Mechanics

FUEL MILAGE

2002 Pontiac Grand Am

Engine Performance problem
2002 Pontiac Grand Am 4 cyl Front Wheel Drive Automatic 91,500 miles

I just purchased this vehicle from a dealership " as is" after a customary look at it and a test drive. They assured a thorough inspection for safety and performace was completed. My first road trip with the car occured the next morning when I drove about 200 miles on a turnpike as well as about 10 or so miles of city driving. The gas milage for this combo was only about 14 mph. The car is rated at like 23 city and 34 highway. Despite this, the car starts excellent, runs smooth, accelerates what appears to be normally (it is a 2.2 liter 4-cyl), and makes no unusual motor sounds. My concern is with this crappy fuel milage.

I am planning on doing a traditional tune up (replacing the plugs, wires, air filter if needed, and probably coil packs) as a start. I have also looked around the engine for any vacume leaks. There is no water bubbles forming in the cooling system nor overt water in the exhaust pipe.

Do you know if there is some common problem with this engine that would cause poor fuel milage should the tune up fail (i.E. A sensor or something like that)?

I realize its a high milage vehicle, but I don't think thats the exclusive cause for the milage. Any direction I need to start towards would be appreciated.

~ Randy
Avatar
Rwbenner
January 16, 2009.




Hello
Thanks for the donation.

I did not find any TSBs (Technical Service Bulletin) or Recalls on your vehicle for this issue.

Oxygen sensors, EGR valves, catalytic converter. These are a few things that can cause poor fuel mileage. However, when these components start to fail, the computer will detect it and illuminate the check engine light. If the check engine light is not illuminated, I would say a good tune up including fuel filter and cleaning fuel injectors (with bottle of fuel injector cleaner into fuel tank) will raise your MPG a great deal. Also ensure your tires are inflated to the proper PSI. Tire pressure is a big key when it comes to MPG.

Thanks for using 2CarPros. Com!
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Bluelightnin6
Jan 16, 2009.
Thanks for the fast response!

Two real quick questions about the same thing.

Do you know where the fuel filter is mounted? Last time I've ever changed a fuel filter on a car, it was back when they were still mounted inside the frame near the tank. With these newer style cars, I don't know if they are in the tank (which I doubt) - or up near the engine somewhere.

Second, is there anyway to test a coil pack. Or is it just wise to swap it out?

Thanks again! Randy

Tiny
Rwbenner
Jan 16, 2009.
No problem.

Your fuel filter is located below vehicle, in the middle of underbody on fuel rail (pictured below) .


http://www.2carpros.com/forum/automotive_pictures/261618_Noname_146.jpg



Removal and installation procedures are listed below for your fuel filter.


http://www.2carpros.com/forum/automotive_pictures/261618_Noname2_51.jpg



http://www.2carpros.com/forum/automotive_pictures/261618_3_2.jpg



http://www.2carpros.com/forum/automotive_pictures/261618_Noname4_12.jpg



http://www.2carpros.com/forum/automotive_pictures/261618_Noname5_6.jpg



http://www.2carpros.com/forum/automotive_pictures/261618_Noname6_2.jpg



FIGURE 13


http://www.2carpros.com/forum/automotive_pictures/261618_Noname_147.jpg




http://www.2carpros.com/forum/automotive_pictures/261618_spec_2.jpg



http://www.2carpros.com/forum/automotive_pictures/261618_spec2_3.jpg



http://www.2carpros.com/forum/automotive_pictures/261618_sp3_1.jpg



http://www.2carpros.com/forum/automotive_pictures/261618_sp4_1.jpg



You can review the following link for testing your ignition system, including your coil packs.

http://www.2carpros.com/how_to/how_to_test_an_ignition_system.htm

Hope this helps..
Thanks for using 2CarPros.com !

Bluelightnin6
Jan 16, 2009.
Previously, you responded to a query I had about bad gas milage (the below thread will hopefully bring you back up to speed again).

You had asked that I let you know how things went after making the changes you suggested (which I've done). Unfortunately, the fuel milage is still the same (24-25 city OR highway).

In the same vein, I have noticed that at turpike speeds, in overdrive, the car will barely ever drop into (what I call) the " lock-out" or " lock-up" for the tourqe converter (when the tourqe converter locks - much like a standard transmission). You'll occasionally see the RPM dip when it does lock, but it holds it for only seconds. It is not dependent on speed, incline, or head wind. It just fails to lock.

Is not that locking mechanism electronically controlled? If so, I'm thinking about changing that part since the RPM never really drops to a crusing RPM - thus burning more fuel and contributing to poor fuel milage. I just don't know where that sensor/control module is. Could you help with locating it?

Anyway, I was going to change the tranny fluid and filter while there. Figured with 90,000 miles, it would be time to do so.

Looking forward to your reply, and thanks again. I'm sure eventually we'll figure this out : )

Enjoy the day. Randy Benner

Tiny
Rwbenner
Apr 15, 2009.
Hello

The TCC (torque converter control) PWM solenoid is what you are speaking of. It is located in the transaxle valve body, pictured below...


http://www.2carpros.com/forum/automotive_pictures/261618_Noname_456.jpg



Thanks for using 2CarPros.com!

Bluelightnin6
Apr 15, 2009.
Does this solenoid have an external electrical module to control it that mounts to the tranny, or is the whole thing controlled through tranny fluid flow/pressure internally? I used to have a chevy beretta that had an external electrical switch that mounted to the tranny. When it failed, I just replaced it. I was hoping this GM product was similar.

I'm looking for what I can service extenally, without having to remove all the stuff needed to even reach the tranny side cover and pull it off to get to this TCC PWM solenoid.

Thanks again.

Tiny
Rwbenner
Apr 16, 2009.
Below is the wiring diagram for the solenoid I dug up for ya..


http://www.2carpros.com/forum/automotive_pictures/261618_Noname_457.jpg



may need to email to you so you can read it better..what is your email?

Bluelightnin6
Apr 16, 2009.

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