Hi all on H-T, I have a question thats pretty in depth and dependent on a few different variables, but I figured H-T would give me the best shot at finding my answer. I am aware that there is a similar thread on this section of the forum, but I'm hoping to get a set of straight forward answers. My question is what is your average gas mpg's and under what conditions? I have a b16a2 swapped eg coupe, and I am lucky to see 22mpg city and 20mpg hwy and I know "if I wanted good gas mpg's, I should have stayed single cam!", but anyhow. I have almost nothing done to the car (SRI) and I'm thinking the b16 tranny is a fairly big reason for my poor fuel range. The car is my DD and I drive about 70-80 miles a day (on days I work) and when I don't work, between 30-40. I honestly try and shift before 3k when driving, though I do get the urge to pop madd vtak sauce every once and a while. My route to and from school requires me to get on the highway for 5-7 minutes and keep up with the traffic that moves between 70 and 85 mph, so I know for sure during that stretch of time at 4500+ rpms hurts me, but this route is 20 minutes quicker to/from school and about 12 miles shorter than going through town. This swap has seemed to plague me with CEL's and they have all be corrected with the exception to the code 1 (oxygen content) code that I currently have. Since January I have changed/replaced the following:
-Basemap-3 times (current b16a3, previously gsr, and b16a2)
-Computer-2 times (stock p06 and jdm p72) currently on a chipped p72
-Injectors-All have been changed atleast once, with another set of 240cc injectors
-Fuel Filter
-Spark Plug Wires-2 times (got a bad set)
-Spark Plugs-2 times, roughly 5-7k on the set
-Oil Changed every 4-5k with Mobil 1 Clean 5000
-IAT cleaned
-IACV cleaned and replaced
-FITV cleaned and ultimately eliminated
-TPS replaced and re-wired
-02 sensor-2 times with Bosch
-Throttle Body- 4 or 5 different times (gsr, itr, d15b7, ls, jdm gsr) currently using an obd2 gsr (no FITV)
-Intake Manifold Gasket (purple powered the runners and let dry)
-TB gasket
-Always run 93 octane
I am in North Carolina where temps average around 80 degrees and on a daily basis drive pretty conservatively. I'm wondering if anyone is willing and able to share with me their experiences with gas mileage and their set ups. I have been told it would be helpful to get my car tuned, but when it was pulled out of the last car it ran fine and averaged a 250+ mile tank (high 20's easily) on the highway. The motor was pulled from a friend's car, converted to obd1, and swapped into mine. If you have any insight on something that I haven't mentioned or thought of please share, I truly love wrenching on this car, but its becoming highly stressful when I'm forced to. If anyone is running a b16, gsr, itr, ls/v, with work done, I'd really like to hear from you all.

Cliffs:
-b16
-bad gas mpg's
-tired of blindly throwing money at possible problems

If you read all of that, you deserve an award.

 

Hows your fuel pressure? Injectors on-time?

 

Honestly I have no clue to either question. How would I check either of those, aside from replacing the FPR and getting a gauge for the fuel rail?

 

b16 tranny is killing you on the highway, oh and dont ever use bosch anything on a honda, its ngk or denso and thats all you want to use, bosch parts work well on vw's and thats about it

 

Have you got it tuned? A Hondata may help you solve some of your gas mileage issues while increasing performance.

 

will look into replacing the o2 sensor soon, and no its un-tuned right now.

 

I've got a 97 del sol vtec with a stock B16a2 with 103k on it. I get 30-34mph around town or highway it does not seem to matter. It seems like it needs a six speed on the highway because it runs around 4k at 75mph in 5th. I'm using 91 octane because that is all there is around me.

 

I have a gsr and get 30ish on freeway and 22-25 in town, depending on how I like the drive it. I usually shift at 3-4k and cruise in 5th going 40+. Your gas mileage sounds about right though, maybe you just have a heavy foot? Try driving for your gas mileage, and make sure you go to the same station at the same spot when you refill and calculation how much you fillup.

BTW how are you calculating? top off and divide by miles?

 

why dont you get the right ecu and see what gas mileage you get after? it doesn't look like you have anything done to the car to warrant any thing that requires a chipped ecu or hondata as someone else suggested you also need to fix the CEL before you go calculating the mpg's since a cel would set you in limp mode aka shoot a ton of gas to stay away from running lean.

 

i agree but a chipped ecu should be ok as long as the program is correct. since its pretty tough to find an obd1 p30, a chipped ecu may be the only choice.

as far as the CEL, that should be your top priority. if replacing the o2 sensor didnt fix your code 1 then you need to inspect the wiring

i have a 94 del sol vtec and get about 30mpg on the highway. i dont think the short gearing in the tranny really hurts the mpg all that much. car tachs at about 4k at 70mph, 4.5k at 80mph.

 

same here. 95 del sol S with a b16a SIR2. i get 28-34 combined. 28 is if i highrev it more then usual. otherwise i average 30-32.

with most of what you said i have replaced. and a SRI which is a pretty mute point.

as said before bosch blows when it comes to honda.

 

I drive ~75mph for 20 mins (30 min drive) for work, and I get 30-33mpg on a STOCK b16a3 (94 del sol VTEC). That's what the car came with though, with the exception of Crome running the show w/knock sensor disabled (had weird power loss at 4k w/sensor enabled). Tranny/wiring/head/etc untouched, just some ebay exhaust from last owner. I also beat the motor at each on-ramp, and the last turn before work.

Sounds to me you may have a shitty knock sensor, some weird knock-enducing sounds (unadjusted lifters?), or you're using crappy gasoline. You also might have bad wiring for the o2 sensor, as no o2 corrections can waste tons of gas. Sometimes its just a matter of bad grounds (corroded t-stat housing + battery). If there's lots of resistance there, the o2 could possibly read much leaner than normal (and ecu dumps gasoline).

Also check your cam timing is correct. Sometimes people will put it together with 1 tooth off, and it will run - but terribly. I'll also assume you have ignition timing spot-on at 16*, since that's #1 importance from a tuning aspect.

 

completely off-topic, but can you tell me what size the brake master cylinder is on that car? no abs on that year right?

 

I had a similar setup as the OP on my first EK B16a3 OBD1 chipped P72 I/E only
and gas mileage was horrible, i always blamed the short gears on the B16 tranny but I also admit my car was running rich as hell so that didn't help much.

Get that CEL taken care of, then average out your mpg again

 

That gas mileage you have seem about right. I think you just have a little heavy foot. My car gets 23 on the highway 65-70 mph cruising, if I sometime rev it high I would get less mileage. city haven't even try yet. My car a 93 civic dx with complete jdm itr swap basic bolt-on, p28 chip, 50 fuel psi. Do a tune up, and what size of rims do you have on your car? Bigger the rims the more weight your engine pushes = more gas

 

I didnt have this swap but i had em1(stock b16a2), on freeways i was getting atleast 30+ mpg, i had same 5th gear rpm. You do need a fuel pressure gauge to check fuel pressure, injector on-time, talk to your tunner.

 

This all leads back to the B16 trans. IMO.

try running 60mph for a week or two on your normal commute where you would be doing 75-80mph. I can guarantee your MPGs will be up in the mid-low 30s

Also, a wideband O2 would be a VERY helpful tool. It will help out alow to know where your AFRs stand under different loads

 

Thanks for all the replies. I will try my best to check everything suggested and report back. I'll admit I am a tad heavy footed at times, but for the most part drive like I have sense. Another factor I hadn't listed but was aware that its helping drain my gas is that in the daytime (between 10am and 6pm) I run my a/c on fan level 2. As far as calculating my mpg's I get gas when my needle is right above "e" and it takes 8.2-8.5 gallons to fill up. Out of that ~8.5 gallons I can stretch it to about 180 miles or so, which puts me a hair above 20mpg consistently. I would try and run a tank without using my a/c, but showing up for class and work smelling bad isnt an option.

 

I have a built GSR w/a JDM ITR tranny (4.7 final) and I don't see anything as bad as 22 mpg. When it was stock (w/the JDM ITR tranny), I was getting 30mpg. After it was built, I added a a Hondata S300 to my P72 ECU. With a good tune, it was still doing 30-32 mpg, depending on how much I got on it. I just swapped headers and put on a high-flow cat, so now I'm running pig rich and I'm getting a miserable 26-28 mpg. Next week this will change after another tuning.

This is all to say that even with your B16 tranny, you shouldn't be getting numbers like that. It sounds like you're dumping gas by running rich. Check your exhaust tip...is the inside black?

fm

 

BTW, if you don't have one, you should seriously consider getting a Hondata and getting a tune on a Dynapak. A Dynapak will let you tune under part-throttle as well as full-throttle conditions. If you get a tune on a roller dyno like a Dynojet, you'll only get tuned under full-throttle conditions, which does nothing for your normal DD routine.

fm

 

wrong...

Roller-style dynos also have eddy current load cell add-ons

 

Not the ones in my area. My last tune shows it. :p

Let me amend that comment:

There...better?

fm

 

get an ls trans and all your mpg problems are solved

 

I cruise at 70-75 and get 27mpg on a bad tune (running rich) with my GSR/JDM ITR tranny (4.7 final). I don't think it's just the tranny folks. Doesn't hurt to test by cruising at 55-60 between fill-ups just to be sure, but I doubt you'll see that drastic of a change. I still think you're running pig rich and are dying for a tune.

fm

 

BTW, here's an interesting post regarding the myth of short gearing adversely affecting your gas mileage. While drastic changes can affect your mileage, it's not as drastic as you'd think.

fm