more fuel economy issues...UPDATE! PROBLEM SOLVED!

[Sean37]

I've already done all the basic stuff you mentioned so it's gotta be something else. I actually even put new gear oil in fairly recently when I swapped rears. But my mileage was never very good, even with the 3.08's I would be lucky to see 250/tank. A radiator flush might help but I did that probably 4-5 months ago too. Clean the radiator? I may just try that. I probably need to get my transmission flushed soon too because I just rolled over to 60,000 miles. I was guessing maybe it was an oxygen sensor, but doesn't it show an SES light when they go bad? I'll try fuel injector cleaner too even though it never seemed to help before.

[oil pan 4]

Do a compression check, You could have a burned valve.
How about the coils, I have herd that the 3.8 coils dont last a real long time.

[ordlord11]

it's hard to believe that anyone is getting over 300 miles per tank. "just my 2 cents" I get about 270 and I always keep my car in top shape ie tune ups are always done on time.

[gt1953]

Yesterday drove to Flagstaff and back on I-40 elevation about 6000 feet temp mid 50's at 85 MPH I got 27.5 MPG. and did not get stopped either.
hmm low mileage you guys get I cannot figger out.

[MississippiMaro]

Oxygen sensors are usually the number one culprit for poor gas mileage. i would pull them and see if they have black soot on them. If they do it means your enigne is running rich and fouling the sensors. A normal o2 sensor will have light gray deposits on it and have consistant voltge readings.

[awesomeame]

i AM running about 50mV rich according to autotap, but would that be enough to only give me a max of 230 miles/tank??

--matt

[lifeguardinme19]

I have had problems from day one with gas milage too. I have 3.08s, an A4, and 180 degree stat. I've tried everything thing you guys have sugested except the oxegen sensor. Doing 75mph on the highway the best mpg I ever got was 25. I have no clue how some of you are getting over 30mpg, some claiming they get 30mpg with cams and stuff yet. My exhaust and intake mods helped a little, but still no wheres near what the car is rated for which is 29mpg highway. I'll have to look into the oxegen sensor in the spring when I pull my car out of storage. I dont think my oxegen sensors will be full of soot because after two 3 months of haveing my new exhaust on, there isn't a hint of soot on the inside of the exhaust tips. So I dont think it's runing rich. I just have no clue at this point.

[ December 22, 2003: Message edited by: lifeguardinme19 ]</p>

[staticpike]

Just so we are clear: numerically higher gears, and thermostats are going to worsen your gas mileage some; MAFT+ tuning will also apply, probably not the extent that some of you are experiencing, but just so you know this if it affects your setups...

That being said, and you've tried everything listed above, it's time to get down to the nuts & bolts of the problem.

If it were me, I'd check my 02's again. Then re-check them, and then have a friend check behind me just to be sure because that would be the most probable culprit. If they go bad, they should show an SES light - but it doesn't mean they will, it all depends on the type of malfunction. But also, with all parts regardless of mileage, don't assume just because it's only got 5 miles on it, it's not broken. Especailly if it's something you can check in a few minutes...

After the 02's, I head for the coil's. Not enough spark would mean that you're not burning all of your fuel. You're 02's should show this, but not taking that for granted, check em anyway. If it turns out you need a replacement, from what I've heard in the past, I'd go with the MSD's over the Accels; but do as you choose. I would not replace with stock unless I had no other choice. Spark controller might also be at fault, but I highly doubt it. You'd most likely get other symptoms such as misfires and such.

After that, it's into the engine you go... Valves and things that I'm not anywhere near qualified to even recommend where to begin... At least not until I learn some more...

[FirebirdHatesRice]

I can remember back when I first got my car that I was getting around 300-350 a tank. This might sound weird, but it seems to me that my fuel economy has been going downhill since I upgraded the intake and exhaust. Those are supposed to increase fuel ecomony, not decrease it.

[awesomeame]

<blockquote>quote:</font><hr>Originally posted by staticpike:
Just so we are clear: numerically higher gears, and thermostats are going to worsen your gas mileage some; MAFT+ tuning will also apply, probably not the extent that some of you are experiencing, but just so you know this if it affects your setups...

That being said, and you've tried everything listed above, it's time to get down to the nuts & bolts of the problem.

If it were me, I'd check my 02's again. Then re-check them, and then have a friend check behind me just to be sure because that would be the most probable culprit. If they go bad, they should show an SES light - but it doesn't mean they will, it all depends on the type of malfunction. But also, with all parts regardless of mileage, don't assume just because it's only got 5 miles on it, it's not broken. Especailly if it's something you can check in a few minutes...

After the 02's, I head for the coil's. Not enough spark would mean that you're not burning all of your fuel. You're 02's should show this, but not taking that for granted, check em anyway. If it turns out you need a replacement, from what I've heard in the past, I'd go with the MSD's over the Accels; but do as you choose. I would not replace with stock unless I had no other choice. Spark controller might also be at fault, but I highly doubt it. You'd most likely get other symptoms such as misfires and such.

After that, it's into the engine you go... Valves and things that I'm not anywhere near qualified to even recommend where to begin... At least not until I learn some more...<hr></blockquote>

is there any way to check o2's other than visual??

--matt

[staticpike]

Is there anyway to check the O2's other than visual... not that I know of now that I think of it. I usually just swap em out with new ones whenever I do something significant. Check around though, somebody might know a way that I'm not familiar with.

awesomeame - I was looking at your profile and thats a fiarly large cam you are sporting. That might be the major culprit of you fuel consumption issues. You might try consulting with others that have installed a cam with similar stats to your's and see what kind of losses they incurred. I bet that GT cam is nice though... :D (can't wait for my cam swap!)

[awesomeame]

i just installed the cam like 2 months ago, hasn't been on the road since the install. my fuel consumption issues are on my stock car.

IF i do actually have something wrong, i'd like to figure out what it is, cause like you said, staticpike, the cam is NOT going to help in the fuel consumption area. the last thing i want is to get less than 200 miles/tank with the cam

--matt

[Cheezebandit]

<blockquote>quote:</font><hr>Originally posted by snatch:
I have a 180* thermo and mileage still blows. Someone mentioned O2 sensors, is their a way to tell when they are going bad, any signs?
Shane

[ December 20, 2003: Message edited by: snatch ]<hr></blockquote>

yep you go to autozone and have them "run a code check " and they will tell you that you need like 3 or 4

[Sean37]

ugh... on my last tank I drove conservatively and got like 204 miles and on my current one I'm only going to make it to 175-180. I've taken care of all the basic things - tire pressure, clean air filter, plugs, wires, used fuel injector cleaner, and also changed the pcv valve. The car runs great as far as performance but gas mileage is as bad or worse than V8 powered cars. I don't wanna sell my V6 but if this keeps up I might get rid of it for a V8 with a stick. My gas mileage is just getting ridiculously bad. My dad says he doesn't know either and to take it to the dealership and have them check it out, but I figured some people on this board know these cars better than the people that work at the dealerships so I'll ask here. What else could it be that is causing my gas mileage to suck?

[ReodDai]

Before my headers I got 300-350 going to work and stuff and 375-450 highway. Lately seems Like I get 200-250 of course it could be because I'm having a hard time not going WOT everywhere.