Code P0303 - Misfire in Cylinder #3 [Archive] - GrandAmGT.com Forum

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Mike Jung
10-01-2003, 11:20 PM
Please give me your opinions.

I drove home normal today 17km/10.5miles for 1/2 hour in traffic on the highway ranging from bumper to bumper, stop & go to driving a 110km/h -> 68mph.

After getting home, I go shopping about 7km/4miles away - I drive in city driving up to speeds of 60km/h -> 38mph.
Come back from shopping & remote start car.
The car had a funny/rough idle at 600rpm.
I put it in Drive & the car sputters, rpm jumping up & down a few hundred rpm's & the SES light is flashing.
I park & turn off engine. Re-start (by hand using key) & same thing happens.
I drive out of the parking lot to across the street to another parking lot. SES light still flashing with car sputtering.
Turn off engine & read the code as P0303 (misfire in the cylinder #3).

Drove home gently with the 4-way flashes on. About 7km/4 miles with the SES light flashing the whole way.
Me going gently on it, up to 50km/h -> 31mph.

The engine sounded like it had a hell of a time backing in to the drive way with a slight slope for rain water to run down to the road.
The engine sound like it was sputtering with no power & there was a kind of knocking noise [like somthing broke loose-?] (that I noticed when backing up with the door open).

Get home turn off for a few minutes & re-start...when I put the car in gear & move the SES light flashes.


The gas filter has been changed & the injectors flushed clean through the rails at 51k km/31k miles about 2.5 years ago.
I do use complete fuel system cleaner in the gas tank every spring & fall.
I.P.A. gas anti-freeze & water remover every month during the winter months.

My GA with the 3.4L V6 engine had the lower manifold intake gaskets, water pump, right axleshaft seal, ATF pan fluid changed (with filter change) & NGK TR55IX iriduim spark plugs put in back in Feb '03 at 75.1k km/46.6k miles at a GM dealer.

It is now almost 8-months later at 83K km/51.5k miles at 5.5 years old.

2-weekends ago I washed my car by hand in the driveway.
The next day (I didn't drive it after washing the car because it rained afterwards) remote starting it, there was a few seconds of cranking before it turned over.
Their was a spilt-second of like a explosion/bang that was unusual when it did turn over.
But seem normal afterwards until now.
Leaving the parking lot afterwork today; I noticed once a slight bang noise going down the sidewalk curb to road while coasting slowly.

My car is outside 24/7 (no garage for my GA) & it has been raining on & off with colder temps around 3-15C/37-59F this week.
It was raining on & off while driving home; & was raining when I went shopping.
I only/mostly use Sunoco ethanol (blended up to 10%) gas.
Just gassed up on Friday & Monday night. I got on around 1/2 tank, 20.5 MP(US)G.

Please help & what do you people think ?
How does a misfire usually sound ?

:crying: :(

I guess my GA is going to a GM dealer on Monday (I still have a GM extended warranty for another 1/2 year on the powertrain).

Is it safe for me to drive to the dealership that is like 5km/3 miles away?

iceman
10-02-2003, 07:48 AM
I'll just relate some of my personal experiences w/ misfires, maybe it will help.. First or me they were a PITA to trace, mainly because mine weren't severe enough to trigger an SES. A flashing SES = severe misfires, bad enough that any tech with a scan tool should be able to track it down pretty easy.

Anyways, it can be a number of things - plug, wire, coil pack, injector, fuel system.... Plug + wire you can inspect on your own, other than that I can't help much. I've had clogged injectors, and bad wires before, and they both have the same symptoms..

I will tell you that don't be surprised if it is a clogged injector - I used fuel system cleaner w/ every oil change, and my injectors were clogged out the wazoo by 20k miles. Again around 30k, that stuff is staying out of my tank forever.

Mike Jung
10-06-2003, 07:36 AM
Well my car is at a GM - Chevy dealer right now :(
I wait for the phone call.

Kind of on the bright side:
After parking it since Wednesday night.
Yesterday, my SES light stopped flashing, stayed steady & turned off (the misfire code is still in the PCM memory).

Is it normal for you to get a severe misfire with flashing SES light; then severe misfire stops by itself & the SES light turns off :confused:

Mike Jung
10-06-2003, 09:54 AM
Got a call from the dealer:

My ignition wires are bad & my car is running lean.
The injectors need cleaning & the throttle body is carbonized/dirty (& recommends it to be cleaned).

:(

Blackrider
10-06-2003, 11:29 AM
Originally posted by Mike Jung
Got a call from the dealer:

My ignition wires are bad & my car is running lean.
The injectors need cleaning & the throttle body is carbonized/dirty (& recommends it to be cleaned).

:(

All Problems you can take care of yourself:)