Can anyone help me understand why the O2S and HTR flash read while I’m having a misfire?

 

Have you recently cleared the cars codes on your car to see if they come back? If so, those two monitors haven't completed their readyness cycle and are probably flashing when the cycle to "make them ready (green)" is interrupted. Several different pending codes (like a misifre code) will impede their ability to turn green and be "ready".

What's been done to the car? When did the problem start?

 

I have chased this misfire for a month now. It was after I took it to the dealership to get its first clutch change (at 123,000 miles). They replaced the clutch and flywheel, and after I got it back it started having misfires. It was only on #3, now it’s moved to both 3 & 4. I’ve replaced coil packs, spark plugs twice, injectors and MAFS. When I changed the canister purge valve, the misfires stopped happening frequently. I used to get at least two misfires a day driving, now it’s only when I run it hard. But I got tired of having to call people and take my car places because they could never find anything, so I bought a scanner to see what’s happening when the car has a misfire. The gas mileage still seems a little bad than before, and there’s excessive heat under the hood. The electric fan is always cycling on and off. I’m thinking it’s either plugged cats or the O2s. It never throws a code for malfunctioning O2s or for the cat. So I’m not sure about this. I’ve been throwing parts at it and the issue is still there.

 

So you had the clutch and flywheel replaced, important piece of information. The fact that it started happening right after the clutch replacement tells me that something was missed in the installation.

Whenever you separate the engine and transmission you have to do the crank relearn process. If that isn't done you will get random misfires just as you are experiencing. And it will damage the engine eventually if not repaired.

The crank relearn teaches the computer where everything is so that proper timing is set; without doing that you could have the computer calling for 20 degrees of timing but the engine may actually be getting 30 or 40 degrees because the computer and engine haven't been together.

 

So how do I perform this crank relearn? Is this something I can do without taking it back?

 

If you have a SCT X4 type tuner you can do the crank relearn. If you don't have that capability with your stuff, then the dealer can do it.

Had to have it done to my 2013. The guy who replaced engine #3 didn't do it and I almost lost engine #4 as a result; didn't figure out that he hadn't done it to #3 until #4 acted up.

 

any mods on the car? When doing repairs on any car, many dealers will "update" the tune on the car to the latest stock firmware, mods be dammed.

Had that happen to me when I brought it in for a transmission problem (automatic). The called me about chasing a lean condition which did not exist before they got the car. Turns out they completed ignored the aftermarket intake and simple put the car to a stock tune before troubleshooting the problem I brought it in for.

 

I don’t have the capability with my scanner. When I called the dealership they told me 120$ to fix the issue. Which passed me off because why did I have to pay them $2100 for a clutch and flywheel job and now I have to pay you again to fix what you messed up? I just have refused to take it back because of that reason. The car is also running rich, no tunes, no mods, it’s all stock

 

If I have no other option, then I guess I’ll do that. So I need to ask them to do the crank relearn? They must obviously know how to fix it because he gave me a price in which I did more research, and most dealers do this so you have to come back to get it fixed after removing the flywheel.

 

Pretty crappy thing for your dealer -- they know it HAS to be done so it should be part of the work.

On my car for engine #2 they knew at MRT it had to be done and it was just part of the deal.

When I blew up that engine I was near home and 60 miles from MRT so left it with the guy who I trusted. When #3 went I chalked it up to bad luck.Then when #4 started acting up I exhausted everything that I knew and asked the tuner if I was missing anything. His first question, "you did the crank relearn, right?". When I called Todd his response was, "uh, I'm sure if it is required we did it". Not confident in that response and asked the dealer to check -- sure enough, crank relearn had to be done.