Multiple misfires after rebuild ** FIXED **

If O2 was not wired properly, it was causing bad feedback to ECU. If not hooked up means not feeding ECU Properly….things that make you go Hmmm

 

But I am not getting any o2 sensor codes so I don’t see how it could be the sensors.

 

If your not getting O2 codes when it is unplugged, I question the code reader or something else abnormal

 

This would be the other thing one of us should've recommended. I assume your O2 are old/OEM, not newer/aftermarket too?

If timing is right, but misfire on one entire side, given the wiring order, I can see it being grounds for sure, but there are a few other things (other than bad gas) that could be amiss, including MAF, O2, fuel pressure.

It's weird for sure. I hope you end up finding this is something really stupid and we're all just missing the obvious. Hindsight is 20/20.

 

Don’t the O2 sensors have to run open loop for a certain time before they’ll trigger a run lean or run rich condition?

I think the fuel trim numbers would be way off right away.

 

Was going to comment this, but I see you've already gotten it handled....

OP ~ good luck. These fellers here will help get you sorted if it can be.

 

Yes, they are the ones that came out of the old manifolds.

 

The similarity to your problem was eerie. And I saw two different posts about it. Not sure it’s your answer, but it’s an easy check.

 

I found this on another site:

"The first thing I would do is verify your O2 sensor wiring. Make sure your upstream sensors are plugged into the factory harness that they are supposed to be plugged into. If they aren't, correct that problem and retest. You shouldn't really ever repair an O2 or A/F sensor wire, especially with solder. They take ambient oxygen samples by drawing outside air down the wire...yes, inside the wire. You should never repair a broken oxygen sensor wire by soldering the wire. If you must repair it, use cold crimps like a typical butt connector and don't use brush-on electrical tape or sealers. On A/F type O2 sensors, soldering can change the precise resistance required for it to read properly."

Is this correct? I soldered my connections when I extended the o2 sensor on the drivers side.

 

I would be shocked if that statement was true. The sensor end is capped, the part that's drilled with holes.

I've never heard of any vehicle system that "samples ambient oxygen inside the wire", the wiring should be solid-sheathed.

Why would it need to do that, when it could rely on the MAF to detect ambient oxygen sample for pre-combustion sensing? The whole point of an O2 sensor is to test the combustion mixture, both before the cat with the upstream sensors to verify whether fuel/spark/air trim is needed, and downstream sensors to verify the cats are doing their job of filtering said combustion.

What that person is saying makes no goddamn sense to me. But then again, I've never visited the TundraTalk forum so I don't know how savvy they are. But the fact the guy who posted that uses a 57 Chevy as their avatar, and in their username, I'm skeptical.

I feel like this was asked before, but I don't recall if we got a full answer. It's been a lot of pages. Your engine was rebuilt. Stupid ass question, but you have verified compression, correct?

 

Yes, I have verified compression, but I am going to start all over on it from the beginning. I installed MSD coilpacks several months ago and everything seemed fine, but I am going to put the stock ones back in. At the same time I will do a full compression test on the motor, all 8 cylinders and report back.

 

In your original post you'd mentioned swapping to 'known good' coil packs (vs. the MSD coils I saw), so I assumed you'd tried that already. We've all read stories on here of fake and/or aftermarket coil packs causing codes and havoc.

Going back to square 1 is probably a good idea. Double-check your work.

 

Yes, I swapped a few of the stock ones in, but not all 4 on one bank. I am going to put all the stock ones back in, then start it up to warm it, then do the compression check.

 

So I put the stock coils back on and fired it up. I am only getting the misfire codes and not the circuit codes anymore. I will be doing a compression check after lunch.

 

I think I can say that compression is not an issue:


1 - 200
3 - 204
5 - 220
7 - 210

 

Here are a couple pictures. One is of the plugs on the problem side and one is some o2 data.

 

I swapped the plugs from the good side to the bad and the issue didn’t follow so I assume the plugs are good. I am still getting misfires on the 1-3-5-7 bank.

 

Can you plot your upstream 02 sensor voltages with the new reader you have?

 

Probably. But I don’t know how to do it.

I will say, I am starting to take the drivers side fuel rail off to check the injectors and I took off back fuel fitting and it appears that the fuel in the rail is bubbling. Could there be air in the fuel lines?

 

My fuel pressure gauge says 42 psi at the rail.

 

I want to say the expected pressure is 40-44psi, so that'd be about right, but bubbles would be suspicious IMO.

 

I made this video of the readout.

https://youtu.be/g_LIkQQ8hr4

 

Bank one rear o2 is disconnected, this reading 0.

 

Nothing jumps out at me about the 02 sensors which seems to be working and the bank 1 fuel trim being on a slightly more positive side which may indicate a lean condition.

 

It keeps getting better. I took the drivers side fuel rail off, cleaned the injectors, put new o rings on them and put it back in. Now it won’t start. It cranks but won’t start. I’m getting more frustrated by the minute.

 

So....this maybe a stupid question...but have you checked the fuel pump?

 

I just turned the fuel pump on using my scanner. I can hear it come on but no fuel is hitting the rail. Does the fuel feed in through the drivers side or the passenger side?

 

That’s what I am going to do tomorrow. I’ll start with the fuel filter.

 

Those are fun jobs (I say that sarcastically). If you do find a blockage, post some pics.

 

Nice video....couple comments.
Both of the front sensors appear to possibly form a proper sine wave....going from ~ .8(rich) - .115(Lean). When you have time, learning how to graph the sensors will give you a better picture and see that it is indeed going from Rich to Lean.
The pic below is showing the front sensor as a sine wave in black going from Rich to Lean approx every second. The red line is showing a rear sensor when graphed, you want it to be a straight line, no set number but below .45



As for the O2FT(bank1 sensor2)/O2FT(bank2 sensor2) reading of 99.15 are N/A and simply represent a static number that's not used and are not listed as tolerances in FSM. Their main purpose is to show the Efficiency of the CAT not to adjust air/fuel mixture like the fronts.

As Jack said, the STFT #'s are fine, some say concern when they get around +-10%....FSM shows tolerance of +-20%
Note for another time....Long term fuel trims are important to look at also.

If and when you get time, this Toyota Master Tech has some very good videos concerning O2 sensors, Fuel Trim, etc...
His Fuel Trim video