Mysterious misfire after Reconnect battery

[wolf4runner]

Misfire after Reconnect battery

I DCed the battery before doing water inlet housing reseal. After reconnect the battery, the 4r misfired for the first time after Reconnect battery. and today it misfired one time again. they both happened when cold start.

checked battery terminals, checked the MAF sensor plug, they are both fine. No CEL.

Once the 4r started, it runs fine. Took a 30 miles test drive and didnt notice any problem. The problem only occasionally happen when first start the engine: twice in about 15 starts.

Does the ECU need to relearn everything and possibly cause misfire ?

 

[eddiebx]

I am not sure if this is your problem or applicable to your generation 4runner at all, but if I recall correctly, in my 5th gen manual it says that after reconnecting the battery, the first time trying to start might stall and that it is normal. This was also the case on my old Toyota as well...I think it's something to do with learning some parameters after disconnecting the battery?

While this doesn't explain why you had a 2nd stalling again later on, I probably wouldn't jump to conclusions just yet since you said you have not stored CELs. Maybe if it happens again then perhaps you might need to take it to the dealer to see if they can hook up their techstream software and retrieve any hidden codes?

Just to be clear, what happened to me is, after I reconnect the battery and try to start it, the engine runs real rough for a split second and then stalls. I turn it off and back on and it's as if nothing went wrong. Hopefully your case is similar to this, and you don't need to visit the dealer!

 

[wolf4runner]

I am not sure if this is your problem or applicable to your generation 4runner at all, but if I recall correctly, in my 5th gen manual it says that after reconnecting the battery, the first time trying to start might stall and that it is normal. This was also the case on my old Toyota as well...I think it's something to do with learning some parameters after disconnecting the battery?

While this doesn't explain why you had a 2nd stalling again later on, I probably wouldn't jump to conclusions just yet since you said you have not stored CELs. Maybe if it happens again then perhaps you might need to take it to the dealer to see if they can hook up their techstream software and retrieve any hidden codes?

Just to be clear, what happened to me is, after I reconnect the battery and try to start it, the engine runs real rough for a split second and then stalls. I turn it off and back on and it's as if nothing went wrong. Hopefully your case is similar to this, and you don't need to visit the dealer!

"the engine runs real rough for a split second and then stalls", this is exactly what happened to me.

before the second time stall, I hadnt driven it and the 4r just idled. think this might be the case?

I have tried for like 10 times today, no issue so far. Hope this is because of battery re-connection, since there was really no issue before I DCed the battery.

 

[eddiebx]

"the engine runs real rough for a split second and then stalls", this is exactly what happened to me.

before the second time stall, I hadnt driven it and the 4r just idled. think this might be the case?

I have tried for like 10 times today, no issue so far. Hope this is because of battery re-connection, since there was really no issue before I DCed the battery.

Sounds like it's a possibilty but unfortunately I just don't have much experience with the 4th gen 4runners to really say one way or the other...hopefully someone more knowledgable chimes in.

Out of curioisty, when it happens, are you holding the key to start it, or do you just flick it real quick to the start position and let the ecu hold the cranking?

I read about how your 4th gen has this nifty feature where you don't need to hold down the key in the start position for it to crank over...maybe the descrepancy lies there? Like I said before though, I don't think I would be too worried right now if I was in your shoes, see how it behaves from now on, and then panic later if need be

 

[TFJ-4runner]

I've had something similar happen after disconnecting it to replace a few lights. It didn't stall but had a very unsteady idle at first. Go for a drive and go WOT at lest once. This should sort everything out with the computer and have it running right again. The key feature that was mentioned is called bump start IIRC.

 

[BlackWorksInc]

The vehicle WILL stumble/stall/run poorly after having the battery disconnected for a long period of time or intiating a memory reset. The reason is because the system is designed to be adaptive to its operating patterns and you've now reset it to a default value and the vehicle must relearn the various inputs and variables ranging from average air temp, throttle position, engine load, shift patterns, ect ect.

This is normal and should go away after driving a while.

 

[20034RunnerV84x2]

I've had the same thing happen and after the 3rd or 4th start it goes back to normal. If it sits for more than around 12 hours it'll stall when it starts, it's all normal.

 

[wolf4runner]

the problem went away today.

I drove for about 100 miles with several(more than 5) restarts, No stall/misfire. thx for all the replies and I thought I messed some up first. But its all good now. even more peace of mind with having Blackworks confirmed.