Does removing the smog pump affect your gas mileage?

 

Might help a little for a while...

However, the smop pump mainly provides extra air to the cats so they can light off quicker and burn more effiecently when the car is cold. In many cases the cats eventually fail because the car is richer at start up than it should be when the smog pump is disabled. The smog pump helps povide air to help the cats light off. Slower light off can accelrate cloggig and/or cat failure.

 

I have my smog pump, my cat on and I pulled 28 mpg on my latest trip today coming from camping...

 

My A.I.R. and Smog pump is gone. Gas mileage is above.

 

You know, i have been reading around and from my own somewhat limited experiences so far this is what i have found. GM wanted to make availible a reasonably fuel efficient, affordible, reliable (its a gm small block that was already going to happen), and reasonibly powerful (although more is always better) V8 for those that wanted a bit more punch, but didn't want the gas bills of the TPI units. You know what? They succeeded. Granted there are now better and more powerful engines that do all of the above, but our engines are anywere from 11-15 years old and have early smog equipment which is notoriose for being poorly designed and implemented. So the LO3 doesn't have the power that a tpi has, whoopy doo, its still a pretty amazing engine in its own right.

 

GM succeeded in their designs back then in my opinion. A fuel efficient V8 engine is nothing short of a miracle, and on top of that it was designed back in 88... There is a middle of the road here... its the lo3...

 

Well its 3:40 I'm leaveing for the upper peninsula of michigan in 20 min. 495 miles of open road. Yeah right more like 495 miles of road construction or so I hear. I wonder what kind of mileage i'l get. I'll post it when I get home sunday night.Alright lets go 9 hours of driving. WOOHOO!

 

Hey man, I didn't know ur were in Michigan. Good luck driving and watch out for those deer!!!

 

I,m back. *** thats a long drive. Well I got 24.5 on the way up And 26.5 on the way back Cruise set at 75 MPH most of the way.
91bird305 thanks for the advice, I tend to be a little cautious of deer. One wrecked my 92 Firebird a couple years back. Oh, I'm not in Michigan though I'm in the South Suburbs of Chicago. I was just going up to seee a friends wedding. Anyway thats pretty decent gas mileage, but you all seem to be getting better than that what gives.

 

Are there any mods to help gas mileage besides taking off the cat and AIR system.....I live in the city so i'm constantly getting 15-17 mpg.....

When i lived in Iowa, 13 miles after i got my car, yes the first day i got it.....driving it home.......then BAM.....damn deer out of nowhere.....

 

Just calculated my MPG (mostly highway miles at 75 mph and 2200 RPMs)... out of a full tank I used 13.8 gallons for a total of 406 miles. That comes to about 29.4 mpg which is an improvement over my previous best of 28.5 mpg. The only things I've really done since the previous best are new plugs, advanced base timing to 4* BTDC, oil change, and "flow enhanced" my cat. Not too shabby for a 10 yr. old 305 with 120K miles on it! I'm sure it could have seen 30.0 - 30.5 mpg if I had only been a little more restrained with the lead foot and/or had made multiple fill-ups along the way to avoid the extra weight.

 

I really wouldn't call a bone stock lo3 real efficeint motor. Until I did some basic mods like exhaust and intake I didn't really get very good milage. Now that Ive gotten rid of a couple crappy stock parts including the cat now im getting much better milage.

 

For mpg a bone stock LO3 is pretty efficeint. Bone stock my car got 29.5 mpg back when it only had 11,000 miles on it.

A lot of newer (& smaller) engines get similar MPG. My mom's 00 Lexus has more hp is a V6 but it gets about the same MPG as my RS. Seems like to me GM did an excellent job considering the LO3 is 80's tech and it's MPG results can equal state of the art engine.


My cars mods are 160 stat, straight wired fan, Bosch +4 plugs, Dynomax cat back, other wise stock or stock replacement parts.

MPG issues are usually either driver or preventive maintance related ie needs plugs, filters, new wires, coil, alignment, tire pressure, etc a lot of the time.

 

hey guys


when i first got my car it was bone stock down to the paper filter. It had 140k on it. Right after i got it i took a trip to bristol TENN. I checked the mileage their and back i averaged 28.2, i got a little better mileage than my buddies 4 banger s10. he got around 27. But since then i have gutted the cat, and put in a K/n filter in the stock housing ( open air cleaner's rob power! why cause of engine heat is being pulled in!) and i hhave put in a fresh set of plugs one step cooler since it has age on it ind a 180 thermostat ( why you ask 180. well the ecm uses the coolant temp along with o2 sensor to get it in closed loop. if it does not get up to operating temps the ecm thinks it is in cold run all the time and makes the motor run rich and in turn hurts mileage and washes the rings down and such). other than that it is stock lo3 with now 149k on it. and i'm getting reeady to make that same trip to bristol again so i'm going to check my mileage to see if i have gained anything from my mods.


ALSO guys what is the bennefits of using the msd coils. since my car seems to run well on the stock one

as far as calling the lo3 a efficient motor for MPG yes for real power no

 

lol, tim is gonna kill me for this one but...

do you really want hot air being sucked in? no. do you actually want to be able to suck in air? yes. please sir tell me why so many cars, not just third gens and not just chevys, use an open element air filter? did you buy a nondrop 14x3 and use that? maybe you did, but im guessing not. IMO you should try that, you might just find out what you are missing. also are you telling me that when you look at the stock air filter housing you say to yourself, "hey thats large enough to flow plenty of air" i think not. i have tried both setups on my car. i do know what im talking about. if you honestly think there is more power to be had in a stock setup with a little k&n over an open element with a 14x3 or 14x4 filter your on crack.

 

well dude i'm not calling you out. But i put a open air cleaner on my 88 305 tbi. The only advantage that i seen for it to make was it did in fact make a bunch of noise LOL. But as far as using the butt dyno i could not tell any diffrence in the way it pulls. So thats why i opted to go with the stock housing route. Also i forgot to mention that i removed the choke stove pipe and blocked it off and removed the flap. But if your really serious about it. Give me some dyno sheets showing where it makes more power.

 

TTT

Hehe, I'm all about some old posts lately aren't I? ANyhow, just thought I'd let all of you know that I beat my best previous MPG yesterday. How I did it I'll never know. I filled up thursday before it started snowing here and put about 200lbs. of "ballast" in the back for driving around in the snow (I know it sux to have her out in the snow, but when you gotta go to work you have to do something). So I drove around town Thursday, Friday, Saturday, and Sunday with all this extra weight (including a good 15 minutes of doughnuts in a parking lot) and then yesterday took out the extra weight and drove my girlfriend back to JMU for a total of 374.5 miles on 12.06 gallons of 93 octane. That comes to 31.1mpg!!! SOmething could be seriously wrong here though... With all the warming up and doughnuts and extra weight I should have been WAY down from my previous best which was just 406 miles to and fro, no stopping and no city driving. This could be signaling a lean condition, but I should have WinALDL up and running in the next week so I'll have to check it out then.

Has anyone else gotten better mpg in cold weather than in warm?

 

my gas guage doesnt even work so i'm estimating around 12 and i fill up around every 150 miles

 

You don't need the gauge to be working. Just reset the trip odometer when you fill up, then record what it is and how much you have to put in next time. That's x miles divided by gallons = mpg.
Highway for me just doesn't want to change for the better. I've been stuck at 24mpg for a while now and I think it's the safe limit so long as I'm using the open element. If I restrict the intake (like an LS1) I'm sure I could improve it by a couple more especially city. Oh yeah, that's with the 330ho motor, 2800stall tc (lockup), 3.73 gears and 26" tall tires, crusing around 2800rpm. Gears are just killing my highway milage, city has been improved.

 

I'm still amazed with the 31mpg... the only thing I've changed is I'm running synthetic blend in my tranny and about 1/2 a quart of Lucas stabalizer in the oil (50% more than last time). I still don't think that could have given me 31mpg THis is driving me nuts! That's a full 2.5 mpg better than last time. It just doesn't make sense when everything is factored in! Argh! I've got to build a new WinALDL cable before I go crazy. Even the new Civic SI (Slow Import ) only gets 30 mpg hiwy.

 

something has got to be wrong lol

 

I ran a 60 mile journey at about 21 MPG (only do about 3000 miles total each year), but I didn't think that was a "man enough" mpg figure, so I told my friends it does 12 mpg tops! I'm being serious.

 

Man these things don't like extreme cold though. Its been down at below or just at about 0*F and got about 6mpg because of my short drive times and long warmup times (sat there for 30 minutes and didn't come off the cold peg, even with the stock air box and 195* t-stat). Runs like a bat outta hell though once its warmed a bit.

 

I drive my car mostly city. Chicago is very snowy right now and the temperatures are a little lower than10F (-20C). 8-12 MPG city (I rarely use overdrive in city). Around 20 MPG highway if I am lucky.. If I drive 80-100mph all the way it comes to around 16-18MPG..

Smells like fuel when started. "Mods" are in the sig. EGR is not working right. Vacuum trouble.

Anyway, do you guys calculate the error in your speedo caused by higher gears? What looks like 100 miles on odometer is actually only 80 miles if you switched from 2.73 to 3.42 ...

 

Kay well this has been great to read sence my 91 bird with a L03 is going on the road in a few weeks, also, my 3.1 only gets about 19 mpg in the city....

And for great mpg's try getting around 120 or 130, and let the torque converter lock up.. it'll cost u to get there, but going 130 and taching at like 1500 is a beautiful sight....

 

I thought 31 mpg might have been a fluke, so I did some more calculating today after a new tank of gas...

NEW BEST MPG (this is scaring me now) 362.4 miles on 10.7 gallons = 33.8 mpg!!!

Something is definitly wrong here. I should have my WinALDL cable repaired by tomorrow, I'm just hoping that I can figure this one out. The first thing that comes to mind though is *gasp* fuel pump. I have GOT to be lean... I have never seen anyone run those kind of mpg figures and it just seems to keep getting worse.

 

what type of driving is that

 

About 260 miles of that was hiway the other 100 or so was city. Mods are in sig, nothing big so far, but I've got lots coming soon with my tax return...

 

Hmmm.. might be the upgraded ignition and higher-than-stock gap --- .040 is pretty high -- might be more fuel efficient? I am pretty curious to see your BLMs and INTs after your WinALDL cable comes back.. Maybe O2 got worn so the CPU thinks it's running close to 14:1 (or whatever) when it's actually really lean.

I am about to do an ignition upgrade myself so this could be a real motivator, I'll feel better rationalizing my spending spree (you see, it pays off because of better mileage and that's what owning a muscle car is all about, right, right? ) For real, I wouldn't mind a couple of extra mpg and a little less carbon in the chambers...