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Tofuball's '94 XFi; It's all about city MPG
Topic Started: Mar 12 2011, 08:59 AM (39,407 Views)
Tofuball
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Strange Mechanic

I bought this 1994 XFi at 86,000 miles for $1700 with some extras. Did I get ripped off? Maybe. I think it was a fair price, especially since it was RUST FREE and I'd been looking for over a month without finding even a normal Metro without at least some rust on the forks, all the XFis were toast. And the compression test was 185,185,185.

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Shortly after I got it through inspection (it needed tires, the tint torn off and the a new drum brake piston) it snapped its timing belt.

On 8-10-10 I did Oil and filter, Air Filter, Timing belt\tensioner, Crankshaft front seal (the REASON the timing belt failed), Alternator (it was really loud and not working too well), Alternator belt, Wipers, MBC reservoir seals replaced, patched TINY rust hole in passenger side control arm mount (ARRGGHH!!) I set the timing at 8 degrees and ran some fuel system cleaner through. Changed the spark plugs. Did another comp test, 185, 185, 185. Getting 44MPG. Combined

On 10-10-10 Noticed car was producing less power then before, esp at lower RPMs. Noticed vacuum flutter. Suspected valve or lifter problem. Getting 38MPG (Combined)

In February at 87K or I reset the ECU codes and fixed the check engine light (it was removed by a previous owner). Changed the spark plug wires. Getting 33MPG City only (Most of my driving is short distances, cold, light to light or stop signs everywhere) Flushed coolant system - heat works much better now :)

March, got a junkyard head to start doing my build. And replaced the factory steel jack and pole with lighter RX-7 jack and pole. Fixed the previous owner's radio installation (tired of blowing random fuses when bare wires hit things)

Head apart:
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Lifters reassembled\lubed:
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I have the "plug and play" adapter mostly complete, have started to assemble the MegaSquirt II, and the rest of the parts are in the mail. (manifold, fuel rail, injectors, etc)

MPGuino installed but the VSS isn't giving it a signal.

March 13 2011 - did a leak down test, 20% (perfect) on all cyls. No leak from the valves. Implies the flutter is from a vac leak (I strongly suspect the idle control valve). MPGuino indicates ~48mpg highway, I suspect a bad O2 sensor is already part of that equation. I have a spare TechEdge j2z that I shall install.

March 15 2011 - Prepared the WBO2 to be installed. MSII complete, adapter complete, just need to upload the new firmware and actually install the stuff in the car. I need a baseline of a working XFi in my conditions before I MS it, I want a good set of data to show if my ideas work and how well.

March 19 2011 - Filled up. 36MPG, all city, usually short trips (I work 3.5 miles from home and it's all light to light). Did my own version of the "TB Mod." Did a better vac test, found a leak in a vac hose behind the TB that closed up when it was cold! Replaced it. Car is now using much less fuel at idle (.17GPH instead of .24GPH). I must verify O2 operation or install the WBO2 before it is a real baseline though. Can't start testing the usefulness of mods without it :)

March 20 2011 - Filled up 2 gallons after 80 miles, mostly highway. It is cold out, I am using E10, I do lots of stop and go, and I usually have two or three passengers and a bunch of stuff. Uploaded firmware and tested MS on the stimulator, works perfectly. Can't wait to install it, but I need baseline fuel economy before I start modding this thing.

Cut up the spare head for the grooves, ported it and polished the chamber.

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March 26 2011 - Got the head to the machine shop yesterday. Today installed TechEdge 2je wide band O2 sensor and gauge. Re-ran the VSS wire and now my MPGuino works.

Cleaned the bolts and painted some parts (cast iron grey, and gloss black, both 500F engine enamel)
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Painted the injectors too, I will use these for batch and initial sequential testing. The plan is to eventually replace them with insight injectors and record the MPG change (if any) after appropriate tuning.
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April 10 2011 - Head\valves still at the shop. I painted my hubcaps silver, it makes the car look a whole lot better.

April 16 2011 - 88277mi on the odo. Changed trans fluid with Synchromesh. Noticed I have a fluid leak from the seal for the passenger side half shaft, and the dizzy seal. Noticed I have an exhaust leak behind the cat. Advanced the timing gear one tooth past the line and re-timed the engine to 8 degrees. According to MPGuino I'm getting 50mpg combined now. I definitely have much more low end power and vac flutter has been cut in half.

May 28 2011 - 88331mi on the odo. Changed MBC and flushed brake fluid. Installed custom straight-through exhaust with Magnaflow muffler. Sounds deep. Slightly loud for me, perhaps a reducer and tip turndown will help. Removed the crank gear and found source of all my problems:
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The woodruff key decided it wanted to lay down on the job. This is probably due to me not tightening it down enough the last time I checked it.

June 10 2011 - New key came. Fixed crank and gear with JB Weld. Put everything together with copious amounts of blue locktite and torqued it down hard. Engine runs. Just have to wait for weather to co-operate so I can button it up and see if it holds, and if the exhaust is bearable or has noticeable gains in power (butt-dyno)\MPG.

July 4 2011 - 89Kmi The key fixed the issue and I advanced the gear 1 tooth. 2 teeth gave MASSIVE low end but the car simply had no power above that. I'm getting 52-54 city and 60 on the highway (70 if I can do a constant speed flat) and the gear is staying put. I changed the oil but not the filter. I started a new job on the 1st and I am still going to school full time, but when things calm down a bit I will install the MegaSquirt, my baseline has already been collected and I have a very good idea on how the stock ECU works and places to improve it.

Aug 15 2011 - 54 city continues. Thanks to a really bad job by some local road crews, my ball joints were destroyed. I replaced both A-arms, tie-rods, end-links, rotors, pads, and transmission output shaft seals. I cut the front springs 3/4 a turn and the rears 1/2 a turn. I painted the driver's side frame horn red, then undercoated it.

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Aug 17 2011 - 89719mi - The car is pretty flat after cutting the springs. Got an alignment. So far I like it. Haven't had a chance to really see how big a change the modifications have made. Definitely a lot tighter and the new brakes help a lot :) Cutting the springs was a huge + and I don't regret it at all. If I didn't have to deal with snow I would cut it another quarter all around.

Aug 19 2011 - Installed a recycled RBC2 battery. It weighs 5.5lbs vs the old battery\tray at ~40. We'll see how this goes.

Sept 29 2011 - 90777mi - Getting 44mpg ultra-urban, 54mpg city, 58mpg highway. Confirmed speedometer reads 5.5mph slow, but VSS reads correctly. RBC2 causes undervoltage on startup (radio stations lost) but starts the car fine. Bought two new ones and going to see how that works. Installed aluminum RX-7 rims (185-70-14) and replaced the stock spare with the RX-7 aluminum spare tire. Filled the tires to maximum (35PSI on the front and 44PSI on the rear). That's a 14.5% speed difference, plus the set 5.5mph I'm already off. So if my speedometer reads 55, I'm really doing 70!

Oct 11 2011 - 91080mi - 52mpg city. The rims make the car handle awesome. The two RBC2 batteries + Capacitor starts the car right up every time without an under-voltage issue.

Nov 2 2011 - Because the car is lowered, 185-70-14 is too tall. Front fender took a small chunk out of the tread. I swapped on 185-60-14s. MPGuino died again for some reason. I've started amassing the last of the parts to finish constructing the super MPG engine.

Nov 11 2011 - Installed block heater last week, it works well. Installed new tires (Continental ContiEcoContact EP - 145-65-15) on RX-7 aluminum spare tire rims. They're 23lbs each (tire+rim).

Dec 11 2011 - Changed oil to 5W30 Castrol Edge. Installed child seat bracket, fixed MPGuino and radio again. RBC2 batteries still start the car just fine at 24 degrees F. Block heater is very convenient.

Dec 13 2011 - Hit a huge pothole. Need new wheel bearings and front tires. :(

March 19 2012 - Removed the factory engine out of XFi, preparing to put this new one in. Noticed that the lifters in the old engine were frozen solid.

April 3 2012 - Changed the front wheel bearings - http://geometroforum.com/topic/4749908/1/

My observations of the XFi stock ECU:

1) It runs in closed loop almost all the time, even at WOT and very low RPM (Nice!) But also when it's at very high vac (Not nice!).
2) It runs too far too rich outside of closed loop: It dumps in way too much fuel when the engine is cold, it dumps fuel before the O2 kicks on, it dumps fuel for startup enrichment.
3) Fuel cut happens on decel above 1500rpm and fuel turns back on at 1300rpm
4) It dumps way too much fuel when you move the throttle
5) Startup enrichment (it ignores O2 sensor and runs crazy rich) lasts 20 seconds from when you turn the car on, even if the car is warm.
6) Timing advance SEEMS too advanced between 1800RPM and 3300RPM under load

Work to do:
| - A new paint job would be nice . . . (light blue metallic, or just white)

Plans:
| - Megasquirt Extra II
| - BMW Coil-on-Plug with appropriate spark plugs
| - Head Work:
| - - Raise C/R (Haven't decided how much yet, hopefully do this by finding a thinner head gasket or changing the pistons with some from a late 80s samurai). I may take the C/R very high and use water injection controlled by the MegaSquirt to continue using pump gas.
| - - Cut one groove in squish area, index spark plug to the groove, maybe add material to increase quench area size.
| - - Polish combustion chamber, no raised\rough areas to promote hot spots - pay special attention to spark plug sockets
| - Custom header
| - Upgrade hamster feed, grease wheel
| - Areo mods (eventually)
| - - Kammaback, Rear wheel covers, Under-tray,rear diffuser, coat the car in fresh butter every morning, front lip, hood vent for radiator ("V" Mount) and seal the engine bay, wheel spats, side skirts, either zero-degree the wipers or scoop the hood to shroud them)
| - Try and identify weight reduction without impacting function (no getting rid of interior, heater, spare, etc):
| - - Lightweight main pulley (this stock thing weighs like 7lbs, all around the outside!)
| - - Diet and exercise (Saved 30lbs already!)
| - - Older seatbelt mod
| - - Would aluminum calipers fit on this vehicle? I'd only consider this if I could find some cheap off a junked car, not a big fan of the stock breaks.
| - Make friends with people who have parts cars. Bonus if they're Canadian or European with those MPFI Geos! ;)
| - Dual passageway air intake. Warm air for warming up the car and on cruise, cold for everything else. EGR off at lower vacuum.
| - 205 degree thermostat
| - Insulate under hood around engine to discourage sitting heat loss and help a block heater do its job.
| - Fill the sidewells with great stuff to help cut down noise.
Edited by Tofuball, Apr 3 2012, 01:59 PM.
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cdmccul
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I love the way you laid out your valve train parts... Looked real good.

Great start to a car for FE. I'll be watching with interest.

For lightening the load, you might consider wheel changes to aluminum - don't know if you'd gain much, but something to consider - you'd likely have to go to 13 inch though. Might be worth it just to save on tire costs.

For drilling holes, I want to say I've got an intake with cast in bosses for sequential fuel injection - I'll have to go look in the garage at the parts intake I have sitting there.

For Aero mods, consider a different whip antenna base.
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CityConnection
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Sir, yes sir!

I'd like to see that RX7 jack. Less weight while still having a spare tire? This is a mod that all of us can enjoy.
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Tofuball
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cdmccul
Mar 12 2011, 10:57 AM
I love the way you laid out your valve train parts... Looked real good.

Great start to a car for FE. I'll be watching with interest.

For lightening the load, you might consider wheel changes to aluminum - don't know if you'd gain much, but something to consider - you'd likely have to go to 13 inch though. Might be worth it just to save on tire costs.

For drilling holes, I want to say I've got an intake with cast in bosses for sequential fuel injection - I'll have to go look in the garage at the parts intake I have sitting there.

For Aero mods, consider a different whip antenna base.
Stock was batch injection, on the turbo models and such - and the bossess are in the head, not the intake. :)

Once I get the injectors\rail and such in the mail I'll make a jig so I can cut the holes accurately in other people's heads too, should they want to run sequential after reading about the insane gains I get from mine ;)

I don't have that antenna on the car at all anymore. Aluminum wheels are a great idea, I wonder what the Honda VX guys use . . . * hint *
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Tofuball
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CityConnection
Mar 12 2011, 01:54 PM
I'd like to see that RX7 jack. Less weight while still having a spare tire? This is a mod that all of us can enjoy.
I can get a pic sometime, but it looks just like ours, just longer and made of aluminum. I doubt it saves more then a pound or two.
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mcmancuso
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The honda rims are 4X100 pattern and are too thin to be re-drilled for ours :( you can get the 14" suzuki alloys (came on swift GTi's) which weigh about 9lbs per wheel though.
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yiffzer
Forgot His Manpurse

Honestly, I think you got a fair deal out of it. I look forward to following your progress!
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Good write ups Jason. I like your organization skills. Is that a shop or just your garage?

Thanks
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Tofuball
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Thanks; it's my basement :P That workbench is two full pieces of plywood (4x8) and a bunch of 2x4s put together with deck screws. You could drop a car on it.

I just did a leakdown test on the car to see if leaky exhaust valves might be the issue. Nope. _Perfect_ readings on all cyls. MPGuino says I'm getting about 45mpg average on the highway (55 to 60 mph) . . . bleh.
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I picked up an MPGuino last fall but haven't gotten around to configuring it. I'm still working around an all-inclusive instrument cluster to sit on the center dash angled towards the driver. Does your MPGuino come with buttons on its face or on the top? The one I got had buttons on the top which limit my installation options, I may send it back for the 'standard', front button variety.

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Tofuball
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I can help you put those buttons anywhere you want, it's a snap to move stuff around on those. You could even put wires on it and position the buttons remotely. Or use different buttons.
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Bad Bent
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Facetious Educated Donkey

I know you flushed hour coolant system and you mention the coolant temp sensor as a suspect so may I suggest the coolant hoses on the Throttle Body as being clogged? And if not maybe the temp sensor simply has some 'scale' build-up on it and it's reading cold.

Coolant hoses should be hot as radiator hoses.
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Tofuball
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Bad Bent
Mar 13 2011, 09:07 PM
I know you flushed hour coolant system and you mention the coolant temp sensor as a suspect so may I suggest the coolant hoses on the Throttle Body as being clogged? And if not maybe the temp sensor simply has some 'scale' build-up on it and it's reading cold.

Coolant hoses should be hot as radiator hoses.
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My thoughts exactly. However the whole system is going soon so I am not going to bother. ;)
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Tofuball
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Got my nice new manifold from a Turbo Sprint! :)

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....

AAAAAAAAAARRRRRRRRRRRGGGGGGGGGGGGHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

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NOTHING LINES UP.

Making an adapter plate would be just as much trouble as making a whole new manifold.

I guess not all G10 engines had compatible parts! What year manifold would I need?
Edited by Tofuball, Mar 15 2011, 09:39 PM.
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Tofuball
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. . .




RRRRRRRRRRGGGGGGGGGGGGGGGGGGGGGGGGGGGGG
Edited by Tofuball, Mar 15 2011, 09:40 PM.
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