Still misfiring

No, I'm sure the shop checked it as one of the first things. This was from a friend not in the shop. Just someone that knows a little bit about cars. Just trying to help me is all.

 

Did your friend do any backpressure testing?

Not trying to be rude, but anyone can take a guess. Anyone can offer a "diagnosis". Over the phone, over the internet, whatever.. the question is does that diagnosis have any value to it?

We keep asking about test results because that's the only tangible way we can steer you in particular direction

Yes clogged cats are a thing
Yes injectors can go bad
The list is endless..

In order to truly help we need scan data on a screen with short and long fuel trims while the problem is happening.

We need compression test and leak down numbers. Do these tests both cold and warm after driving

You keep saying the shop probably already did this stuff, how are we supposed to know more than them?

Not trying to chew you out, I'm just saying that there are limits to the help we can give without knowing more about what's going on in real-time with the truck

 

I understand. I was only asking about Cat because a friend asked me if the shop checked it, and I just wanted to get your opinions on that being a cause. I hope the shop IS checking all the stuff listed here, so maybe that is why it is taking so long today to figure it out? Thanks for your input.

 

Maybe i zoomed past it...but how many miles is on this truck?

 

Ask them what spark plugs they used, too

 

Just over 50k

 

I'm gonna have to leave my truck there overnight, since the main times I get these codes is first thing in the mornings, when the engine has sat all night. It seems that even if it sits all day, the air is warmer and it doesn't happen for some reason? They have been trying to get the error code for the air fuel ratio imbalance that I got, but have not been able to. That will run me over $300 if it is concerning that, I forget exactly what he said.

 

Your truck may be eligible for the cat recall; mine was. Check your vin with Toyota.

 

Hopefully it's not the CAT. Just have to leave it with them overnight so they can check it first thing in the morning.

 

There are only 2 sensors "surrounding" the cat - the AF and O2 sensors, and neither one comes into play right at startup during open loop

Edit: Must have been my fault, but the second half of my comment got dropped - I don't PERSONALLY understand how a bad cat could cause a misfire in one particular cylinder all the time. Of course it could be two separate issues that only seem like it's connected because it happened at the same time. I know a plugged cat can cause starting issues by itself, but I don't think the SENSORS play in because at startup, everything's open loop.

 

A Toyota dealer will replace the cat for free if it’s under the recall.

 

The A/F sensor hole is just a way into the pipe so you can attach a pressure gauge. You're looking for a completely mechanical problem - too much pressure in the exhaust due to clogged cat. Not concerned about A/F sensor activity during this test

Remember, at its core, an internal combustion engine is an air pump. If you take away all the fuel and spark its just a pump that moves air. If the exhaust is clogged the whole thing backs up and power will lag. Exhaust backpressure should always be less than 1-2 lbs. Anything over that is inhibiting airflow, rpms and power delivery

In regards to the A/F sensor code he's got, any kind of misfire in a cylinder can/will result in unburned oxygen going down the exhaust. That can confuse the A/F sensor. Doesn't matter what causes the misfire (lack of spark/fuel/compression), if it doesn't go bang there's a whole lot of air going down the exhaust that shouldn't be. Oxygen sensors will see all that air and get confused.

 

Okay so I just got off the phone with him. He's saying somethng about the open circuit relay? If I heard him correctly, that may have to do with affecting everything? Something about the fuel at startup. He told me about it when I mentioned how I punched it from 5-10mph, and it immdiatley punched into lowest gear, then error codes came. I can't be verbatim here, this is just what's sticking in my mind from our phone call. He is my friend, so I know he is not trying to give me the run around. He is trying to hoefully save me as much money as he can. This wouldn't run that much he says...I think.

 

Tell them to hook up a fuel pressure gauge, duct tape it to the windshield and go for a drive. If the fuel pressure drops out you're getting somewhere

And yes obviously, a failing fuel pump could also set the A/F code..

 

And as far as the Air/Fuel Ratio Imbalance error code I got a few days ago, the only time I have ever gotten that code, they have been trying to see it again. They won't take care of that unless they get that code again. But as far as all the cylinder misfires I have gotten at startup,and the restarting issued I've had lately, he thinks this latest thing could be the main problem....my words.

 

I’ll stick to the VC and tube gaskets followed by ignition coils, for now

 

We are all just products of our lived experiences

And sometimes you're just a pastrami sandwich

 

That’s all

 

Left truck there overnight, so that it could hopefully get an error code at first start in the morning. The air was too warm already I think, when they started it up at 8am...really good weather here today. So they got no error codes when starting it up. Like I said, it only happens when the truck is super cold. I did mention the above quote to him. Not verbatim his response, but he said they did check the VC and tube gaskets, and there was no leaking...or something like that. He said they were moving around the coils again, to test the new coil number 2(again, not verbatim). I also mentioned the head gasket remarks to him too yesterday, and he said that was all good. So if they didn't put the coil in wrong the first time, and have that have been the issue, then I don't know WTF to do? I know if I took it into a toyota dealership, they would figure it out. But that would cost me thousands of dollars!