Okay so when I sit at idle and press the throttle the car hesitates and th rpms go down and then come up and the car shakes a bunch. When I am in gear its 10 times worse. If I push the pedal like reversing out my drive way or pulling up the curb to my drive way it goes to like 200 rpm and then jumps back up and I've had it die before. I dont know what the issue is I heard throttle body can be the problem so I had it completely cleaned and it still does it. Anyone know what it could be? Thanks.

Also it's a 2003 trailblazer ls 4.2l l6

 

Do you know if the party who cleaned your throttle body disconnected the battery for at least 30 minutes in order for the PCM to do an idle relearn procedure?

I would also check the fuel pressure (fitting is by the fuel filter) and also test the operation of the fuel pressure regulator.

If you plan on doing your own repairs/maintenance, invest in a Haynes manual for your TrailBlazer. It is invaluable!!!!

Good luck!

 

...+1

 

So I called the place and they said they never unplugged the battery so I went ahead and unplugged it and let it sit and I just put it back in and went for a little test ride. I dosent do it anymore and it feels like it runs better to!! Thanks for the help!

Also I took your advice and I bought one of the manuals since I usual do all this stuff my self.

 

Edit: it's starting to do it again after I took it to the store. I hit the pedal and it still bugs down then revs up.

 

How many miles are on your 2003? Are you the original owner? Do you know if/when the spark plugs were changed? Do you have a code scanner or have you had it scanned at an auto parts store like AutoZone, Advance Auto Parts, or O'Reilly - and are there any codes?

Just as an FYI, specialty tools like a fuel injection system pressure tester, brake, A/C tools, etc., can be obtained for leaving a deposit at the above mentioned parts stores. When you return the tool(s) you get your deposit back. Just go to their websites and start browsing.

Need more information on the history and maintenance in order to assist you in your efforts.

 

It's got about 150k miles and I am the original owner amd I do have a scanner and their are no codes I just changed the sparkplugs and the ignition coils just 2k miles ago. Also I have always had the maintenance done by a shop I normally would do it myself but i have just always let the shop do most of it except for the simple stuff like sparkplugs and such.

 

Unplug the maf and see how it acts. It will kick on your cel

 

I would go back and make sure the Coils are securely snapped onto the spark plugs. I saw a similar problem on another TrailBlazer/Envoy forum that is similar and the problem turned out to be one or more coils that did not snap onto the spark plug properly. Gentleman reseated the coils and his TrailBlazer ran like new again.

Good luck!