tdbhonda

I've seen so many forums with this crank speed fluctuation sensor and everyone just debates and debates

im running a b16
when i run an obd2A p72 this code doesn't throw (54 or p1337)
however when i plug in my A to B conversion harness and run my p2t, my p2t throws the codes and puts my car in limp mode

1st where is the CSF sensor?
2nd does it plug into my wiring harness?

any help would be greatly appreciated

hondadriver

The crank fluctuating sensor is located on the OBD2 b-series and d-series oil pumps. I'm asuming you have a JDM b16a and not a USDM b16a2. The JDM motors do not have this sensor. Your options are

1st: replace your oil pump with a OBD2 one and buy the sensor and wire it in ( a alot of work)

2nd (easiest and proven it works) you can splice your ckf (crank fluctating sensor) wire to the ckp (crank positioning sensor) wire thats located on the distributor plug.

My first b16a swap into my 98 civic that i did years back, I didn't know about this easy mod, so I replaced the oil pump and bought the sensor so that I wouldn't throw the code with my p2t ecu. But 2 years ago I sold that b16a and bought a JDM gsr b18. And instead of replaceing the oil pump, I did this mod and have been driving trouble free for 2 years.

Heres a link with more proof it works:

https://honda-tech.com/forums/tech-misc-15/possible-bypass-crank-position-sensor-w-crank-fluctuation-sensor-1029958/

Basically you need to find/take the ckf wire that goes from the ecu and splice/solder it to the ckp wire on the ecu harness or run the wire up to the distributor plug. Its simple, i don't know the wire colors off the top of my head but you can search the wire diagrams on here or look through a haynes/helms manual.

tdbhonda

excellent thanks man

woudl this indeed cause my car to go into limp mode?

hondadriver

I never had to deal with that particular code because, when I did the swap I already changed the oil pump the first time and spliced the wire the second time. So i don't know if running without this sensor will cause you to go into limp mode. BUT, if the ONLY code your getting is for the ckf then the answer would have to be yes, Not haveing this sensor hooked up will cause the ecu to go into limp mode.

tdbhonda

okay i am running a jdm b16 with an obd2a harness... when i run an obd2a p72(gsr computer) the ONLY code i throw is 41... which is with the o2 sensor im not worried about that, i didn't even throw code 54(the CSF sensor)

when i ran the obd2a to b conversion harness and the p2t i WAS throwing code 54 AND code 22.... 22 ihas to do with vtec...
so i spliced them like ya said and now im RID of code 54
HOWEVER im still throwing code 22 (vtec)
like i said currently im ONLY throwing code 22 when i run the p2t

NOT throwing 22 when running the gsr p72

hondadriver

Ok I looked in my helms book, and code 22 is a vtec malfunction like you said and it says
to check:

-VTEC solenoid valve
-Open or short in VTEC solenoid valve circuit
-VTEC pressure switch
-Open or short in VTEC pressure switch circuit

I'm not to familiar with the p72 ecu so I can't explain why your getting different codes
with the ecu's. As far as the vtec malfunction, does your vtec solenoid have a oil pressure switch on it? Because my JDM GSR didn't have one and I through a code 22. So I had to bypass the pressure switch by splicing the vtec oil pressure wire together with the vtec solenoid wire.

tdbhonda

yeah i have two plugs on the vtec solenoid

im wondering maybe if there is crap like oil gunk stuck in the screen in the gasket of the solenoid and if the p2t is very sensitive to the oil pressure so since it isn't flowing properly its throwing the code... on the other hand with the gsr p72... it isn't as senstive to the oil pressure so with all the gunk in there it will just try to flow eventhough it isn't .... if you know what i mean

hondadriver

Honestly I highly doubt a clog screen would cause this code. I remember years back, My buddy had a 90 crx si with a 1st gen b16a, and he had a vtec code and for 4 mons we couldn't figure it out. We weren't to good a diagnosing electrical problems. We cleaned the solenoid, redid all the wireing. And one day we tryed a vtec oil presure switch from a buddys car and the code was gone.

So if your p72 ecu doesn't look for the vtec pressure switch then it won't know if its bad and wont throw a code. Since your p2t ecu does look for that switch its probably, letting you know its bad. So what I would do is, do another bypass deal like you did with ckf sensor and take the vtec oil pressure signal wire ( the black/blue wire is the ground) so its the other one, and splice it together with the green/yellow vtec solenoid signal wire. I did this and everything works fine. OR borrow a vtec oil pressure switch from someone and see if it gets rid of the code.

tdbhonda

so the pressure switch is the one with two wires?
also would the pressure switch cause my car to go into limp mode?

hondadriver

yeah the pressure switch is the one with 2 wires. As far as the limp mode part i'm not sure. I would think the CKF sensor would cause the limp mode instead of the vtec pressure switch. Because my buddy was reving his car up fine when he had the vtec code, he just didn't have vtec kick in. But once you get the 22 code solved you'll be good to go.

tdbhonda

alright... beacuse im still being shut off at 6800ish with the 22 code...
after clearing the 54 code

hondadriver

Oh ok. Well like I said, once you get that 22 code solved everything will be fine. Let me know what you find once you solved it!

tdbhonda

alright man thanks