Gas Mileage....

Justin

Justin

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Mar 31, 2005
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Spokane, Wa
I finally got my air/fuel gauge installed today... I've been waiting to see my AFR to post about my mileage....

I am getting ~9.5 MPG.

Fresh cleaned injectors (440)from RC eng.
New Plugs, new o2 sensor
158 psi compression on all 6 cylinders
plugs look perfect, o2 sensor looks good, even on the lean side

my afr when cruising is 14.7 +/- .3, my afr when under boost is a suprisingly steady 10.5


any ideas why i could be getting such shitty mileage? My dad's 88t got ~30 miles to the gallon... yes, that's right, 30. even with me driving it, and my driving style has not changed...

that engine had ~115,000 when we sold it, mine has 1,250 miles on it....


one other thing is that my idle insists on sitting around 1200... may be irrelevant, may not be, but i thought i'd throw it out there
 
ToyoHabu

ToyoHabu

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Jun 25, 2005
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is it possibly pissing it away? , I had this old Datsun 260 that normally wouldn't leak but discovered on an incline that a breather tube had cracked and when fuel sloshed around it would leak. Or how about this given fuel is so expensive, I had a friend with a diesel rabbit that had been converted to gas engine. He had just fueled it earlier in that day and later that day found it was empty. He had noticed a construction truck at a neighbors house that same day. Later when he went to refuel after cursing about getting 10 gallons to the mile he went to the fueling station and lo and behold that same "Diesel" truck was getting its tank pumped :evil2: the guys who owned the truck had the nerve to glare at my friend. Talk about instant karma
 
Justin

Justin

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Mar 31, 2005
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HAH! That is EXCELLENT! Stupid Fucking Thieves!!!!


Right when I fill up I smell gas for a few miles then it goes away.

I spend 8 hours a day at work, so I would see any leaks ( I park my car right outside the install bay which I am in the entire day ) and my car is locked up at night... Its either always in my sight or locked up so its definatly not getting pumped... I've never seen ANY leaks or smelled anything other than after the first couple miles... that was a thought I had as well so I investigated as well as I could... nothing out of the ordinary.




ToyoHabu said:
is it possibly pissing it away? , I had this old Datsun 260 that normally wouldn't leak but discovered on an incline that a breather tube had cracked and when fuel sloshed around it would leak. Or how about this given fuel is so expensive Also I had a friend that had a diesel rabbit that had been converted to gas engine. he had just fueled it earlier in the day and later it was on empty, He had noticed a construction truck at a neighbors house. later when he went to refuel after cursing about getting 10 gallons to the mile he went to the fueling station and lo and behold that same "Diesel" truck was getting its tank pumped evil2: the guys who owned the truck had the nerve to glare at my friend. Talk about instant karma
Click to expand...
 
C

chandley

mkIII owner
Apr 27, 2006
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SoCal
well if you're idling that high you would be wasting just under twice the gas of normal idle, so that could be it, but I can't see it going that far down.
 
Justin

Justin

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Mar 31, 2005
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Spokane, Wa
Bishop92t said:
Check your Vf at idle and cruise. Check for engine error codes. Can you smell gas in the engine bay, just in the cockpit, etc?
Click to expand...


Just in the cockpit... none in the engine bay.


I'll have to get back to ya on Vf, I have no way to monitor that at the moment.
 
jdub

jdub

Official SM Expert: Motor Oil, Lubricants & Fil
SM Expert
Feb 10, 2006
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Valley of the Sun
You throwing any codes? You want to fix the high idle...there's the trouble shooting flowchart in the TRSM here:

http://www.cygnusx1.net/supra/library/TSRM/fi/FI_018.html

As you can see, there's several potential problems that could cause a high idle...3 of them have to do with fuel that could cause excessive consumption. Get the idle problem fixed and go from there.
 
W

wizard_len

New Member
Feb 27, 2006
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Louisiana
I'm fighting the 1K idle problem right now but still getting 14~15mpg in town driving, so I don't think the high idle is the problem.
 
S

SnowMongoose

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May 20, 2005
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Bellingham, WA
Same boat, less mods...
Newish O2 sensor, not throwing any codes, no gas smell...
experimented with no boost for an entire tank
<didn't even pass 3 grand RPMs>
and ended up getting 14.9 MPG.

Thoughts?
 
Justin

Justin

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Mar 31, 2005
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I still havn't figured out my damn idle either! I am goin gto take my TPS off and double/tripple check its in spec... block off the CSI *just to test*, and anything else that's not nessesary... i want my car to idle like the old 88... flawlessly at 650.

oh, my mpg is still shitty.
 
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