Ok so I have a 85 V6 GT. I'm getting around 18 to 22 MPG. I want to get close to 30. I've replaced the EGR, Spark Plugs, Cap, Rotor, and TPS and fuel filter. Now with that said I drive about 8 miles to work, but I believe the engine is running hotter then the sensor says. Also the fan doesn't come on at the radiator and I'm not sure how to test to find out why it isn't working. I wanted to put hotter plugs in to see if I could get better gas mileage but I really don't want to chase a ghost. Can someone tell me what the avg mpg for this car is? Any advice is good advice at this point. Thanks for the help you guys have never steered me wrong.

You didn't state the transmission in the car. That's going to be one of the largest deterrents in how much MPG you'll be able to top out at and we cannot give a definitive answer. Another issue will be age of the drivetrain, which over time will obviously begin to rob the power output and overall performance of the car - i.e., how many miles does the car have?

You can test the radiator fan by simply turning on the A/C (if the car is equipped with it). The radiator fan is designed to come on when the A/C is activated under normal operation. If it doesn't come on when the A/C is activated, there is another serious issue.

30 MPG from a current 22 MPG is not going to happen unless there is something very wrong with your car and you fix it. A hot motor within normal limits is good for fuel economy because it keeps more heat in the combustion chamber for better gas expansion and force against the piston. Another measure that's sure to improve economy is inflating your tires to max pressure especially if you have any near or in the twentyish psi range. The higher tire pressure reduces rolling resistance.

If you have an auto that is not bad mileage for driving to work 8 miles. Short drives are never going to give good mileage. Hotter plugs will not really help much either could even lead to some ping.
My 85GT with3.4 and 4sp averages around 24 in my 10 mile drive to work with very little stop and go. But on a 50 mile drive on hwy I can get around 30+. Since it's got cold my drive to work is probably down closer to 20 average.
There is probably no way you are ever going to get 30 driving to work if that is what you hope for...
Reminds me I need to check the tire pressure.

[This message has been edited by Dodgerunner (edited 12-03-2011).]

quote Originally posted by yourplayin: Ok so I have a 85 V6 GT. I'm getting around 18 to 22 MPG. I want to get close to 30. I've replaced the EGR, Spark Plugs, Cap, Rotor, and TPS and fuel filter. Now with that said I drive about 8 miles to work, but I believe the engine is running hotter then the sensor says. Also the fan doesn't come on at the radiator and I'm not sure how to test to find out why it isn't working. I wanted to put hotter plugs in to see if I could get better gas mileage but I really don't want to chase a ghost. Can someone tell me what the avg mpg for this car is? Any advice is good advice at this point. Thanks for the help you guys have never steered me wrong.

O2 sensor? use a denso or delco sensor, not bosch or some other cheap brand..

I have a 4spd, I did replace the o2 sensor. Thanks for all the input, but nobody has really answered my question. Oh also I use the highest gas which I believe is 91 octane. I've heard that using the high octane gas requires a higher temp. Anybody know about that?

quote Originally posted by yourplayin: Oh also I use the highest gas which I believe is 91 octane.

Why? All Fiero use 87. See My cave, fuel & knock in general engine section.

Trans gearing has major effect on MPG... cave, gear ratio in trans section
Tire choice has an effect on MPG too...

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(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

No. Simply running hotter plugs that what is proper for your engine won't boost your mileage. It may however damage your engine.

Are your spark plugs fouling out? Or did they look like they were running at the correct temperature range?

quote Originally posted by yourplayin: Oh also I use the highest gas which I believe is 91 octane. I've heard that using the high octane gas requires a higher temp. Anybody know about that?

Premium fuel in a low compression engine intended for regular unleaded will hurt mpg more than it will help. Premium requires higher compression to benefit from it's use so switching back to regular unleaded will result in an immediate mpg improvement in the form of the money you save per gallon.

Switching plugs will only show an improvement if something was wrong with your old ones.
Low MPG can be caused by lost of things and you will need to check them all to track down where your MPG is going

Rolling Resistance - bearings, brakes dragging, alignment, poor tire inflation, excessive tire width...
Engine performance - running w/o missing, good compression, good stock ignition (no worn/cracked plug wires, and clean plugs), working (or not leaking) egr, working sensors: O2, coolant temp, & MAP, correct thermostat (180+), proper fuel pressure, proper engine timing, good exhaust flow (no clogged cat).

quote Originally posted by yourplayin: I'm getting around 18 to 22 MPG. I want to get close to 30 ... I drive about 8 miles to work

That's typical mileage for the kind of drive cycle you describe. Under similar conditions I get about 20-23 mpg in my '88 V6 w/ auto transmission. 30 mpg is probably not achievable for short-trip, in-town driving with this engine and any of the OEM transmissions. Your driving style (i.e. your right foot) also has a big effect on fuel economy.

quote ... fan doesn't come on at the radiator and I'm not sure how to test to find out why it isn't working.

The fan's not supposed to come on under normal driving conditions. The Fiero temperature gauge is notoriously unreliable. If you want to check what's actually going on, hook a scanner or a laptop running WinALDL to the ALDL port. The temperature you see there is from a different sender than the one used by the gauge, and it is the temperature the ECM uses to adjust fuel delivery to the engine.

quote I wanted to put hotter plugs in to see if I could get better gas mileage ...

As others have already said, hotter plugs won't gain you anything if the ones you're currently using are correct for the engine. Hotter plugs may even cause (expensive) problems rather than fixing anything.

Similarly, higher-octane fuel is a waste in an 87-octane engine. Unless you make other changes to the engine tuning, using higher octane fuel may even hurt economy somewhat.

What thermostat are you running? Contrary to popular misconception, the GM-specified 195 degree thermostat is correct for these engines under almost all circumstances. Within reason, a hotter engine correlates with better fuel economy. Are you using the correct 5W30 viscosity motor oil? Even that can have a small effect on mileage, especially in short driving cycles.

[This message has been edited by Marvin McInnis (edited 12-04-2011).]

Short trip or not, I don't see how 30 mpg is possible with a 2.8/muncie. The best I can get out of my 3.4/muncie setup is 28. I suppose maybe a highway trip at 55 mph, or by converting to a 7730 setup.

Check your fuel MPG using 2 tanks of 91, be precise,wtite it down then 2 tanks of 87
use quality fuel for test..
after your trip,check wheels to see if one is hotter than the others
to get MPG out of the 4 speed you have to drive moderately shift at dash shift point if thie still works
to increase you MPG 4 to 5 MPG you have to spend $1000.00 at a minimum
your first choice would be Truelo headers or at least port the stock exhaust manifolds ,, the stock exhaust manifolds are notorious for haveing a blockage manufactured in..I now have the truelo headers not for increase horse power which they do give,but for the small increase in MPG they will give me
you can cut back the electrode on the stock spark plugs,the upper L is cut back so it is centered on the lower electrode ..this works ,,adds HP but is a pain to do
Porting the head will give the best increase,along with precise port match
if you are forced to buy 10% ethanol mix you are climbing deep hill,,ethanol really cuts milage
there are a few places to buy 100% gas this will increase MPG by 10%
many Fiero.s have had the fan temp & thermostat changed becaus the temps the Fiero runs at are scary if the fan does not go on,, you need to be at 180o to 220o to get good MPG
read about hypermiling to achieve better MPG
My car probably gets better MPG than the average Fiero V6 ,,BUT,BUT, I drive less than 5 miles on 95% of my trips ,so my MPG sucks because I have not brought the sensors into play
the 4 speed V6 Fiero has excellent acceleration around town ,it will never get Good MPG with out serious modification,expensive to do.
..The alternative is to use hypermilling techniques,read about this on the net
I am serious about my Fiero ,I will spend many hours & mucho bucks just in case gas is hard to get,,I have lived long enought to see gas lines and gas unavailable,imagine a line of 30 cars waiting to buy gas!!
porting the exhaust manifolds is the best modification to make on a V 6 Fiero,cooler running, more power,cars pull smoothly into high RPM better idle,better acelleration

quote there are a few places to buy 100% gas this will increase MPG by 10%

Not true, using E10 will at most reduce your fuel economy by 2.5%.

In addition to the previous suggestions, the combination of a power pulley and CS alternator should give you a few percentage points in fuel economy, especially on the highway with high RPMs.

.tHE ETHANOL WAR VS GAS WAS FOUGHT IN THE 1990,,eTHANOL IS AN EXPENSIVE BOONDOGGLE ,,ONLY POLITICAL CORRECTNESS KEEPS THIS CRAP GOING ,,YOU ONLY HAVE TO CHECK YOUR mpg WITH 10%,THEN RUN REGULAR gAS YOU WILL BE SURPRISED AT THE INCREASE IN PERFORMANCE WITH STRAIGHT GAS,, ETHANOL SUCKs THE PERFORMANCE LIFE OUT OF A V6

ethanol would be fine when gas is not available..Ethanol cost a lot more to produce than gas
Brazil has been using ethanol for years, oil has been discovered off the coast of Brazil,,they can not wait to dump ethanol
10% ethanol sucks 10 % of your gas MPG ,,you burn more fuel,,actually ethanol adds a lot of cost to the average cost of the cars fuel for the year,,you better do some research on this ,,I did not believe any one still believe what you posted unless they were a green involved in corn to fuel ,, the truth on this has been kept fromthe public ,, there weremany comparo test done ethanol always lost by a large margin,, there is a move to increase the percentage of ethanol in gas MANY,MANY democrats are involved in making profit from this, so worse is comming,,more smoke & tax is comming ,, just like the 134 air conditioning coolant tax fiasco,, that causes us to pay double the price,, more hidden democrat taxes
Ethanol is a hidden tax & liability on the consumer worse is comming people want der gov ment check,,I DESERVE IT..

In Dr. Jacobs book "Performance Ignition Systems", he states that increasing the gap .006" over stock should give "4% increase in gasoline mileage, noticeably smoother operation, no change in power."

quote Originally posted by phonedawgz: No. Simply running hotter plugs that what is proper for your engine won't boost your mileage. It may however damage your engine. Are your spark plugs fouling out? Or did they look like they were running at the correct temperature range?

Indeed, plugs that are too hot you do damage, plugs that too cold will simply foul and misfire. Read your plugs -check them - against the chat he posted.
As others have stated, high obtain in a comp unboosted engine is wasting money. BTW: higher oct numbers doesn't mean the fuel is more powerful, it simply means it is more resistant to detonation, IE lets you run higher comp ratios etc

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trueleo.com
RSpiderII@aol.com

Developing better driving habits might get you better mileage. Rolling up to red lights and waiting for them to turn green is better than making complete stops. Shifting to neutral, and not down shifting when braking also helps. Many small things can add up to better mileage. I believe the term used is hypermiling.

quote Originally posted by RotrexFiero: Shifting to neutral, and not down shifting when braking also helps.

Fuel injected engines have deceleration fuel cut-off (DFCO). When the ECM senses that the car is decelerating with the throttle closed, it will temporarily shut off the fuel injectors. This, of course, uses less fuel than idling.

That said, it's still a good idea to coast for a bit when approaching a stop. Then, when you start getting close, downshift to decelerate.

quote Originally posted by onesexyfiero: Short trip or not, I don't see how 30 mpg is possible with a 2.8/muncie. The best I can get out of my 3.4/muncie setup is 28. I suppose maybe a highway trip at 55 mph, or by converting to a 7730 setup.

yeah, i have a 2.8 muncie that was in very good condition(all sensors tested good and egr was working properly, and no exhaust leaks), interstate road trips i managed a lucky 26 mpg if i drove 65 mph the whole time- thats 5mph under in TN and 10mph in KY.
i did have a problem where the lower shroud for the radiator broke off and coolant fan switch failed at the same time, i ran that 2.8 at 270*F for almost 400 miles. i got 32mpg doing 75mph(after this really hot drive i noticed a exhaust tick- there went the mpg back down to 24mpg at 65 and a measly 15 city)

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1985 gt notchie auto (pic)| 3800 SFI N/A coming soon
1986 se notchie standard 4spd | for sale after 3800 swap

quote Originally posted by uhlanstan: .tHE ETHANOL WAR VS GAS WAS FOUGHT IN THE 1990,,eTHANOL IS AN EXPENSIVE BOONDOGGLE ,,ONLY POLITICAL CORRECTNESS KEEPS THIS CRAP GOING ,,YOU ONLY HAVE TO CHECK YOUR mpg WITH 10%,THEN RUN REGULAR gAS YOU WILL BE SURPRISED AT THE INCREASE IN PERFORMANCE WITH STRAIGHT GAS,, ETHANOL SUCKs THE PERFORMANCE LIFE OUT OF A V6 ethanol would be fine when gas is not available..Ethanol cost a lot more to produce than gas Brazil has been using ethanol for years, oil has been discovered off the coast of Brazil,,they can not wait to dump ethanol 10% ethanol sucks 10 % of your gas MPG ,,you burn more fuel,,actually ethanol adds a lot of cost to the average cost of the cars fuel for the year,,you better do some research on this ,,I did not believe any one still believe what you posted unless they were a green involved in corn to fuel ,, the truth on this has been kept fromthe public ,, there weremany comparo test done ethanol always lost by a large margin,, there is a move to increase the percentage of ethanol in gas MANY,MANY democrats are involved in making profit from this, so worse is comming,,more smoke & tax is comming ,, just like the 134 air conditioning coolant tax fiasco,, that causes us to pay double the price,, more hidden democrat taxes Ethanol is a hidden tax & liability on the consumer worse is comming people want der gov ment check,,I DESERVE IT..

I don't support or like ethanol, but you're saying 10% ethanol reduces fuel economy by 10%. The chemistry just doesn't work. If that was true, ethanol would have zero energy content.

quote Originally posted by BlackGT Codde: yeah, i have a 2.8 muncie that was in very good condition(all sensors tested good and egr was working properly, and no exhaust leaks), interstate road trips i managed a lucky 26 mpg if i drove 65 mph the whole time- thats 5mph under in TN and 10mph in KY. i did have a problem where the lower shroud for the radiator broke off and coolant fan switch failed at the same time, i ran that 2.8 at 270*F for almost 400 miles. i got 32mpg doing 75mph(after this really hot drive i noticed a exhaust tick- there went the mpg back down to 24mpg at 65 and a measly 15 city)

I get about 27 mpg on the highway with the V6/muncie...however, I think I have a 4.10 final drive from the 4-cyl, since my RPM's are over 3000 on the freeway.

With the normal V6 muncie and driving at 60 mph, I think it would be doable to get 30 mpg consistently.

According to http://www.ethanol.org/pdf/...EconomyStudy_001.pdf

E10 yields 1.5% lower gas mileage.

Therefore, E10 = 8.5% less imported oil to fuel gasoline engines.

quote Originally posted by masospaghetti: ... you're saying 10% ethanol reduces fuel economy by 10%. The chemistry just doesn't work. If that was true, ethanol would have zero energy content.

Correct! Ethanol is not just an inert filler ... but don't expect the "arithmetically challenged" to get it.

quote Originally posted by 30+mpg: E10 yields 1.5% lower gas mileage.

That's probably overly optimistic. One source I checked gives an energy density of 116,000 BTU/gal for pure gasoline vs. 112,000 BTU/gal for E10 ... about a 3% difference ... and that is generally consistent with my personal experience in computer-controlled, fuel-injected vehicles. (Other sources list similar values ... e.g. 34.2 MJ/L for gasoline vs. 33.2 MJ/L for E10.) Carbureted vehicles would probably produce poorer results. YMMV. There's truly no substitute for your own data, but remember that the easiest person in the world to fool is yourself.

quote ... E10 = 8.5% less imported oil to fuel gasoline engines.

Incorrect. You (or your source) overlook the energy (much of it derived from fossil fuels) that goes into making ethanol. The most authoritative and unbiased end-to-end studies I've seen indicate that it takes about 70 to 80 BTU of energy input (most of it from fossil fuel sources) for every 100 BTU available from the ethanol produced. That would work out to less than 5% reduction in "imported oil to fuel gasoline engines" when E10 is being used instead of 100% gasoline. Both opponents and proponents of ethanol as a motor fuel need to be scrupulously honest when doing the numbers ... although I don't realistically expect that to happen any time soon.

There are other often-overlooked positive reasons for using E10. As just one example, ethanol is an oxygenated fuel that, when blended with gasoline as E10, can help reduce certain exhaust emissions related to urban air pollution, especially in winter.

Finally, one big down-side to producing ethanol from grain (corn, etc.) that's seldom mentioned, perhaps because it's not generally quantifiable: soil and water depletion. A century from now our descendants may wish that we had conserved more of that precious, irreplaceable farm soil and deep groundwater for future food production.

[This message has been edited by Marvin McInnis (edited 12-05-2011).]

85, 2.8. I use Delco AC-1 RapidFire plugs and average 23 town and 30 mpg highway. I'm happy with that. As others said: premium fuel presents a hazard not a benefit.

quote Therefore, E10 = 8.5% less imported oil to fuel gasoline engines.

Funny we actually export a lot of gas to other countries then...

Yeah I notice a big difference in milage when I use husky fuel vs shell fuel here in canada. I get 6-9 km/L more on shell than the husky fuel that has ethanol in it. On a 900km trip it adds up going a extra 6km/L I know its enviomentally friendly but I dont use husky if a shell is around.

Sorry that I haven't responded. Working 12 hour shifts makes it hard to do any thing. Thanks for the help on this issue. I'm going to try some other techniques before I give up. Does anyone know what kind of injectors will work in the fiero? I was think of going to the wrecking yard and grabbing some off a different car if they will work, I believe any model with vin 9 is that correct?

Any Fiero with VIN #9, yes. But there were other engines that were designated with VIN #9 on other makes and models. Your best bet is to look for an 80's GM vehicle with a 2.8 V6.

One of the biggest factors in fuel economy is the driver. If you haven't already, you might want to check out a couple "hypermiling" websites, and read up on fuel-saving driving techniques.

Also, check your tires' air pressure. If the tire pressure is low, it can have a noticeable impact on fuel economy.

And if I remember correctly, the EPA fuel economy rating for the V6 Fiero is 19 city / 24 highway. Your fuel economy numbers are pretty close to that, which is not bad considering that your Fiero does a lot of short-hop driving.

[This message has been edited by Blacktree (edited 12-06-2011).]