HELP! Engine Shutting off Randomly.

[gamefreakgc]

I would love to change the plugs and wires on my own. Please let me know what the best to use are. I'll look up some write ups to see procedural things.

-also, we have the same color 4Runner

Yeah it's a common color. Good though because it hides dirt haha.

You will want either DENSO K16TR11 (dual ground) plugs or NGK BKR5EKB-11 (also dual ground). Both are the "OEM" parts. You will also need a 16 mm deep socket or spark plug socket and wrench with 12" extension to reach down in there. Also some anti-seize to put on the threads on the new plugs. Also helps to have a "magnetic finger" or something like that to reach down in the spark plug holes and retrieve the old plug.

The spark plug wires are either DENSO or NGK wires (NGK comes in blue if you are into that sort of stuff). Any decent parts store like Autozone, Advance Auto will have all of these items. I've attached the instructions from the service manual to help simplify it with pictures and such.

The biggest thing is to not over-tighten them. The FSM says 13 lbs ft of torque, but basically that means snug. You'll thread them by hand with the extension (no tools) until you can't turn it any more, then give it about 1/2 turn more with the wrench. No more.

Wires are easy, just pop the old ones off and put new ones on!

 

[Sotovo]

Check to see if the fuel filter has been changed.

If not, then possibly look into changing it but if I were to bet that the Astros were going to win their division this year, I'd say it is the fuel pump. Any hard cranking? You may need to check the fuel pressure.

Yeah it's a common color. Good though because it hides dirt haha.

You will want either DENSO K16TR11 (dual ground) plugs or NGK BKR5EKB-11 (also dual ground). Both are the "OEM" parts. You will also need a 16 mm deep socket or spark plug socket and wrench with 12" extension to reach down in there. Also some anti-seize to put on the threads on the new plugs. Also helps to have a "magnetic finger" or something like that to reach down in the spark plug holes and retrieve the old plug.

The spark plug wires are either DENSO or NGK wires (NGK comes in blue if you are into that sort of stuff). Any decent parts store like Autozone, Advance Auto will have all of these items. I've attached the instructions from the service manual to help simplify it with pictures and such.

The biggest thing is to not over-tighten them. The FSM says 13 lbs ft of torque, but basically that means snug. You'll thread them by hand with the extension (no tools) until you can't turn it any more, then give it about 1/2 turn more with the wrench. No more.

Wires are easy, just pop the old ones off and put new ones on!

Thank you so much!! I'll be attacking this this weekend, maybe this whole engine shutting off thing is a blessing in disguise, I've really started to get hands on with my 4runner. I've always been too scared! haha

 

[Sotovo]

Since this seems to be tied to going WOT for a lot of people, I suspect it might be the throttle position sensor, and it may just be dirty. It may be that there's gunk built up on the section of the rheostat that the wipers only hit during WOT, and it's giving the ECU bad readings and causing it to freak out and shut down.

The only way I could see a dirty fuel filter causing something like this is if it's so clogged up that it's causing the fuel pump to trip a circuit breaker that automatically resets, and I think the fuel pump on these trucks is fused so that would rule that out.

There's no way it's the plugs or wires. You'd get missing on individual cylinders, not a random shutdown. The MAF is a possibility, but typically when those start going bad they cause serious drivability issues.

Hey Jeremy - I wanted to update you and ask you some further questions, took the 4runner in to my toyota guy, he said that of course anything is possible, but in all his years of work he has never seen the TPS be a cause for anything except major drivability issues, he said that when they get dirty or start to go bad, you absolutely know it. BUT my mechanic isnt God, and doesnt know everything, what do you think about that?

 

[jeremyc74]

Hey Jeremy - I wanted to update you and ask you some further questions, took the 4runner in to my toyota guy, he said that of course anything is possible, but in all his years of work he has never seen the TPS be a cause for anything except major drivability issues, he said that when they get dirty or start to go bad, you absolutely know it. BUT my mechanic isnt God, and doesnt know everything, what do you think about that?

The mechanic is going to have a lot more experience with these trucks than I do without a doubt. Did he have any other ideas about what could be causing it?

There are a couple of different signals that come from the TPS. There's the actual position reading, and then there's one for the throttle completely closed (or something like that). My theory was that maybe the contacts for fully closed weren't working right and was causing the ECU to do something screwy. It's really hard to say though. Intermittent problems like this are always the hardest to fix.

 

[Sotovo]

The mechanic is going to have a lot more experience with these trucks than I do without a doubt. Did he have any other ideas about what could be causing it?

There are a couple of different signals that come from the TPS. There's the actual position reading, and then there's one for the throttle completely closed (or something like that). My theory was that maybe the contacts for fully closed weren't working right and was causing the ECU to do something screwy. It's really hard to say though. Intermittent problems like this are always the hardest to fix.

Unfortunately he's a bit old fashioned, and doesn't like talking theory without actually looking at the truck, so he wouldnt say what he thinks it is. But he did say it sounds electrical, because mechanically my truck is in amazing condition. And these things are a bugger to figure out. Only time will tell.

 

[gamefreakgc]

The mechanic is going to have a lot more experience with these trucks than I do without a doubt. Did he have any other ideas about what could be causing it?

There are a couple of different signals that come from the TPS. There's the actual position reading, and then there's one for the throttle completely closed (or something like that). My theory was that maybe the contacts for fully closed weren't working right and was causing the ECU to do something screwy. It's really hard to say though. Intermittent problems like this are always the hardest to fix.

I've owned OBD-I and OBD-II Toyotas and on the pre-96 OBD-I vehicles, the TPS was known to cause a host of funny issues like what the OP has. I was thinking the same thing and I see you've got an older Toyota as well so you know how that is. I replaced mine on my old 91 to fix a similar issue. It seems on the OBD-II vehicles though, the TPS plays a smaller role in fuel and timing management. Still can cause issues but not as drastic as on the old ones.

It's one of those things that unless it acts up when the mechanic has it in the shop, it probably will not be fixed any time soon. By the way Sotovo, it seems like you have a good mechanic and shop you are going to. A lot of places will just throw parts at it and then mark them up for labor to make money off of you. Seems like your mechanic is genuinely trying to help you fix up your vehicle.

 

[Sotovo]

I've owned OBD-I and OBD-II Toyotas and on the pre-96 OBD-I vehicles, the TPS was known to cause a host of funny issues like what the OP has. I was thinking the same thing and I see you've got an older Toyota as well so you know how that is. I replaced mine on my old 91 to fix a similar issue. It seems on the OBD-II vehicles though, the TPS plays a smaller role in fuel and timing management. Still can cause issues but not as drastic as on the old ones.

It's one of those things that unless it acts up when the mechanic has it in the shop, it probably will not be fixed any time soon. By the way Sotovo, it seems like you have a good mechanic and shop you are going to. A lot of places will just throw parts at it and then mark them up for labor to make money off of you. Seems like your mechanic is genuinely trying to help you fix up your vehicle.

Yeah he really is a great guy, it's a one man shop that hires in contract help when he gets really busy, but its a Mom and Pop shop, without the "mom" he runs the entire operation by himself, and only does toyotas. And charges unbelievably fair prices. I always like driving by to see what all he's working on. And he throws in freebies all the time, he fixed my throttle cable when it was loose, doesnt charge me for minor diagnostic stuff, just a good guy. He's Been doing toyota's since the 70's. But yes Im hoping this is the end of my WOT issues. I'll keep all updated.

 

[gamefreakgc]

Yeah he really is a great guy, it's a one man shop that hires in contract help when he gets really busy, but its a Mom and Pop shop, without the "mom" he runs the entire operation by himself, and only does toyotas. And charges unbelievably fair prices. I always like driving by to see what all he's working on. And he throws in freebies all the time, he fixed my throttle cable when it was loose, doesnt charge me for minor diagnostic stuff, just a good guy. He's Been doing toyota's since the 70's. But yes Im hoping this is the end of my WOT issues. I'll keep all updated.

Yeah I had a shop like that once. I gave him all the hard jobs I couldn't do or didn't have the time. Then they changed owners and staff and I've been doing the hard stuff myself. Having a good mechanic like that is great since stuff will not always break at convenient times when you can fix them over a weekend.

 

[Tylerpugh]

Likely the ignition switch

Also, this.
You know, it could also be the keyswitch. Something internal could be messed up such that it may cut ignition power to the engine when certain conditions are met.

I have a 1999 4Runner Limited, 110,000 miles and perfectly maintained. I had this happen just today, making a left turn in the city, not revving anything. Everything shut down instantly, not just the engine, everything at once, complete shutdown. I had to steer to the curb, put the gear shift in park, turned off the key and then turned it on again and started perfectly. It wasn’t that the engine just quit or some electrical system failed, everything shut down instantly. I cant imagine anything that would do that other than a complete electrical cut off at the switch. I am not an expert, but that is my suggestion.