Just got some miss fire codes in my Jetta check engine light is on but not blinking I know and sorry for saying like this but I can’t take it to the shop I’m trying to learn also so any suggestions I was thinking about replacing the coils and spark plugs
Before throwing parts at a problem, the codes can save you time and money.
What misfire codes did you pull?
Tester
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This was at advance Auto and I need to change My battery soon also
When was the last time the oil/filter was changed?
The engine in your car has Variable Valve Timing. And if the oil gets too dirty it can effect the VVT, which can cause multiple misfires.
Tester
Not sure I have a lot going on in my life but I will check and look in to it
I bought Al Santini’s OBD II book a few weeks ago, and my wife brought it back when she came home.
He says anything which can cause vibrations can give the misfire code. Alternator imbalance; bad motor mounts; bad belts, and lots more.
He says misfire testing uses an accelerometer to detect the small acceleration when the piston fires, and if it doesn’t seem to be there, it will show a misfire code.
Full disclosure. I have no personal knowledge on this, just quoting his book.
“misfire” means the engine computer has detected that the crankshaft isn’t accelerating (rotationally) as much as it should after a cylinder fires. A proper cylinder firing requires
- the proper air/fuel mixture in the cylinder
- adequate compression
- spark
- at the right time
- ability to push out exhaust gasses afterwards
So you’ve got a problem with one or more of those. Spark is usually the easiest to test. Connect a spare spark plug to the spark plug wires one by one, make sure you are getting a good, healthy looking spark during cranking. Whitish blue colored, not reddish dim. Swapping parts between cylinders is a common method to diagnose misfires that occur mostly on one cylinder. Spark plugs, coils, fuel injectors are the three most common things to swap. If the problem follows the swap to the other cylinder, you know what it is. Since you have multiple cylinder misfires, that points to something common to all cylinders: crank position sensor, engine air filter, variable valve timing malfunction, exhaust system clog or bad cat.
My personal uneducated hunch is most misfire codes are going to be true misfire, as George says.
But, electronic computerized cars are weird, and Santini reports from a very large knowledge base. So, it would be inappropriate not to make it clear that the computer can produce a so-called misfire code from anything, as I listed, which causes unusual vibrations as reported by the accelerometer.
Yeah kind of stuck on what to do because of funds working on that now light is on but not blinking do you guys think it’s still safe to drive
Here’s something that doesn’t take much of your time, and no more money than you’d spend anyway: Try filling it up with a full tank of fresh gasoline. It that seems to help, maybe you just got some bad gas at a prior re-fueling.