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 Post subject: Fuel Economy Mod
PostPosted: Thu Aug 27, 2009 3:05 pm 
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Joined: Fri Aug 21, 2009 3:07 pm
Posts: 56
Location: Sacramento CA
I have pretty extensive car and truck knowledge, just need your take on this mod for better economy.

On the OBD1 controlled Metros (3cyl), people have used a rheostat and boost switch in the Air Temp Sensor input to ECU to trick it COLD and signal more fuel.

Could we install just a rheostat in parallel to the output and ground where it would trick the ECU thinking it was HOTTER and lower the fuel being sent out.

Rheostats are adjustable resistor for those unfamaliar to them, so running the wires inside cab to adjust this, would be easy and simple. Like a budget tuner module.

_________________
"If it doesnt fit, use a bigger hammer"
"Cheaper, Faster, Better, Pick Any Two"
http://actfast1234.wix.com/itsmycar

- 89 Daihatsu Charade CLX 1.0L MPFI 3cyl 5spd (*SOLD*)
- 01 VW Beetle GLS 1.8L Turbo (*SOLD*)
- 63 Datsun NL320 Sport Truck 4x4 (Converted by Me & Son)
- 04 GMC Yukon (Fam Hauler)
- 92 Suzuki JR50 (Fun Tiny Dirt Bike)
- 84 Dodge B350 Royal High-Top Van (Heavy Item Hauler)
- 92/94 Geo Metro's (Rebuilt & Sold)


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 Post subject: Re: Fuel Economy Mod
PostPosted: Thu Aug 27, 2009 10:40 pm 
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Joined: Wed Sep 15, 2004 3:58 pm
Posts: 246
Location: The Arctic
My thought was to mount my IAT inside the cabin of my car so it would read warmer air temps. Might try it since I do live in one of the coldest places on Earth

_________________
1993 GEO METRO 1.0 lsi (xfi swap)
1995 Eddie Bauer Exploder
1983 CHEVY C-10--the gas guzzler
1997 VW GTI VR6 Turbo--dead as a door nail
1994 GEO METRO 1.0 xfi (retired and parted out)
1989 Suzuki Swift GTi (sold)


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 Post subject: Re: Fuel Economy Mod
PostPosted: Fri Aug 28, 2009 7:58 am 
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Joined: Fri Aug 21, 2009 3:07 pm
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Location: Sacramento CA
That is an interesting idea to mount it inside car. It could be possible to see what output range this sensor has by measuring its resistance in different temps. Then find an appropriate range in a rheostat and mount the rheostat in cab on the dash. Like the old Mercedes Diesel with the dash pot adjustable idle knob.

You can tune your car for running at different situations cruising for better econo and scenarios like that.

_________________
"If it doesnt fit, use a bigger hammer"
"Cheaper, Faster, Better, Pick Any Two"
http://actfast1234.wix.com/itsmycar

- 89 Daihatsu Charade CLX 1.0L MPFI 3cyl 5spd (*SOLD*)
- 01 VW Beetle GLS 1.8L Turbo (*SOLD*)
- 63 Datsun NL320 Sport Truck 4x4 (Converted by Me & Son)
- 04 GMC Yukon (Fam Hauler)
- 92 Suzuki JR50 (Fun Tiny Dirt Bike)
- 84 Dodge B350 Royal High-Top Van (Heavy Item Hauler)
- 92/94 Geo Metro's (Rebuilt & Sold)


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 Post subject: Re: Fuel Economy Mod
PostPosted: Fri Aug 28, 2009 10:58 am 
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Joined: Mon Dec 08, 2008 8:13 pm
Posts: 65
Location: Maine
just stick it between the radiator fins :shock:

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1995 Suzuki Swift
SOHC 8V G13B, rebuilt with .020" oversize pistons, decked block ~ 9.8:1 comp, mild head porting, same old worn out camshaft, 2" cat-back w/cherry babomb, factory CAI modd3d with spray paint cap, urethane motor mount, TT front chassis brace, gutted rear interior, Razo RA25 shifty knobbzor, extra seat belts, H&R springs, '86 Maxima wheels with 195/55/15 Dunlop SP Sports.


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 Post subject: Re: Fuel Economy Mod
PostPosted: Sun Aug 30, 2009 1:48 am 
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Joined: Wed Sep 15, 2004 3:58 pm
Posts: 246
Location: The Arctic
Geod wrote:
That is an interesting idea to mount it inside car.


Got the idea since it is often 40 to 50 below zero up here in the winter.

_________________
1993 GEO METRO 1.0 lsi (xfi swap)
1995 Eddie Bauer Exploder
1983 CHEVY C-10--the gas guzzler
1997 VW GTI VR6 Turbo--dead as a door nail
1994 GEO METRO 1.0 xfi (retired and parted out)
1989 Suzuki Swift GTi (sold)


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 Post subject: Re: Fuel Economy Mod
PostPosted: Sun Aug 30, 2009 10:35 am 
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Joined: Tue Mar 16, 2004 6:23 am
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Location: Washington, DC
Yes, you can trick your sensor to report cold, getting a 1 or 2 hp boost, wasting gas and poisoning your catalytic converter. You can also trick it hot, saving gas and sending combustion chamber temperatures soaring, shortening valve life and maybe burning a hole through a piston. You could even put a potentiometer on the dash and desperately try to ride the sweet spot from second to second as you drive.

Or you could face the fact that that is what your engine computer already does, the engineers at the factory with millions of dollars and hundreds of years experience carefully wrote the program to balance all these things together with having an outcome they could warranty. Leave it the fuck alone if you expect it to continue working.

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91 Pontiac Firefly Turbo
10 Suzuki Kizashi


Alcohol, Tobacco, and Firearms
Should be the name of a convenience store, not a government agency


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 Post subject: Re: Fuel Economy Mod
PostPosted: Sun Aug 30, 2009 6:49 pm 
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Joined: Tue Oct 24, 2006 3:09 pm
Posts: 4998
Location: Palm Springs: Too hot from June to Oct.!
Woodie wrote:
You can also trick it hot, saving gas and sending combustion chamber temperatures soaring, shortening valve life and maybe burning a hole through a piston.

Ouch.
Yep, again I agree with the old Woodster.
Once upon a time, a long long time ago in Bethlehem ...we used carburetors.
Tuning them by ear was very fashionable under the shade of a pepper tree by home mechanics.
We'd lean them out using a screw at the bottom of the carb near the throttle plate.
This is a recent example of the results of that technique:
Image
...presented for your viewing enjoyment courtesy of another Teamswift member (not me).
:drunk: :drunk: :drunk: :drunk: :drunk:

Arctic temperatures provide an environment not readily understood by most of us.
bmg_customz has his radiator blocked completely off most of the time, or so I'd guess.
He's more concerned about getting it to warm up, which it rarely would do. I don't think the engineers completely mapped the ECMs for each climate zone, but rather picked a reasonable compromise. bmg_customz's case is an extreme example, and might require extreme solutions.
Plus, he'd have to travel for days heading south to see a pepper tree!
:pirate: :pirate: :pirate: :pirate: :pirate: :pirate: :pirate: :pirate: :pirate: :pirate:


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 Post subject: Re: Fuel Economy Mod
PostPosted: Sun Aug 30, 2009 8:18 pm 
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Joined: Wed Sep 15, 2004 3:58 pm
Posts: 246
Location: The Arctic
Phil N Ed pretty much got it right. These little engines don't always like to go in Interior Alaska's winter temps. I fabbed up a warm air intake one cold winter that made a huge difference in how the car ran.

I figure that dang near anything may help up here!!

Woodie: While I can appreciate your input which is damn near always spot on, and I have read many of your posts, your negative attitude regarding this matter isn't really needed. We are all on here for common reasons--to learn, educate, and pass on our experiences in this fun hobby. Please try to keep it enjoyable for all.

_________________
1993 GEO METRO 1.0 lsi (xfi swap)
1995 Eddie Bauer Exploder
1983 CHEVY C-10--the gas guzzler
1997 VW GTI VR6 Turbo--dead as a door nail
1994 GEO METRO 1.0 xfi (retired and parted out)
1989 Suzuki Swift GTi (sold)


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 Post subject: Re: Fuel Economy Mod
PostPosted: Sun Aug 30, 2009 11:28 pm 
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Joined: Fri Aug 21, 2009 3:07 pm
Posts: 56
Location: Sacramento CA
Just talking about ideas here. I didnt think I would be castrated by talking about a basic mod. The O2 sensor wouldnt let it get too lean as it would sense it and adjust the best it can.

I'm pretty consciencious on what I do with things. If I did perform this mod to test, I would have an EGT gauge, wideband O2, good gas, and possibly an XFi or econo cam.

Depends on what is available and how far you want to go.

Also, the computers are programmed to be the middle ground between economy and power. Sorry if I offended you Woodie, but I really would have only expected that reply from someone who created the programming language or has lots of stock in ECU programming.

_________________
"If it doesnt fit, use a bigger hammer"
"Cheaper, Faster, Better, Pick Any Two"
http://actfast1234.wix.com/itsmycar

- 89 Daihatsu Charade CLX 1.0L MPFI 3cyl 5spd (*SOLD*)
- 01 VW Beetle GLS 1.8L Turbo (*SOLD*)
- 63 Datsun NL320 Sport Truck 4x4 (Converted by Me & Son)
- 04 GMC Yukon (Fam Hauler)
- 92 Suzuki JR50 (Fun Tiny Dirt Bike)
- 84 Dodge B350 Royal High-Top Van (Heavy Item Hauler)
- 92/94 Geo Metro's (Rebuilt & Sold)


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 Post subject: Re: Fuel Economy Mod
PostPosted: Mon Aug 31, 2009 4:34 am 
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Joined: Tue Aug 18, 2009 8:15 pm
Posts: 118
Location: Oklahoma City
Geod wrote:
Also, the computers are programmed to be the middle ground between economy and power.

I doubt you're going to do much better than an XFI ECU with XFI cam. The designers were willing to do with just one compression ring per piston to save a tiny bit of friction, for the gods' sake! I don't think they were thinking in a particularly "middle of the road" way when they made that decision.

BTW, I took Woodie's post as being strongly worded, good advice.


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 Post subject: Re: Fuel Economy Mod
PostPosted: Mon Aug 31, 2009 7:56 am 
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Joined: Tue Mar 16, 2004 6:23 am
Posts: 1745
Location: Washington, DC
Oh, I wasn't offended in any way, nor did I intend to offend. I use that word about as much as I use the word "the". Edit it out of my posts here most of the time, I'll try to make that all of the time, sorry.

My point was that the proper fuel mixture changes many times per second and with proper sensor input the computer keeps up pretty well. Skewing the information going into the computer is a recipe for disaster.

_________________
91 Pontiac Firefly Turbo
10 Suzuki Kizashi


Alcohol, Tobacco, and Firearms
Should be the name of a convenience store, not a government agency


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 Post subject: Re: Fuel Economy Mod
PostPosted: Mon Aug 31, 2009 8:20 am 
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Joined: Fri Aug 21, 2009 3:07 pm
Posts: 56
Location: Sacramento CA
If we go around and tell everyone to stop modifying stuff and be happy with what you got, things would be boring and cookie cutter.

Woodie dont know me, to apply someones advice does not mean you can be disrespectful.

There is always room for improvement. Running MSI and modifying for multi-port injection would help with refining fuel control.

What would also help in fuel economy is running the cam with true bearings to lessen friction.

Just imagine you are cruising along at a constant speed on freeway and expect a nice long 20+ mile ride. Adjust your dashpot and enjoy some more mileage from your hard work tuning. Not saying to race and constantly adjust this, but again the computer does readjust to a point from O2 sensor readings.

_________________
"If it doesnt fit, use a bigger hammer"
"Cheaper, Faster, Better, Pick Any Two"
http://actfast1234.wix.com/itsmycar

- 89 Daihatsu Charade CLX 1.0L MPFI 3cyl 5spd (*SOLD*)
- 01 VW Beetle GLS 1.8L Turbo (*SOLD*)
- 63 Datsun NL320 Sport Truck 4x4 (Converted by Me & Son)
- 04 GMC Yukon (Fam Hauler)
- 92 Suzuki JR50 (Fun Tiny Dirt Bike)
- 84 Dodge B350 Royal High-Top Van (Heavy Item Hauler)
- 92/94 Geo Metro's (Rebuilt & Sold)


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 Post subject: Re: Fuel Economy Mod
PostPosted: Mon Aug 31, 2009 11:22 am 
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Joined: Tue Aug 18, 2009 8:15 pm
Posts: 118
Location: Oklahoma City
Geod wrote:
If we go around and tell everyone to stop modifying stuff and be happy with what you got, things would be boring and cookie cutter.

As a Linux and OSS guy, you don't have to convince me of the benefits and joys of freedom to experiment. And it's your car and no one can stop you. However, I'm a bit skeptical that you're going to be able to make a measurable positive difference with such a crude manipulation of a sensor input. And demonstrating that difference is going to be more challenging than making the mod. There is so much variability involved in real world MPG that it's going to take a lot of very meticulous measurement and record keeping to pull a small positive difference out of the noise. ("Adjusting the dashpot and enjoying the savings" is a bit optimistic, IMO.) That said, people jump to conclusions here all the time. (I inflated my tires to 80psi and got <amazing number> MPG on my last tank!) I think it's more likely that you'll end up lowering the economy, possibly in a rather easily measurable way. But... that would be useful information in itself. I don't think you're going to be able to outguess an XFI ECU.


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 Post subject: Re: Fuel Economy Mod
PostPosted: Mon Aug 31, 2009 11:40 am 
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Joined: Fri Aug 21, 2009 3:07 pm
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Location: Sacramento CA
The ECU has always been a compromise between economy and power for emissions purposes, especially here in California. Things that we do here must be able to either be disabled for smog testing/inspection, or put back to stock by pulling it completely off.

You can manipulate sensor signals and still be within reasonable safe conditions if done right. I work on SRT4 cars with turbos that have the 2.4L putting out 300hp with just a new "Remapped" ECU. Its a high speed 32bit processor in there, very high speed data. We dont have that in our Geo's. Very basic fuel tables 16x16 I believe. By adjusting a sensor input it will shift the fuel to a new point on table to enrichen or lean. Very simple and again it may be a small gain mpg, but 5mpg safely is worth it and very cheap to do.

I appreciate your all inputs, things get done and minds get moving around ideas.

_________________
"If it doesnt fit, use a bigger hammer"
"Cheaper, Faster, Better, Pick Any Two"
http://actfast1234.wix.com/itsmycar

- 89 Daihatsu Charade CLX 1.0L MPFI 3cyl 5spd (*SOLD*)
- 01 VW Beetle GLS 1.8L Turbo (*SOLD*)
- 63 Datsun NL320 Sport Truck 4x4 (Converted by Me & Son)
- 04 GMC Yukon (Fam Hauler)
- 92 Suzuki JR50 (Fun Tiny Dirt Bike)
- 84 Dodge B350 Royal High-Top Van (Heavy Item Hauler)
- 92/94 Geo Metro's (Rebuilt & Sold)


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 Post subject: Re: Fuel Economy Mod
PostPosted: Mon Aug 31, 2009 12:25 pm 
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Joined: Fri Aug 21, 2009 3:07 pm
Posts: 56
Location: Sacramento CA
The ideal thing would be to use MSnSpark control unit. This way you can tune and actively control a "lean burn" profile using a wideband O2 for sure and good gas.

I do have a spare XFi cam with gear and matching ECU for sale right now. Its posted in the Classifieds here if anyone is interested.

_________________
"If it doesnt fit, use a bigger hammer"
"Cheaper, Faster, Better, Pick Any Two"
http://actfast1234.wix.com/itsmycar

- 89 Daihatsu Charade CLX 1.0L MPFI 3cyl 5spd (*SOLD*)
- 01 VW Beetle GLS 1.8L Turbo (*SOLD*)
- 63 Datsun NL320 Sport Truck 4x4 (Converted by Me & Son)
- 04 GMC Yukon (Fam Hauler)
- 92 Suzuki JR50 (Fun Tiny Dirt Bike)
- 84 Dodge B350 Royal High-Top Van (Heavy Item Hauler)
- 92/94 Geo Metro's (Rebuilt & Sold)


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 Post subject: Re: Fuel Economy Mod
PostPosted: Fri Sep 18, 2009 9:37 pm 
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Joined: Thu Apr 13, 2006 10:42 pm
Posts: 126
Location: winona mn
Not on my GEO, but I have used a variable resistor on the IAT sensor and radiator temp sensor on am old 4 cyl Mustang that was DIS in order to make the car think it was stupid hot. The computer pulled timing and ran "fat".

The purpose? 125 HP shot of nitrous on a 105 hp motor.



I put a tank heater on my GEO and completely block off the radiator every winter. It gets about 5 mpg this way than wide open. Otherwise it runs pig rich trying to warm itself up.


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 Post subject: Re: Fuel Economy Mod
PostPosted: Mon Sep 21, 2009 12:03 am 
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Joined: Sat Oct 11, 2003 7:44 am
Posts: 451
Location: near Burbank, Calif
Rather than 'tricking it' into thinking it had hotter air
how about actually giving it warmer air even quicker?

Say, make an old fashioned air shield going around
the exhaust manifold right after it comes out of the head.
Use a well insulated large tube to feed that warmer air
into the air cleaner.

Probably need some bypass in case it gets too warm?
Kinda like they did it in the old days of carbs?

Btw, do you use a block heater?

Pres

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 Post subject: Re: Fuel Economy Mod
PostPosted: Mon Sep 21, 2009 9:17 am 
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Location: Oklahoma City
Pres wrote:
Probably need some bypass in case it gets too warm? Kinda like they did it in the old days of carbs?

In fact the carbureted mk1's had all of that. (At least the U.S. Sprints did.) Exhaust manifold bolt-on stove w/duct. Thermally controlled air damper to regulate between heated and unheated air. I was recently surprised to discover that FI cars, in general, *don't* do that. I went to a couple of auto parts stores looking for the duct, explained to them what I needed, and then watched them stare blankly at me until an "old-guy" employee showed up to explain.

Seems odd, since it seems to me that *real* warm air would be better than any sort of fancy ECU compensation strategies newer cars might apply in cold weather. I guess the injectors atomize the fuel well enough that it doesn't make much difference?

Anyway, that's a very good idea. The block heater, too. I'd do the block heater myself, but apartment living puts a damper on a few of the things that I would otherwise to. I also have a tendency to get distracted and drive off without remembering to unplug it. I remember one time in Tulsa, a fellow flagged me down to mention that I had a 100 foot extension cord trailing me. :oops:

-Steve


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 Post subject: Re: Fuel Economy Mod
PostPosted: Thu Sep 24, 2009 3:56 pm 
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Joined: Tue Feb 10, 2009 4:09 pm
Posts: 238
Location: Brinkworth, UK
sbergman27 wrote:
I was recently surprised to discover that FI cars, in general, *don't* do that. I went to a couple of auto parts stores looking for the duct, explained to them what I needed, and then watched them stare blankly at me until an "old-guy" employee showed up to explain.
Seems odd, since it seems to me that *real* warm air would be better than any sort of fancy ECU compensation strategies newer cars might apply in cold weather. I guess the injectors atomize the fuel well enough that it doesn't make much difference?
-Steve


I believe that the warm air ducting is mainly to eliminate carb icing which FI doesn't usually suffer from.


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 Post subject: Re: Fuel Economy Mod
PostPosted: Thu Sep 24, 2009 5:30 pm 
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Location: Washington, DC
sbergman27 wrote:
I guess the injectors atomize the fuel well enough that it doesn't make much difference?


I think that's the key right there, the mixture is much better under all conditions. Warm air can help during the winter though, and feeding it true warm air instead of feeding it cold and lying to the computer is a much better solution. Please note that the later three cylinders have a heater underneath the throttle body for warmup, after the engine is warm, the coolant warms up the throttle body.

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91 Pontiac Firefly Turbo
10 Suzuki Kizashi


Alcohol, Tobacco, and Firearms
Should be the name of a convenience store, not a government agency


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 Post subject: Re: Fuel Economy Mod
PostPosted: Fri Oct 02, 2009 8:45 am 
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Joined: Thu Mar 27, 2008 6:52 am
Posts: 228
Location: Fort Atkinson WI
I completely blocked off my air dam and made a fuel warmer. This coupled with normal foot to the floor boards driving habits still yeilds 50+MPG in the warmer months and 45MPG in the winter. No matter how much I baby it it doesn't get better,so I drive normal...for me that is.

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Just when I thought I was about to get back on my own 2 feet life kicked me in the shorts.

94 GEO METRO PARTS FOR SALE EVERYTHING MUST GO!!!!
94 XFI rust bucket
96 Honda Accord


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