Cyls 2 & 3 share the same ignition coil. Good chance that coil is going bad.

 

I've pull the wires while it was running and all 4 are firing

 

The presence of spark is no necessarily proof that it’s producing spark inside the cylinder under compression. Try swapping the coils and see if cyls 1 & 4 start misfiring.

It’s throwing the lean code because the O2 sensor is seeing oxygen in the exhaust stream when it misfires. So the ECU, thinking it’s too lean, adds more fuel. It keeps doing that until it gets to the max fuel trim of +25% and throws a code that the engine’s running too lean. Fix the misfiring and the lean code will go away.

 

Will give this a try thanks

 

I put coils 2 and 3 in the front and 1 and 4 right behind it and cleared the codes let it run for a few minutes and it's still showing 2 and 3 misfire and the lean code hasn't popped up yet but I'm sure it will so the coils are good

 

Yes, it seems the coils are good.

How old are the plug wires and plugs?

Any reason to suspect low compression?

 

I wouldn't suspect low compression yet but I did replace the plugs and wires but the old spark plugs looked ok I thought since it was misfiring I would start there first I sprayed some alcohol it's what I had around the engine when it was running to see if it was a vacuum leak or something didn't recognize any change in idle I want to check the timing I'm not sure when the last time the belt was changed I've only had the car about 3 months and it has 235k miles and check fuel delivery like the injectors or whatever

 

It’s kinda rare for injectors to go bad on these. But not impossible.

And if the timing belt slipped a tooth, it’ll run, but poorly. On the other hand, it is a common problem on this engine. The tensioner is not self adjusting, so as the belt stretches with time, it gets loose. So checking the timing would be a good thing to do.

 

I've been trying to find a vacuum leak which I was told I do have the cylinder 3 misfire anymore yet its just cylinder 2 now with the p0171 code I'm gonna order a new intake hose cause it looks pretty rough but I've sprayed around it and nothing happen I just need to narrow it down

 

I'm gonna order a new intake hose cause it looks pretty rough but I've sprayed around it and nothing happen I just need to narrow it down

Vacuum leak is unmetered air. If intake hose is leaking past the MAF then all cylinders would show lean. I don't think you have a MAF, but a MAP - leaking intake would not affect O2 sensor.

Throw some injector cleaner into the gas in case there is some fuel nozzle obstruction in injector.

Other possible is bad injector 0-ring which will suck air. Usually vac leaks improve on higher rpms as percentage of air leak is less than normal air intake.

 

Try swapping injectors around and see if misfire moves. Not all that hard to do. Just be real careful and don't damage the seals or, pick up some new seals just in case.

 

Ok

 

I tested the fuel injectors resistance I watched a video on YouTube with the same vehicle using a multimeter and 1,3, and 4 where at 14.0 and cylinder 2 wasn't reading at all so that injector is probably bad

 

"wasn't reading at all" = infinite resistance? I think you're getting somewhere now. A failed injector on these is kinda rare, but not impossible, of course. FYI: It's really common to slice an injector o-ring when inserting them into place. Use a smear of lube on them to help them slide into place. I use motor oil, but just about anything would work. Also, it helps to give them a twisting motion while inserting them.

 

This the injector from cylinder 2 and all the other read

 

My #2 injector failed many years ago on my 99 Avalon. Would have to check my log but I am guessing it must have been 10-15 years ago. I got a misfire code and she was running rough. I diagnosed by disconnecting injector power supplies and listening to engine. Same way you would check for a bad plug by sequentially removing ignition wires.

 

Ah, yep. Infinite resistance. That injector is toast. Thx for the pic, which makes it perfectly clear. Some meters display an open circuit differently than others.

 

Now I was curious to see what would happen if I switched injectors so I put the bad one on cylinder 4 and put everything back together and started it up now its cylinder 4 and 1 misfiring question is can 1 misfire cause another cylinder to misfire as well cause it can?

 

On wasted spark systems, a "sympathetic" misfire DTC code will sometimes appear on the (non-active) "wasted" spark cylinder, in addition to the cylinder having the issue - I've seen that here in the past, when I was running older Kia Sportages w/ Bosch ECM.


Great job on the diagnostics there Carlos / in finding the issue, and great help from all the TN folks above - nicely done.

 

Interesting. I'm not exactly sure how the ECU determines which cyl is misfiring. I know it involves the igniter, which senses the collapse of the field in the coil. But with a waste spark system like this, with a single coil supplying spark to two cylinders, how does it know which cylinder is misfiring?


But in your case, the misfiring is caused by a bad injector, not lack of spark. So HOW does the ECU figure that out? I'm stumped.

 

a misfiring cylinder will have a slower movement of the piston going down on the combustion stroke (3rd stroke), the ECM can "see" it on the pulse generated by the crank sensor. so it will be something like bum-bum-off-bum....now in the program code inside the ECM is a limit of how many times it can happen before turning the CEL on. So you can have a few misfires without light on.

 

If the previous code was not cleared than would it not show up again until long drive to reset?

 

Correct.

 

I did clear the code but when I moved the bad injector to cylinder 4 it was previously 2 and 3 misfiring now after I switched the injector its 1 and 4 which is the bad injector

 

Which I think is conclusive proof of a bad injector. I've purchased replacement injectors on eBay. As I mentioned, these aren't notorious for going bad, so getting a used one isn't a bad bet. But if you're leery of that, you can get a new one for $40 - $80 on Rockauto.com. Be sure you get the right one; there are two. You can either match the p/n, or the color of the upper part also gets you the correct part. Light green or dark green are the two colors.

 

I was just on rockauto it's way cheaper then autozone they want $116 plus tax just for 1 injector I found 1 for $26 plus $10 core

 

Replaced the injector now its running like normal thanks guys for your help

 

On OBD2 cars there is a sensor that counts the teeth on the flywheel ring gear and compares the rate of acceleration-deceleration of the flywheel as each cylinder contributes it's combustion pressure. This passive "cylinder balance" is much more accurate than the old "kill the cylinders individually" test and requires no action to diagnose the misfire other than reading the code. It's been a long time and my experience was primarily Nissan, but I know of the sensor from having to replace one damaged in a collision. It actually counted 105 teeth in the ring gear for every revolution of the flywheel. It was a 1995 Nissan 200SX, first year of OBD2 for that new model.

 

What confuses me is the "dead" injector would never fire which would bring on a different code, versus a "random" misfire code.

 

I believe the ECM/PCM only detects the variation in crankshaft acceleration, as you and @castironman described above (Crankshaft Position Sensor), but not the root "cause" of the variation (Ignition, Fuel, Air, Compression).



The ECM/PCM does have the ability to calculate the severity of the misfire rate: Type A / Severe * Blinking MIL, or Type B / Moderate - Steady MIL.


The Camshaft Position Sensor is used to determine "which" cylinder is on the TDC power stroke, for fuel timing / management, in addition to knowing the cylinder to report is misfiring, in a wasted spark system.