recently swapped in a b16a4 in my 99 civic ex... when i had my stock d16 motor i get a average of 25 miles per gallon totaling around 275 miles to the tank. which is pretty low for a civic... but now since i swapped in the b16 im getting like 10-15 miles to the gallon which is even worst...

what might be the problem

as of now...
the car has an exhaust leak, coolant leak...

the sparkplugs were replaced, so was the oil as well as tranny fluid... let me know on what might be the problem

 

Well based on your other post the coolant leak is on the TB. Could it be related to any idle components? If so how is your idle?

Also where is the exhaust leak? it could be affecting o2 readings and running you rich.

 

Is the CEL ON?

The exhaust leak may interfere with the ability of the O2 sensor to send correct information to the ECU, causing the engine to operate at non-optimal air-fuel ratios. Bottom line - fix the exhaust leak as it may improve your gas mileage.

 

fuel filter maybe??

 

cel is on, the coolant leak is fixed now.. the exhaust leak is probably comming from the collector on the cat... i do have a bad o2 sensor on the header... and yes the car is running rich... i see white smoke and it smells like gas

 

...so fix your oxygen sensor. You know what that does, right? It tells your vehicle how much gas should be going into each cylinder per cycle. If it's not functioning properly, your car just guesses with its safest parameters - super rich.

 

bump

 

It sounds like you have got more than just an exhaust leak. White smoke means you have got water/coolant in your combustion chamber. PERIOD! that means one or more of the following: bad head gasket, cracked block, cracked head. Hopefully just the head gasket. The fact that you have water in your cylinders means that you are getting an incomplete burn, causing a high level of unburnt fuel (HC) and a high level of O2 flowing through your exhaust. The computer will try to compensate for this by dumping fuel into the cylinder, which onlyu serves to make the problem worse. More often than not O2 sensors are the symptom of a problem rather than the root cause. Look for the water in your oil. also, put a voltmeter on your o2 sensor, money says that it reads less than .3 volts. I'm very interested to hear what you find. Hopefully I was of some help

 

what you said was right, i just found this out yesterday, i actually found another coolant leak other than the 1 i already fixed, its comming from near the heater hose inlet on the block and is leaking probably from the head gasket, the car does burn either fuel or coolant because my rear bumper is like dirt black from the fumes, there is white smoke comming from the exhaust also... what would you suggest doing... i was going to buy a vafc to see if that would work. b/c i just thought it was a bad tunning.... for sure im going to fix the head gasket, hopefully only just the head gasket.... i was trying to figue out a way to run w/o the o2 sensors, will the vafc fix that?

 

would be kinda nice to know the history of the motor too. i know it's not always possible, but some preventive maintenance can help. i wouldn't buy the vafc just yet. i've changed things before dropping in a motor like clutch, manifold gaskets, seals, head gasket, fuel filter/ pump, exhaust piping etc. although some problems also can't be diagnosed until the motor is put in. good luck hopefully it's nothing internal.

 

ok i recenly bought a new headgasket and the vafc.. .. im in process of replacing the head gasket right now but the vafc will have to wait untill i get my obd2b to obd2a jumper harness...im running a jdm / emd motor so i dont have 2 plugs for vtec so i dont have vtec right now... i got a jdm si ecu but its obd2a so yea...


bump