EJ1120

I have about 124k on my accord and the check engine light has been on and off. The codes that pop up are P0300, P0301-306 (misfiring in multiple cylinders).

I got a full tune-up which included replacement of all ignition coils, spark plugs, water pump and all belts. Also, all fluids (oil, brake, transmission, power steering) were replaced. This still did not fix the problem. My mechanic recommended and performed a valve adjustment. The CEL went off for a few days, but turned on again. The car drives a lot smoother than before the full tune and valve adjustment.

I've been trying to get my car smogged, but cant because of the CEL. It was off the past 2 days, so i decided to get it smogged, but the light began to blink as soon as I pulled up to the smog station. I noticed the light is off while im driving, but begins to blink while i'm sitting at a stop light.

I'm running out of patience and can't think of what else I can have done to fix the problem. Any help/advice would be really appreciated.

lazlong

Are you in LIMP mode (can't go over 3000rpm or so)? Is the CEL flashing? With all 6 mis-firing I'm thinking there's either a connector loose, timing is off, oil pressure or fuel pressure. Start by checking every single connector in the engine bay and see if you have enough oil.

dandaman15

Its either a valve adjustment or a stuck EGR valve. Both are common to cause these types of symptoms. Did you have a dealer do the Valve Adjustment? Its possible he didnt do it right, the backs can be a pain in the *** and he could have done it half assed. The exhaust valves tighten up and cause these misfires, or the EGR can get stuck and cause them.

EJ1120

Its not in Limp mode. The car actually runs pretty strong and smooth and can rev over 3000. However, I try to drive it as easy as possible. I noticed the idle is a bit shaky, but nothing that seems too extreme. The CEL flashes at idle as well. I'm taking the car in to another mechanic for a second opinion and thorough diagnostic.

EJ1120

The EGR valve has already been cleaned, so I don't think its that. The mechanic I am taking it to today said the valves may not have been adjusted correctly, so he's going to run a full diagnostic and recommends a readjustment of the valves.

dandaman15

The first time I did mine, I didnt have angled feeler gauges and it caused me to gap them way to large. After I got everything together and started it up I was very pissed. It is very easy to mess it up. The car HAS to be cold, under 100 degrees and you pretty much need the bent feeler gauges. You can do it without, but it is a pain in the butt to do it right. I learned the first time the hard way. Ever since then my car has been cherry. I hope you get it figured out.

EJ1120

Sooo...I brought the car to have the valves readjusted. The codes that came up prior to adjusting are P0301, P0302 and P0304 (not P301-P306 anymore). The car ran fine for 30 minutes, but the CEL began to blink once the car warmed up. It only begins to blink when the car is idle at a light, then turns off and on after that. What else can be wrong? I' m frustrated and running out of patience at this point.

lazlong

Every single connector and ground in the engine bay needs to be checked. Oil and fuel pressure need to be checked. Also may need to be diagnosed for a bad ECM/PCM.

dandaman15

What codes are popping up when it does that? Same ones? Does it run smoother/better now that they were re-done?

EJ1120

Same codes (p0301, p0302, p0304) were present after readjustment was done by 1st mechanic.

I gave up and brought the car to the dealership. They updated ECM (didnt fix the prob).They readjusted valves to factory specs (intake valves were right, exhaust valves were a tad bit loose). Slight misfire is still present. They are now performing a leakdown test. We'll see what the results are in a couple hours.

Racer02gtstang

Exhuast valves are always better looser thantighter in a valve adjustment

dandaman15

Any updates? Was it a bent valve?

EJ1120

Unfortunately, it was a bent valve. Front and rear heads are being replaced. Im picking up the car tom.