Gas mileage?

Berda · 03-16-2006

Hello,

Car is a '91 Talon AWD.

I need help with my gas mileage. Most recently I got 60 miles out of a half tank (8 Gal) which equals about 7.5 MPG. Ouch. LSE said the o2 sens wasnt reading 100%. Brakes are NOT stuck. Yes it does need an alignment/balance. Tires are inflated correctly. And no its not because I'm a lead foot

. Without flooring it once i got 200 miles on the first tank. Now im down to 60 miles for 1/2 tank. When driving for mileage, I always try to use the turbo as little as possible but I just cant figure out why I am getting such crappy mileage. Please help with any suggestions before I go bankrupt lol. Thanks.

**Kracka** · 03-16-2006

Moderate acceleration yields the best gas mileage, not granny acceleration. Are you basing these figures off of what it actually takes to fill the tank or from the gas gauge readings? If gas gauge readings, they are known to be VERY inaccurate.

s1ngletracker · 03-16-2006

true... something is hugely wrong, you shoudlnt be actually getting that kind of mileage. alignment and tire inflation wont make that big of a difference.

94talonawd · 03-16-2006

maybe you have a fuel leak somewhere...

**JET** · 03-16-2006

Go off a full tank once. Partial tank readings can be way off, like Hughes said.

Berda · 03-16-2006

Ok, few things i forgot to mention in the first post because i was in a hurry before work lol: the car is completely stock other than the clutch which wouldnt matter, i just had almost 2000$ worth of enginework done by LSE, which is when Josh told me the o2 wasnt reading correctly, and thats all i can think of for now.

S2kracka - I try to accel with the factory boost guage reading "0" so niether boosting, or vac

94talon - haha yeah I wish it was that simple. As far as i can tell there are no leaks in the fuel sys but the garage floor is wet and it would be hard to find, however i do not smell gas when around the car.

Jet - Yeah i did that 3 times. After I got out of LSE with my new clutch(the first time heh) i was on the "break in" period so i figured hey since i cant beat on it and have fun anyway, i might as well see what i can get for max MPG. All 3 times I got around 200 miles to a tank (running it from full down to the gas light) i thought the guage could be messed up but when i went to fill up again, i payed around 35 bucks for like 15 gals around that or somethin, so therefor i knew the guage was correct.

My next step...
I found out my o2 sens is under a recall so called chrysler and scheduled an appt for a new one, had to argue "once a recall, always a recall" with the older technician in the service debt there

because apparently they just installed a new o2 in 2004 so he thinks it should be just fine. Whatever. Dealer is ordering the part and the appt is for this tues so we will see how it goes. Who knows how good of quality this "new" OEM o2 sens is gonna be. So as for now im stuck with shit gas mileage and just have to suck it up and pay, but hey guys thanks for the help/suggestions so far keep em coming it is greatly appreciated.

-Adam

unreal808 · 03-16-2006

Dirty or clogged air filter,
Incorrect ignition timing,
Dirty or clogged fuel injector,
Idle too high,
Maybe you MAF is on its way out,
Faulty ECM,
Faulty coolent senser,
I dont know maybe you have a damaged turbo.

94talonawd · 03-17-2006

The 02 sensor isnt going to affect gas mileage much. My 02 went out for a while, and I didnt even notice any change in Gas mileage. Check for any vacuum leaks and boost leaks. And the other thing you should do is get a pocket logger and see if your car is running ok. There could be many factors involving poor gas mileage. Check your base ignition timing. Also check to see if timing gears are aligned correctly. I would also check your manifold, it might be cracked. Also check your turbo, it might have gotten fucked up on you. Check the wastegate on the turbo to see if it isnt stuck since you arent reading any boost. I would also check the emmission lines for vacuum leaks.

Again, I am not too sure if the ones stated above would solve your problem. But atleast, this is what I would do to check.

I hope this gives you somewhere to start, and good luck.

acidrumz · 03-17-2006

If you have access to a datalogger that would help you out. if you have one on hand, chk the fuel trims. see if your ecu is in closed loop mode or open loop. the datalogger and tell you if your o2 sensor is out or not.
from there you can adjust according to a s-afc if you have one to get the right fuel trims.
timing will also play a good role in the adjustments of your fuel trims too. it will be good to chk to see if you have the correct timing.

gluck
yy

Berda · 03-21-2006

Hey guys sorry I havent responded in a few days because ive been so busy. Anyway I go in tommorow to chysler for the o2, so they can scan the car and see if its bad, and in the meantime ive been keeping track of the mileage on paper like jet had suggested earlier. Another post that ive been meaning to write is about a knocking question. The car is having fuel issues which are most likely having something to do with the car's knock issues. Anyway for now im just going to try and check this post every day and reply with comments on everyones suggestions *time permitting*. Thanks again to everyone who is helping me out your suggestions are awesome!!

unreal808 - some of those ive tryed and some i havent. So I will try/check all of the things then get back to u. For now, I know for a fact that my K&N filter that came on the car needs replacing, but sheesh those things are expensive, so I might just buy a fram filter for cheaper for now. Anyone know where to get cheap K&N filters? or knock off equivalents? I ran a bottle of Sea Foam in the tank too to see if it would clean up some stuff but havent noticed to much.

94talonawd -
1.now that u say that i see that ur right the o2 sens wouldnt make that big of a diff. Now i want to check ALL sensors to see which one(s) need replacing, but how would i go about doing that? Datalogger? Scan my car (its a 91 so it has OBD1 tho)?

2.Now that u mention it about the scanning, also the car came with a wierd ass port i can plug some sort of machine into. I had LSE look at it and they didnt know off hand. Sometime i am going to make another post with pics of it and follow the lines to see where they go.

3.Yes my Exhaust manifold is cracked in the norm place for 1g but i didnt think that affected gas mileage? Or did u mean a crack in the intake manni?

4.Im gonna do a boost leak test and i already did a vacuum guage test at school in autos class, but it was my first time and from what i could see my engine scored pretty good as far as vac.

5. Ignition base timing im not familiar with, but will do my research on that.

6. Last time i checked the turbo (14b) was in excellent condition.

7.Emissions. Dont know much about it and was going to remove all teh crap (dsm free mods) that you dont need but i will look into it.

8.Wastegate. Thats a good idea and i will do that ASAP. Is there any way to grease it if its stuck or not sliding as well as it should be? Im not to familiar with wastegates and stuff im still learning haha.

Acidrumz - Im workin on the datalogger situation (see above response to 94talonAWD). Im not sure what fuel trims are, maybe u could explain a bit more. send me a pm or somethin doesnt matter. As far as the ecu dont know much about that either other that it IS an EPROM and the caps are good on it. o2 sens is bad supposedly (see above posts). Car is totally stock so i really dont have a way of tuning yet.

To everyone *updates/questions/comments*

*Timing should all be set perf because i just got it back from LSE and they timed it.

*Today My friend made a good comment about how my stock boost controller could be messed up and thats why I am knocking (it may be setting itself to like 20 psi or something that my stock car cant handle lol), but could that have anything to do with the fuel probs?

*All information yall have givin so far has helped so once again just want to thank you guys. Dont be afraid to PM me with specific info/comments/questions.

thanks again,

-Adam

joesushi · 03-21-2006

I'm the guy who thinks his boost may be altered. His car knocks regularly....yet its completely stock. And its a LITTLE too quick for a stock tsi

I think adam should spend some money and get a BOOST GAUGE and a DATA LOGGER. We can get a lot of valuable information from those two that can be added to this post to help figure this out.