08 c300 with 116000 miles. Recently purchased with no issues for a day or 2. Now it misfires under high rpm usually 4500. Codes are p0300 p0304 p0305 p0306. Sometimes I get a p0303 and p0410. I've changed all plugs 3 coils and swapped them. Change cam sensors and magnets. Changed maf sensor and ran injector cleaner as well. Injectors all tick like they should and replaced pcv valve. No luck and no vacuum leaks as far as I see.
positive 25 fuel trim makes me think it's time to smoke test it
Might have to try that. Thought it was odd bank 1 short fuel trim would be high yet bank 2 misfires with normal fuel reading
P0305 is misfiring in cylinder 5 which is on bank 1, so it's not just a bank 2 issue.
First thing I would do is look at the live data. Get misfire counts for each cylinder, look at fuel trims, and anything else out of the ordinary coming from the various engine sensors. That will probably give you some direction to pursue.
Also check out the misfire article in our FAQ.
On this engine bank 2 is 4 5 and 6. Fuel trim seems OK except bank 1 short term is positive 25 when freeze frame of the misfire occurs. Have a basic scanner so not much other data I can pull sadly.
sorry I thought this was 'C' pickup truck which is numbered differently. It helps if you type out the full make and model in your question.
anyway, bank related issues could be gaskets (intake or head) , catalytic converter, O2 sensor. A scanner will save you a ton of time. Otherwise you'll have to go blind and run a bunch of tests... smoke test, cylinder compress and leakdown test, exhaust backpressure test.
It's OK should have clarified the make. I'm lead to believe possible cat or 02 sensor but with no testers might have to just take it in and stop throwing parts at it.
it's normal for STFT to jump around a bit. Long term trims are the best tell-tales.
New to the whole fuel trim readings but long terms are 1.6 and -.8 if that means anything I believe that's good long term.
are those idle? Trying revving it up 4500 or whatever makes it misfire, hold it there a few seconds and then take a reading. Freeze frame data should have provided some info too.
Those were the fuel trim readings for freeze frame data of the misfire. 3100rpm, 18 map inhg, maf was 5 lb per min. The car only misfires when I rev it past 4k usually have to hit it twice to flash and misfire.
When in drive and you accelerate quickly acts like it bogs and will misfire...I've tried to search previous owners and found someone that claimed they tuned this car...also high revs make a pop and bang sound. Believe the car was possibly tune for this.
ooo that's a wrench thrown in the works. I would never touch a "tuned" car.
I agree at a loss with no response from previous owner or the so called tuner.