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2003 chevy trailblazer_ls
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Discussion Starter · #1 ·
Hello, I am new to the forum and this is my first post. I did not know this site existed and I ran across it the other day accidentally but I am thankful that I did. I am having some problems with my 2003 Trailblazer LS, 4.2 liter engine. Last week I was accelerating up a hill and the reduced engine power light along with the service engine light. After that happened it would not go over 20-30 mph. I pulled over, put it in park, turned the engine off, restarted it, and the problem went away. During the course of the day the problem got progressively worse until it went out all together. Fortunately I was not far from home and was able to limp it to my garage. A friend at work let me borrow his computer and it had a code P1512 on it twice. I reset the code, started the engine, and the lights came on after about 20 seconds. During this time there was a bumping noise coming from under the hood until the lights came on. When you first turn on the key to accessory there is a ticking noise for a few seconds as well. I turned off the engine and rechecked the codes and this time I got a P1515, P1516, and P 1512, twice for a total of 6 codes. My biggest problem is I live in Germany and I can't just take it down to the local dealership. The closest place I could take it is about 40 miles away in Nurneburg but I would not feel good about driving it that far, especially through a town that size. I would have to tow it, which means alot of dinero, nothing in Germany is cheap, except beer. Also, the labor rate here is 130 Euros an hour which is about $160, so I would like to try and fix it myself. Today I am going to start with cleaning the throttle body. If that does not work I figure it either needs a new throttle body or pedal sensor. My main question though, is could this be caused by a bad spark plug? The engine is running very rough at idle. Is it normal for the engine to idle rough with a reduced power light or should it run normal until you try to press the pedal? Could it be the PCM? Any ideas or experiences would be helpful. Thanks,

P1512 = Control Module Throttle Actuator Position Performance
P1515 = Same as above
P1516 = TAC Module Throttle Actuator Position Performance
Todd
 

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2004 gmc
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Welcome! You didn't say how many kilometers on the vehicle, but it will definitely be better after a throttle body cleaning.

Your problem is not likely to be a spark plug without having codes for misfires. Also not likely to be the pedal position sensors, but more likely to be the throttle body position sensors.

But I would guess that 90% chance it's just a dirty throttle body, especially if your rough idle was caused by low RPM in the 400-500 RPM range. Anything less than 600 RPM will sooner or later result in a code. Your codes are not a result of a bad sensor - those have their own specific codes. It's complaining that the throttle body position doesn't conform to the pedal position commanded and anticipated position, and a sticky throttle body will do that.
 

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I don't know how to post new treads

Hello I'm New to the site.. I been having on going problems with my 07 Envoy 4.2L I-6. I have check engine light with P0171 and P0411. If the check valve for the AIR pump was stuck close or open wound that cause improper flow and could that result in the vehicle running lean and setting the P0171..
 

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Discussion Starter · #4 ·
Roadie,

Thanks for the advice. I posted a reply last night but it did not go through. The car has just north of 83,000 miles on it. I took the throttle body off yesterday and there is a housing on the side where you plug the wiring harness in to. I could hear peices of something rolling around in that housing, sounds like about 6 or 7 pieces, so I figured something is broken internally. It was not that dirty, took me less than 5 minutes to get shiny clean with some intake cleaner. I called a dealership in my hometown and explained my situation and they were real helpful and the mechanic concurred. The dealership has it set aside for me and my stepfather is picking it up today and getting it in the mail.

Todd
 

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my 02 t.b. was doing the same thing. It had 2 codes 1516/1512. I cleaned the throttlebody, negative unplugged for an hour. This was done about 3 weeks ago, and I have not had any codes come back. The rough idle is gone and haven't had the reduced power/check engine lights come back on. I've noticed better fuel mileage especially on the highway!
 

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...I could hear peices of something rolling around in that housing, sounds like about 6 or 7 pieces, so I figured something is broken internally. ...
Ick. What's in there is the butterfly valve actuator, and two sensors to determine what angular position the valve is in. For safety reasons, the two actuators have to agree with each other or else the PCM gets suspicious and throws you into Reduced Power mode. That kind of failure agrees with your symptoms.
 
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