93 Honda Civic VX horrible fuel economy

[benfrogg]

UPDATE:
Figured i'd post this as the many could benefit. One word, Thermostat. Replaced it just after I bought it. Trusted the parts store to give me the right temp. 180 df is not the right temp. Went to a 195 df. I'll update mpg's at the end of this next tank. I'm guessing I will be pleasantly surprised, what do you think?

PDXchrisVX, check your thermostat temp!
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[GasSavers_1stHonda]

So did replacing the thermostat do anything? I'm positive that I have a 180 in mine. My mileage is 43mpg @55mph highway. Lowest has been 34mpg.

[benfrogg]

The right thermostat is 195, me thinks. Either way hotter is better for FE. The thermostat did help, although maybe only a few mpg's. (no, I did not ABA test) I wouldn't hesitate with the price of em'!

New news!
The 02 sensor I bought was a Standard SG335. It crossed as the same part, and did turn off the check engine light.
It does also make the lean burn work, as far as I can tell.
It does not provide peak efficiency. It just cant. THat's my opinion about it. Anyone else wanna weigh in? It plugs in with no splicing. It looks the same. I suspect it is NOT the same. My gaslog seems to suggest that. I've done a ton of aero mods, driving changes, weight reduction, everything really. (within my pocketbook) Still in the low 50's at best. Worse this time of year because of winter fuel and weather.

Have you ever replaced your 02?
Does it say L1H1 on the side?
Is the check engine light on?

One thing I found out today through another forum is that the new Insights use the same sensor (L2H2 instead of L1H1)as my VX. I'm gonna find one in a scrap yard to try in mine. No insights in the junkyards around here though...

BTW, aftermarket numbers are NTK 24300. Insight uses same thing, supposedly. This could be a cheaper fix for people if it is true!
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[GasSavers_vxhatch]

Originally Posted by benfrogg

Have you ever replaced your 02?
Does it say L1H1 on the side?
Is the check engine light on?

I did replace mine in '08 with a NTK 24300. The NTK was not stamped L1H1.

No Check Engine Light before or after.

MPG stayed roughly the same but the car feels different going into and out of Lean-Burn with it being more noticible with the NTK LAF vs the L1H1. I have kept my L1H1 as backup.

Doug

[benfrogg]

Good to hear. How many miles on that old 02? Ever feel like selling the old one, let me know!
I still sell some junk to pay for that new sensor. I think they say L2H2 in the numbers on the web from oxygensensor.net.

I'll be going from an un heated (or the heater failed because it's the wrong part) 02 to the NTK model. I'm hoping for a few mpgs. That would make me happy.
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[GasSavers_vxhatch]

Originally Posted by benfrogg

Good to hear. How many miles on that old 02? Ever feel like selling the old one, let me know!
I still sell some junk to pay for that new sensor. I think they say L2H2 in the numbers on the web from oxygensensor.net.

I'll be going from an un heated (or the heater failed because it's the wrong part) 02 to the NTK model. I'm hoping for a few mpgs. That would make me happy.
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Over 130k on the L1H1, not interested in selling, sorry for the price these things go for I'm gonna keep it as backup.

Doug

[benfrogg]

So, I hate to drag up an old thread, but I found my smoking gun.

I just got the right size tires installed on the car. (165/70 r13) I've been searching the threads tonight and saw PDXCHRIS's graph about rpms/gears/speed. Turns out, my transmission matches nearly exactly with his car with the worse fuel economy. Here are the numbers:
1500rpm 2000rpm
gear 2: 17 24
gear 3: 29 38
gear 4: 36 47
gear 5: 44 58

Those numbers are not even close to his numbers of the lower revving better performing vx he has. This would also likely explain power issues in certain gears and rpms... the car seems to lack power in funny places like 4th at 45mph, etc.

Another thought is that the speedo is off. It's 1-2 mph slower than my MPGUINO, which agrees with my GPS. That is to say, the speedo is 1-2 slower than both. However, the odometer measures the same amount of miles.... perplexing.

As HolyCow said, tranny swap confirmed.

So, honda guys, what transmission do I have?

Also, I have a guy locally who will sell me the whole engine/tranny for $100. Is there anyway to tell if the new tranny is vx or not? Any numbers?

Anyone live near maine with an engine hoist/wanna help? I've got many spare vx parts in trade.
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[GasSavers_Erik]

Originally Posted by benfrogg

Is there anyway to tell if the new tranny is vx or not? Any numbers?


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The easiest way is by simple comparison of the ratios of the number of crankshaft rotations to number of axle rotations. First measure these on your car- jack up the entire front end (both wheels so they both spin together) put the car in 5th and turn the crankshaft pulley bolt counterclockwise exactly 5 revolutions with a socket (use the TDC marks on the front cover- more crank revolutions will be more accurate) and count the number of revolutions the tires make. Be sure both tires are turning while you do this test.

Then go and do the same thing when you inspect the engine/tranny combo that you are interested in and be sure that the tranny output spins more rotations than yours does per similar number of crank revolutions.



I know that some high altitude HF trannies were geared closer to stock than the regular HF trannies- perhaps yours is a similar situation- perhaps they made a high altitude VX and someone swapped one of those trannys into your car

[benfrogg]

Okay; I'll have to find a way to repeat this test with the other motor/tranny out of the car. Someone has already pulled it. I figure for $100, I can't go wrong. The motor alone is worth that!

One thing that might confirm this is comparing the cases of the tranny's side by side. Every auto parts store in town wanted to sell me a drivers' CV axle that seemed about 1" short. Since install, the boot on the tanny side is extended with the car off of the ground (and on the ground, I recently learned after putting the stock suspension back under it). Perhaps the VX tranny casing is slightly different? Maybe the shops just have the wrong listing.

As for a high elevation model, I have no idea. This is a federal model that was manufactured in Canada.
I bought it from a younger guy, who bought it 3rd or 4th hand already. It had the wrong size tires on it. I didn't realize it until a tuner told me, but the rear taillights are JDM not stock. I guess the turn signals are white and not amber. So, at this point, anything is possible with tuners.

Thanks for the advice, more is welcome!
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[imzjustplayin]

Originally Posted by benfrogg

So, I hate to drag up an old thread, but I found my smoking gun.

I just got the right size tires installed on the car. (165/70 r13) I've been searching the threads tonight and saw PDXCHRIS's graph about rpms/gears/speed. Turns out, my transmission matches nearly exactly with his car with the worse fuel economy. Here are the numbers:
1500rpm 2000rpm
gear 2: 17 24
gear 3: 29 38
gear 4: 36 47
gear 5: 44 58

Those numbers are not even close to his numbers of the lower revving better performing vx he has. This would also likely explain power issues in certain gears and rpms... the car seems to lack power in funny places like 4th at 45mph, etc.

Another thought is that the speedo is off. It's 1-2 mph slower than my MPGUINO, which agrees with my GPS. That is to say, the speedo is 1-2 slower than both. However, the odometer measures the same amount of miles.... perplexing.

As HolyCow said, tranny swap confirmed.

So, honda guys, what transmission do I have?

Also, I have a guy locally who will sell me the whole engine/tranny for $100. Is there anyway to tell if the new tranny is vx or not? Any numbers?

Anyone live near maine with an engine hoist/wanna help? I've got many spare vx parts in trade.
B

I don't know what you guys are talking about but....
You have a VX transmission or at least a transmission with a 3.25 final drive:

http://fatboyraceworks.com/gears/ind...raph&Compare=1

Use that calculator for when ever you want to figure out the MPH and RPM for a given transmission configuration.

BTW, all HF transmissions are cable driven and VX transmissions are hydraulically driven. If your transmission is cable driven and you're getting those MPH and RPM numbers, then you have an HF Cali/High altitude transmission with the 3.25 final drive.