Cylinder misfire

SHITBOXGIRL

MEMBER
2001 CHEVROLET BLAZER
4.3L
4 CYL
4WD
AUTOMATIC
210,000 MILES

My grandma gave me this car because it won’t pass smog. I ran the codes, and a bunch of brake related codes came up, plus a cylinder 1 misfire code. I changed the spark plugs and wires and dumped the fuel injector cleaner in it, but the code is still there. I do most of my mechanical work myself with the help of friends who are a little more handy. What else can I do before folding and taking it in?

1 Reply

AL514

MECHANIC
4,675 POSTS

Hello, do you own an automotive 12volt test light? And a scan tool?
The first thing is to test for spark at that cylinder, I know you replaced the wires, but it needs to be ruled out. Below is a guide on how to test for spark. You can really just take the spark plug out and attach the spark plug wire to it and ground the outside of the sparkplug to the engine block and watch to see if spark is jumping the spark plug gap. When you take the plug out, also notice its condition, is it wet with fuel? Is it white or carboned up at all?
Also, can you give me all the codes you're getting, including the ABS system codes too? I will look those up for you also.
After you check those things listed, I'm going to have you do a Cranking Cadence Test. I will explain that after we see if you have a good strong spark on the plug.
The spark should be bright blue and be consistent. No dropouts.

Also are the Fuel Injectors wiring harness plugs accessible to you?

https://www.2carpros.com/articles/how-to-test-an-ignition-system

https://www.2carpros.com/articles/engine-misfires-or-runs-rough