Civic EG

Alright so last weekend I swapped a Jdm d15b into my sedan, runs like a top doesnt skip a beat , nothing, heres the problem, its a PIG on gas, I got 150 kilometers on half a tank of gas, there is no check engine light on or anything, no smell of gas, or leaks, What possibly could be giving me such shitty mileage, when you rev it or drive it hard, it sometimes gives a puff of black smoke, which to my knowledge is unburnt gas, Im running it on a po6 ecu. I dont know whats wrong, im stumped, any suggestions.

D15b only has 50k on it

sometimes an 02 sensor can be going bad, but not bad enough to throw a CEL. a poor alignment can decrease mileage too, if you had the front end apart for the swap. And you're sure you hooked up all the vac lines correctly?

would timming affect the gas? running extremely rich? yeah the O2 sensor is probably the big one .. have the right ecu? my 3 pennies

yeah, Ill try switching my oxygen sensors, and vacuum lines.

You running a cat?? If so how many miles are on it?? Honda cats are designed to only go about 80,000 miles. Yours might be getting clogged, that is if you have one.

yeah im running a cat with like 315 thousand ks on it.

you should probably get a new one then or...delete it

Yeah im cutting it out, I can weld, so anything is possible, Does anybody know where i can get an aftermarket cam for a d15b, non vtec?

my old hatch was a pig for a 4cyl as well, yeah it was an auto, but the most i ever got out of it was 520 highway km's, but on normal driving i'd be lucky to get 400km's from a full tank

puff of black smoke is oil. any fuel entering into the exhaust would vaporize and create that pop you see on some cars.
I would change your cat also, it's probably really fucking around with your readings and like many have already said o2 sensors don't necessarily throw a CEL when there bad.

Could be oil but most likely it's gas. Check your fpr and the vacuum line. Did you use the injectors that came with the engine? They're usually clogged up pretty badly from sitting on the docks before they're shipped over. They'll just squirt a stream instead of a spray.

It's not the cat, although if he continues to drive it that way he will destroy the cat. Don't replace it until you've fixed the problem. And don't run w/out it unless you don't mind having the EPA crush your car. It happens all the time and there's nothing you can do once they've caught you. Besides that it hurts low end power, makes your exhaust smell like eggs, and it sounds very raspy.

Just because your dash doesn't show a CEL doesn't mean your ECU hasn't stored a code. Try retrieving the codes.

Its not oil, now the car doesnt burn anything, nothing, off rev limiter not a puff of anything, could it be shitty injectors?

-EG8- wrote:Its not oil, now the car doesnt burn anything, nothing, off rev limiter not a puff of anything, could it be shitty injectors?

Did you take the cat off??

suspendedHatch wrote:.

It's not the cat, although if he continues to drive it that way he will destroy the cat. Don't replace it until you've fixed the problem. And don't run w/out it unless you don't mind having the EPA crush your car. It happens all the time and there's nothing you can do once they've caught you. Besides that it hurts low end power, makes your exhaust smell like eggs, and it sounds very raspy.

Where he's at they don't have emission regulations, so i don't think he has to worry about it being crushed lol