Impala Forums banner

1 - 18 of 18 Posts

·
Registered
Joined
·
51 Posts
Discussion Starter · #1 ·
My car has been getting around 400 km to the tank, when it would usually get 500 to 550. What could cause this to happen? I was thinking a hole in the exhaust or a bad air filter.
 

·
LIFETIME HILLBILLY
Joined
·
6,197 Posts
When is the last time you done a tune up? I would clean the throttle body, change plugs, wires, pcv, air filter, fuel filter, oil change and a can of seafoam.
 

·
8th Gen Antagonist
Joined
·
13,660 Posts
Guessing at a bad air filter tells me you haven't bothered to check, come on man. As Scotty asked, when was the last tune up? Last fuel filter? Oil change? Maintenance is key.
 

·
Registered
Joined
·
51 Posts
Discussion Starter · #4 ·
I have no clue the last time the plugs and wires were changed, not the fuel filter. But the air filter was changed in November, and the oil was done 2 weeks ago. Tomorrow I'm going to remove the air box and see if it's dirty, and check and see if it may be a O2 sensor because of the exhaust leak.
 

·
LIFETIME HILLBILLY
Joined
·
6,197 Posts
How long have you owned the car, and how many miles have you put on it? I would defiantly say plugs, wires and a throttle body clean would help with MPGs majorly.If you have no clue when they were changed, change them. As king said maintenance is the key. You don't wanna run strait at an o2 sensor, I had a bad one and it didn't affect my MPGs much. They are not by any means cheap.
 

·
Mr. Handy
Joined
·
6,289 Posts
Def change the fuel filter. Chances are if you can't hear an exhaust leak it's not causing the problem.

Do you have a check engine light on? Are you monitoring engine temps? Do you have heat? Any rough idle or weird shifts? Please explain all issues whether you think they are related or not.

The best thing you can do for your car is to monitor gauges and leave car parked while running and listen for a good amount of time.

Likely a fuel filter, plugs/wires, pcv, dirty intake/egr


^^ Agreed. Figure out what the problem is by getting codes read before replacing more expensive parts. Fuel filters are cheap enough that you can replace on a regular basis with no worry.
 

·
Registered
Joined
·
51 Posts
Discussion Starter · #8 ·
I have owned the car 2 years this August, and put roughly 11,000 km(7000 m) on it since then. My grandparents owned it before I did, and they always had it maintained. I'll have to see when they last had plugs and wires done.
As for symptoms, I feel like it has less power, and gas mileage is also suffering. Other than those two, everything seems to be normal. If doing plugs and wires and Anything else easy to do can be done at my school by myself, where I usually do work to it.
 

·
LIFETIME HILLBILLY
Joined
·
6,197 Posts
Free test, go to an exhaust shop and have them test your cat.
 

·
Registered
Joined
·
62 Posts
maybe check your fuel pressure, smell the exhaust, does it smell like gas? should be like low to mid 40 psi range with key on, pressure should hold steady too, ive seen issues like this, but nonetheless monitor your temp, idle, drivability, if it lags when hitting the gas i'd almost lean towards the fueling, have it tested, otherwise give it a full tune up, usually always helps, pull your spark plugs they should all look the same. all the work ive done on these were all 3.8's tho 2 2003's and a 2004, should be similar tho.
 

·
Registered
Joined
·
51 Posts
Discussion Starter · #12 ·
How do you check fuel pressure? I've noticed my car is starting to run hot, in the middle of the gauge ( Between 60 and 125.) It's never ran that hot before.
 

·
LIFETIME HILLBILLY
Joined
·
6,197 Posts
running hot and Poor mpgs sounds like a clogged cat. Go to an exhaust shop, not a mechanic and have them test the cat. A mechanic isn't gonna have the tool to test the flow of the cat. Its a free test and could save you a lot of money. Running it with a clogged even partially clogged can do serious damage to your engine.
 

·
LIFETIME HILLBILLY
Joined
·
6,197 Posts
Thunderboltperformance.com part # 435225 is a direct replacememt. I got my larger 435250 installed for $57 total. No check engine lights.
 

·
Registered
Joined
·
51 Posts
Discussion Starter · #16 ·
Something else has come up that may be the culprit. One of my friends filled my car up with Supreme gas when I ask them to fill it for me, an I usually run just regular, my AutoMechanics teacher says that might have done it, since I usually use regular I was mixing the two types of fuel. He said it was unlikely but it was something.
 

·
LIFETIME HILLBILLY
Joined
·
6,197 Posts
I would throw that option out the door if its already ran more than that tank through it. That is highly unlikley tho. Maybe if you were tuned for premium like me and ran regular in it like I just done a few weeks ago, but not being tuned for it I doubt you would notice a huge difference in mpgs. Have the cat converter checked. It's a free test and you can walk in without an appointment. Test what is plausible and free before you let them come up with random "possibilities".

Most of the time a run a mix of 89 and 93 with no issues. I have ran 87 and 93 mixed in the past. Have you filled up anymore since the supreme tank?
 

·
Registered
Joined
·
51 Posts
Discussion Starter · #18 ·
I'll check out a muffler shop tomorrow. I've never filled the tank since then, just added $20 here and there, no a lot of gas in Canada. I put $40 in today and it seems to be running slightly better, but I'm still getting it checked none the less
 
1 - 18 of 18 Posts
Top