Civic VX cant get over 41ish MPG

[JRMichler]

Originally Posted by Shortie771

Advanced timing, warm air intake, kill-switch, vacuum gauge, grill block, belly pan, rear wheel skirts, interior mirrors, the list goes on...

There are a lot of options out there to getting higher mpg. What are you willing to do? Do you have a long term mpg goal?

He's doing the right thing by first getting the car to run the way it should.

[jlk16188]

Originally Posted by JRMichler

Does that engine have a distributor? That kind of MPG would be consistent with timing retarded 5 or more degrees. Especially look at the vacuum advance. If the vacuum advance is messed up, the engine will develop full power, but get lousy MPG at part throttle.

It does have a distributor. I haven't pulled out my timing let yet but ill check. I assumed based on its current position it was set decently but ill double check. I'm not sure why I never did check now that I think about it.

[Rusty94cx]

Yes the car has a distributor but no vacuum advance. Lol. I have the cx vx trans in both cars. At 65 on freway I'm at like 2100. It is all about getting everything else correct first. And I have herd it said many times a cx will out preform a vx if your not maximizing leanburn.

[jlk16188]

Originally Posted by Rusty94cx

Yes the car has a distributor but no vacuum advance. Lol. I have the cx vx trans in both cars. At 65 on freway I'm at like 2100. It is all about getting everything else correct first. And I have herd it said many times a cx will out preform a vx if your not maximizing leanburn.

Is that in 5th gear? If it is that's right about where my car runs. I don't have any instrumentation yet so I can only tell if I'm in lean mode by the butt dyno

[brucepick]

Get an MPGuino, about $50. Works on VX and HX and just about any car with fuel injection and a modern type VSS. Read about it in the Instrumentation forum - see the MPGuino subforum there.

Good luck with the VX. Hmmm. Correct weight thin oil in engine and tranny? Put tires up to sidewall max pressure. Pop off the AC belt, see if compressor is starting to freeze up (spin pulley by hand to test). Happened to me but it made the belt squeal, that's how I discovered it.

Your new tires will need some time to break in. Hopefully they have a nice smooth highway tread.

[Rusty94cx]

Yes 65 5th gear 2100 ish.

[California98Civic]

Originally Posted by jlk16188

accelerate smoothly using ~75% throttle until i reach 55-60 MPH.

Did you really mean throttle, or do you mean engine load? I get to 75% engine load with about 25% throttle, maybe 30%. If you meant "throttle" you are really stomping on the accelerator. How are you judging throttle position (or load, even)?

[Ryland]

Stop putting it in Neutral, your engine cuts fuel any time it's over about 1,200 RPM in gear with the clutch engaged, so by putting it in neutral you are using fuel to keep the engine turning.

It's almost impossible to find Low Rolling Resistance tires in the stock tire size, so that right there is going to give you a small hit in mileage, but my VX has 233,000 miles as well with non LRR tires and I'm getting 47mpg or better with mostly short trips.

Ethanol in your fuel will also kill your mileage in the VX, the higher price of Premium should be offset enough by the increased mileage to make it worth while, if it doesn't you are only out a buck or two.

Thermostat, there is a ~180F and a ~192F thermostat that most auto part stores carry, they are both listed as stock parts, the 192F is the proper stock part.

Stock sized exhaust will extend the life of the o2 sensor and help with mileage.

Some VX's had piles of dealer options like mud flaps, A/C, passenger side mirror... each one of those hurts your mileage a little.

Motor oil, 0W 30 works great in the engine! it also works great in the transmission, the transmission takes regular motor oil, NEVER GL5 gear oil, owners manual tells you to change transmission oil every other year, I have 0w30 and let it go longer because it's synthetic, but I haven't found anyone who's selling a Honda civic who remembers changing the transmission oil, so there is a possibility it's 20 years old!

[Mira]

JRMichler;

After buying my civic last October, I too suspected I was getting less than stock mpg, with relatively "mild" hypermiling I was finding it hard to hit 30. Since I've had em I've done everything in my knowledge base to keep him in top shape regardless of cost.. But anyways, thank you for the info you put into this thread, I am going to check into these things on my car as well, maybe it'll be good for a little improvement.

[jlk16188]

thanks everyone for the replies. I have found my problem.

The civic is totally stock including stock sized exhaust, no mud flaps. I do use 5w 30 oil however.

I did pull out my timing light before heading to work this morning and found my timing was way retarded, literally and figuratively. I can tell a huge difference. Before I was having trouble keeping the car in lean burn when climbing very slight up hill grades. Now i have no issues and the car seems to transition into lean much smoother. I just filled up the tank yesterday so it will be two days before I have real numbers to compare but I can definitely feel a difference and i believe my problems and quest to 50 MPG have been solved

Thanks guys