2013 TRD Stalling under WOT

Hey all,

I searched the forums a bunch but haven’t found anything exactly like I’m experiencing, or maybe I’m just wording it wrong. Anyway…I’ve had my 2013 TRD Off-Road about a month. Had 53k on it when I bought it and I just passed 55k miles yesterday. I did my first off road shake down run yesterday, running the Old Pony Express route from 5 Mile Pass, Utah and ending just outside Ely, Nevada. Altogether about 120 miles on dirt roads. Truck did great till I got back on the pavement. It threw a P0171 code as I was doing about 80 with cruise control on and then when I went to pass a semi on a small incline and the throttle stumbled and then stalled. I was pushing on the gas but the engine was slowly losing RPM. I pulled over and shut the truck off and started it again, started right up but I decided to take it easy the 70ish miles till I got home. Researched the P0171 code here on the forum and decided to clean the MAF and the Throttle Body, both where absolutely filthy (this truck came out of California and was owned by the state before I bought it and I’ve cleaned about a metric ton of fine dust and dirt out of it since buying so why should the MAF and TB be any different?)

Here is a photo of how bad they where:


Anyway, truck is idling and running smoother now, but the stalling thing is still happening under WOT. I’ve drove it about 75 miles since cleaning and the code has never came back but I can’t figure out the stalling.

here is a link to a YouTube video of what I’m Experiencing:

https://youtu.be/vQLHhf3Hi2U

The dealer I bought it from covers all used vehicles he sells under a 45 day warranty so he’s already planning to take it Monday and start diagnosing (He’s a super stand up guy, and I’ve bought a few vehicles from him over the years so we have a good rapport and I know he’ll get it taken care of) but any input here would be appreciated cause I’m at a loss.

My best guess is fuel pump or sending unit issue but I don’t know.

 

By the look of how filthy your maf and throttle body were (good job cleaning them by the way as a starting point) is it possible your engine air filter is just as bad or worse, and the stalling is simply to due to air being restricted from its similar condition?
How’s it look? Is it an OEM dry type filter or an oil based K and N one?

 

I should have put that in my original post, that was the first thing I checked, but it looks like the dealer had it replaced when he did the oil change just before I picked it up. It’s an OEM type but it’s in good shape.

 

Hmmmm, I’m mechanically inclined but not nearly as experienced as many of my fellow TW members so hopefully they will chime in with a more focused next step, but if I were shooting in the dark, I would say to change the spark plugs as a next step. I don’t want to cause any unnecessary anxiety but you need to look into this video. It may be the cause of your truck going into a possible limp type mode, I’m not certain, but it’s possible, hopefully others chime in. And do this mod regardless and sooner than later.
Fudging YouTube, I don’t know why but the video doesn’t start at the beginning, make sure to start at the beginning.
Hopefully it’s just the spark plugs needing to be replaced or some other basic type tune-up
https://m.youtube.com/watch?v=XO5d4MqZu5I&t=154s&pp=ygUaVGFjb21haG9saWMgdW5pIGZpbHRlciBtb2Q=

Also here’s something you’ll dig.

 

It’s possible it’s a bad fuel pump or dirty fuel pump filter.
These trucks use a 2 speed fuel system. Under normal driving and lower engine load, it uses a lower speed for the fuel pump. Under high load and high throttle, it uses a higher speed for the fuel pump.
Your pump may be weak, you’d need to check the pressure.

Failing fuel pumps can cause lean codes. Which is what you have.

 

Shoot, I just thought of this. Do this as well, especially since you cleaned your throttle body, takes 2 minutes and it’s super easy.
https://m.youtube.com/watch?v=x2YNC_CMbC0

 

Well, small update, after about another 50 miles of driving (so about 120 total since cleaning MAF and TB) the CEL came back on after the throttle stumbled with the P0171 code again. I’m actually kinda relived because when the CEL was off it was worrying me it was something else… anyway, went and sprayed some carb cleaner around the vacuum lines to see if there was any changes and wasn’t able to pinpoint anything. My brother (former diesel mechanic) thinks it’s a small tear in the intake gasket, which is why the stumble is only happening at heavy throttle when vacuum is at its heaviest, essentially it’s staying sealed at lower RPM but when I punch it the vacuum pressure is great enough to pull the tear open and that’s why it comes back to life when the rpm’s drop and vacuum decreases. Either way, it’s back to the dealer tomorrow so I’ll post an update once I find out more.

@10thMTNgrunt thanks for the tips on both, I orderd that filter and did the Throttle Sensor reset. The sensor reset did make a difference in idle so that’s good!

 

Great to hear

 

Vacuum actually decreases at heavy throttle and acceleration.
As the throttle blade opens, there is less restriction and vacuum will decrease.

 

It's your fuel pump (or in a rare but not entirely unlikely case: a pinched fuel line). Get a fuel pressure gauge and double-check, you should be in the 40-50 psi range. It's not an air leak, more air would just make you go faster and the fuel trim would compensate for unmetered air.

Good thing your brother changed professions.

 

Welp....final update, got the truck back from the dealer.

Looks like we were all wrong.

The dealer's mechanic pulled the codes after I got there and it was throwing the same P0171. Because he had a new MAF in stock he threw it in just to see what it would do. He and I drove the truck about 75 miles with the scan tool attached and monitored everything. Fuel trims were normal and the stalling issue at WOT went away completely. After our test drive, I topped it off at the gas station and we headed back to the shop. As we were pulling into the shop, CEL came back on. This time the code was a rich code, rather than lean code. He also noticed that the temp was running lower than normal. I left the truck with him for another day so that he could go through everything again and see what he could find. He ended up pulling the thermostat and it was stuck open so he went ahead and replaced it as well as the housing. Also had him do an oil change and recharge the AC. I picked the truck back up on Tuesday and have driven about 250 miles with no issues with stalling or the temps. Everything seems to be back to normal, but I'm keeping an eye on it.

Also bought myself a new scan tool to replace the one I've had since about 2009. Went with the X-Tool D8 and its light years ahead of what I had before.

Thanks to those that left constructive input. Hope this thread helps out if someone runs into the same problems I had.