Hatch Man

hey guys, i recently finished having my b20v (b16a CRX si head) (b20b high comp) dropped in, installed, and tuned, but im running into a small problem.

so, the gist of it is this....

i found out my coolant temp sensor and vtec sensors were swapped, accidentally, and when they were swapped, i lost all check engine light codes, except now i get a knock sensor code shooting after driving for about 2-3 miles. however, the code goes away when i restart the car- when i warm up, and drive away, it comes back on about 2-3 miles down the road- rinse repeat....

i dont hear any knocking, and my tune calls for 91+ octane, but im using 93 ALWAYS.... is there any tricks / tips / suggestions anyone may have??

i've searched far and wide, but found nothing in regards to this.


little more technical specs

em1 obd2b harness
99 ek obd2b dash harness
obd1 p72 (chipped/tuned) w/ obd1->obd2b jumper
b20b block w/ KS
1989 b16a head
rdx injectors
obd1 alternator

im not having any other issues with the car, except for the knock sensor CEL that comes and goes.
open to all suggestions but i dont wanna buy another one if i dont have to.

any sort of tests i can do? its a pain in the *** to get to, so getting continuity might be tough, and pulling it off it a last resort kinda deal, im sure you guys can understand.

egsleepercivic

it is a wiring or sensor issue, if there was knock the ecu would pull timing not trip the CEL

Also im surprised it is even throwing knock sensor code, usually chipped ecus disable the knock sensor

Hatch Man

yeah, I kept the knock sensor enabled, since the block had a sensor in it, and wasn't swure if it would shoot a code for emissions / whatever... any thoughts as to what I should do? again, it only springs the CEL about 5 mins after being on the road. Could I rule this out from being a wiring issue, and point it towards a sensor issue??

egsleepercivic

check the jumper to make sure there is a wire at d3 on the obd1 side of the harness

then check its in the right spot on the obd2 side, it looks the rest of the wiring in your setup is factory

egsleepercivic

any luck? updates?

Hatch Man

hey Egsleepercivic- sorry about the delay in reply...

basically.... i havent gotten around to checking it lately.

since i work at a honda dealership, i decided to ask a few techs on their take take, today- they mostly said to just replace the sensor. The other guys said it may be a bad tune, which i have a hard time believing, because it was tuned by a very good tuner, and im not sure how the tune would affect it....

i kinda forgot that i purchased the b20b block that already had the sensor on it, and whoever painted the block painted on the sensor too, so i feel its an old, worn out sensor...
-i also get the feeling i can rule out the wiring issue, because the CEL doesnt stay on indefinitely-, where its intermittent... basically, it only turns on while im actually driving- maybe 7-8 mins of driving, and after warming the car up to operating temp for about 5 mins.... so it doesnt come on while warming up- only while driving.

to my understanding the CEL wont shoot if it detects a knock, too- it will do all of the retardation and limp it out, should the sensor detect knock without shooting a code (can someone verify this??)

so at the moment, im deciding whether or not to buy a new one. since i work at the dealership, i get a discount on parts, and the parts guy i work with said its gonna be $155 after discount =///

honestly, since im still on a good basemap, im thinking i MAY just end up taking my car to the dyno for the first time, and having the sensor disabled, and getting the car on its real tune.

400 for a tune and sensor disable, or 400 for a tune and +155 for the sensor....

any thoughts / recommendations?

94 Civic Si

Were your harnesses originally equipped with wiring for knock?

I ask because @wxman94ej1 discovered some important info about Honda using shielded wiring for knock: https://honda-tech.com/forums/honda-.../#post51324737

egsleepercivic

I got my replacement knock for my b16a from advanced, lifetime warranty for 69 with online order store pickup coupon, no cel since I installed it

EM1 hareness had factory knock

I don't think the ECU looks for the sensor until its warmed up open loop \ closed loop thing I believe.

I would still check the jumper harness the Knock might not be pinned.

Hatch Man

dumb question: would this sensor, being bad, or broken, or unpinned------- would this reduce my power output??

the tune on my ECU is set for 91 octane minimum, and is always, again 91-93.

i drew a diagram of the pins im supposed to look at, so i will check and let you kind folks know about the harness / converter!!!!

thanks gent,s ill letcha know

94 Civic Si

I am not sure what the ECU does if it does not think it has a valid knock sensor attached?

I would guess it trims timing?

Hatch Man

alright guys, so i just found out by my local tuner that my basemap, while running conservative / safe, had advanced timing too much, which was causing the knock sensor to trigger after warmed up.

getting it on the dyno in the next few weeks to get some numbers as she sits now, dyno tune, and then street tune and then dyno charts. hopefully all will go well

egsleepercivic

really surprised by this, the manual only has you trouble shoot voltage and continuity

Hatch Man

hey again EG, thanks for the fabulous reply and doing my homework. I wish i could conduct this series of tests, however as much of a badass i think i may be, i dont believe i can get this done.
Next week i will be getting my car dyno tuned, and the KS will be disabled via Neptune.

I am confident that the tune will make things go much better for me, as i am only getting 200 miles per tank of 91+ octane, which was one of the things i ended up pulling the d16 for (amongst a thousand other problems).

right now i am running a conservative tune, which is running richer than i'd like it to be running. I believe i am sitting around 12:1 AFR which is way too rich- im even running a high-flo cat, and it still reeks, so until then, ill just have to deal with the ordeal that is my knock sensor which is tripping out. I am 94.1212%(repeating) certain that the motor is not knocking, as it is a fresh build, and it is tuned for 91+. i did notice i do get a little bit of a backfire / spuddle when i let out of throttle above 4500 in 3rd or 4th. im sure thats pretty normal for a b20v with around ~10:1 compression and a ~12-13:1 AFR, a 4-1 header and a 2.5" setup front to back.

thanks again for all of your help and advice.. i just cant wait for the real tune, and off the basemap!!!