sleepyS14se

Ok so i am in the process of doing a 5 speed swap as well as a new ka24de while we are doing the conversion.

I got curious and i looked up whether a 95 240 is a obd1 car or 2.

I came up with conflicting info.... Keep in mind i am unable to inspect my 240 because i am at work now. ( i spent saturday and sunday rebuilding my whole ka24de which is now done..but some things popped into my head.)

i notice that i got a whole 5 speed engine harness with the swap, well the plug that goes INTO the ecu is White (which seems like from my online reading is a obd2 harness...I also have a matching ecu.
SO, what problems am i going to face when i install this badboy into the 95 s14? being my car MAY or may not be a obd2.

here is my list of facts and unknowns as of right now
the engine swap i received has a ONE wire UPSTREAM o2
the engine harness has a big white connector that goes into the ecu
my 240sx may or may not be obd2 i havent checked yet.
the old engine thats still in the car has no exhaust manifold so IDK how many wire upstream o2 it had to begin with.


I will inspect my 240 after work but i am curious if anyone has some info regarding DEFINITE way to figure out what is obd1 and what stuff is obd2



Side note: i noticed that the harness has a huge grommet that appears to would pop into the firewall to seal the hole. I am thinking this harmess when it was removed went from the engine itself and down through the firewall and plugged into the ecu. if thats the case then i will install it that way... but will any obd1/2 issues occur??

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95 S14 se RB25DET 348whp

sleepyS14se

seems as if my engine/trans i got is obd2,

it has a white ecu plugs
it has a little baby sensor on the to[p of the trans housing i am guessing is a CAS.
but the exhaust mani only has a single wire o2




Now being my car is a automatic...and i assume is obd1.. what harness do i use? the harness that Came with the new engine/trans...or do i use the auto one and cut off the auto plugs?

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95 S14 se RB25DET 348whp

jr_ss

This belongs in the small questions thread, please learn to use it.

All 95's are OBD1

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My SR20VET

sleepyS14se

i dont see a "small questions" forum...


i guess if anyone has any ideas i would sure love to hear em'

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95 S14 se RB25DET 348whp

idlafie

WARNING!!!...LOOOOONG POST...Read at your own risk!!! Hahaha...

OBD-II is a system used in automobiles to monitor various components of the vehicle, detect malfunctions, and store the information in the vehicle’s on-board computer to be recovered later by a service technician. OBD-II is an acronym for on-board diagnostics; the “II” denotes the second and most current version of this technology. Beginning in the late 1970s, vehicles sold in the United States have been equipped with electronics to control various systems and diagnose malfunctions with the goal of minimizing pollution. This came about in response to Congress passing the Clean Air Act and establishing the Environmental Protection Agency (EPA) in 1970. These electronics varied between manufacturers and model years, making the retrieval of diagnostic information potentially costly and time-consuming.

In 1988, the EPA and California’s Air Resources Board (CARB) mandated that vehicle manufacturers include self-diagnosing programs to ensure that their emissions equipment would remain effective for the vehicle’s service life. The Society of Automotive Engineers standardized a connector plug and a set of diagnostic test signals. Upon equipment failure, this system illuminated a malfunction indicator light (MIL) on the vehicle’s dashboard, often called the “check engine” light. This system, required in all 1991 and newer automobiles, became known as on-board diagnostics I, or OBD-I.

CARB studies soon concluded that OBD-I systems would not detect emissions components unless they completely failed, and that in some cases the vehicle could still pass an emissions test. New laws and requirements went into effect on 1 January 1996 - the standard adopted for OBD-II. Every vehicle built for sale in the U.S. from that date is equipped with OBD-II.

Your 95 S14 is OBD II compliant...which means your S14 is OBD II. Nissan VOLUNTARILY began installing OBD II equipment on all 1995 model year cars in preparation for the 1996 cutover to OBD II standards.

Now the reason WHY you have an ONE-Wire Oxygen sensor is because you probably have a February 1994-July 94/95 production date on your S14 model year car. I don't recall exactly when during the 95 production month that Nissan switched over from the one wire O2 sensor to the three wire O2 sensor - three wire O2 sensors are found in ALL 1996 model year S14's and some LATE model year 95's. The one wire O2 sensor basically sends the signal to the ECU. The THREE wire O2 sensor includes a heater circuit & ground circuit in the O2 sensor. The three wire O2 sensor uses a heated circuit in the O2 sensor to help monitor & control emissions better especially during "cold" starts - when most smog / vehicle emissions pollution is generated. 1997-1998 S14's switched over to a FOUR wire )2 sensor. I think Nissan threw in an extra ground with the four wire O2 sensor - not sure -you'll have to double check.

If you have an early production 1995 S14, (Feb 94-July 94), you will find the OBDII plug in connector port on the PASSENGER side of your car by the heater area. If I recall correctly it's a white connecter just underneath the center console area...kinda hidden but easy to spot when you are looking underneath the passenger side dash by the heater area. Later model production S14's, (after July 94/95 - don't recall exactly when Nissan made the switch), you can find your OBD II connector port underneath the dash on the DRIVER side by the hood release.

Any, hope this answers your question regarding your S14. If you have any more, feel free to post & PM me.

ID

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Weekend Mechanic for my Not-So-Mechanically-Inclined buddies....

idlafie

Since you are doing the 5 speed swap and are switching out the Auto ECU for the MANUAL ECU, put the harness that came with the engine/tranny. Just make sure to check the wire for the O2 sensor to see if it is one-wire, three wire OR four wire & get the appropriate O2 sensor.

You might also want to check your Throttle Position sensor. I BELIEVE the Auto Throttle Position sensor will not work with the Manual Harness. You may have to get a Throttle Position sensor that will work with your Manual Harness.

Good luck...hope everything works out...

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Weekend Mechanic for my Not-So-Mechanically-Inclined buddies....

sleepyS14se

well the new ka24 came with a complete manifold (intake) and it has its original tps (5speed) so it should be ok...

it has no downstream o2 and it has a one wire upstream so it is a obd1!

this coming saturday we are installing the engine/trans and putting the 5 spd pedals in

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95 S14 se RB25DET 348whp

sleepyS14se

ok the UPSTREAM is one wire and the Downstream is 3 wire....WTF? is this still considered obd1?!?!!?

on hondas/toyotas obd1 had NO downstream o2... im confused as f now.

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95 S14 se RB25DET 348whp

idlafie

Didn't you read my post??? Your 95 S14 is OBD II compliant...which means your S14 is OBD II. Nissan VOLUNTARILY began installing OBD II equipment on all 1995 model year cars in preparation for the 1996 cutover to OBD II standards.

Still don't believe me?? Click on the attached link to verify....
OBDII - On-Board Diagnostic's System - Does My Car Have OBD-II? The Connector and Communications.

Hope this unconfuses you....

ID

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Weekend Mechanic for my Not-So-Mechanically-Inclined buddies....

sleepyS14se

i am very clear on what obd1 and 2 is. but i have had several seasoned s chassis owners tell me it is obd1.

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95 S14 se RB25DET 348whp