Engine random misfire with codes?

Recheck your timing belt marks and verify everything lines up. If all is good then depending on the brand sensor you bought, it could be defective. If timing is not correct that could cause the random misfire. this guide can help us fix it

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

On a side not. When you got the vehicle was the timing belt broken? If it was then some valves could have bent? Once you verify your timing is correct I would recommend you do a compression check.

PO141 oxygen sensor heater circuit. Verify power and ground are good on rear oxygen sensor (behinde catalytic converter) That will be pins #3 and #4 see diagram below. Using a test light connected to those two pins key on engine off it should light up. If it does your good and you will need to replace the rear oxygen sensor.

I strongly recommend you replace the sensor with a Denso brand or preferably a dealer one for the simple fact the resistance on the heater is too high on other brand sensors that your light will return.

So check those things out and keep us posted please.

I am going to recheck the timing, I checked it four times before reassembly since I wanted to make sure it was right and not have to take it apart again, but maybe it jumped, I didn't figure the O2 sensor would cause the misfires and lurching but I have never owned a Honda before so figured I would include all information.

Oh and the timing belt was off by a tooth and several teeth were missing, would bent valves cause it to only misfire and throw the codes on all cylinders? I thought it is odd it only starts the lurching at 3500 rpm's, does not do it until you reach that point.

If all the valves bent then yes. But that is assuming timing belt had broken off. But if the timing belt is not set up properly you could get misfire codes. With the high mileage on the engine also check your valve clearance when engine is at room temperature.

Checked all connections and they are tight.
checked the timing and it is still lined up dead on.
Compression test: (#1) 195 (#2) 200 (#3) 200 (#4) 195
Is the compression bad? I couldn't find any specs
I forgot about the O2 sensor, will check it when I get a test light. but so far I'm baffled.

Compression looks good. Check your engine coolant temp. When engine is warm voltage should be close to 0.5 volts Check map sensor and at idle should be around 1 volt when back probing.

One thing I do stress is the valve adjustment. What did you measure on the intake valves and exhaust valves? Have seen shops miss that also? You might need to do a cylinder leakage test to check for leaking valves?

I think the problem is solved. I had forgotten to mention that while it was throwing the codes the RPM's would not go above 3500 and the engine would surge at that RPM. I decided to swap an OEM Denso Crankshaft sensor for the after market one I first installed. Drove it 80 miles at 70mph/3500rpm and ran fine and no codes. so guess it was the cheapo aftermarket sensor. Thanks for the help!

Glad we could get it fixed please use 2CarPros.com anytime we are here to help

Best, Ken

In response to JIS001, I checked the 02 sensor as you suggested but connecting #3 and #4 connections the test light does not light up, checked the #4 fuse and it looks fine, so I'm not getting ground somewhere?

Check pin #4 for battery viltage. Pin 3 is the control circuit. So depends when the computer actually turns it on. Majority of the problem is the sensor. Only time I have seen a computer problem was because they swapped engine with harness but not the computer for that engine so pin configeration was different.

Electrical problem
2000 Honda Civic 4 cyl Two Wheel Drive Manual 220K miles

Came out from classes the other day and had a CEL. Got it read and it told me random cylinder misfire on cylinder #3. Noticed constant missing "sound" today while driving.
Occasionally, the CEL blinks. Pulled plug on cyl #3 and heard no change in the engine idle. Spark tested fine.

Bought new plugs and swapped them in - old plug threads were soaked in oil; can't tell if it was coming from inside, or if it was laying in the spark plug tubes. Film of wet oil on spark plug boot.

Oil barely touches dipstick before 3k mile oil change due.

I can see oil laying on the tranny as well as dripping off of the bottom of the tranny leaving a small puddle.

Lots of black ?carbon? deposits on rear bumper; black deposits left on shop floor behind muffler while working on it today.

I plan on doing a compression test ASAP - Should I purchase a valve cover gasket kit, or is this a ring problem?

Hi there,

Do the comp test and if there is a low one do a wet test, wash the engine and drive for a while this will make it easier to locate the oil leaks, fix as needed report the comp test readings for an evaluation.

Mark (mhpautos)

Compression test showed 150 PSI in all except cylinder 3 which took so many cranks to get it up to 60 PSI.

The fact that it doesn't smoke seems to rule out bad rings.

Leak-down test pretty-much eliminated the possibility of cracked head or block. The guy that's helping me out with it suspects a valve issue. Under the valve cover, it looks ok - He's going to take the head apart and inspect the other side of the valves for #3.

Any thoughts?

The wet comp test will tell you if it ids rings or valves, just squirt a small amount of oil into the cyl and re test comp, this will seal the rings and if the comp is still low it will be a valve problem, have you checked the valve clearances as they are manually adjusted on these engines? you may just have a tight valve...

Mark (mhpautos)

Inconsistantly my car starts and seems to be "missing" on one cylinder after a few seconds it levels off and runs like a sewing machine
Pleas help I'm about to take this thing across country. The timing belt, water pump, plugs, wires, rotor button and distributor cap, along with the radiotor are all new. the exhaust manifold has also been replaced. currently the check engine light is not on. by the way I just bought this car and am stilling getting to know her.

Unplug each injector one at a time. What does the engine do?

If you unplugged one injector and the engine rpm did not drop then you have found a dead cylinder. You will then have to test: fuel, compression and spark going to that particular cylinder.

Another check test would be to listen to each fuel injector with a stethoscope, you should hear all fuel injectors giving out a rapid ticking. If one injector is making no noise you have a problem with the circuit or injector.