I have swaped a d15b in my 1992 honda civic and it is getting 5 mpg. No Joke. I have 10in. of vaccum line pressure and the wire harness i have hooked up to it is for an American V-tec not JDM. So there is one plug behind the intake that does not go to any thing and the ECU is JDM. Please Help me, I kill myself at the pump.

 

Oh my god. This seems so outrageous I'm inclined to ask if you're sure that you're getting 5 mpg? If you really are, have you checked to see if you're shooting fire and smoke out the back of your car, or if you're leaking obscene amounts of gasoline onto the ground underneath your car?

Seriously though, I would check for a fuel leak or something, because 5 mpg just seems ridiculous for a wiring problem. I've got a JDM D15B VTEC in my car, and I ran it on my stock DX wiring harness and the JDM ECU with no problems at all. As for the plug, if we could get a picture, we may be able to better help you out.

 

Are you saying your getting 10 inches of vacumm from the engine??

 

No, no fuel leak. and the timing is not the problem either. I was told that the engine might be going into a fail safe. Spraying a pissload of fuel into the engine to cool it down insted of going lean and burning a hole in the piston.

 

yes 10 inches of vaccum from the engine.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by simond15b &raquo;</TD></TR><TR><TD CLASS="quote">No, no fuel leak. and the timing is not the problem either. I was told that the engine might be going into a fail safe. Spraying a pissload of fuel into the engine to cool it down insted of going lean and burning a hole in the piston. </TD></TR></TABLE>

Do you have a CEL?
And what d15b motor did you swap in, and why? a d16y6 would have been a better choice compared to say, a d15b7 (if thats whats in)

 

the vacuum is very low, as you have said you have an open port in the back of the engine. plug it. it is a massive vacuum leak, and the computer adds fuel for the false secondary air it sees. plug the vacuum leak. how does the motor run is it smooth or is it struggling to run, how is the idle. it almost sounds as if an injector is stuck open. this can be mechanically stuck open or electrically.

 

careful...my d15 did that once but it was kinda weird....i was driving and all of a sudden i kinda feel my car choke...didn't think much of it...got on the freeway and just watched my gas gauge go down, no smoke or nothing...comes to find out my injector was stuck open...it filled my WHOLE intake manifold with gas....

 

an easy way to trouble shoot the presence of a fuel leak that is internal, as in either an injector leaking, [not electrically] or a bad pump check valve, or a bad pressure regulator. run the car, shut off the car, wait 10 minutes, crack open a fuel line on the pressure side, such as the filter, or at the rail, unless you can find the test port to poke the valve. there should still be a gush of fuel, if not, then you may have found the track to follow. generally when an injector is mechanically bad, you can run the car, shut it off, wait 5-10 seconds, then restart, and it will stumble, or struggle, or just take long to start, due to the fuel that accumulated in the intake while the car was off because of the residual pressure.

 

The car's idle is a about 1000rmp and does not seam to struggel. The distributor is advanced all the way to keep it idling though. Can a bad injector really give me that bad of gas mileage?

 

What is on an American D-series on the back of the intake manifold area that is not on the Japanese D15b??? I do have the correct ECU. I just have an American wire harness which is idential except for one little plug that is posistioned behinf the maniflod that has no where to go?

 

if the dizzy is fully advance and it runs like crap, i assume you bean if you retard it at all it wont run, or gets worse and then wont run, fully advance timing indicated that mechanically something is astray. for you to need to advance the ignition, that means its normal setting is retarded. keepin mind that reguardless of you adjusting the ignition timing, this is an indication of the relationship between the cam and the crank is off. this caould be caused by a slipped belt, or that in the past the head or block was machined, thus decresing the distance between the cam and crank is smaller, so the cam is actually retarded. advanceing the dizzy only helps the ignition, not the valves them selves. i would reccomend take off the front timing covers and check the alignment of the marks of the cam gear when the crank is at the specified spot. this will let you visually see if it is off, and how much. before you can fine tune the idle, the engine mechinical basics need to be adressed.

 

before i get into timing, if i took out the injectors could i visualy seen if an injector is bad???

 

if the injector is mechanically bad, you should be able to remove the rail with all 4 injector attached to the rail, and the fuel line still attached, key up the car to position 2 for a couple seconds, then look at the injectors, if any are leaking, they will be leaking then. but also verify if one is, that there is no full circuit of power to the injector to ensure its not getting shorted to turn it on. meaning, if you unplug the leaking injector and it stops leaking, its a wiring issue, if it still leaks, its the injector.

 

That means your spending about .75 cents every mile you drive. That sucks man. GL on getting that fixed.