Multiple misfires after rebuild ** FIXED **

If you trace the coil pack wiring from rear of block to front of block, you should also find the harness terminates to ground at the front of the valve cover/cam area up top.

There are multiple grounds like this around the engine, this specific one could be suspect, and I'm pretty sure there's similar on the other side, I'd need to look at my wiring. I have an '06 though.

Note my coil pack is unplugged here. It's got the grey shiny looking wrap. If that helps.

 

My truck does not have that front ground. It didn't before I took it apart.

 

Ok, it's probably just a later-model or VVTi ('05-'06) thing then. Maybe the earlier models terminate where Bubba is showing only.

A PDF of the FSM (factory service manual) is somewhere around here, as is the EWD (electrical wiring diagram). It should show all expected grounds.

 

Keep in mind that the pic I posted earlier is all your Eng Bay gnd point locations for your 2002 from EWD….rectangle & triangle figures. These gnds may have nothing to do with your cylinder issue but doesn’t hurt to check since you did do an EG swap.

 

what is an EG swap?

 

Yeah, I erred, meant EG rebuild, if I followed you correctly.

 

what is EG? I don’t know that abbreviation.

 

He's obviously referring to the engine, although EG isn't an abbreviation I've used either.

 

From what I found, all the coils are supposed to be grounded in the same location. I will be checking the grounds tonight.

 

sorry, short for ENGINE….used to writing twitter short hand, less characters, carry on

 

Here is the electrical diagram I found.

 

No good. I tested the ground on the coils and it is good. It is reading 0 on my ohm meter. I went ahead and tightened the ground a little just in case but it didn’t make a difference. Still the same. It’s only running on 4 cylinders. I’m going to clean the crank sensor but I am at a loss at this point.

 

I cleaned the crank sensor and unplugged the upstream o2 sensor. Still the same. I cleared the codes and now it is not throwing a code. I will disconnect the negative batter my terminal and try again another evening. I am beyond frustrated.

 

Don’t give up, we’re rootin for you!

 

Here are the pictures of my ECU. I don’t know what I am looking for.

 

I can feel the injectors pulsing when the car is running. I have to assume I am getting fuel. The exhaust coming out of the headers is about the same on both sides. It idles really low and feels like it has a serious big block cam in it. I know something isn’t right. I will have to try hooking my scanner up again and see if I can see live misfire data. Unfortunately, I left it at work.

 

It might just be trying to relearn, maybe let it run longer and see if it evens out

 

I will try that on Thursday evening when I get to work on it again.

 

Or cycle the key a few times starting it and then turning it off.
On 5th gen 4Runners; after a battery disco, they fall flat on their face first try, then second try is super low rpm and a little rough, then it slowly starts to even out. On the tundra, it will stay started first go, but definitely rough for a little bit

 

Looks awesome to me, pristine. @Jack McCarthy can you throw eyes on this and give your pro opinion?

Do you have a way to actively monitor the fuel pressure?

 

I might have a fuel pressure gauge I can hook up. I’ll have to check.

 

What’s going on here? Guess I’m late to the party.

A lot of failures aren’t necessarily visible unless you know you burnt something and can smell it. Had my share of those.

Check for conformal coat spray (shiny polyurethane spray meant to protect the board) on the edge connector pins for one that would interrupt a circuit.

Another less obvious issue are latent electrostatic discharge failures. The output of ICs will rail to a one or logic zero and cause issues. Without a schematic, it’s hard to diagnose unless you know the pin being driven and if it’s supposed to toggle.

Sometimes circuits are damaged by having the IO source or sink too much current which may be a case if the output being driven is shorted externally.

That’s all I got.

Also, don’t lay the circuit board on carpet, that’s a static generating ESD source!

 

So I purchased an Autel MK808 scanner. It has lots of tools and I am going to be using it. Anyone have an experience with this logger?

 

Are you just looking for the number of misfires on each cylinder over the logging period? I don't think it'll tell you exactly when it happened, just that it happened.

I've got an Actron OBDII scanner that logs data and that's all it tells me.

 

@N84434

 

im trying to find any info about what is going on. What would you suggest I look for?

 

I’m hoping to do a cylinder power balance test, if the truck supports it.

 

Havest thou verified spark at the misfiring zylinders? I mean visual verification that spark is actually present.

 

I have the MK808. Love it. Very versatile, updates automatically when it's on, loads of info monitored. I liked it because I was able to watch the wheel speed sensors in real time to decipher which one of mine had failed.
You should be able to monitor coil activity while the engine is running, among other parameters

 

yes, I took out a coil with the plug and grounded the plug and there was a spark. It seemed pretty sporadic but there was a spark.