Weak Acceleration Rough Idle Diagnose a Car or Truck Throttle Body

What is wrong with this thing now? Let's check this thing out. Okay, certainly poor acceleration. It seemed like it was idling funny. I think I know where to look. All right, I wanna get under here. Oh, look at that? It looks like I got an idea for another video.

Hey, friends. It's Len from 1A Auto. Today I want to talk to you about if you're having a problem with your vehicle and you happen to notice that you're having an issue with acceleration. Maybe it just seems a little doggie and doesn't wanna go when you first accelerate or when you're sitting idling, you happen to notice that your RPMs or your engine speed tends to go up and down, kind of, erratically. I wanna get into it, let's do it.

One of the first things we have to do to start diagnosing this, of course, is to find the throttle body. I said you're gonna wanna follow the air filter, along the air duct, and it's gonna lead you to the engine. The part closest to the engine, where the intake is, is where the throttle body is gonna be. So as you can tell, not all vehicles are the same. You find your airbox, you follow the inlet, it's gonna lead you right down to the throttle body. The throttle body is gonna be in between the air inlet and, of course, the air intake which is attached to the engine.

In older vehicles with carburetors, the throttle body is gonna be integrated in with the carburetor. So now that we have that out of the way, we have a clear view of the outside of the throttle body. Of course, all this out here really isn't gonna make much of a difference, an exception of the steel in between here and the actual intake itself, but we'll talk about that in a minute. If I was to look along this area, which is where the hose was connected, you wanna look for any dark areas, some areas that maybe look like they have some dark carbon or debris of any sort. Anything like that, that you might see, could cause this to restrict in some way, which of course would cause a delay in acceleration when you go to accelerate.

What happens is is when you go to accelerate, the little flap inside here is supposed to open up, and as it opens up, it makes it so your vehicle is gonna draw in more air. If it's getting blocked by anything, such as any of this debris or carbon that's in there, of course, it's gonna cause a delay or even erratic idle.

Now, as we're taking this apart, any time I remove an electrical connector, I always like to take a peek. You wanna make sure you don't see any funny colors in there. You see any reds, blues, rust, or anything like that, you need to make sure you either clean it up or, of course, replace it. Of course, if this side has an issue, this side might as well, so take a peek at that. Any type of corrosion or issue that's in between the electrical areas could cause resistance, and, of course, that's gonna cause an issue as well.

Okay, so now we're just gonna remove this from the vehicle. So of course, there's gonna be some mounting nuts and probably a couple of hoses that go to it. Okay, friends, so we made our way over to the bench with a couple of throttle bodies here because I wanna be able to show you them right out in the open. If you were to look at the front of this, you can tell that it's not really in the worst of conditions, yeah? There is some carbon buildup that you can see all along that flap right there. Would I say that it's horrible? No. Is it gonna cause an issue? Probably not, just looking at it as it is right now. Of course, if I was to turn it over and look at the back side, we've got a kind of different story here. All this black down along here is all carbon buildup. Look at it, it's flaking right up. This is horrible.

So as this is trying to turn or spin so it can open up, as you accelerate, any of this that's built up could be slowing this down from moving. If you were to look at this one over here, this is an extreme case. The front side, as you could tell, looks horrible, worse than the other one did on the back side. Now if I was to turn this over, holy, moly, this is very bad. You can see all over this thing, it is so bad. This is, of course, gonna cause an issue. If you were having an issue with acceleration or any of the symptoms that I had mentioned before, that's what you're gonna see on the back side more than likely.

When it comes down to cleaning these, you definitely wanna make sure you don't go with something that looks like this, where it says multi-purpose solvent or parts cleaner or anything like that. It needs to specifically say, "Carb Choke and Throttle Body Cleaner." That's very important, okay? Okay, so at this point, we're gonna talk about cleaning down that throttle body. So the first thing that we need to talk about in this aspect is safety. Make sure you're wearing hand protection and eye protection. That's both very important because we're gonna be dealing with chemicals, specifically the throttle body cleaner.

Now, looking at the throttle body, we're gonna clean up the front area first. Something that's important to think about is you wanna use a nice, soft bristle brush, okay? You don't wanna use a metal brush or anything like that, and you especially don't wanna use a screwdriver. So if I was using this, you could use it to try to get out just the hardest bits, but you definitely don't wanna go scraping up your whole throttle body because any imperfections that you make inside here could cause an issue with the airflow mixture overall. Over a nice collection bucket, like what we have here, so we can recycle the fluid properly, we're gonna go ahead and spray this down and let it soak. Something to pay attention to is, of course, this shaft right here. It's gonna be attached to the interior area here. There's gonna be a seal, of course, but we don't necessarily need to try to force any fluid inside there. So as we clean this, don't tip it this way so the fluids gonna try to make its way inside of the electronic throttle body.

I'll hold it just like this. I'm gonna give it a nice spray. It's gonna, of course, come spraying back a little bit, so keep your eyes away. pray it down, let it sit. This is gonna start eating away at all that carbon that's in there. While that's happening, I can take my nice, soft brush here. I'm just gonna work it around. This is great. As I'm doing that, I'm paying special attention not to push too hard on this butterfly and mess up the calibration of your electronic throttle body. If your throttle body is not electronic and it has a little cable with a lever, you can go ahead and pull on that lever and you can open this up. If it's electronic, do not.

So we got the front side as clean as possible. That looks great. Now we need to make sure we do the same to the back side. Now, if your throttle body looks like this one, as I said before, this is an extreme case, if it looks like this, odds are you're not gonna be able to get off all of that carbon just by some light scraping and cleaning and all that stuff, it's still gonna be kind of gunked-up. You can try and you can reinstall it, and hopefully it works for you. If for some reason it doesn't, it's probably because the carbon buildup is too much and it's just not gonna function right off the bat. If that's the case, I would go to 1aauto.com and I would check us out to order a new one.

Now, going from something that looks like this to something that looks a lot more like that, obviously, your vehicle is gonna run a lot better. Something to think about is that the throttle body isn't the only cause of these symptoms all the time. There are other parts on the vehicle that could cause similar symptoms. It could be something such as maybe an air filter. If your air filter's dirty or clogged in any way, that's gonna cause an issue. Most vehicles are gonna have a mass airflow sensor. If that's dirty, same thing, gonna have an issue. Low fuel pressure, obviously, that's no good. Maybe you have a frozen pulley on that belt system. If you have a pulley that's seizing up and the serpentine belt's having a hard time turning, that's gonna, of course, cause an issue.

One last thing that I'd, of course, check would be a vacuum leak. That's something that's a little bit harder to check, but if you were to tug on your hoses or even just kind of listen as the vehicle's running, you might happen to hear one.

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