Uphill stumble

My truck has always done something I don't see talked about on here and I finally have to ask. Is it 'normal operation' to feel a constant stumble or what feels like a misfire at steady throttle on long uphill sections at freeway speeds?

I've had the latest ECU flash and it seemed to improve throttle response some, shifts slightly less. It doesn't seem related to the CPS recall, no complete cutouts or major stumbles. It just feels like it's running on five cylinders at times. I don't notice it on flat sections or under acceleration.

My assumption is it's fuel mileage/lean fuel related.

Is it just me?

 

if you are flooring the pedal. The engine will try to shift to Otto-cycle which is rather rough. This is what happens in my opinion.

 

It is not just you, this symptom has been discussed A LOT in the OVtune threads. Don't get brow beaten by those who say it doesn't happen on their truck, and that you are just being whiny.

We have learned that two identical trucks, running the same ECU calibration and the same fuel (well, the same octane at least) under similar environmental conditions can behave quite differently.

I personally have had issues with "the stutters" since my truck was new. Some of OVtune's calibrations have had it too (on my truck but not on others). He did manage to kill it with some custom tuning in my case.

 

To add to this, I admit that even different fuel qualities have a drastic effect on these engines! I've used 91, 92 and 94 octane from different companies (I'm running OVTunes 91 Octane tune) and the American 92 Octane seems to perform the worst, while the ethanol free 91 and 94 runs the best.

 

it's not just you and the comments so far are accurate, but it does seem you'll need to figure out more. the stumble is a thing, and there are actual solutions available. it may or may not be straightforward but odds are good you'll be able to 100% fix it.

 

It's incredibly difficult to recreate exact conditions when troubleshooting machines. The least little thing (humidity, temperature, exact fuel, etc) can make a difference at an exact moment in time to cause a difference in performance. I have run enough datalog traces and conducted enough tests on off highway vehicles to know that even in a lab it's tough to make two machines identical.
Basically, it's entirely possible one truck can "stumble" and one truck won't in similar situations.
I enjoy your posts!

 

Yeah I've seen it there but thought it was only an issue with the OVtune.

Not willing (yet) to go that route but it's damn annoying. I have a long slight uphill as part of my daily commute and it's an every day thing.

 

I'd be interested in these solutions please!

 

There is this thread and s few others
https://www.tacomaworld.com/threads...ota-for-stumble-condition-tsb-0062-18.559435/

 

Yes and it's not nearly as black and white as it used to be it seems. I can't count how many times I've seen old school guys post about this issue, and start down a troubleshooting path associated with misfires etc. Plugs, coil packs, CKPs etc... you know the drill. While these could definitely cause similar symptoms (although you'd probably throw a code), the complexity of the 2GR-FKS ECU software is also troublesome in that it is an order of magnitude above most anything that Toyota has produced in the past (paraphrasing Mat). He recently lamented the lack of a MAP sensor in these trucks, instead we have "a billion maps" to compensate.
It's unnecessarily complex, and Toyota has not gone with this type of programming in their newer engines (again, according to Mat).
Sigh... cmon 1.05!!

 

first question, and sorry if i missed it, i can't reread cus i can't find my glasses..

can you confirm what ECU version you have now? after whatever last updates you mentioned.

 

Have you verified that you get the same stumble when using an S mode gear? If you haven't already, try running in S4 or S5 (depending on speed) and see if it's any better?

I'm not minimizing complaints here, nor it it a "fix", but I find the S modes to be much more "normal" feeling, in comparison to other vehicles. I don't like the feel of "D" in these trucks. S modes are much more friendly.

 

I've had mine at the dealer for this issue several times. Even filed a case with Toyota and they sent engineers to look at it and do testing. Some of the trucks just do it. I have several long mild grade hills on my commute everyday. I ordered OVTUNE last week. Just waiting on my cable tomm. Gonna run 1.04r and see if it helps. Them on to 1.05

 

It drives me nuts.

 

Yeah it's the same in D and 4th or 5th in S mode. Same with my SSP plugged in or not.

 

It's the stock ECU with the 0062-18 TSB applied a few weeks ago.

 

Mine does it too, only under heavy acceleration while pulling a hill. I'm talkin 5,500 rpm. Feels like a miss it or torque converter related. Either way I set the cruise and let it eat.

 

04B13?

 

I believe so, it's a '17.