1996 850 Wagon Non-Turbo How to Maximize Gas Mileage?

PeteB · Post by **PeteB** » 20 Mar 2016, 09:54

My son bought his 850 a few years ago, has been putting about 2000 miles
per month on it, and constantly complains about the gas mileage. He knows
about driving very gently, slower the better on the highway and I've given
him literature on hypermiling. I don't think he's going to improve his driving
at all. I wouldn't doubt if he still goes 65 MPH or so when in a hurry. It is
mostly highway miles.

I've also stressed keeping the tires inflated to the max allowable pressure.

We've checked and don't have any issues with brake pad drag - it did in the past.

I'm going to get a used engine splash guard to hopefully make it more aerodynamic,
it was missing when we bought the car.

I just fixed the odometer so that he can finally keep track of his actual mileage.

We were wondering if there are any aerodynamic add ons, or ECU chip upgrades
or anything else that is effective.

We run Valvoline High Mileage dino 10W-30 oil and are considering going to full
synthetic 5W-40 since I've read that this can help a bit and to get down to 2 or 3
oil changes per year.

We know that the engine always starts fine, runs fine and does not give any CEL
codes. I've seen Robert in his videos use some sort of monitor to see more about
how the ECU and engine are running. Is there a preferred model for this to see
lean/rich conditions, etc?
It idles at 1000 RPM which seems a bit high, is this abnormal?

Post by **tryingbe** » 20 Mar 2016, 10:54

Turbo or non turbo? What MPG? Please don't give us miles per tank.

Post by **matthew1** » 20 Mar 2016, 11:01

Stage 0 items are the End All Be All of MPG. Only strange statistical outliers outside of those procedures can account for missing MPG, like a bad wheel hub bearing, or a skipped timing belt tooth.

Post by **oragex** » 20 Mar 2016, 13:21

The things I looked into on my car when the mpg was pretty low, in this order: restricted fuel injector flow (varnish will accumulate at high miles, $15/injector to clean in ultrasonic bath), stuck intake air thermostat if non turbo (Youtube), make sure the intake air duct behind the front grid is in place, stuck engine coolant thermostat, clogged fuel filter, very worn spark plugs.

PeteB · Post by **PeteB** » 20 Mar 2016, 14:34

It has a new coolant thermostat, fuel pump, timing belt that I just put on properly, and new plugs.
The old timing belt had not skipped a tooth.
I've done 3 drain and fills on the transmission, and it has never had any issues, shifts fine.
I will go over the stage 0 list, thanks for that.

I hope to get actual mileage in the next week or so since the odometer is now working.

Beyond mileage, my question is how to confirm that the ECU/engine are operating normally
even though there are no CEL codes.

Then next, if there are any mods to get a few more MPG here and there.

Post by **RussB** » 20 Mar 2016, 14:44

Again, what MPG is the car getting?

Inflating the tires to the max is a bad idea. It gives a crazy harsh ride and lowers traction considerably.

PeteB · Post by **PeteB** » 20 Mar 2016, 14:53

RussB wrote: Inflating the tires to the max is a bad idea. It gives a crazy harsh ride and lowers traction considerably.

I seem to recall all the hypermiling guys suggesting it and reading this probably 20 years ago.
I don't believe it harms traction, but probably does cause slightly uneven wear.

This seems to confirm your claim, at 70 MPH at least but they also point out that the
aerodynamic drag at 70 is the dominating frictional loss so it might be around town, or
at 55 MPH (frictional losses are usually square law with speed IIRC) where you'd see the
most gain and they didn't bother to test that:
http://www.popularmechanics.com/cars/a940/4199963/

They had tires rated for 50 psi and ran them at 45, I think that ours are rated for 42 and
he runs them at 38 which is not crazy high, much better than when they are low at 24.
On the other hand that article also states:
"What's more, we know under-inflated tires have a negative effect on fuel economy. The U.S. Department of Energy says that for every 1-psi drop in pressure, you can expect your gas mileage to lower by 0.4 percent."

Another test done under simulated city driving conditions:
http://ecomodder.com/forum/showthread.p ... 17151.html
MythBusters: Tire Pressure Test : Video : Discovery Channel
TV Review: Mythbusters 8.23 – “MiniMyth Madness” | Fandomania

Control, 35psi (manufacturer recomendation)
tyres at 10psi = 3.7% increase in consumption
tyres at 30psi = 1.2% increase in consumption
tyres at 40psi = 6.2% decrease in consumption
tyres at 60psi = 7.6% decrease in consumption

im amazed that even at 5PSI over recomended pressure there was a 6% increase!!!

test car: 2004-2007 Ford Taurus

PeteB · Post by **PeteB** » 20 Mar 2016, 16:44

Stuck intake air thermostat discussion - thanks oragex:
https://www.matthewsvolvosite.com/forums ... 0&start=10

I have to check this.

PeteB · Post by **PeteB** » 20 Mar 2016, 17:15

Any opinions on the TOAD diagnostic software? It uses the ELM327 cable and
includes the cable at the $127 price:
http://www.totalcardiagnostics.com/toad/

I looked carefully at Robert's videos and I think that he uses Scan Gauge. It
is standalone and small so it can be mounted in the car for permanent use:
http://www.campingworld.com/browse/skus ... gQodukUBAA

Post by **tryingbe** » 20 Mar 2016, 20:02

$127 can roughly buy 1270 miles of gas, assuming $2/gal and 20 mpg. Let's say the device can increase your MPG by 2% (I highly doubt it), it'll take 63,500 miles, just to break even that $127 you spent on the device.

I don't think he's going to improve his driving at all.

Are you paying for this gas? If so, stop it. If not, it's his money.