel filter, I saw a suspiciously large wet spot on the driveway. Then I noticed the persistent drip of coolant.

Anybody want a blazer for parts?

04crewvt · Post by **04crewvt** » Sun Jan 25, 2009 9:55 am

Gasket time. $500-$700 or so and you should be all set if it isn't a cracked block. Less if you want to do it yourself.

Post by **HenryJ** » Sun Jan 25, 2009 10:12 am

Dex ate your intake gaskets? Bummer.

GeorgesBlazah · Post by **GeorgesBlazah** » Sat Jan 31, 2009 10:29 am

That stinks...the job is a lil big, but not that bad entirely. Let me know if ya decide to do it yourself, I could maybe swing by and lend a hand.

barch97 · Post by **barch97** » Mon Feb 09, 2009 9:21 am

Thanks, George. I appreciate the offer but as you probably know by now, the problem has been resolved.