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Throttle position sensor


jessdela
08-17-2004, 07:53 AM
Thank you for that great advice you've all given me! I went to Autozone, and they read them on the spot for free and it was so fast! So, the codes they told me was that there was a misfire in cylinder 1 (he said likely it needed a tune up, which I have just replaced the spark plugs, distributor cap and rotor, and had the timing adjusted). The other code was saying there was something wrong with the throttle position sensor. Does anybody know what that is, where it is (I have a 99 Blazer ZR2), and how easy it is to fix/replace??

SpitAndDirt
08-17-2004, 11:04 AM
The throttle postion sensor is located on the side of the throttle body, where your accelerator cable is connected. This is also where the large air intake pipe/hose connects to the engine. Should be directly on top. Here's how to find it, should you not know exactly all the terminology. Have a friend press the accelerator pedal down and up continuously(1 time a second or so) and you look for movement of the cable on top of the engine. The shaft that the cable is connected to is the butterfly valve shaft. Look on the opposite side of where the cable is connected and there will be a electrical sensor with 3 or 4 wires coming out of it. That sensor measures how much the throttle butterfly valve is opening, hence, how much your foot is pressing the accelerator. After you find it, you can make the determination yourself about how hard it will be to replace. Most TPS sensors are not that difficult to replace, but then again I don't know your skill level or the tools you have available. One last thing, consult a shop manual such as Haynes or Chiltons. www.AllData.com is another avenue if you dont want to spend money buying a factory GM manual from www.helminc.com . You really can't beat the information in a shop manual, even if your just trying to reference a repair that you paid someone else to do. It keeps you informed and them honest. Hope this info helps -Chris

jessdela
08-17-2004, 12:03 PM
Does it need further adjustment once it is replaced? From something I dug up online, it sounded as though it more just might need adjusting. Of course, I'm fine with replacing it if needed, it is a cheap part, but wonder if it would need adjusting still?

SpitAndDirt
08-17-2004, 12:40 PM
Maybe. On older GM's with adjustable sensors, the sensor is rotated while the output voltage to the computer is measured. This is to set minimum voltange. Most of the vehicles I have had to set were alot of the time .55Volts . You need to check the service manual for accurate values. Once .55Volts was achieved, the sensor was tightened into position and voltage rechecked. One last thing is to make sure there are no carbon deposits holding the butterfly valve open so as to offset the sensor position. Any other ???? -Chris

SpitAndDirt
08-17-2004, 12:43 PM
I should have added that I believe GM was trying to move away from adjustable sensors, if the mounting points have oblong holes, its probably adjustable. If the holes are just that, holes, then probably not. -Chris

jessdela
08-17-2004, 12:54 PM
Thank you SOOO much for all your advice. After being ripped off way too many times on repairs, I'm trying to learn this stuff. I'm certainly not advanced, but no more than many females my age! hahaha.

I looked up the part online and if the picture matches what the part really is, the holes are round. So, from what I gather, as long as I can find this thing (which shouldn't be hard), I should just be able to take one out, put the other in, with pretty much just a screwdriver. You think??

BlazerLT
08-17-2004, 12:57 PM
Yes.

But go get a Haynes or Chilton's repair manual or even both.

I have saved literally 1000s because of it.

SpitAndDirt
08-17-2004, 01:09 PM
Torx screws. Same as star bits, or possibly with a 7mm hex-headed screw. Can't tell you for sure. A suggestion for tools. If you want to start out, even if just to make yourself acclaimated to your vehicle, but quality. I would spend about $50 to $100 on Craftman tools. A standard phillips, and flathead screwdriver(or an assorted set of like 20 different ones), pair of needle nose pliers, pair of channel lock pliers, torx screwdrivers( sizes T10,T15,T20,T25) and possibly a starter socket set if you can afford it. Just remember that 99percent of your vehicle is made up of metric fasteners. This is very basic to me, but everyone had to start somewhere. As for learning more about specifically where to find free information, I like Barns and Noble or Borders. I'm talking about the physical stores you can go into and peruse automotive books. There is one book inparticular which is very informative: "How to Tune and Modify Chevrolet Fuel Injection" by Ben Watson. It will explain in detail facets of your fuel injection and emission related components that seem really vague, including your TPS, I promise. I read it, but then again, I enjoy books like that. You just need to pull out a few details. Don't forget your local library. Tell me how it turns out -Chris

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