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.

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.

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?

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

Best, Ken

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.

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)

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)

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.