WTF Man? 1/4 tank for 33 miles

Texaswildman · Dec 15, 2009

OK, this can't be good. I am using way too much fuel. For 33 miles (virtually all on cruise (also tried it without cruise another time)) I used a quarter tank of gas. :ohdamn:

I repaired all turbo leaks (had about 5), replaced spark plugs and wires.

Symptoms= idles up and down but only after it warms up.

What do you think? I have no CEL lights on, could it still be a bad 02 sensor? HELP!! :confused:

saechao04 · Dec 15, 2009

Could be still a faulty O2, I just replaced mine even though I wasn't throwing a code, I was running way rich. Also is it 33 miles til your gas light turns on or til its empty? I think the gas light turns on when you have 2 gallons left and also .6 gallons is unusable or something, correct me if I'm wrong people.

LD25Delta9 · Dec 15, 2009

Test/Clean your IAC valve. When that starts going wonky it'll search for idle. Could be something to check into. If it was your o2, it would just idle like crap no matter what. It wouldn't idle up and down. (ECU hunting for proper idle)

Is it a fast up and down or a real slow one? Post some video if you can.

rEclipserGST · Dec 15, 2009

Fuel leak. Gas tank leak or a fuel line is leaking. Check the fuel filter. Check your gas cap. Check your o2 sensor. Scan the car for codes, even if it isn't throwing a CEL.

Colt4G63 also · Dec 15, 2009

I'm just a dumb auto technician, but it sounds to me like a temp sensor issue.

ziggo0 · Dec 15, 2009

Colt4G63 also said:
I'm just a dumb auto technician, but it sounds to me like a temp sensor issue.

Can you explain your reasoning? That sounds to far out there to not have a good reason behind it...I'm curious because I've never owned one of these cars, and I'm about to have mine together (hoping for good/stock mpg).

knochgoon24 · Dec 15, 2009

If you temp sensor is bad, the car will never leave the open loop warmup cycle and will just run rich all the time.

Also, are you going by the gas gauge when you say 1/4 tank? My gas gauge is all but useless.
It doesn't move off the full mark for almost 50 miles,
then it drops 1/4 tank in the next 50,
drops the next 1/4 in 100 miles,
then the next 1/4 tank in 30 miles,
the next 1/4 tank in 30 miles,
then it will go below the E mark, and it takes about 15 miles for the light to come on.
I can drive another 20 miles and at that point, and I still have 2.5 gallons in the tank when I fill it up.

Not the most accurate thing in the world...

Rob10_99 · Dec 15, 2009

Looks like you have a few mods but no logger? If you do have a logger watch the 02 sensor voltage.
IAC wouldn't cause bad gas mileage, at least as bad as he's getting.
Have a volt meter for testing all the other sensors?

Texaswildman · Dec 15, 2009

knochgoon24 said:
If you temp sensor is bad, the car will never leave the open loop warmup cycle and will just run rich all the time.

Also, are you going by the gas gauge when you say 1/4 tank? My gas gauge is all but useless.
It doesn't move off the full mark for almost 50 miles,
then it drops 1/4 tank in the next 50,
drops the next 1/4 in 100 miles,
then the next 1/4 tank in 30 miles,
the next 1/4 tank in 30 miles,
then it will go below the E mark, and it takes about 15 miles for the light to come on.
I can drive another 20 miles and at that point, and I still have 2.5 gallons in the tank when I fill it up.

Not the most accurate thing in the world...

HA! Yeah, that is what I was going by. It drops steadily though. But, you could be right that it likely isn't the best gauge.

Rob10_99 said:
Looks like you have a few mods but no logger? If you do have a logger watch the 02 sensor voltage.
IAC wouldn't cause bad gas mileage, at least as bad as he's getting.
Have a volt meter for testing all the other sensors?

Nope, no logger. I have never gotten a good answer as to what I need for a logger to work. I have read different things about sending off the ECU for a socket and such. Is there a plug and play logger/programmer? I have the Diablo Sport Predator for my Charger R/T and it is easy.
I do have a volt meter. You think start at the temp sensor? Where is it?

Rob10_99 · Dec 15, 2009

There's 4 sensors right under the radiator cap, temp switch for fans, ecu temp sensor, gauge sensor etc, I forget which is which I need to look that up myself because one of my plugs are broken, I'll get whats what up on this thread by tonight if its not done before me =)

river · Dec 15, 2009

Texaswildman said:
HA! Yeah, that is what I was going by. It drops steadily though. But, you could be right that it likely isn't the best gauge.

Nope, no logger. I have never gotten a good answer as to what I need for a logger to work. I have read different things about sending off the ECU for a socket and such. Is there a plug and play logger/programmer? I have the Diablo Sport Predator for my Charger R/T and it is easy.
I do have a volt meter. You think start at the temp sensor? Where is it?

You need a laptop or a palm pilot, logger software, and a cable to connect the computer to your OBD1 port on the car. I have a full setup with PocketLogger on it that I'll sell. PM me for details.

Buurma · Dec 23, 2009

Rob10_99 said:
Looks like you have a few mods but no logger? If you do have a logger watch the 02 sensor voltage.

So what numbers should i be seeing? i'm getting ~0.7 then it drops to 0.0 randomly. gettin just as bad of mileage as texaswildman

jeffo · Dec 23, 2009

Are you getting any CEL's? A bad coolant temperature sensor will usually throw a code.
What about the thermostat? Is it the stock 190* one? Some guys put 170* ones in these cars, and then the ECU never gets out of the warmup mode, and keeps adding enrichment.
A logger is one of the first and best investments you can make in these cars. They are invaluable for diagnosing issues like this. The software is free, all you need is a PDA or laptop and the cable.
Another thing the logger would show you is the fueltrims, which will tell you if the ECU is trying to add or remove fuel. You can also log the O2 sensor voltage. Proper operation of the O2 sensor is that anytime you are in closedloop (idle and light cruising) the O2 voltage should swing back and forth around 0.5 volts several times per second. The higher the rpm the faster it cycles.
Are you sure the car has stock injectors?
There are tons of DSM guys around the Clarksville area, including Curtis who is quite knowledgable. Ask around.

Buurma · Dec 23, 2009

jeffo said:
Are you getting any CEL's? A bad coolant temperature sensor will usually throw a code.
What about the thermostat? Is it the stock 190* one? Some guys put 170* ones in these cars, and then the ECU never gets out of the warmup mode, and keeps adding enrichment.
A logger is one of the first and best investments you can make in these cars. They are invaluable for diagnosing issues like this. The software is free, all you need is a PDA or laptop and the cable.
Another thing the logger would show you is the fueltrims, which will tell you if the ECU is trying to add or remove fuel. You can also log the O2 sensor voltage. Proper operation of the O2 sensor is that anytime you are in closedloop (idle and light cruising) the O2 voltage should swing back and forth around 0.5 volts several times per second. The higher the rpm the faster it cycles.
Are you sure the car has stock injectors?
There are tons of DSM guys around the Clarksville area, including Curtis who is quite knowledgable. Ask around.

No CEL and i have a pocketlogger :hellyeah:

Fuel trims are from 80-95

car runs right at 199 all day, and o2 sensor says voltage but it shows 0 several times a second if i'm WOT

DSM1G90 · Dec 24, 2009

What's your coolant temp gauge reading? If you got a stuck open or running with out T-stat, colder coolant will also send things into an open loop causing you to run rich as well.

Are you playing with larger injectors on a stock ECU? That'll eat up fuel as well.

-DSM

tim4g63fast · Dec 24, 2009

I have seen guys hunt down these problems before and all it turned out to be was bad injector seals.. make sure nothing is leaking form them... I have seen a lot of people replace a lot of stuff before they ever figured out that fuel was puking down the back side of their engine.

Mr4G · Dec 24, 2009

Could also be something to do with your maf sensor or ecu could be bad. if the ecu is messed up it may not send a check engine light.

420sx · Dec 24, 2009

rEclipserGST said:
Fuel leak. Gas tank leak or a fuel line is leaking. Check the fuel filter. Check your gas cap. Check your o2 sensor. Scan the car for codes, even if it isn't throwing a CEL.

I agree with a leak. 1/4 tank in 33 miles is what, 8-10mpg? If youre running that rich, the car would be almost undriveable.

kawgomoo · Oct 5, 2010

i dont know but you better change your oil....Gas washes the lubricating coating off every part in the motor.

If you are runnin that rich, then you are definately washing down the cylinder walls and diluting your oil with gas.

Change the oil NOW!! then proceed to diagnose it. After its fixed change the oil again.

Possibly a leaking injector constantly dripping fuel into the cylinder. Pull the plugs and look down in the holes to see if any piston has a puddle of fuel on top. or if one hole is just really really clean.

When my coolant temp wire broke my car was almost too rich to drive. Much like yours.

However i run aem, and no idea how much authority the stock ecu has when the CTS craps out. This table is yet to be tuned in my aem so it clearly has WAY too much authority.

Swoopkev · Oct 5, 2010

Don't to everything people say. Including me.
You need to FIRST make sure you aren't leaking gas anywhere, because that makes fires, fires hurt DSMs.
Second, if your burning that much fuel its going to show out your tailpipe...
Also not a bad idea to pull out your dipstick and smell the oil. if it smells like gas then you need to change the oil. that could mean more than one thing, although that can be a warning sign that you got way to much gas going into your cylinders...

Another diagnostic thing you can do is check the spark plugs, what do they look like?
http://www.aa1car.com/library/reading_spark_plugs.jpg

idoke1 · Oct 6, 2010

You got a fuel leak somewhere. Check your fuel injectors. I had something similar to your situation and found that my fuel injectors were not on tight enough. You'll notice it after you pull over and pop the hood.

idoke1 · Oct 6, 2010

You got a fuel leak somewhere. Check your fuel injectors. I had something similar to your situation and found that my fuel injectors were not on tight enough. You'll notice it after you pull over and pop the hood.

arowell9 · Oct 6, 2010

i have the same problem man, idk what it is. i average 12MPG

chenk18 · Oct 7, 2010

kawgomoo said:
Change the oil NOW!! then proceed to diagnose it. After its fixed change the oil again.

I hope he changed his oil by now, too. What would that be, like 10 or 11 months?

Swoopkev · Oct 7, 2010

chenk18 said:
I hope he changed his oil by now, too. What would that be, like 10 or 11 months?

Nice... never caught that for some reason... HAHAHa

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WTF Man? 1/4 tank for 33 miles

Texaswildman

saechao04

LD25Delta9

rEclipserGST

Colt4G63 also

ziggo0

knochgoon24

Rob10_99

Texaswildman

Rob10_99

river

Buurma

jeffo

Buurma

DSM1G90

tim4g63fast

Mr4G

420sx

kawgomoo

Swoopkev

idoke1

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