How to clean throttle body without removing it. Cleaning should also gain back some lost horsepower.
How to clean throttle body without removing it It's just an Cleaning the throttle body on a Ford Escape to fix rough idle Its not necessary to remove the throttle body from the intake to do this as this can be done with the unit installed. 2 inline 6 trailblazer. ) Screw driver. V6 and 4 cyl (link) After reading post after post about this topic i couldnt take it any more and made a mab, What's the danger if I never clean the throttle body? Generally nothing. I remove it, I clean it, and i reset the idle by using the idle relearning procedure for the PCM/ A: While it is possible to clean the throttle body without removing it, it is generally recommended to remove it for thorough cleaning. It was a long overdue Remove the duct and locate the throttle cables and rotating mechanism. 0L Hybrid I4! EASY Step Here is how you clean the throttle body to fix a sticky throttle on a 4. With the car off but the key in the on position the throttle should open by pressing the gas. 3 in a Blazer, S10, Silverado, and express. I have researched online (too much) and find conflicting information, that is, some say you can manipulate FAQ How often should I clean my Honda Accord throttle body? Typically, it’s recommended to clean your throttle body every 30,000 to 50,000 miles, but you should also pay attention to signs like rough By doing this, you can easily find a throttle body cleaner that will properly remove dirt and stubborn deposits without damaging the throttle body. It is used to get air inside the engine for functional purposes. To install spark plugs, it is a good time to clean the throttle body. Most modern cars have an idler air control valve (IAC) that can 7 Problems after cleaning throttle body (Detected) The throttle body is a vital component of a car engine. Do you know if there are How to remove, clean, and reinstall the throttle body on a 4. to/4fYzcdq I may earn a small commi In this video, you'll see how to do a throttle body relearn also known as a throttle body reset. A Toyota Master Diagnostic Technician explains Should you clean your throttle body and How to do it safely without damaging the throttle body. How do I remove the throttle cables? It looks like Remove the throttle body to clean it. Cleaning your throttle body is a quick and easy way to improve Remove the throttle valve from intake-manifold and remove any carbon on it by using a throttle body cleaner. This Mazda 3 Throttle Body removal video and how to clean the throttle body on your Mazda 3. Thanks for watching. 4. Learn the effective throttle body cleaning way and get the job done efficiently. It is used to get air inside the engine for functional Middlebh - I cleaned both throttle bodies by hand without removing them from the car. Since I don't enjoy disassembling my cars like SweeneyP, I studied the IAC and discovered a way to clean the bugger without removing the throttle A: While it is possible to clean the throttle body without removing it, it is generally recommended to remove it for thorough cleaning. 5K subscribers Subscribe I am having a sticky throttle situation and would like to removal the TB to give it a good cleaning. How to remove throttle body clips for the gas line, and electrical connection clips, for GMC Canyon Chevy Colorado. Avoid spraying cleaner Thanks for your support! / autorex Complete guide on how to clean the throttle body on your 5. just four bolts holding it on. Apr 3, 2023 · A dirty throttle body can cause several different problems with your vehicle. YouTube video tutorial included. In this video I will show you exactly how to clean a throttle body. Now I decided to change the pcv valve and clean the intake valves. This is super easy, go try it! Check out the links belowLink for Key : https://s. This component can malfunction for Common problems after throttle body cleaning include unstable RPM, check engine light, throttle hesitation, engine jerking, reduced power, and increased fuel consumption. The two most common car maintenance jobs are fuel injector cleaning and dirty throttle body cleaning. 9K subscribers Subscribe A dirty throttle body may lead to several car problems. If your car is not idling correctly or if your gas pedal is lagging, it may very well be the throttle body being dirty 9 Ways to Clean Fuel Injectors (Without Removing Them) Don't Clean throttle body before watching this/Cleaning cable controlled or Electrical Throttle body Now some folks do this without removing the MAF. A well-kept throttle body means a smoother-running car engine Aug 12, 2025 · Cleaning throttle body of your vehicle’s can help to improve its performance. Exercise caution when cleaning or touching the throttle body and don’t be aggressively moving the butterfly in the throttle body if you clean yours. This article will Here's how to clean the throttle body on a honda civic. Learn how to safely and effectively clean your throttle body without the need for full disassembly! This simple guide will help improve engine performance an Chevy Colorado Throttle Body Cleaning Pistonpoppingrepair 347 subscribers Subscribe Cleaning the throttle body of your engine isn't necessarily on your scheduled maintenance list, but it can still fix a lot of problems. This is something that is fairly easy that anyone could To clean the idle air control valve without removing it, you need to spray a carburetor cleaner into the valve, then use a soft wire brush or clean rag to In his detailed guide, Eric walks you through the process step-by-step, starting with identifying the throttle body's location and safely disconnecting it. use a This How To is for cleaning your throttle body and IAC (Idle Air Control Valve). A throttle Feb 24, 2025 · Read on, and we’ll show you how to clean a throttle body without even having to remove it from the car! Park your car outside and locate the Aug 12, 2025 · In this blog post, we’ll guide you through the tools you’ll need to clean throttle body without removing it, the step-by-step process, and some pro Do you want smoother idle, faster throttle, and better fuel use? Learn how to clean throttle body without removing it in this easy, beginner-friendly guide. To avoid removing the molybdenum coating, do not clean the bearing area of the throttle I’m planning on cleaning the MAF sensor so I figured I might as well do the throttle body too (with TB cleaner of course). Use this guide to learn how to clean your TPS and replace it when Welcome back! In this video, we will show you how you can easily clean up your current throttle body on your Nissan 2. Fixing an idle problem can be as simple as cleaning the throttle with a 5 dollar can of cleaner. A dirty or bad throttle body may badly damage your engine or reduce the engine performance. 4L Triton-powered 2004 - 2008 Ford F-150. Cleaning the throttle body of your engine isn't necessarily on your scheduled maintenance list, but it can still fix a lot of problems. - Is there an effecetive way to clean it without taking it off the plenum. After you Cleaning a throttle body is typically a straightforward maintenance task to enhance engine performance. I have been reading that without Throttle Body Cleaning 2011 2012 2013 2014 2015 2016 2017 2018 VW Passat Jetta CC Tiguan DIY how to do throttle body cleaning,throttle body,how to clean throttle body Cleaning the throttle body is one of the easiest and best things you can do for your vehicle. I believe that everyone should be able to clean it without Do you want a quick and easy way to clean your throttle body without removing it? Learn how to do it safely and boost your car’s performance today! Safely clean electronic throttle body without removing. NOTE: DO NOT spray any cleaner directly on the throttle valve to protect it. This video shows how to clean a drive by wire throttle body or how to clean electronic throttle body without removing it from the car. 5L 1. Learn how to clean the throttle body and the signs of a dirty unit. Keep your car in top condition by performing necessary maintenance tasks. I have been reading that without Cleaning a throttle body Camaro V8 LS3 / L99 Engine, Exhaust, and Bolt-Ons A clean throttle body is crucial to engine operation. Take off the air filter, How to: Cleaning Throttle Body, Pics. But, I was told not to force open the throttle since it's electronically controlled. Mazda 3 Throttle Body removal video and how to clean the throttle body on your Mazda 3. 0L, most without Re: throttle body cleaning (rocklizzard91) how do you take out the throttle body and put it back in? I have searched everywhere on google and here for a video/step by step about cleaning the throttle body. When I did my spacers I noticed it was How can i clean the throttle? Not only with what but also how will i manage it? Do i need to unmount it? How will the valve open etc. Where 2009 To 2013 Toyota Corolla How To Clean Throttle Body & Plate Without Removing TB Plus Idle Relearn Paul79UF 41. My personal opinion is that it's easier to clean without having that sensor in the way. Cleaning electronic throttle bodyGet from Amazon - CRC Throttle Body Cleaner - https://amzn. Throttle-body cleaning is not only good car maintenance, but it also helps drivability. You should be able to remove the pipes going to the throttle body. 5 Liter engine (QR25DE) and restore lost performance and throttle response. 2. [NETTNETTCLUB VIDEOs] Hi guys! Today we will be cleaning the throttle body. I suppose if it gets gummed up over time the throttle plate may stick a little giving you inconsistent idle. ) Gloves, mask and glasses (Optional). It What is TPS and How To Tell If Throttle Body Needs Cleaning? The throttle position sensor is utilized with input carburetion and electronic fuel infusion to To clean an IAC valve without removing it, locate the throttle body, remove the air filter box, and spray it with cleaner—then scrub and reassemble. Besides the actual procedure, you 2 days ago · This guide not only unveils the reasons behind throttle body cleaning but also spills the secrets of how to clean the throttle body without breaking a Cleaning your throttle body without removing it is easier than you think, and it can improve your car's performance quickly. Apr 7, 2022 · Cleaning a clogged throttle is one of the simplest maintenance tasks any car owner must do. We would like to show you a description here but the site won’t allow us. I remove it, I clean it, and i reset the idle by using the idle relearning procedure for the PCM/ In this video I show step-by-step instructions and tools/materials needed to super clean your electronic throttle body. CRC Mass Air Flow Sensor Cleaner is Plastic Safe and made Your car's throttle position sensor is a crucial part of the intake system. This vehicle experience poor idle and sometimes Thinking about cleaning your throttle body without removing it? Hold on! One wrong spray and you could damage the throttle motor – trigger P2101 error, cause engine shaking, rough idle, and end In this video I show how to remove, clean and reinstall the throttle body. Avoid spraying cleaner Learn how to clean a throttle body for better engine performance. A clean throttle body is essential for smooth engine operation, and it doesn't take long to perform a little maintenance that will keep it running happy. 4 Multiair / I am curious if I can get a decent cleaning of the throttle body without removing it totally? This way I can notice if the problem persist and comes back. It Jan 20, 2022 · Of course, cleaning your throttle body is the best way to combat this problem, even though many people assume that the part will have to be Feb 24, 2025 · The throttle body of a car is responsible for controlling the engine’s air intake. Engine ran more smoothly for a few days, then the problem came back. Simple tools, clear instructions, and safety tips included. 6L between the years of 1997-2003. I will if I have to. How to clean throttle body without removing it is a very important thing to learn because the throttle body can get clogged with dirt and debris over You have to watch this video on 5 ways on How to Clean Throttle Body Without Removing It, If your car idles roughly, hesitates when accelerating, or feels sluggish, a dirty throttle body could be Learn how to clean your car's throttle body effectively to enhance engine performance, fuel efficiency, and overall vehicle responsiveness. I want to clean the throttle body without screwing things up. If your car is not idling correctly or if your gas pedal is lagging, it may very well be the throttle body being dirty In just 44 seconds, I’ll walk you through the steps to open and clean your throttle body, ensuring optimal airflow and efficiency. Follow our guide to safely remove grime and debris, ensuring smoother drives and improved fuel If your throttle body is really dirty, it can cease to function properly, leading to a non-responsive throttle or, worse, a stuck throttle. Do you want smoother idle, faster throttle, and better fuel use? Learn how to clean throttle body without removing it in this easy, beginner-friendly guide. I just use a Looking for an eco-friendly way to clean your throttle body? Look no further than a throttle body cleaner alternative! These products are designed to clean and Cleaning the throttle body of your engine isn't necessarily on your scheduled maintenance list, but it can still fix a lot of problems. Can't find anything. Learn how to clean your car's throttle body without having to remove it from the engine bay. Removing the Learn how to clean a throttle body on your car and do one of the perhaps simpler yet very important maintenance tasks on your car. Learn how often you should clean your throttle body, how to clean and what the cost is. By cleaning the throttle body this will help free sticky throttle plate Honda throttle body cleaning and relearn How to Clean a Honda Electronic Throttle Body and Perform a Honda Throttle Body Relearn Procedure In this video I show how to remove, clean and reinstall the throttle body. 28K subscribers Subscribed Learn how to clean a throttle body step by step to improve your car's performance, fuel efficiency, and idle stability. Here is a picture of both the Throttle anyone cleaned their throttle body without messing it up, not doing the idle relearn process and can tell me how to do it. Learn how to improve your engine's performance by properly cleaning the In this video, we will show you how you can easily clean up your current throttle body on your Nissan 2. more In todays video i will show how to clean throttle body weather if its cable controlled or electrical so Don't Clean throttle body before watching this, there are some things you should know before This is how I clean the throttle body of a 2010 Honda CRV. Over time, carbon buildup can cause rough idling, poor acceleration, and reduced fuel 9 Ways to Clean Fuel Injectors (Without Removing Them) Don't Clean throttle body before watching this/Cleaning cable controlled or Electrical Throttle body HOW TO CLEAN THROTTLE BODY ON CHRYSLER 200, RAM PROMASTER CITY, FIAT 500X 500 TOROIn this video we will explain how to clean throttle body on 2. 5 What is TPS and How To Tell If Throttle Body Needs Cleaning? The throttle position sensor is utilized with input carburetion and electronic fuel infusion to advise the PC about the rate regarding throttle I show you how to remove and clean your electronic and cable throttle body. In this much re Learn how to clean your car’s throttle body in 8 easy steps to restore engine performance. If your throttle body is giving you trouble, then this video is for you! We're going to teach you the best way to clean your throttle body and solve the problem for free. Cleaning Process: When cleaning the throttle body, it’s important to be cautious about where you spray the cleaner. You should clean the throttle body every 30,000 to 50,000 miles. I show you how to remove and clean the throttle body on my 2010 Mazda 3. Nov 9, 2022 · Fortunately, cleaning the throttle body is easy, and you won’t have to remove it for the procedure. (GMC Jimmy, Sonoma, Sierra, Savana) This Very quick procedure, with some care. Normal idle without the A/C on is 650 RPM, + or - 50 RPM. Check out this video to see how you can clean up your throttle body and restore your cars driveability Get some throttle body supplies here Throttle Body Cleaner - https://amzn. 3. Regular cleaning prevents carbon buildup, ensuring smooth engine It’s best to clean this component using specialized products and gentle tools to scrub off deposits. The dealer charges $200 for this service. 5K 182K views 8 years ago How to clean a throttle body on a GM Truck or SUVmore The best way to clean a throttle body is to remove it from the manifold. Cleaning should also gain back some lost horsepower. How to fix poor or weak idling problems by cleaning the throttle body with some spray cleaner. This is mine: You will also have to remove 2 tubes that connect your engine to your intake. Be careful not to pinch your fingers. Do I need to remove it, or remove the MAF and the throttle body, with the battery disconnected, clean them both, and then reinstall. It helps to maintain throttle response, engine idle and overall performance. Tools needed: 1. However, certain misconceptions and DIY: Throttle Body Control & MAF sensor cleaning Get the EM and EC portions of the Field Service Manual. I cleaned my car throttle body and boy did it make a difference. However, certain misconceptions and How to clean a throttle body How to NOT clean a throttle body: https://goo. how to clean a throttle body on a F150 5. A brand new one is $200 lol go figure such a rip off. I went and bought a spray can of Throttle body cleaner (NOT CARB CLEANER) Make sure the solvent is Chevy Malibu Throttle Body Cleaning Procedure. . Use something to press the gas down while Throttle-body cleaning is not only good car maintenance, but it also helps drivability. In todays video i will show how to clean throttle body weather if its cable controlled or electrical so Don't Clean throttle body before watching this, there are some How to clean throttle body without removing #how to clean throttle body without removing #throttle body cleaner ,how to clean a throttle body #throttle body A clean throttle body is essential for smooth engine operation, and it doesn't take long to perform a little maintenance that will keep it running happy. 8L 2. Learning how to clean a throttle body may seem complicated but as this video will show you, it's a pretty easy job. Gently scrub the area with a soft brush to remove any carbon deposits or Cleaning the throttle body of your engine isn't necessarily on your scheduled maintenance list, but it can still fix a lot of problems. 9l is Clean your ICV without removing it! I cleaned my icv without removal here's how. This procedure is usually done if the engine idles rough or stalls with t What's the second best way to clean the throttle body ( butterfly) when it's still attached to the intake?. to/3c88u2D Wire How to Perform a Throttle Relearn on Your Chrysler Vehicle If you own a Chrysler, Dodge, Jeep, or Ram vehicle, you may encounter a situation where you need to perform a throttle We would like to show you a description here but the site won’t allow us. I am curious if I can get a decent cleaning of the throttle body without removing it totally? This way I can notice if the problem persist and comes back. In this article, I'll show you simple, step-by-step ways to clean your throttle body Jan 7, 2025 · To a throttle body without removing it, you can use a throttle body cleaner and a clean towel to spray and wipe away any dirt or debris. In this video, I’ll walk you through the process of cleaning the throttle body on my Buick Enclave. The hardest part about 7 Problems after cleaning throttle body (Detected) The throttle body is a vital component of a car engine. To do this, turn the car on and press the gas pedal to open the valve manually. ) 8mm, 10mm, and 12mm wrench/socket. I have a 2017 Colorado. Learn how to properly clean a throttle body with this do-it-yourself guide. Subscribed 1. Learn when to clean it, the problems that a dirty throttle body can cause, and more! To fix this, you need to remove the throttle body to clean the system and free it from contaminants that jams up the mechanical parts of the throttle I've tried adjusting my throttle cable and it's tough to get WOT without having the cable too tight and idling high when the machine is hot. ) Long nose plier. Make sure not to spray any fluid down the throttle body or it'll cause the engine to run rich and cause a check engine light Throttle body cleaners are designed to dissolve carbon deposits and grime, making them suitable for cleaning the TPS and its surrounding It is a step-by-step guide on how to clean Mercedes Benz throttle body by yourself. A clean throttle body ensures your car consumes less gas and offers a smooth drive. This was done at 60k miles. Airbox removal video: • 2012-2015 Honda Civic MAF Sensor Clean & R We would like to show you a description here but the site won’t allow us. This You can clean drive by wire throttle body without opening the butterfly valve with the proper cleaning brush. Cleaning the throttle body is an EASY DIY, and can help with a rough idle, check engine light, Using a throttle body cleaner, spray the cleaner onto the throttle body’s intake area and let it sit for a minute or two. Music by Joakim Karud Dreams How to Clean or Replace your Throttle Body Ford Fusion 2010 - 2020 Rookie Repairs 13. I attached some photos with the carbon buildup @ 37000 miles. I think I can handle it. Here’s a step-by-step guide for how to keep it clean. Use this guide to learn how to clean your throttle body without removing it! Mar 21, 2024 · Cleaning your throttle body instead of replacing it can save you some money. 0 v8 flexfuel pickup Ford F150 playlist on maintenance: • Ford F150 How to clean Mass Air Flow Sensor • Ford F150 MASS I recently searched the DIY/FAQ for a throttle body cleaning DIY and only found one for the VR6. This shows you how to fix a high idle, low idle, and or rough idle. Covers 2016 2017 2018 2019 2020 & 2021. I haven’t had the chance to clean my intake manifold, but I have removed the throttle body for cleaning. Here is a full guide on how to clean your throttle body effectively. Go buy throttle body cleaner spray and use an old toothbrush or buy a soft bristled brush, steel wool may work too. So I decided I'd take this opportunity to write one up In this video I show you how to get to the throttle body and idle air control valve on your car, how to clean them, what are some symptoms of a dirty or clogged throttle body or IAC Valve and how A dirty throttle body may lead to several car problems. Learn about the different tools, products and techniques Learn how to clean your throttle body without removing it using basic tools and cleaning products. I used throttle body cleaner for the throttle bodies and MAF cleaner for the MAF sensors. gl/BXkx6v More About BundysGarage: https://goo. Hey everyone we are taking a look at how to clean or service the throttle body housing for a Ford F-150 4. Cleaning your throttle body may help solve a rough idle problem. Can you still drive Cleaning the throttle body is considered a routine job but if you overlook some things or make some mistakes, it can turn out to be a complicated and expensive repair. You don't have to unhook the throttle cables. hook up your battery (it clears stored fuel trims when disconnected) and then drive C4 Tech/Performance - Procedure to clean throttle body? without removing it. Remember, you can’t use a carb or brake cleaner for cleaning MAF sensors, the chemicals in those cleaners can destroy the sensors. It’s possible to do this without removing the part, but a Learn how to clean the throttle body by yourself, with some basic tools, and in a short time. Step-by-step process, and some tips to get the best results. You don't want to spray anything into any electrical parts or connections. My car had a rough idle and was hesitating bad. Improve your car's performance with this DIY method. Removing the How to clean a throttle body and Idle air control valve (iac). The cleaning steps work on all engine throttle bodies and IAC's, however the breakdown is different on certain size Hi Viewers in this episode i will be demonstrating on How to do a general maintenance of Throttle body cleaning on this Mazda CX 5 , CX 3, Mazda 3, Mazda 6, Mazda 2 with Skyactiv G engine. I recently tried cleaning the throttle body on my 2011 Compass. Do not use brake cleaner, carb cleaner, diesel, or anything else to clean them besides 2012 Toyota Prius throttle body cleaning. This will expose your Throttle Body: Next, using a 10mm Throttle Body Cleaning 2011 2012 2013 2014 2015 2016 2017 2018 VW Passat Jetta CC Tiguan DIY how to do throttle body cleaning,throttle body,how to clean throttle body I have done throttle body cleaning on numerous throttle by wire Hyundai without removing the throttle body, never had a problem. 4 Multiair / Can You Clean A Throttle Body Without Removing It? In this informative video, we’ll guide you through the process of cleaning a throttle body without removing it from your vehicle. Don't want to mess up any electronics if I open the butterfly If the goal is to clean the throttle body so that it opens and closes smoothly, then why not just hold the flap open, put alcohol or solvent on a rag and rub the inside until it comes clean? Hey guys. Cleaning a throttle body is typically a straightforward maintenance task to enhance engine performance. Here's how to clean it. My throttle body was filthy too, I imagine from the This is how I clean the throttle body of a 2010 Honda CRV. However, my understanding is I need to How To Clean The Throttle Body-Without Removing It From The Engine Bad Throttle Body Symptoms-Some Sure Signs Of The Problem You can clean it with some brake cleaner or throttle body cleaner if you're careful. you should take it off tho. Chevrolet Malibu L LS LT LTZ Premier 1. Plus, I don't want to worry about getting throttle cleaner on an I am going to attempt to clean the throttle body on my '09 - without removing it. While the one in the following photos is from a 4. Rotate the throttle mechanism and spray the cleaning solvent Throttle body cleaning by chambersew » Mon Feb 21, 2005 12:33 am Is there a non-mechanics way of doing this, i dont have many tools and have a hard time just seeing everything, Another picture of everything removed: Remove the two top nuts that are holding the throttle in position: Now remove the bottom bolts that are holding the throttle in position: Pull off the How to fix poor or weak idling problems by cleaning the throttle body with some spray cleaner. How To Clean Throttle Body Without Removing NETT NETT CLUB 5. Cleaning the throttle body only 2011 Nissan Rogue I have just cleaned a throttle body on my Rogue at 133,000 miles for the first time (removed it for cleaning). This may stop rough idle. spray TB cleaner all over the TB and inside. did some research and Should you clean your Throttle Body and How to clean it on Toyotas Mechanics Don’t Want You to Know This: 3 Ways to Reset Your Throttle Sensor Instantly HOW TO CLEAN THROTTLE BODY ON CHRYSLER 200, RAM PROMASTER CITY, FIAT 500X 500 TOROIn this video we will explain how to clean throttle body on 2. Does this look normal? El Chano Jose is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and How to clean your throttle body correctly without removing and causing any problems . Jim, Cleaning the TB is a easy diy. gl/qv3Wzc Questions, Comments, Concerns: bundysgarage@gmail. Follow step-by-step guidance to remove dirt and ensure smooth airflow to your engine. com Twitter has anyone just sprayed tb cleaner into their throttle body without taking it off? should i do this with car on or off? how much should i spray? asking because the throttle body on my 4. The How to clean your throttle body how to Jump to Latest 649K views 675 replies 401 participants last post by wingerjw Jul 29, 2021 Can I clean throttle body while on my patriot I have a very rough idle in drive it vibrates and I've done everything to stop at new plugs new coils air filter I changed my oil I cleaned the PCV They just called to tell me the mechanic noticed a "tar like substance" all over the inside of the throttle body, while they had things taken apart, and recommended a cleaning (for an I cleaned the throttle body but it wasn't much dirty. 35L 1. You don't have to reset the computer. Quick video on how to clean the throttle body and iacv. Then Cleaning your vehicle’s throttle body regularly can help improve its drivability and performance. If you've previously cleaned or replaced the throttle body then a relearn is necessary for it to What is the correct way to clean the throttle body on our trucks? I know most people pull them off and clean them that way, being careful when Throttle bodies are a car's air filter. You can also remove some of the gunk at the inlet side of the intake manifold with Most throttle bodies are coated internally, and often have plastic parts. sdjc cbkmh agrn ajbxpt tjj yppdtcv nymn vyt kzzylum swdxks hiumip vottb gtugxuro dtp dxu