The Under the Hood Show dives into a listener's puzzling experience with a 2021 Toyota 4Runner that unexpectedly entered limp mode, raising questions about potential programming issues. The hosts discuss the complexities of modern vehicle electronics, the importance of diagnostic codes, and the role of manufacturer engineers in troubleshooting. With humor and expertise, they explore the impact of environmental factors on vehicle performance and share insights on how dealerships handle elusive problems. The episode is packed with practical advice for navigating dealer interactions and understanding vehicle technology.
Under The Hood gives car repair advice to callers over the air and on their you tube channel if you want to ask questions in the comments instead of calling. youtube.com/@underthehoodshow All calls are done without using any in-studio computers. Watch the show to see for yourself. Call to get on the air 866-594-4150 Here are today's callers. 1. 21 4 Runner won't accelerate brake override is on 2. 17 Equinox Rear main oil seal leaking how to fix 3. 96 Ranger Runs Lean P0171 and P0174 4. 18 F150 Turbo rattle 5. 18 Caddy XT5 lack of steering assist 6. 97 Mercury Marquise coolant leak 7. 18 Durango P0171 lean fuel trim one bank facebook.com/underthehoodshow underthehoodshow.com
"I have a 2021 Toyota 4Runner. It only has $6,000 miles on it because it's primarily a winter vehicle."
The Toyota 4Runner is a type of SUV that is great for off-roading and is built to handle tough conditions, making it a good choice for winter driving.
The Toyota 4Runner is a mid-size SUV known for its off-road capabilities and rugged design. It's popular among outdoor enthusiasts and is often used as a reliable winter vehicle.
"And when I pushed on the accelerator, it went into limp mode. And on the dash, it said brake and accelerator pressed simultaneously."
Limp mode is when your car slows down and won't let you drive fast because it has detected a problem. It's a way to protect the car from getting damaged.
Limp mode is a safety feature in vehicles that limits engine power and speed to prevent further damage when a serious issue is detected. It allows the driver to safely get the vehicle to a service location.
"...where it would go into a little bit of traction control before it would go into lip mode. So the next morning I brought it in again and they were interested."
Traction control helps your car stay on the road when it's slippery, like in rain or snow. It stops the wheels from spinning too fast when you accelerate, making it safer to drive.
Traction control is a safety feature in vehicles that helps prevent wheel spin during acceleration by reducing engine power or applying brakes to specific wheels. This is particularly useful in slippery conditions to maintain grip and stability.
"...they may have just reflashed everything in the software just to see what would happen. They're like, well, we couldn't find anything..."
Reflashing is like updating the software on your phone, but for a car's computer system. It can fix problems or make the car run better by using new software from the manufacturer.
Reflashing refers to the process of updating or rewriting the software in a vehicle's electronic control unit (ECU). This can help resolve issues or improve performance by installing the latest software from the manufacturer.
"...the noise from the unintended acceleration challenges that were out there, I mean, we talked about this in the show where..."
Unintended acceleration is when a car speeds up on its own without the driver pressing the gas pedal. This can be dangerous and has led to many safety investigations.
Unintended acceleration refers to a situation where a vehicle unexpectedly accelerates without the driver's intention, often leading to loss of control and accidents. This phenomenon has been a significant safety concern in the automotive industry, prompting investigations and recalls.
"I have the 17 equinox with the rear main seal needing replacing any tips or tricks. Fix the problem that caused the rear main seal to leak before replacing the rear main seal."
The rear main seal is a part of the engine that keeps oil from leaking out. If it breaks, oil can spill out, which can be a big problem for the engine.
The rear main seal is a critical component that prevents engine oil from leaking out of the rear of the engine, where the crankshaft exits. If this seal fails, it can lead to significant oil leaks and engine damage.
"When you pull the intake off, which is going to be really easy for you if you're pulling the engine, probably 10 minutes, take it off."
The intake is the part of the engine that brings in air. It's important because the right amount of air helps the engine run better and more efficiently.
The intake is a crucial component of an engine that allows air to enter the combustion chamber. It plays a significant role in the engine's performance and efficiency, as it affects how much air can mix with fuel for combustion.
"When you pull the intake off, which is going to be really easy for you if you're pulling the engine, probably 10 minutes, take it off."
The engine is what makes the car go. It turns fuel into power that moves the vehicle.
The engine is the heart of a vehicle, converting fuel into mechanical energy to power the car. It consists of various components, including the intake, which plays a role in the combustion process.
"but only to the point where the engine will still run fine because if they're too big, if they're drilled out, it won't run properly."
Drilling out means making holes bigger in parts of the engine to let more air in. But if the holes are too big, it can cause problems with how the engine runs.
Drilling out refers to the process of enlarging holes or passages in engine components, such as the intake, to improve airflow. However, if done excessively, it can lead to improper engine function.
"But then that tees off to four ports, one in each cylinder."
Ports are openings in the engine that let air and fuel in or let exhaust out. Their size and shape can affect how well the engine works.
Ports in an engine refer to the openings that allow air and fuel to enter the combustion chamber or exhaust gases to exit. The design and size of these ports can significantly impact engine performance.
"And then spray some carburetor cleaner or throttle body cleaner into that hole and make sure it flows out of all four ports and then blow it out with compressed air."
Throttle body cleaner is a spray that cleans a specific part of the engine called the throttle body. This part controls how much air goes into the engine and needs to be kept clean for the engine to work well.
Throttle body cleaner is a specialized cleaner designed to remove deposits from the throttle body, which can impact engine performance and responsiveness. It is similar to carburetor cleaner but specifically formulated for throttle bodies.
"And then spray some carburetor cleaner or throttle body cleaner into that hole and make sure it flows out of all four ports and then blow it out with compressed air."
Carburetor cleaner is a special spray that helps clean parts of the engine, especially where fuel and air mix. It removes dirt and gunk that can cause problems.
Carburetor cleaner is a solvent used to clean the carburetor and throttle body of an engine. It helps remove carbon buildup and other deposits that can affect engine performance.
"and then blow it out with compressed air. That's what happens to the engine."
Compressed air is air that is squeezed into a small space and then released quickly. It's used to blow dust and dirt out of engine parts.
Compressed air is air that is stored under pressure and can be released to clean or blow out debris from various components in an engine. It's commonly used in automotive maintenance for cleaning purposes.
"That plugs up with a tiny bit of carbon and then you get that back pressure."
Back pressure is when the gases trying to leave the engine have trouble getting out. This can slow down the engine and make it work less efficiently.
Back pressure refers to the resistance that exhaust gases encounter as they exit the engine. Excessive back pressure can lead to reduced engine performance and efficiency.
"the tube that you see that you're talking about that goes from the air cleaner down to the engine, it's got a little loop in it."
An air cleaner is a part that keeps dirt and dust from getting into the engine. It helps the engine run better by making sure it gets clean air.
An air cleaner, also known as an air filter, is a component that removes contaminants from the air entering the engine. A clean air cleaner is essential for optimal engine performance and fuel efficiency.
"...you can either use an emission system cleaner kit and use it regularly, you know, about once a year will usually do it, but you've got to spray it in there. It will go into the intake port, the CRC kit we use..."
CRC is a brand that makes products to help keep cars running smoothly. They have special cleaners that you can use to clean parts of the engine.
CRC is a company known for producing automotive maintenance products, including cleaners and lubricants. Their emission system cleaner kits are designed to help maintain engine cleanliness and efficiency.
"...it's not really, it's a PCV, but it's a passive PCV without an actual valve. It just has those drilled ports, but it'll suck it in there and clean those out."
PCV is a system in cars that helps clean up harmful gases from the engine by sending them back to be burned again. This helps the engine run better and reduces pollution.
PCV stands for Positive Crankcase Ventilation. It's a system that helps reduce harmful emissions by recirculating gases from the crankcase back into the intake manifold for combustion.
"See, that'll get into the fuel system and it will clean the injectors, which is perfect on that engine too. You do need to clean the injectors, but you also need to go through that intake so it'll pull it through that port,"
Injectors are parts of the engine that spray fuel into the engine for combustion. Keeping them clean helps the engine run better and use fuel more efficiently.
Fuel injectors are components that deliver fuel into the engine's combustion chamber. Cleaning them helps maintain engine performance and efficiency by ensuring a proper fuel-air mixture.
"Okay. I have a 96 Ford Ranger and it's a four liter."
The Ford Ranger is a small truck that many people use for work or personal projects. The 1996 version has a four-liter engine, which gives it good power for carrying loads.
The Ford Ranger is a compact pickup truck known for its durability and versatility, popular among both work and recreational users. The 1996 model features a four-liter engine, which is a common choice for those needing a balance of power and efficiency.
"...I keep getting a code PO171 and 0174. I know it's both banks lean."
These codes mean that the engine is getting too much air compared to the amount of fuel it should have. This can cause the engine to run poorly and use more gas.
Codes P0171 and P0174 indicate that the engine is running lean on both banks, meaning there is too much air and not enough fuel in the combustion mixture. This can lead to performance issues and increased emissions.
"Okay. So I've cleaned the mass air flow sensor. I've cleaned the throttle by just because I've checked for vacuum leaks."
The mass air flow sensor helps your car's engine know how much air is coming in so it can mix the right amount of fuel. Cleaning it can help the engine run better.
The mass air flow sensor measures the amount of air entering the engine, which is crucial for the engine control unit to calculate the correct fuel-to-air ratio. A clean sensor ensures optimal engine performance and efficiency.
"...it could be a fuel filter or a fuel pump. So I put a pressure gauge on it..."
The fuel pump moves fuel from the gas tank to the engine. If it stops working, the car won't get the fuel it needs to run.
The fuel pump is responsible for delivering fuel from the tank to the engine at the correct pressure. If the fuel pump fails, the engine may not receive enough fuel to run properly.
"...it could be a fuel filter or a fuel pump. So I put a pressure gauge on it..."
The fuel filter cleans the fuel that goes into the engine. If it's dirty or blocked, it can cause problems with how the car runs.
A fuel filter is a component in a vehicle's fuel system that removes contaminants from the fuel before it reaches the engine. A clogged fuel filter can restrict fuel flow, leading to performance issues.
"Our partner at Road Ready Wheels has wheels. Thousands of wheels, affordable in stock and ready to ship to you."
Road Ready Wheels is a company that sells wheels for cars. They have many different styles and types, including ones that look like the original wheels that came with your car.
Road Ready Wheels is a company that specializes in providing a wide range of wheels for vehicles, including options that resemble original equipment manufacturer (OEM) wheels. They offer both replacement and upgrade options for various types of wheels.
"Replace or upgrade your damage or plain steel factory wheels with new OEM looking road ready wheels. Maybe steel is the way to go for you to mount a second set of winter tires."
OEM means Original Equipment Manufacturer. These are parts made by the same company that made the original parts for your car, so they fit perfectly and work well.
OEM stands for Original Equipment Manufacturer. It refers to parts made by the same company that manufactured the original components of a vehicle, ensuring a perfect fit and quality that matches the original parts.
"Maybe steel is the way to go for you to mount a second set of winter tires or you just don't like the aluminum look."
Winter tires are special tires made for driving in cold weather, snow, and ice. They help your car grip the road better when it's slippery outside.
Winter tires are specially designed tires that provide better traction and handling in cold weather conditions, particularly on snow and ice. They are made from softer rubber compounds that remain flexible in low temperatures.
"or you just don't like the aluminum look. Road Ready Wheels has many choices for you."
Aluminum wheels are lighter wheels made from a metal called aluminum. They help your car perform better and look nicer than regular steel wheels.
Aluminum wheels are lightweight wheels made from aluminum alloy, which offers better performance and aesthetics compared to traditional steel wheels. They are often used for their improved handling and fuel efficiency.
"Mercedes Cadillac Ford Chevy Chrysler and many more with the OEM fit and look that you want."
Mercedes is a famous car brand that makes luxury cars. They are known for being high-quality and having lots of technology.
Mercedes-Benz is a well-known luxury automotive brand that produces a range of vehicles, including sedans, SUVs, and sports cars. The brand is recognized for its quality, performance, and advanced technology.
"Mercedes Cadillac Ford Chevy Chrysler and many more with the OEM fit and look that you want."
Cadillac is a luxury car brand from America. They make high-end cars that are known for being stylish and comfortable.
Cadillac is an American luxury vehicle brand known for its premium cars and SUVs. It is one of the oldest and most prestigious automotive brands in the United States, often associated with luxury and innovation.
"...I have an 18 F-150 with the 2.7 EcoBoost 100k miles and over the last year or so it started..."
The Ford F-150 is a popular truck that can be used for work or personal use. The 2018 version has a good engine that saves fuel while still providing enough power for heavy tasks.
The Ford F-150 is a full-size pickup truck known for its durability, versatility, and strong performance. The 2018 model features various engine options, including the efficient 2.7 EcoBoost V6, which balances power and fuel economy.
"...now I'm worried it's a turbo waste gate that's acting up on me and so if that's true my main question is how long can I go with this before I think about a repair."
The turbo waste gate is a part of the turbocharger that helps manage how much power the engine gets from the turbo. If it doesn't work right, it can cause problems with the engine's performance.
A turbo waste gate is a valve that controls the flow of exhaust gases to the turbine in a turbocharger. It helps regulate boost pressure and can prevent engine damage by diverting excess exhaust away from the turbine when the desired boost level is reached.
"...m really surprised we have a we have a we have a bronco raptor and it makes noise on startup and we had t..."
The Ford Bronco is a tough SUV that can handle rough terrains and is great for outdoor activities. It was brought back after many years, and people love it for its cool design and ability to go off-roading.
The Ford Bronco is a classic American SUV that was reintroduced in 2020 after a long hiatus. Known for its rugged off-road capabilities and retro styling, the Bronco has become a symbol of adventure and outdoor exploration, making it a popular topic among automotive enthusiasts.
"...nd when somebody calls me and says I have a 2019 Silverado and it burns two quarts of oil every thousand mi..."
The Chevrolet Silverado is a big truck that many people use for work or hauling things. Some 2019 models have a problem where they use too much oil, which means you might need to check and add oil more often than usual.
The Chevrolet Silverado is a full-size pickup truck known for its durability and versatility, making it a popular choice for both work and personal use. However, some models, particularly the 2019 version, have been reported to have issues with excessive oil consumption, which can be a concern for potential buyers.
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Welcome to the Under the Hood Show podcast.
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Thanks for listening to the Under the Hood Show podcast.
Here's the show.
This is Under the Hood.
Welcome to the Under the Hood Show.
We are glad to have you with us.
Russ Evans is here to answer your automotive questions.
Thanks for joining us Under the Hood.
Shannon Nordstrom is here to do the same.
Welcome, Hoodies.
Thanks for tuning in so we can help you tune up.
I'm Chris Carter here to answer your calls at 866-594-4150.
Quickly before we get to calls, there's a lot of calls coming in.
We'll get to them.
Shannon, you were out snowmobiling.
Were all laws and common sense followed?
Yes.
Okay.
That's good to know.
We had a very, very good time.
Okay.
Good.
Everyone's safe.
Everyone's safe.
Did all of the snowmobiles make it back in one piece?
Did you read the text?
All of my snowmobiles made it back in one piece.
All right.
Yeah.
A friend of mine still was able to ride his, but there was a booboo.
Not all the pieces were there.
No.
And we had to creatively hold it together on the trail.
And not all of your snowmobiles came back with the same parts they left with.
Yes?
That is true?
I had a...
Yeah, we had one of them that had a blown belt going across the lake at speed.
At common sense speeds.
You were driving the, what is it?
The 55 mile an hour DNR regulated speed.
Isn't that what it is?
I think that's what it is.
55?
I'm not sure.
45?
Well, let's talk to Jeff from...
Let's go to North Dakota and talk to Jeff and change the subject.
Jeff, you're on the end of the hood show.
What can we do for you?
Thank you, take on my call.
You bet.
I have a 2021 Toyota 4Runner.
It only has $6,000 miles on it because it's primarily a winter vehicle.
And recently I've had an event end of January.
I was going to get on a busy street.
And when I pushed on the accelerator, it went into lip mode.
And on the dash, it said brake and accelerator pressed simultaneously.
And I was not doing that.
And that kept doing it.
And then I got where I was going and I started it up again and it was fine.
But I still made an appointment for the next morning anyway to have it checked out.
And they said everything checked out fine.
There's no codes, nothing's wrong with it.
That night we went out for dinner and it did it constantly.
To the point where it was like somebody was not happy with me because why are we driving this
vehicle?
And then it was kind of slippery that night.
We're early the day before it wasn't.
And it got to the point where it kind of got better, where it would go into a little bit
of traction control before it would go into lip mode.
So the next morning I brought it in again and they were interested.
Yeah, we'll take it, bring it in right away.
And they had it all day long and they said they could not get it to duplicate.
Everybody was dry of it.
And it got to the point where they said, okay, it did it once.
But they couldn't re-duplicate it again and there was no codes, nothing was wrong.
And then finally they still get in closing time, they said, come pick it up.
And then they told me that they had been in touch with Toyota corporate engineers.
And made it sound like nothing was wrong.
But it has never done it since then.
So I'm just wondering if there would be something going on behind the scenes.
Because I went down a long rabbit hole on this whole thing.
And it all ties back to the programming that's put into the vehicle with
the accelerator issues they had back in the 2000s, early 2000s or whatever it was.
So I just want your thoughts on it.
Yeah, that was over 20 years ago.
Well, I'm flummoxed as to who could have been upset that they were in that vehicle.
That's a mystery to me, I can't imagine who that would be.
So this only did it one time and it's never did it again?
No, no, it did it multiple times the first time and then I made the appointment.
And then after they had it for four hours, they said there's nothing wrong,
no codes, nothing's wrong with it.
But then it did it all that night after I picked it up.
And it did it constantly over and over again.
And then I brought in the next day and then that's when the next appearance happened.
When they said, okay, we had to do it once, but they really weren't sure.
There's no codes.
They can't do anything.
They've been talking that.
Yeah, if there's nothing in there that's a hard fault,
even if the shop sees the problem, that problem has to occur continuously
and never stop for them to be able to find it.
If they got in it and you had 10 people at that dealership drive the car
and say, oh yeah, I see it doing it right now.
And then they plug into it.
They try to diagnose it and it doesn't do it continuously.
It could do it just once here and there.
They are never going to find it.
It needs to be broken every time they try to accelerate.
Then they can find it because while they're testing it, if it's not actively occurring,
there's no way to find out what it is.
That's like, I don't even know what to compare it to.
It's just not possible to find it.
But if it's a hard code, then they'll say, okay, we've discovered this issue
because of this code that's being set.
We should replace this component.
I'm kind of curious when you said you went down the rabbit hole.
I'm assuming you started asking a lot of questions on the internet and you ended up
with someone saying that it was safeguarding programming that was put in back from years ago.
All cars do this now.
If you step on the brake in the gas, most of the time it won't give you a message,
but it won't accelerate.
It's made to shut off the throttle when you step on the brake.
So if it's got a bad brake switch and the brakes are actually being activated,
if somebody was following you and saw that your brake lights came on when you were trying
to accelerate, that would be a great tell right there because there's no codes.
It thinks it's doing what it's supposed to, but it's going to turn on.
And weather differences could affect that if you've got a problem with that brake switch.
So it thinks you're braking, but you're not braking because that is standard.
It's supposed to do it.
Yeah.
They checked all that stuff.
Everything was perfect.
Nothing was wrong with it.
But it just intrigued me that it was after they had contacted Toyota corporate engineering
that all of a sudden I haven't had the problem anymore.
Well, they may have tried something.
If it was in there and they didn't make any repairs,
they may have just reflashed everything in the software just to see what would happen.
They're like, well, we couldn't find anything.
You got some updates that need to be done.
Let's do it.
Because almost every car is going to have updates after it's three or four years old
because it's parts where parameters need to be changed in order to not have lights come on.
Did you know, did they say if they did any programming to it or did they just analyze?
They were really quiet about it.
It was just kind of like when that came up, the Toyota thing engineering,
and all of a sudden it was like, well, they were done talking about it.
And that's not unusual at all because the techs to do or to say...
No.
Well, no, but I know techs, Russ knows techs that are in dealerships.
And there's times where they've got a resource to reach out to.
If they're beating their head against the wall and they're not figuring something out,
they've got a path they can follow that connects them to the resources at the manufacturer,
including engineers, if they need to go that far.
And the service managers, they have to elevate things,
but they have an ability to do that.
That is not unusual for that to happen.
But I would just, like Russ said, I'd be curious if that phone call
or that email exchange or whatever it was led to them saying,
hey, why don't you hook up to this thing and we're going to update the software.
This shouldn't be it.
But we'll do this and then just see.
Or whatever they said or whatever they did.
We're going to do this and don't.
But we do know that with confidence that because of the noise from the unintended
acceleration challenges that were out there, I mean, we talked about this in the show where
they even took it to NASA engineers trying to figure out and said,
there's no way that could have happened with the safeguards that they had.
And that's when the advent of the floor mats with the pegs in them to hold them back.
So they don't slide up under the accelerator.
All that came into play was all during that time.
And like Russ, I'm repeating him again, but they did put safeguards in the systems
just to make sure even more safeguards, just like the throttles have redundancy
on the contacts in them, numerous ones on them.
So before with the electronic throttles to have safeguards in place.
So I think that I would, I appreciate you, Colin.
I'd let my heart not be troubled about it because at least it's not where it is
completely stopping you.
It goes into that limp mode and you're able to get somewhere
and it hasn't happened now for months.
Yeah, about a month.
Yeah, close to a month.
And we've had some, you're in North Dakota.
What part of North Dakota are you in?
Fargo.
Fargo.
We've had some crazy temperature swings.
We've been super cold.
We've been moist.
We've been, now you're probably experiencing better weather.
You know, we've been all over the board here this winter.
So, you know, those things can affect the environment too, the ambient surroundings.
And I think, you know, those are such good vehicles.
This is highly unusual, obviously.
Is it, is it possible or is he going internet crazy a little bit that he brought it in?
They talked to the corporate engineers.
The corporate engineers fixed something and said, don't tell anybody.
Is that logical or is it possible?
I think that's conspiracy theory too much for me.
I think that if they found something and said, you know what, we reflashed the computer,
they didn't know if that would fix it or not.
But we're going to, we want to get everything reset.
It's just like your home computer.
Sometimes the printer doesn't work.
Yeah.
And you just, you're like, I can't figure out what's going on.
And you just restart everything.
Relate it and reinstall it.
Well, no, not even that.
You just started, you restart the computer and the printer works again.
Everything reconnects.
Yeah.
You know, that, it's, that happens.
It, this, these, these are sophisticated systems in these vehicles.
There's, there's computer can bus networks talking to each other all over the vehicle.
Sometimes my printer doesn't work if I don't use it for like a month and a half.
And I'm not taking it outside.
No.
It's not raining where I take it.
Well, and then you find out the kids took all the paper out of it.
Yeah. Where, why is it out of, where's the paper?
Jeff, does that help you out at all or just kind of let you move along?
No. Yeah, that does help me out quite a bit.
So I'm not going to worry about it because it's been driving perfectly
over since that I'm going to go with, they maybe reflashed it like you said and cleaned it up.
There you go. Jeff, thanks very much for the call.
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