Higher RPMs Than Usual When Driving & Misfire Codes

Tiny
SILVERBULLET81
  • MEMBER
  • 2008 HONDA FIT
  • 1.5L
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 134,000 MILES
Vehicle started driving at higher RPMs than usual while cruising and accelerating, but especially having a hard time while accelerating. Shaky/random jerks from engine as well. Check engine light came on. Brought it to Autozone. All misfire codes. Changed the spark plugs, thinking that was the obvious thing to do. That didn't solve the problem. Brought the car in to the shop. The owner told me I need a new ignition coil on cylinder 2. Did that. Paid him $300 (found out later it costs about $30). Ran good for 2 weeks, then engine light came back on again and rpms also went back up to higher than usual. Also, once again. All misfire codes for the engine light.P0301, P0302, P0304, P0300, and P0420. Cylinder 2 (the coil he changed) is in that misfire code. I pulled the ignition coils out myself, I have a multimeter, but not sure how to test the 3 prongs. One other thing I noticed is the smell of gasoline from Coils 1 and 4. I don't know if it should smell gasoline or not from the coils or if this could be a clue to anything. Coils 2 and 3 don't smell gasoline at all. I would like to be able to fix the problem myself if it is not too difficult because I have had a number of people tell me the shop is known to way overcharge people. Any help would be greatly appreciated.
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Sunday, March 2nd, 2014 AT 6:04 PM

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Tiny
SILVERBULLET81
  • MEMBER
Also, if a certain tool or instrument can help with the problem I can go to AutoZone and get it. Just need to know what to get.
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Sunday, March 2nd, 2014 AT 6:10 PM
Tiny
TY ANDERSON
  • EXPERT
P0301, P0302, P0304, P0300 are all misfire codes meaning something is disrupting the air/fuel mixture in cylinder: 1, 2 and 4. P0300 is a random misfire
P0420 is the vehicle's computer has detected the catalytic converter is no longer reducing emissions out the tailpipe (it could also be related to the oxygen sensor cause this code). This could be due to the misfire damaging the catalyst.

I want you to do some basic checks. Check the engine oil level, transmission oil level (after driving awhile then checking fluid level with the engine off), and unbolt the one bolt on each ignition coil. Start the engine look at each ignition coil (use a flashlight) do any of them get push up or move? If not, good. If it does move and you can smell a fuel smell or an exhaust odor then suspect that spark plug for looseness.
If you hear a ticking noise when first starting (gets louder with engine speed) the engine when cold you might have a exhaust leak causing the odor.

What spark plugs did you use (brand and style like platinum, iridium, etc.)

There are a few components that can cause a misfire. Typically, on Hondas a misfire is cause by the spark plugs, spark plugs being loose, Ignition coils, and valve lash clearance (there is more components). If the spark plugs are of good quality then it is probably safe to say the plugs are not causing the misfire. If the shop replaced cylinder 2 coil its probably not that coil causing a misfire.
Answer my question and do those checks I mentioned and get back to me. I threw a lot at you. So, let me know and we will go from here.
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Monday, March 3rd, 2014 AT 8:35 PM

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