You know Gorn, I thought about that too. I did check it though and its full. And even fairly clean! Even check the oil for the dreaded chocolate milk, but its clean too. That and the car runs to good, if its not idling, it runs great. Doesn't smoke at all. I really don't think it is a major problem, its just that I cant nail down what the problem is. My plan of attack is to swap the injectors around and try that. If the problem moves to the other cylinders, then it has to be the injectors are bad. If the problem stays with cylinders 3 & 6, then I am going to take off the balancer and check out the crank and cam position sensors for any obvious damage. UNLESS somebody has any other ideas?

Another thing real quick, I think that most of the misfires are coming on deceleration. Its kinda hard to drive and check the scanner and think all at the same time so I'm not sure. But that is what it seems like. And I'm not sure why, but that makes me think of the EGR valve. But if it was an EGR valve bad it would effect all the cylinders, wouldn't it?

 

What is the code number you are getting? P0300? You also have misfires on other cylinders too. Have you checked the plugs? I know your engine requires iridium plugs, and if you have copper ones or bosch plugs you can get misfires. You have more misfires on cylinders 3 and 6 which are on the same coil pack. Cylinder 6 is on the left of the engine and cylinder 3 is on the right. I've included a zip file with 2 PDF's on how to remove and install the fuel rail and the injectors. There's a special process otherwise you can mess things up without wanting to!

 

Thanks for the pdf! All the plugs are brand new, not even a week old yet. But, now that you mention it , they are the Bosch platinum plus. Almost all of the misfires are on cylinders 3 & 6. I do have a couple on other cylinders but, the main problem seems to be with 3 & 6. I cleared the codes again this morning and drove to work. When I got there I had 27 misfires on cylinder 1, 952 on 3, 2 on 4, and 795 on 6. Remember this is a 60 mile trip to work. When I left work I cleared everything again and drove home. When I got here I had 12 misfires on 1, 1 on 2, 1646 on 3, and 1399 on 6! From the same 60 mile trip. I am guessing that the heat of the day has something to do with the numbers being higher. But what would the heat of the day affect?

Also, I got to looking around, and the EGR looks real new, but it has a hose clamp around it. On the bottom part of the cylinder part. NO idea what its doing there. The car also has a new cat converter on it. Don't know if that gives anybody any ideas, just thought I would throw it out there.

And ya, its the P0300 code.

 

HOLY CRAP!!!! I think I got it figured out!!! I did some looking around this site and found another thread about a rough idle. So, I checked it out and there was a page in one of the replies from alldata. Got to looking at it and one of the things it said to try was to unplug the MAF, and drive the car. If it didn't misfire, then replace the MAF. I thought, there is no way that will work, but its free and easy so why not give it a try? I cleared the codes and data from the scanner, unhooked the MAF, and drove about 20 to 30 miles. Guess what, NO MISFIRES! Im not 100% convinced yet, Im going to drive it for a day or so before I go and buy a new MAF, but so far it seems like I have found the problem.

Here is a link to the other thread, and by the way, a big THANK YOU to everybody that helped out in this little adventure.
https://camaroforums.com/forum/general-tech-5/99-camaro-3-8l-engine-code-p0300-53531/

 

Glad it turned out alright for you! I hope it was that easy!

 

Your not going to believe this, its still messed up! I went out and got a new MAF, installed it, drove it. Got misfires on cylinders 3 & 6. I only went on about a ten mile trip and it wasn't enough to set a code. But it was showing misfires on the scanner. So, I am up for any ideas. I did check the air filter, its fine. And its a K&N. Thinking that may have messed up the first MAF? I know they are pretty commonly over oiled and burn them up. But now, since it is still messing up, maybe it wasn't the MAF that was bad after all? I don't know anymore, just don't know.

 

The only thing I can think of is your cat could be plugged. My wife's Grand AM's cat was plugged and was causing cylinder misfires too because of all the pressure in the engine not beaing able to be released. It can also put stress on your head gasket and cause it to leak.

 

That does raises another question. How hot should the cat be? Mine runs at 572, which seems a little cold, but maybe I'm wrong? It is a new cat, but I also know that don't always mean a thing. Just got back from a 30 mile test drive, got 1801 misfires on cylinder 3 and 1353 on cylinder 6. AND, how can it register that many cylinder misfires and not turn on the check engine light? It did give me the PO300 code, but it says that the MIL light was off. Fuel trims look good. Changed the PCV valve and gasket. And by the way, how does that thing work? I mean, I know its a valve that opens and closes with the vacuum. But the way it just sits in its little hole with the cap on it, with nothing going to it, just don't understand how it can do any good.

 

if the codes are P0303 and P0306 then I would look at the coil that manages 3+6, look at the wires, and plugs too. In the waste spark system it only takes one component of either side of the coil to kill both sides. My friend and I chased an issue similar to yours on his Z28 and found it was a cracked ceramic housing on the #1 plug.

Massey

 

The only code I get is the PO300. And, I must admit, that tells me it is a bad coil. But Ive swapped out the coil with another one I had, and swapped it out with another coil on the car. Neither one had any affect on the misfires.

New plugs
New wires
changed and swapped coils
New ICM
two cans of Sea foam
Fuel system cleaned
New MAF
New PCV and gasket