Multiple misfires after rebuild ** FIXED **

I just check the readings when I got home:

https://youtu.be/UpQeQzUMDEE

 

Hmmm... I wonder if it's misfiring when the B1S1 O2 isn't reading? I see in the 2nd one, that last video, it's reporting.

I may not be qualified to talk on this one.

 

It doesn’t seem to be cycling like it is supposed to. It was at 0 volts all the way home.

The other issue is I had to extend the wires because I have long tube headers. I don’t think that would cause an issue but it is something I had to do.

 

I dunno, others have suggested the lines are fairly sensitive, and doing anything to the wiring, including purposeful or accidental splices, extending, etc. could impact signals being sent and received.

Why would it only happen on Bank 1? Great question. How would you get around it or test it? No clue.

@empty_lord, you're running LT headers, right? What'd you do on yours?

 

I have extension harnesses.

 

Where did you get them?

 

Ballenger motorsprts.

 

It jumped out at me that the long term fuel trims on both banks were 21%. Something, and it could be o2 sensors, is making the ecu dump tons of fuel into the engine. Are the plugs really black?

 

I can check them today. I do have the 12 hole injectors from dirty deeds. Maybe the ECU needs to figure them out?

 

That could be, but usually I'd expect the ECU to dump lots of fuel if its intake sensor(s), i.e. MAF in this case, detected a shit-ton of air coming in OR the O2 sensors were telling it you were burning overly-lean. Remember, 3 things needed for an engine to run: metered air, fuel, spark. The ECU's job is to use the MAF, IAC, TB to electronically meter and control the air coming in so it knows how much fuel it needs to spray, throws its spark in-time, then measures the result on the backside using O2 sensors. If it detects too rich on the backside, it should adjust the fuel down, or vice-versa, adjust the fuel output up if too rich.

If you think about it as a logical chain like that, it really helps for troubleshooting purposes. It's really easy to confirm spark and timing, as you already have done. It's easy to measure the MAF is in spec. It's not so easy to see what the O2 sensors are doing or reading, or what the injectors are outputting. Also not easy to ensure the TB and sensors associated with it are calibrated and working. That's something I've always needed to lookup on a car-by-car basis.

 

That video was also at idle when I just started the truck. Would that make a difference?

 

Possibly? I'd expect less at idle, but every engine is different. My familiarity with 2UZ isn't huge. I can sit here and talk shop with you about deep internals of GenIII SBC engines all day long. I'm really learning as I go with these Toyota engines.

 

So I used a smoke machine to check for vacuum leaks and I don’t have any, which is good. I have the new o2 sensor and I didn’t have to extend the cable. I just took the connector from the stock location under the header and ran it down between the engine and tranny and it reaches perfectly to the new o2 sensor. I am going to replace one vacuum line that is old and brittle just to be safe then I will fire it up and check it out.

 

For the wiiin!!! Doing an ancient dance to ward off check engine lights and codes right now.

 

Does resetting the ECU actually do anything? I’m wondering if I should just disconnect the battery for a few minutes before trying it again.

 

Good on the smoke test! Would you be able to re-do the data video with the truck at normal operating temperature? That would tell us if the fuel trim anomaly was just because the truck was cold. If it wasn't a real symptom, we're headed in the wrong direction if we chase it.

 

Here’s a video of the start up after resetting the ECU. The misfires start right after I start it. I don’t think the o2 sensors even start working yet.

https://youtu.be/6cwWHo1Jovs

 

Resetting ECU just forces it to start over from scratch on what it's learned so far. Think of it as induced amnesia. The engine can definitely do all the things it needs to survive still, but it hasn't quite tuned itself in to be able to do everything efficiently. So sometimes you'll see weird idling, other strange behaviors.

That said, after you complete a full drive cycle, it may iron the wrinkles out and everything stops failing. I've had a couple of cars in the past that'll automatically stop the drive cycle test if something is 'off' enough to throw a code though. Like, they won't bother to complete the drive cycle / calibration cycle until you fix whatever tripped the code. Not sure if Toyota does that.

 

The number 7 plug is black.

 

Holy shit, that's really really black.

 

Here are all the plugs.

 

What would cause that? Too much fuel?

 

@Darkness

 

That's a lot of misfires causing your spark plugs to foul in such a short period of time.

I think early on somewhere in this thread saga, you said they were fine.

 

So is it more likely that I have too much fuel in each cylinder? If the timing was off would that cause a misfire? I know I checked it 3 times, but it just seems like something isn’t right.

 

Yeah, here's the road I'm mentally following. The fuel trim numbers are saying that the engine thinks it's really lean, so it's adding a bunch of extra fuel to compensate. It's not really lean, so the extra fuel is making the mixture too rich to burn very well (creating misfires). The evidence is the black carbon fouled plugs.

So, if you had an vacuum leak upstream of the cylinders, you would have white or tan plugs because the mixture would really have been too lean and the engine was behaving correctly to add the extra fuel. Since that's not the case, either extra air is getting into the exhaust stream before the upstream oxygen sensors, or the sensors themselves are telling lies to the ECU. Could you have an exhaust leak from the headers, maybe the flanges aren't sealing properly or something?

 

I am following your logic, the problem is, it is misfiring before the o2 sensors have a chance to even warm up to start sending info to the ECU.

I can check for an exhaust leak, but I think I would hear that if it was happening.

I just checked the timing on the drivers side bank and it looks spot on. I really am at a loss on this one. I cleaned my air filter, I have an air raid intake, once it is dry I am going to go drive it some. Just to see how it does.

 

Here’s the latest data:

https://youtu.be/brgPvICqbr8

 

Yes. And it looks like it's on the ports that aren't firing correctly.

Didn't you say you have DD 12-holes?

If yes, you may seriously want to consider cleaning up those plugs and reinstalling OEM, just to test.

Edit: Although it absolutely could be that you're not getting good readings from your bank 1 O2 sensors, or anything @dbittle mentioned.

 

I haven't been following along. What did you suspect was wrong with your throttle body?