Ecu misfire?

[TTO5]

Well done.

It was my 75 year old retired process control engineer father that helped me out here. He steered me in the right direction (you all helped too). My Dad used to automate factories and chemical plants so this was right up his alley. He loves exercising his brain lol. Now to see how the install shop handles this. I'll update tomorrow

 

[AcmeSys]

nice find!

 

[TTO5]

Anyone have a scope trace of the crank position sensor. Interested in comparing it to mine for s***s and giggles

 

[AcmeSys]

Anyone have a scope trace of the crank position sensor. Interested in comparing it to mine for s***s and giggles

try diag.net and search for 3u 5.7 NE crank signal reference plot

 

[TTO5]

Decided to have my shop here at the toyota dealer check into this. Trans was pulled and we found a mangled washer hiding beneath the torque converter in the bell housing. It apparently had a blast tearing the tooth 1/2 off and leaving marks on the back of the engine block. The washer is your garden variety hardware store washer and not from this truck. I speculate that the washer must have been kicked into the bell while the trans was on the shop floor at the repair center. Crazy. Going back together now hopefully finished tomorrow.

 

[AcmeSys]

have the tech pull the torque converter off the flex plate and look for aluminum fragments. use an emory cloth/air flappy fingered abrasive scotch disk and deburr the block casting and toss some rtv in the areas where the washer smacked the castings

 

[TTO5]

have the tech pull the torque converter off the flex plate and look for aluminum fragments. use an emory cloth/air flappy fingered abrasive scotch disk and deburr the block casting and toss some rtv in the areas where the washer smacked the castings

Ok thank you
I'll pass that along

 

[TTO5]

have the tech pull the torque converter off the flex plate and look for aluminum fragments. use an emory cloth/air flappy fingered abrasive scotch disk and deburr the block casting and toss some rtv in the areas where the washer smacked the castings

Praying this fixes it

 

[AcmeSys]

Praying this fixes it

what was the amount of variation in the CKP pulse width when you had it on the scope?

 

[TTO5]

what was the amount of variation in the CKP pulse width when you had it on the scope?

Basically if you look at the "tooth" to the right of the dead zone it's skinnier than the others. Hard to see in this picture due to the angle I took the picture but that skinny signal is the broken tooth. Basically at certain speeds the computer isn't picking up the signal as quickly as it should due to the broken part of the tooth effectively making that dead zone longer than it should be. The computer then sees this as it thinks the motor is slowing down when there should be no reason for it to be. The computer then diagnosis this as a misfire. And that tooth is the one that's closest to the crank sensor tip when piston 4 or 7 is near TDC. Hope that made sense

 

[TTO5]

Basically if you look at the "tooth" to the right of the dead zone it's skinnier than the others. Hard to see in this picture due to the angle I took the picture but that skinny signal is the broken tooth. Basically at certain speeds the computer isn't picking up the signal as quickly as it should due to the broken part of the tooth effectively making that dead zone longer than it should be. The computer then sees this as it thinks the motor is slowing down when there should be no reason for it to be. The computer then diagnosis this as a misfire. And that tooth is the one that's closest to the crank sensor tip when piston 4 or 7 is near TDC. Hope that made sense

View attachment 3791155

A little more obvious in this Pic

 

[AcmeSys]

looks like 1ms vs 3 ms that is a hell of a shift. this was cranking on the starter?

Edit- pulse width timing I listed above is incorrect... disregard - the cursor indices are honked on those scope traces - the shift in pulse width on either side of the keying gap are not a huge 3:1 shift in width it is more like 0.8ms vs 0.6ms. defiantly see it if you trigger on he falling edge.

 

[TTO5]

looks like 1ms vs 3 ms that is a hell of a shift. this was cranking on the starter?

Edit- pulse width timing I listed above is incorrect... disregard - the cursor indices are honked on those scope traces - the shift in pulse width on either side of the keying gap are not a huge 3:1 shift in width it is more like 0.8ms vs 0.6ms. defiantly see it if you trigger on he falling edge.

Yes it triggers on the falling edge. That's well written. Thanks

 

[bloc]

and toss some rtv in the areas where the washer smacked the castings

Easily overlooked, but this advice could be extraordinarily valuable.

 

[TTO5]

Happy to report issue is gone. Now time to go another couple hundred thousand miles

 

[TLC2013]

Happy to report issue is gone. Now time to go another couple hundred thousand miles

What a ride getting to the finish line. Good info shared here documenting the process. Happy to hear this was finally resolved and with positive outcome.

 

[LX4x4]

I think Toyota is being too conservative in reporting codes.
I have seen other cars reporting misfire code together Crank or Cam sensor code which could have help narrow things down faster (possibly, easy to say so after the fact)
But glad you got this solved, and I am worried about the fact even the professionals couldn't find the cause of this.

 

[TTO5]

I think Toyota is being too conservative in reporting codes.
I have seen other cars reporting misfire code together Crank or Cam sensor code which could have help narrow things down faster (possibly, easy to say so after the fact)
But glad you got this solved, and I am worried about the fact even the professionals couldn't find the cause of this.

Yes all good points here

 

[TTO5]

So what are you all thinking about head gasket failure prevention? Drain and fill radiator every 2 years?

 

[mark71]

Oh boy….here we go!