V6 fuel mileage

[mikeinaus]

40mph eh. ive been cruising in the city at 50kmh (roughly 30mph) in 5th. perhaps i should keep the car in 4th and see how that works.

[MrMazda92]

That's when it starts to bog slightly for me, the other gears are more tolerant of low rpm driving... especially 2nd and 3rd. 1st is just too much of a hassle above 5 mph, since any throttle change results in bucking. 4th likes 1,700+ and 5th bogs under 1,900. That's roughly where my '92 sits, the '93 really doesn't like low rpms.

[mikeinaus]

Vacuum gauge has been ordered. I got a cheap glowshift one. Excited to see what effect it has on my mileage.

[_-Night-Shade-_]

These are strong engines with decent bottom end torque. It won't bog down too much at low speeds in a high gear but if good fuel economy is what you're after then that's not how you get it. One time I was in a rush and accidentally mis-shifted right from 2nd to 5th while going uphill and it was fine, but you'll piss away all your fuel if you do that on a regular basis.

[MrMazda92]

In line with my previous post, the '93 now likes low revs just fine. Idling below 2K helps, she's purring at 800

[mikeinaus]

i just changed my oil with mobile 1 high mileage synthetic, plus i added some clean-flo oil conditioner + i seafoamed the intake. the lifter ticking i was getting before is almost completely gone. my tire pressure was also pretty low at 25 each tire. i filled them to 40psi. does anyone know the correct amount to fill aftermarket tire/rims? my teacher said to fill aftermarket rims to 90% of max psi, but 45psi seems high... im running 205/40/17... hope this should help boost the mileage a bit.

[mitmaks]

having those heavy rims on your car WILL NOT help your mileage.

[mikeinaus]

my rims are like 16lbs... not too heavy

[Nd4SpdSe]

I ran my Konig 17's, ran the max on the tires, 51 up front (Kumho Mx), 45 in the rear (Kumho 712).

[BornSticky]

same ran my konigs with komo esctas at max psi at 44 psi

[mikeinaus]

over the period of my last tank ive changed:
plugs (NGK V Power BKR6E-11)
plug wires
tire pressure from 25psi to 40psi
fixed vacuum leak in intake
installed oil catch can
changed oil with mobil 1 high mileage synthetic + kleenflow oil additve
seafoam (these last 2 got rid of my lifter tick)
fuel filter

driving more aggressive (nothing crazy) then my previous tank i netted (91 octane) 14.46l/100km so its still burning a tun of gas. my vacuum gauge should arrive hopefully sometime this week and i can fine tune my driving style to hopefully eliminate my driving as the cause (assuming i dont know how to drive?). new tank is 89 octane petro gas, i also just raised my idle from 550 to 750 thinking it might be working too hard at such a low speed?

work thats been done in the past 3 months or so includes:
disty cap/rotor
o2 sensors
front wheel bearings
air filter clean/oil

im thinking of trying NGK BKR5E-11's as i read somewhere that they will give better mileage. although thats not really fixing any of my problems, it should run fine with the 6's as thats the standard plug everyone uses? maybe ill try another set of o2's one last time. im also thinking of getting an aftermarket fpr and dialing back the pressure but i dont think this would be the safest idea without a wideband o2 or any way to constantly measure how lean or rich its running? im going to hook the car up to a obd1 scanner at school tomorrow and see if that tells me anything more then the egr code im getting. ill also see if i can try that tool that measures exhaust gas probe thingy (external o2? havnt gotten that far in my program yet)

i just checked #2, #4 and #6 plugs. after 250ish km they have a grey/white tint on the ground strap and the last thread or 2 are black and smell a bit like fuel. looks like i need a hotter plug?

[windofire]

Here the lowest is 87, than 89 for mid and 91 is typical for high octane, with Pioneer with 93 octane and Sonoco with 94.

^
WTF!?
here in denmark we've got shell V power its 99 octane.
and 87 seams stupidly low. lowest i can get is 92.
dunno if theres a difference in octane readings, US vs Europe.?

[mikeinaus]

i know in japan the octane ratings are different (high numbers), you guys are more then likely on the same system as jdm. 97+ is like racing gas in north america.

i ran an exhaust analyzer at school today which confirmed that im running rich. i also did a obd 1 scanner o2 sensor test which said the o2s are running in spec (this test isnt 100% accurate). im hoping to test them with a lab scope at some point. i also checked my timing and its in spec. im kind of running out of ideas of what to check here. im hoping to clean/flow test my injectors at some point and if that doesnt help i guess my last resort is to try a klde airflow/ecu or a different chip.

my vacuum gauge arrived today aswell. idle is smooth/steady a little above -20 which shows a relatively healthy motor from what ive read?

if anyone has any other suggestions on what i should check please let me know. the only things left that i can think of are:
clean/flow test injectors
double check o2s with a lab scope
test fuel pressure regulator
test coolant temp sensor
if and when those check out i think my only option left would be a different ecu/vaf or chip...

[MrMazda92]

The octane ratings do differ from Europe to North America.

Related to the tire pressure, I run mine at the maximum, and always have. In case anybody was wondering, you check the pressure before driving the car for the day. Basically, don't check it when your tires are warmed up from driving for hours, it skews the results drastically.

[Nd4SpdSe]

Related to the tire pressure, I run mine at the maximum, and always have. In case anybody was wondering, you check the pressure before driving the car for the day. Basically, don't check it when your tires are warmed up from driving for hours, it skews the results drastically.

You're suppose to check you're pressure after driving because it'll raise you're tires pressure.