This is on the 2008 Sedona my son was given. If you missed the earlier thread, it was jumped with the leads reversed by the PO's son. That killed it. We replaced the ECU, FAM, IAM, and the car has been running fine for about a week.
It has started doing something a little weird.
Yesterday morning, it was misfiring when he cranked it to come to work. CEL flashing, running like crap. After work, we pulled the codes, cylinder 6 misfire, and cam sensor bank one out of range. We cleared the codes and fired it up and it ran perfectly. It is COP and I assumed one of the coils has moisture in it from sitting and it's dying. I told him to drive it and see if the codes came back.
This morning he shut it down to get gas and it was misfiring again when he cranked it back up. CEL flashing, running like crap. The misfire is not occasional. It is running on 5. He had my reader with him so he pulled the codes. Cylinder 6 misfire. He cleared the code, the CEL went out and it stopped misfiring.
That's a new one on me. Why would clearing the code also clear the misfire? Would the ECU shut down a misfiring coil and clearing the codes makes it start firing it again? Why would it only do it on startup.
Ideas?
Some cars will shut down an injector after the misfire counter for a single cylinder exceeds the threshold, so that cylinder isn't getting washed with unburnt fuel, fouling cats, etc.
It is not clearing the problem. When you clear the codes the ECU reverts to the standard parameters and ignores sensor(s) that are telling it something is wrong. But after a few miles or on/off cycles the ECU can't ignore the sensor(s) and responds, in you r case by shutting down a cylinder. You need to find the sensor flagging something and address it.
Had a similar problem on a suby when I buggered my first timing belt install. 4 cam motor, one cam sprocket jumped so a valve tapped the head before I could shut ut down. The uneven running tripped the CEL and it would run rough. Reset the ECU and it ran great until the ECU saw the problem again.
Is it a pita to swap the coil for one from another cylinder?
Given how the system shuts off injectors, and the symptoms up until it does end up doing that- at least that tells you pretty strongly that the issue is ignition related.
Might as well change all of the plugs if you can quickly when you change the one along with the coil for it.
Slippery said:
Is it a pita to swap the coil for one from another cylinder?
Of course it is. The upper intake has to come off the get to the rear coils and plugs. The plan is to pull the intake, change the rear 3 plugs and coils. Then change the front 3 plugs and see what happens next. The parts are on the way.
Toyman01 + Sized and said:
Slippery said:
Is it a pita to swap the coil for one from another cylinder?
Of course it is. The upper intake has to come off the get to the rear coils and plugs. The plan is to pull the intake, change the rear 3 plugs and coils. Then change the front 3 plugs and see what happens next. The parts are on the way.
While you're in there, might as well throw a compression tester on the back bank before you put it all back together. Just to make sure nothing is Borked.
Opti
Dork
5/11/21 1:23 p.m.
you could just change the plugs and move the coil to the front. If the misfire comes back you have a verified failure and an easily accesible coil.
porschenut said:
It is not clearing the problem. When you clear the codes the ECU reverts to the standard parameters and ignores sensor(s) that are telling it something is wrong. But after a few miles or on/off cycles the ECU can't ignore the sensor(s) and responds, in you r case by shutting down a cylinder. You need to find the sensor flagging something and address it.
This is exactly it. A lot of OBDII cars (but not all) will de-fuel a cylinder that's misfiring too much. Once it's de-fueled, that cylinder is dead until you either clear the code or shut down and restart.
Will the codes clear if you disconnect the battery ? and if so how long does it need to be disconnected ?
Opti said:
you could just change the plugs and move the coil to the front. If the misfire comes back you have a verified failure and an easily accesible coil.
The intake has to come off to pull the coil. It's getting a new one.
In reply to californiamilleghia :
No clue. I will pass that on.
In reply to rslifkin :
This only shows up after a restart. It doesn't drop the cylinder or have any issues when running. But shut it down and restart, it has a dead cylinder.
californiamilleghia said:
Will the codes clear if you disconnect the battery ? and if so how long does it need to be disconnected ?
For many, that does have the effect of clearing the codes, which will reset the misfire monitor, and turn the system back on. Until it detects the misfire again, and then it will cut that injector out.
But doing that isn't going to fix anything.
Opti said:
you could just change the plugs and move the coil to the front. If the misfire comes back you have a verified failure and an easily accesible coil.
If the plugs are worn enough that one coil has failed, the others are right behind.
I'd at least replace the most inaccessible coils.
Pete. (l33t FS) said:
Opti said:
you could just change the plugs and move the coil to the front. If the misfire comes back you have a verified failure and an easily accesible coil.
If the plugs are worn enough that one coil has failed, the others are right behind.
I'd at least replace the most inaccessible coils.
This is the plan. The coils for the rear bank should be here by the end of the week. We will leave the old coils on the front of the engine. They can be changed without issue.
