Please Help: Extreme Loss of Power (@ 30% full power)

[mattkc16]

stupid question, but surely someone checked, tried changing the plugs at 100k.

Knock sensors are just microphones... more or less. But they can pick up all kinds of false signals and can also go bad internally.

They are usually down in the valley cover and a bit of a PITA to swap in terms of labor. Sometimes there is a simple bypass harness you can rig up to see if that is the issue.

Most brands support a Knock Retard parameter that can be scanned under load. I'm just not sure about Toyota.

Not a stupid question at all. They did check the plugs and there was no carbon build-up etc. We didnt change them, but not a bad/cheap thing to rule out.

I'm not sure about a knock sensor retard parameter, they didn't mention if that was an option, but i can ask. Toyota wouldn't test out new knock sensors/wiring without me purchasing (each sensor was 150, 50 for the wire harness, plus labor).

 

[JeremyB]

At least his 4WD still works.

I'll see myself out... :behindsofa:

 

[1jzgte]

ok
how about the ctrl alt delete button

no but seriously.. im sure its been tested but how about disconnect the battery for an hour then hook it back up. It's gotta throw some codes.

 

[TOYO74]

Don't see these mentioned, but how about some simple things like:

You said that the MAF was checked, but how about a dirty/clogged air filter, or rodent debris in air box/air intake tube?

Also mentioned was that they checked for a clogged cat, was the rest of the exhaust system checked for restrictions?

 

[mattkc16]

ok
how about the ctrl alt delete button

no but seriously.. im sure its been tested but how about disconnect the battery for an hour then hook it back up. It's gotta throw some codes.

Yep, that was one of the early test. Toyota did a factory reset, which they said was basically a 15min disconnect from the battery.

Another guy on the forum said to check the ETCS fuse (Multiport fuel injection system/sequential multiport fuel injection system). Could be worth a check...

 

[DEERUNNER]

How about looking elsewhere, i.e., Seized brake caliper causing excessive drag?

 

[weeeee]

[MENTION=165143]mattkc16[/MENTION] let us know what you find in case others have the same issue down the road and know where to look.

 

[WindyCity4Runner]

How about looking elsewhere, i.e., Seized brake caliper causing excessive drag?

That's my suggestion. Jack up each wheel and see if it spins.
My classic car had this happen just yesterday. In a light (2,500#) car with about 135 HP on tap, I was nearly full throttle in first gear to get it to move.

 

[mattkc16]

[MENTION=165143]mattkc16[/MENTION] let us know what you find in case others have the same issue down the road and know where to look.

Weee, We got the truck back from Toyota. On the drive back it still had the issue/loss of power. I gave it to a neighbor friend of mine who owns a shop he drove it that night to see the issue and the entire time it was bogged down/low power. The next day, during his drive to the shop....it drove fine. He had it for the day, drove it a bunch with scan tools hooked up....it drove fine. I filled it up with premium, drove if about 150 miles to and from work (40 miles each way)....it drove fine. I want to run a few tanks of gas thru it to see if anything changes, but right now it seems to be running great.

Toyota did quite a bit of work (pulled/checked knock sensors and wiring, throttle position, pulled plugs, checked cat, checked fuel pressure). They cleaned the mass air flow sensor, fuel injectors. So I have a few theories:

1) Bad gas, this was initially what my gut was telling me. We filled up at the beach, at a gas station that is rarely used off season, and the issue came up within about 50 miles after the fill up. I initially ruled this out, cause even after refilling about 5 times we still had the issue. If there was water in the gas, it would sit in the bottom of the tank and take some time to displace since water is immiscible in water...Maybe?

2) Toyota was pretty confident the engine "heard" a knock from the knock sensors. This was what they believe caused the loss of power (the ECU pulled timing based on the knock sensor output). Could there have been an issue with the knock sensor wiring or sensor itself that was corrected as they were troubleshooting (plugging/unplugging wires)? If it comes up a year from now, I would probably look inot that.

3) dirty MAF or injectors? They did a full tune up, etc. This maintenance could have improved the running, which maybe corrected the issue?? im not sure.

4) the plugs were disconnected/reconnected a few times, could it have been a bad connection? Seems unlikely to me because otherwise the engine did run well.

At this point it is running spectacularly, so i'll see how it goes. We only have about 300-400 miles since we had the issue. I'll be more comfoident once we get close to 2000 miles. If it comes up again I will certainly keep the forum posted.

 

[mattkc16]

That's my suggestion. Jack up each wheel and see if it spins.
My classic car had this happen just yesterday. In a light (2,500#) car with about 135 HP on tap, I was nearly full throttle in first gear to get it to move.

Windy/Deer, Good suggestions. I initially thought it was a break issue. tried resetting the parking brake, smelling for burnt brakes, nothing. Plus even with full engagement of the parking break, when the engine is at 100%, it has more power then it did when i had this issue. Thanks for the suggestion!

 

[Airgazm]

Just wanted to add, when you get diagnostic work done pretty much anywhere, expect to get lesser service. Tech's do not make any money on diagnostics, they simply make the diagnostic time. Tech's are usually use to making 2 to 3 times the hours by doing flat rate jobs(pretty much anything but diagnostics and warranty). Keep that in mind, as not many Tech's want to to diagnostics so there isn't much effort there. Although some shops have a Tech that loves to do diagnostics, so if you find one of those, it's like finding Dr House and they are usually really good.

Your issue sounds like a sensor or something electronic as it was doing it, then immediately not doing it, that rules out a lot of stuff right there like bad gas for instance. Any shop that suggests to tear down an engine in this instance is not a place I would go. That being said, I would expect your issue to come back at some point.

 

[1jzgte]

here's a thought:

does anyone hate yoU? ex-girlfgriend? ex-wife? someone crazy who just wants to hurt you?

My point is why couldn't friggin toyota put a locking gas lid. Any weird or burning smells while u were having these issues? Someone could've dumped something foreign into your tank.

 

[nb rob]

Good job updating the thread. I hope this issue is behind you.

your gut feeling about the gas is interesting. I'd tend to agree... 2 gallons of bad gas + 10 gallons of good gas = 12 gallons of bad gas.

 

[SATSTRAIL]

Did the dealer take a fuel sample? Especially since they were checking fuel pressure? Bad gas is very much a possibility and water can easily be spotted when mixed with fuel.

Recently I had two vehicles come into my shop back to back with very similar symptoms. I took a fuel sample from the first one and it looked like crap. I asked for the service advisor to check with both customers to see what gas station they had recently filled up at and he thought I was crazy. Did a fuel sample on the second vehicle and it's fuel looked identical to the first one. Guess what? The advisor confirmed that they both filled up recently at the same exact gas station… remove the contaminated fuel and added good stuff, problem solved.