IanB2

Have you checked to ensure you don't have a seized caliper or something like that? Ebrake stuck on? If you put it up on 4 jackstands, transmission in neutral, can you spin the tires by hand fairly easily?

Robclzr

I forgot to mention that I have replaced all 4 brake calipers and rotors as well about 1 year ago

MrJason

I if all of your statements are accurate... I’d lean towards clogged cats. They can be partially clogged. You’ll know by pickup.... does the GX have the power it used to?

Also. When you changed the calipers? Did you live the slide pins? And has the parking brake wheel cylinders been adjusted? I’d think you’ve also replaced the rotors if you went as far to replace the calipers.
Also check for heat radiating from the wheel area after a few miles... anything dragging is going to produce a lot of heat(don’t actually touch the components).


I didnt realize the i4 models had the older style 4.7.... I’d check timing for sure. If the timing is retarded by one tooth.. your mileage is going to drop severely.

Can you get the car scanned? See if the torque converter is stuck in lockup? You need a scanner that can read the main modules.. not just the ecm...or check for the code “requirement lamp on” in the ecm.

Matsui

Is there a way to clean the clogged cats? I'm getting all 4 O2 sensors replaced this weekend and hoping that would improve my gas mileage. I got codes P0136, P0138 and P2195. Can the mechanic check for clogged cats and do something to clean it?

MrJason

The only way to clean the cats is heat.. and you run a fine line of melting the mesh that way.

Id just check the mesh in the cats with a bore scope to see if that’s the culprit.

I’d do that before replacing the o2 sensors.

But it does the vehicle feel like it lacks power??

Also... have you checked the timing marks to see if the cams are in proper time?

MrJason

After looking through allData with those codes... it appears that it is your o2 sensors... although I’ve seen failed drivers in the ecm cause the same issue.

Ill keep my my fingers crossed that the o2’s correct your issue.

oardila99

Flooring it a lot doesn’t really vary the mpg much
I have an ‘03 with about 196k miles and I drive it VERY HARD ever since I bought it. I love how the truck drives so I floor it all the time and I seldomly slow down for speed bumps, potholes, floods, etc. I drive it like a tank and nothing has ever failed other than normal stuff. I replaced the cv axels, and now at 196k all of the brake calipers have been replaced (likely due to negligence at changing brake pads on time). I also replaced the rear air shocks at around 180k mi. Nothing has ever gone wrong with tranny or engine (timing belt never replaced).
When I first bought it many years back I was overwhelmed with fuel consumption so I drove it like a grandma for a few months. Then I started stepping on it and didn’t notice much difference in fuel consumption!!! She actually seemed to like a rather strong foot. So I drive it very very hard ever since. I get 14mpg in the city and about 16-18mpg in the highway at around 80mph consistently whether driven hard or not. No difference.

Drive it hard and enjoy ! She likes it!


OA

Robclzr

Thanks for the info.
I did a trip to Florida from NJ and I was driving very carefully I never when over 70mph and I started getting much better MPGs the best I got was 18mpg and was super happy but as soon as I started driving back in city dropped to only 8.5mpg and is killing me.
I’m not sure what is causing such several drop on the MPGs since I have done all possible services.
I will appreciate if anyone have any idea of why the truck is doing this.

thanks.
rob.

Robclzr

Hi,
thanks for the info.
I had replaced the 02 sensors in July last year I replaced all four.
do you think that those O2 sensors are bad already?
I ask since I got the OEM replacement and not a after market type.
please advise

thanks

rob

Robclzr

Hi there
I don’t feel the truck with lack of power and I had replaced the timing belt about 16k miles ago
about the Cats Truck still has the originals.
I’m not sure how to check if still good.

thanks.

rob

captainva

iTrader: (1)

Since no one has asked, when you drive in the city how long are your trips? If you only ever drive it when the engine is cold you're going to get really bad mileage on any vehicle.

MrJason

I agree.. I didn’t realize you primarily drove in city traffic. You’ll be lucky to average 10mpg in stop and go traffic. The GX seems to gobble gas at idle too.

Also so if the rear a/c is always on... you’ll get a drop in mileage too.

shakazulu

I stopped hand calculating because it was depressing, but my daily driving involves 5 to 10 short trips, none more than about 20 minutes and mostly in the city. It's not uncommon for me to average 12 mpg for a tank. When driven normally, I usually just make the 14/18 numbers that the EPA posts, efficiency starts to fall off a cliff again above about 75 mph I've noticed. The V8 will definitely drink some fuel in stop and go traffic.

Robclzr

Hi,
my drives are in the city short trips around town and I do get it that stop and go drive will impact on the MPGs before it just to do 12mpg city driving but now dropped to 8mpgs and after all Maintenance done it doesn’t seem to change nothing at all.

jprlexusgx

have you tried using seafoam to clean the internals? Also, try a full can on a 3/4 tank.

I know you mentioned cleaning the MAFS but I would suggest buying a new one. It happened to me when I had the FJ that the MAFS was halfway bad and miles started to plunge before I finally got a check engine light. Bought a new one, disconnected the battery for 30 min and miles went back up.