I could use some help. all of a sudden the other day i went to drive my 03 blazer that was working fine. I went to drive it the other day and noticed rough idle and bogging down of the engine under acceleration. As I drove the ses light came on blinking so, i got the codes checked. I got p0200 and p0303. so, obviously i have a misfire on cylinder 3.

since p0200 is a general code i assumed it was being caused by the 0303 code. i figured i would chase the 303 code first.

I tested the #3 plug with an in-line tester to verify spark at the plug and it was fine. I pulled the plug since spark was getting through. visually it looked fine but, since it was the PITA #3 cylinder and, i already had it out i replaced it with a new ac-delco plug.

ran the engine and, had the same misfire symptoms.

Any help or suggestions would be greatly appreciated.

 

I had the same problem in my 02. I replaced the spark plug, wires, rotor and cap. Nothing fixed my problem until I replaced the spider. Good luck getting her fixed.

 

Mine is an 03 and I thought it didn't have a spider. What can I do to be certain it is the fuel injector before I go replacing expensive parts?

 

To day I did a fuel pressure test to make sure the fuel regulator and spider are not leaking. It was fine. Pressure went up and stayed there after cranking the engine for at least a minute.
-So it looks like I have a spark as I used the inline tester and saw the spark.
-replaced the sparkplug just to make sure I had a good one on there
-and verified the regulator and spider should be good with the pressure test
- it seems like I should have spark and gas found to the engine but, still have a misfire?

 

so i went to the shop and told the guy what i had been through and that i was stumped. he took a look at the codes. I was thinking the misfire in cylinder 3 was the code i should have been figuring out but he said that the p0200 code was likely causing the p0303 code. he said that the next thing he would do is spray carb cleaner in through the air intake. if the car would run smooth that would eliminate something. I am not sure what that would tell me but i am just posting this hoping it might help someone else in the future. what is the name of the part that sits in front of the distributor and send electric into the top of the engine cowl?

 

My diagnostic chart for this year model has several possibilities. Don't know what the carb cleaner would eliminate or not, at least yet.

High Oil Pressure is the first on the list as a cause. However, because you're throwing a misfire code, the other items are a worn or damage accessory drive belt or components, damaged crankshaft balancer; damaged crankshaft reluctor wheel; damaged or loose engine flywheel; damaged or restricted exhaust system (collapsed pipes, plugged mufflers, or malfunctioning catalytic converter); vacuum hoses; and on it goes.

Here would be my list...
1. Check the spark on 2.
2. Check the exhaust system.
3. Check your belts.
4. Check your oil consumption.

My diagnostic chart is pretty long but at least some of the easy things can be looked at before getting deeper.