bakrdkng

Long story short, i had a 97 civic hx 5pd given to me for parts. it had a hole in the block. i decided to get it running with my known good d15b7 i've had lying in the corner.

here is my setup:

d15b7 engine/trans
obd2a-obd1 conversion harness
p06 5spd ecu
obd2-0bd1 dizzy conversion harness
b15b7 dizzy

i swapped the injectors off the old y5 onto the d15b7 so i would not need to wire in the older style injector plugs.

other than that, all the other hx engine wiring harness connectors worked for the d15b7 sensors. i've got a firewall mounted d15b7 map sensor i'm using, and i kept the obd2 iat sensor and mounted it on the intake.

the vehicle starts and idles well.

however, under load it is sluggish and sputters and bucks. if you dont ease into the clutch it will often stall. i noted today that at a certain throttle postion it will chug and die out, but more so at this certain throttle position than any others. i figured tps. i swapped 2 known good tps and i still have the same deal.

above 3200 rpm the car runs great and pulls hard. its idle is smooth and steady.

im just frustrated and i can not find much info on swaps using the factory hx engine wire harness. any info from somone who has delt with these hx's would be MUCH appreciated.

would it be best to just get a ek dx 5spd harness and go from there? maybe i have a dizzy issue?

canadaek

First any check engine light? What are you using for an o2 sensor the hx has a five wire and might not wrk with your obd1 ecu/conversion harness (i dont know ecu code for a vx) so a dx/cx harness might be a good idea. Also you can pull the blue clip out of the injector plugs and they will fit obd1 injectors

bakrdkng

I'm not going to swap back to the d15b7 injectors and hack the tab off unless they are in fact different injectors.

the o2 sonsor is not hooked up right now to force open loop. forcing open loop will not cause drivablility symptoms with obd1.

any more ideas? i might go on the hunt for another ek ewh.

canadaek

you don't hack any thing they just un clip and you can always put them back on and no o2 sensor WILL always cause drivability issues .

bakrdkng

you are wrong sir, forcing open loop on obd1 hondas will not cause driveablity issues. the ecu uses a known good value for o2 and the car will run fine.

after further tinkering and reserch i found that the d15b7 runs great with the factory hx 5spd ecu. of course it throws a couple codes, but i did get it running well enough to drive.

to fix the issue completely i swapped in a ek non vtec 5spd ewh and used the obd1 conversion harnesses to properly run the d15b7 in the civic hx.


thanks for the help, well kinda... i figured i'd update this for others in case this swap is done in the future.

canadaek

then why would they put an o2 sensors on them ? it's for emmisons and fuel economy and will effect drive-ability what do you think the long and short term fuel trim is for ? there are lots of things that effect the air/fuel ratio and you can't make a table to cover them all

bakrdkng

I'll update this thread for the archives. the car has since been sold to a friend and is still running great 2 years later!

The b1 o2 is there for strictly emissions requirements to monitor stoicheometry .. ya i cant spell.

and yes, you are right, bank 1 o2 sensors will cause driveabiliy problems under closed loop operation. but ONLY in closed loop. (especially in german cars using bosch engine management ) however, with the 02 disconnected on a obd1-2 honda the ecu reads 5v (signal) or open circuit. i knew it was not being caused because my symptoms were the same on warm up wich is also open loop. this value, (5v) is read internally through the transistor board as a open in the o2 sensor circuit and the ecu will automatically go into a open loop. when the ecu reads "open in 02 sensor circuit" a known good "tune" curve that is imprinted into the ecu operates as a fail-safe. open loop.

open loop will still take into account iat, coolant temp, tps, etc and will adjust itself accordingly. try it, disconnect your b1 o2 (to force open loop) and then play with the coolant temp sensor circuit. with the engine at operating temp, you can disconnect the cts and the idle will jump up because the ecu will think the coolant is cold, even in open loop.

this is often a "mod" that was used in the past on our obd1 hondas as well when chipping/tuning ecus. many people would just do away with closed loop operation so o2 sensor input will not affect someones tune map. disabling closed loop operation often will give a bit more power than open loop as well, even if your car is in stock form.

in my case, i kept the o2 disconnected for diagnosis. i knew my drivablitiy problem was not caused by the 02 sensor, so i forced open loop to aid in diagnosing the problem. the problem ended up being crossed wires in comparision to the 96 hx and all the other obd1-2 5spd ecus. i dont remember if it was the tps or the map. it was either of those. I figured this out by comparing pinouts for both the 96 hx ecu and the 96 dx ecu. so i could have just switched those two wires to fix.

i ran this car just fine using the factory hx harness, using the factory hx computer. however, there were alot of loose ends and connectors. and i wasnt using the weird hx 02. it was kind of hacked it seemed but it did run good.

i wanted it to be set up as basically a ob1 d15b7 for future diagnostic simplicity.

in the end i ended up getting a nice un-cut non vtec obd2 engine wire harness from the junkyard out of another 96 civic. I then ran the factory p06 ecu with a jumper harness and used the oem ek (non hx) 02 sensor.

the car still runs perfect, 2+ years later.

WhiteyMcBigNose

What codes were you throwing with the HX harness? Just the simple cam/crank position sensor and EGR fault? I'm looking to do this exact swap on my 97 HX just to get the thing on the road