Hi all
I got a 2004 honda accord v6 MT 6spd.

Getting misfire codes all cylinders and random misfire. Car drives fine but idles rough. CEL blinks and then goes away

brand new plugs
Coils are new
Timing verified, belt is also new
Valve lash adjustment done per spec.

Can someone tell me what I am missing ??
Can it be a faulty ecu? I need emissions test and I am sure it will not pass with the CEL

Thanks for your help.

 

I suppose the crank position sensor could have been compromised during the timing belt replacement. I would pull the wire harness plug, on each coil, one at a time, while the engine is running. If you pull a coil wire, and nothing changes, you've found your affected cylinder (plug, coil, or harness wire).

 

Thanks for reply. I did that and while doing this for cyl 1 2 and 3 there is a major change. When I do the same for cyl 4 5 and 6 it changes slightly. The shake is not the same among the three sets of cylinders. What do you think about the ecu? Took the car for a good 1 hour drive and no Cel came. While idling at the light the light blinked and went away

 

First I would check to see if there are any vacuum hoses that are disconnected or damaged from replacement of the timing belt. Also listen for any abnomal air noises within the engine compartment while at idle. If a vacuum leak is hard to find, disconnect and cap all vacuum hoses from the intake manifold one at a time. The one that is disconnected and allows the engine to smooth out would be the suspect vacuum circuit. Dont forget the Purge Valve, Vacuum Brake Booster or vacuum controlled motor mount (if equipped). If no change is noted with the way its running, try spraying brake cleaner around all the upper intake ports while listening for a change in the engine performance. Replace the intake manifold gasket if found to be defective.

If no vacuum leaks are found, try disconnecting the MAF/MAP sensor and start the engine. If the rough idle concern is corrected, check that the air intake does not have any leaks and the MAF/MAP is clean. If the MAF/MAP is clean, replace the MAF/MAP sensor and retest.

If the rough idle concern is still present, take it to a professional and have them take a better look at it. They have access to scanners that can look at data more thoroughly to determine the root cause.