4.0L Loss of power on highway

I have a 05 2nd Gen Tacoma with the 4.0L V6. Recently I was driving home on the highway and was using cruise control doing 75mph. All of the sudden the truck loses power and begins to slow down quickly. I can floor it but truck will not rev or anything. I pull over because I was worried about it being something catastrophic. I can find any leaks or anything abnormal. Luckily I pulled over at my exit and took the city roads home doing 45-55 and truck ran fine. I’ve drove several times and has this issue happen a couple more times. It’s intermittent and only happens 70-80mph. I can slow down and drive 0-65 all day long. I cleaned the MAF. I don’t think it’s transmission because the motor will not regain RPM until I slow back down. No over rev or slipping like a transmission. I’m debating between a fuel pump/filter replacement or Replacing the cats. I’m leaning towards fuel because I was thinking if it were the cats it would do it more often and I’m just losing fuel pressure once it’s under a heavier load. Any opinions or help would be appreciated?

 

Cats would probably throw a code. Does it stumble under hard acceleration as well?

 

Yes I have a code for the O2 sensors. No stumble under hard acceleration at slower speeds

 

Hard to really tell you where to go without knowing the codes, what did it pull up?

 

I don’t have a scanner tool myself but my check engine light came on over a year ago. I’ve checked the code a couple times using the scanner at my local parts store. I don’t have the code written down any longer but I looked it up at the time and was for one of the O2 sensors. The truck always drove fine for the nearly the past two years with the code so never paid it to much attention.

 

So the valve cover gaskets where they meet at the heads are dry? How many miles on the plugs?

 

Valve covers gasket areas dry. Probably 12k on plugs. Trucks isn’t misfiring or running rough.

 

For fun I’d pop a coil out to see if it’s dry at the plug

 

I had similar happen, my fuel level sensor was bad, it said I had 1/4 tank but in reality I had no gas. tows to mechanic and they put gas in it, thing ran like a champ...

 

@YotaFAB

I can slow down and the truck will drive fine at a slower mph. So it’s not running out of gas.

 

IDK bud sucks, if its not throwing a code then maybe fuel pumps cutting out?

 

Having your P codes pulled again could narrow it down. Just to rule this out... did you change tire size before the problem started?

 

Sounds like a fueling issue if you ask me, but without scanner data and some physical test data there is no good way to be able to tell you for sure.

 

Sounds like fuel issue to me too. Unfortunately the pump assemble and everything is in the fuel tank

 

I have seen a decent amount of fuel pumps on the later 2nd gens including my own fail, and the failure emanates in multiple ways.

It wouldn't surprise me if his pump is taking a crap on him as well. He needs to check the fuel pressure and if it is below 41-43 psi at all times, it's a done deal. He also needs to check and report the LTFT and STFT info while the issue is occuring and under normal circumstances as well as at idle.

I had a 2015 in the shop where the injectors failed and were making the truck run like shit at idle, but the primary point of failure was the fuel pump and because the pump was failing for so long it took the injectors with it too.

 

If you have a code for O2 sensors that sounds like bad cats. P0420?

 

A similar issue came up on my wife’s old Escape, turned out to be a clogged fuel filter. Maybe add that to your “to investigate” list, and good luck!

 

OK, so this same thing happened to me in my '06 years ago (maybe '08 or '09). I was on 635 here in Dallas doing 70 + mph and suddenly I lost all power. There was nothing when I stepped on the gas. I freaked out because traffic is moving fast and I'm in the left hand lane. I hit my emergencies and suddenly when I was down around 35 to 40 mph the truck suddenly woke up again and I drove home at speed. I took it to the dealer and they could find nothing. There were no codes at all. The problem never happened again and the truck has been rock solid for me all these years. It was weird and frankly kind of disturbing. Personally, I think it's a computer problem...coding, something related to the computer.

 

Just for info the brake switch will also cause this symptom. Accelerator pressed and the brake switch is activated will cause the throttle to cut off.

 

He's got some point to look at now. hopefully you figure it out