310HPS2k

Hey guys I'm stumped here and need some input.

I've got an itr swap in the hatch and it drives great besides smoking in vtec.

My concern is the gas mileage I get about 220 miles if I'm lucky on a full 11-12 gallon tank.

No cel and I have changed the fuel filter, sparks, cap and rotor.

I was think maybe o2? But no cel?

Please post if you have had similiar problem

300whpej

i had same problem when i first got my swap in. turns out first issue was that my ecu wasnt looking for o2 sensors and so it would guess how much fuel my motor needed to prevent running lean, and instead the motor would dump fuel. fixed that and then i was getting close to 18-20. i then accounted for my short geared tranny (b16) and i now shift as if i was still rocking the "D" (~3k), and im seeing 27-28mpg now...still not great, but a hell of an improvement

DVDr

iTrader: (2)

what ecu are you running ? chipped OBD1 ? or the correct obd2 for your car ?

If you are running the stock obd2 ecu you should definilty be getting way better mpgs, if you have no codes.

IF you have an obd1, then check what program and what is disabled and enabled, as stated above, you can have o2 sensors off, timming too advanced , etc.

Or lay off the foot on the gas, its too easy to burn through the gears with the short gear ratios.

300whpej

^took me a while to adjust to the gearing of a b16 versus a d15b7

Reyracer19

When I had my first B16 EK, that was my main complaint...How could a 1.6L engine go through so much gas.. And that was back in 03' when gas wasn't as high as today.

I was running a chipped ECU with advanced timing no cat and bumped fuel pressure reg.
and i felt like some of my V8 buddies had better mileage.

Also to that note you can add the fact that on the highway your permanently stuck on vtec engaged on a B16 tranny...

You can easily shift from 1-3-5 and it feels like your driving a normal car.

310HPS2k

Chipped p28 and yes the itr trannys got short gears but I shift at around 3500.
I will check in on that ecu prob see if it'll throw a code if I unplug the o2.

Will update soon

300whpej

my 5th gear vtec doesnt engage until like 95mph. its set at 5500 tho

DVDr

iTrader: (2)

Good way to trouble shoot.
is your chipped ecu, tuned ? or just a random chip installed ? My experience with those is always bad MPGs. the generic chip is usually more fuel, more timming all through out. not the best for mileage or for anything.

Reyracer19

I think DVDr nailed it with the above statement. I had a generic "clone" chip that likely was just a ramped up version of the stock maps across the board.

310HPS2k

It's a chipped p28 that came from phearable.net

I bought the car as is with the swap and ecu so I do not know how it is set up. Mechanically the car runs perfect aside from the smoke in vtec. So I think it may be the ecu. If anything I'll have it professionally tuned.

Thanks

raidacaipo

you need a tune or you can always find a stock p73 ecu and run obd2.. btw Im also running a p28 ecu from phearable.net and its also giving me crappy mpg.. but I can fix that with a tune. good luck

DVDr

iTrader: (2)

how did it go ? . As radacaipo said above, If your motor is stock or fairly stock ( just intake and exhaust ) , best for both worlds (performance and mpgs) is the stock obd2 ecu with working o2 sensor.

310HPS2k

Ok here's what I found.

No iat sensor, I did find a plug tucked away under the intake manifold. It's got a green and black wire?

Also if it's missing an iat sensor why isn't the ecu telling me so? Or does it not do that and make it run rich all the time?

What should I do from here?

P73 ecu is like $200 +/-

and a tune is right about there

and this is a daily driver no mods just intake which if I had a stock airbox it would be gone.

DVDr

iTrader: (2)

your chipped ecu probably has the check engine light feature turned off, or for specific sensors turned off.

If you are going to keep it as you said, Then the best is the obd2 route. GET a JDM ecu as you have a jdm motor with not CKF ( cranck sensor ).

A few years ago a buddie had a 99 hatch running obd2b ecu stock minus exhaust and intake , super short tranny and would still get avg 24 mpgs.

310HPS2k

Ok it's not the iat sensor because those wires aren't it, and u found the iat and it's fully functional. I think the plug is for the fan switch? But that still doesn't explain the poor mpg...

I think I'll have to look for a p73, unless someone else has any other ideas assuming my ecu is fine.

DVDr

iTrader: (2)

what kind of chipped ecu do you have ?

ECtune
chrome
etc ?

might be worth reading the chip and seeing what the timming map is. But im pretty sure its mad advanced.

For DD purposes , the P73 will be your best bet.

http://cgi.ebay.com/ebaymotors/96-99...Q5fAccessories