16 MPG in 93 Q45

[Alcyone]

Hello everyone, for some reason, I'm only getting 16 mpg. I do a combination of highway and city driving. Air filter has been replaced and I keep up with oil changes. Any other ideas? There's also a strong smell of fuel that comes through the heater vents when the car is warming up and the fuel injectors are in need of replacement. Car has 185k on it.

Thanks in advance

[CrimsonQ]

There's also a strong smell of fuel that comes through the heater vents when the car is warming up and the fuel injectors are in need of replacement.

ding ding ding! ;0

[silver2k2]

This is a common problem on the pre 94 G50's and happens on the later ones as well.

Here is set of 7 for a decent price

[goody90q45]

> Fix the gas leak. Best place to start looking is the fuel rail towards the rear. Visuall trace the line looking closely at each connection. As you've already figured out it only leaks when the engine is cold. Use a flashlight and you'll see it dripping. With a little perseverence you'll be able to get to most all the hose clamps to tighten them up.

> Ohm and replace the bad injectors. If #1, #2 or #8 are bad they are very east to replace. Used, rehabbed injectors will work fine unless you're taking the Q out on the race track then you'll want to purchase a new set of 8 at about $175/ea. Go with the $30-$40 injectors for now.

Do these two things and you'll see a big improvement in your gas mileage.

[Raxephon]

This is a common problem on the pre 94 G50's and happens on the later ones as well.

Here is set of 7 for a decent price

Link?

Hello everyone, for some reason, I'm only getting 16 mpg. I do a combination of highway and city driving. Air filter has been replaced and I keep up with oil changes. Any other ideas? There's also a strong smell of fuel that comes through the heater vents when the car is warming up and the fuel injectors are in need of replacement. Car has 185k on it.

You're injector leak is a good place to start, but don't over look the oxygen sensors, knock sensors, sparkplugs, tire pressure, etc.... .

[kdkrone]

Don't forget the gas lines that run over the top of the engine. Mine sprung a leak about 105K miles... There was raw gas pooling on top of the engine...

Ken K

[qsiguy]

Mileage does go down in cold weather by about 5-10% or more if it's really cold. I only get in the 17 mpg range in my '94 so you aren't really getting that bad of mileage. How do you drive? Driving style can also change your mpg by 2-5 mpg, or more, quite easily.

How long do you let your car warm up? You know you are getting 0 mpg while the car is warming up....shouldn't need to warm up for more than a minute or two. Just drive easy until the temp gauge begins to move.

[elwesso]

yeah 16MPG doesnt sound so bad... I would only expect up to 18 in combined driving.... MAX.

[Rex]

yeah 16MPG doesnt sound so bad... I would only expect up to 18 in combined driving.... MAX.

Agreed, and that's not taking E85 into account.

[Raxephon]

yeah 16MPG doesnt sound so bad... I would only expect up to 18 in combined driving.... MAX.

I average 20 MPG mixed driving with mostly city miles, and I have a heavy right foot.

Around 25 HWY if traffic isn't too bad.

And all of that is usually with 1/2 tank of fuel, ~100lbs toolbox, ~100lbs worth of parts in trunk, my 200 lbs, my 110lbs wife, ~100lbs firearms/ammo/paperwork/groceries/etc....

[maxnix]

Around 25 HWY if traffic isn't too bad.

Only way a G50 or even a FGY33 could do that is downhill, with a tailwind, at 55 mph.

Someone's using new math.

[elwesso]

Yeah 25MPG is pretty high.... Thats 450 miles before the low fuel light comes on, and Ive never seen that.... Ive seen 400 before (which is 22) but that was on a level road at 60MPH most the time at 50F with no AC before winter gas.

[Q45tech]

I made 50+ round trips from Tampa to Atl when Q45 was new [3k-30k] , used [70-100k], and very used [200k].............There were 3 redlights between start and stop gas stations 483 miles ....................I could always complete trip on a single tank usually the fuel warning light came on at exactly the same point +- 5.0 miles. Never used AC as it was always mild.

No I didn't wear NASA diapers, stopped every 3 hours for 5-15 minutes.

Florida gas vs Atlanta gas [23.7-24.3 mpg at 70 mph +- 2 mph except for decel and rest stop].

The Q was always warmed up at each start of measured trips.

New fast switching O2 are the item most affect steady highway MPG......tire selection and inflation accurate [zero thrust angle] alignments in the 1 Million revolutions the Q V8 requires to complete the journey

[elwesso]

what mileage are you up to now, tech?

[captainluigi]

96Q 117k miles. 18mpg mixed, 23/24 hwy @ 70/75mph. i use the cruise control always.

[Raxephon]

Only way a G50 or even a FGY33 could do that is downhill, with a tailwind, at 55 mph.

Someone's using new math.

Nope, same old arith-uh-muh-tic they've always taught.

[BadQ45t]

I would love to take ANY Q45 that some claims they get 25mph and see how they really drive it. The FY33 gets better mileage according to the EPA tests which we all know are BS to begin with. If I get 20 I'm VERY happy. 25 in a dream world, sorry but I'm very sceptical that you are getting +2-3 higher than EPA estimates.

[92Q45guy]

16 mpg is about right. I average 18.8. But I do more highway miles then city. About 70/30.

[maxnix]

I would love to take ANY Q45 that some claims they get 25mph and see how they really drive it. The FY33 gets better mileage according to the EPA tests which we all know are BS to begin with. If I get 20 I'm VERY happy. 25 in a dream world, sorry but I'm very sceptical that you are getting +2-3 higher than EPA estimates.

And I will add that a FYG33 is at best 1 MPG better than a G50 driven the same way, same environment, same fuel.

[mfarhan_86]

16 sounds really good i get around 11 mpg on a 99 q45 new spark plugs and airfilter.

[Q45tech]

In cold weather the fuel AF is enriched until the coolant reaches 170F so important to replace thermostats every few [3-4] years to get the fastest possible warmup.

The first 5-10 minutes [warm up period] are never counted on EPA testing plus the ambient is 72F. 2000>1500>650 rpm fast idle can burn a lot of gasoline in 10 minutes.

Describe in detail your crankup, warmup, and drive to work what happens in 15 second increments......................some start cycles probably get 6-9 mpg. in very short drives..............under 10 city miles.

[Q45tech]

In theory a 4.1 engine should get 4.5/4.1 = 9% better MPG however the 4.1 has an INCREASED diff ratio 3.694/3.538= 4.4% to make up for torque loss due to displacement decrease.

Net Net 4.5% better highway MPG for exactly the same speed, which is the 1 MPG higher number reflected by EPA.

The 4.1 should use 9% less gasoline at idle and in stationary warmup, however driven warmup might be almost the same?

Same situation with a G35 the smaller displacement should provide 22% better MPG just on engine alone however diff ratios are even higher so one only nets about a 12% highway improvement.

It takes an approximately equal amount of gasoline per hour to create a warmed up horsepower in a 4,6, or V8.

How many PEAK HP do you want to buy and have in reserve is the key.