Knock Sensor

Loach505

Loach505

New Member
Joined
Sep 30, 2022
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14
Location
Santa Fe, NM
I've got a 1990 Jeep YJ with an AMC 258 I6 that I'm rebuilding.

For the life of me, I cannot seem to find a new Knock Sensor for the darn thing.

Everywhere I look online presents me with parts for other cars entirely.

Any idea where I can get a good Knock Sensor?
 
ever hear of rock auto. and see the blue pages, (means top quality) ouch NONE listed, SMP ecat, NONE listed.
the jeep dealer has none, I'm sure they told you that,
most dealers of all cars this old tell you that.(blush)
it is 30years old now. I see they are mostly GONE now. 4.0L: yes sold $$$$, 4.2L: no.
I tell you the oem part number out of the 30 year old parts book is that will help, so here it is. 4.2L only , 4.0 liter is not the same part.
other forums/ have no simple solution:

its 4.2L I-6, and has carb a right?, (a key factor) and yes has CARB computer (a horror) and 1 O2 sensors and 1 knock sensor yes.
unless your cars carb was (nutter bypassed alread) see and of page how.

so run with out it, it only prevents PING. (it is really a microphone that lets the carb-puter hears ping before you do and retards spark to end it.(safely)
(ping/knock/detonation) is never good, so...
or goes richer to end it, IDK at all how it does that. and do not care about carbs now.
the carb has a mixture control stepper motor on the side of the carb, called C2BBD. for mixture control needles.


knock.JPG


also google 4.2Lor see it here nutter bypass ,knock./

i call it the wackynoodle bypass. ( or go any old carb , tuned by you to this engine) 2 steps to bypass C2BBD, is crazy. (using fixed needle tricks)

how about he motorcraft 2100 carb.??? (no puters) he got the carb off of a 77 cj 5 with a 304.
 
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worst of all is the 33000902, also new numbers. 33000902
is lame. it is mounted to intake manifold (bad idea) and then if lifters make noise! , spark is retarded. 15degrees., this is post by others that cured it.
run premium fuel and unplug it.
 
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now smog, what does NM require for smog test, visual, _ roller test (IM240_ and sniffer yes to sniff,
"and this Vehicles registered in all areas of the state outside of Bernalillo County are exempt.
NM DOT says 1989 and up.
A tailpipe exhaustion analysis on vehicles manufactured between 1983 and 1995."
in some states they may fail you seeing, carb hacks , KS missing and the like. (calif will)
mc2100 is best fix. (no stinking puter carbs)
amC sensor KS136 not sold now. I asked SMP what year the last one was made. must be 10 years ago, the wayback machine,fails to see data that deep;
I see googled posts back to 2010 can't find spare sensors. even KS136
RIP, C2-BBD carbs.
 
no, not saying not necessary
just unplug it, see if it pings
if does, go High Octane fuel, or try to retard spark. (at the DIZZY)
this year car know the new sensor can even hear bad HDA or BAD Lifter racket, to there is that pain, cured in 1991.with TBI or MPI.
there are no sensors sold now.zero. (www endless searches, none) 4.0L yes not yours.
so is moot point right lacking one ,try running it missing.
the PING happens if engine is lugged, (using wrong higher# gear than should be (is this manual trans M/T)>?
first things first
did you examine all wires to the C2BBD CARB AND SEE IF ALL MAKE IT TO THE PUTER, UN DAMAGED, (NOT CUT WIRES/)? THAT BE FIRST.
VAST JEEPS 4.2 HAVE BEEN HACKED NOW. looking first is what is done,.
the dizzy (distrib)
FSM pages, on timing dizzy 4.2
chapter 8D page 49 covers it
if engine pings. lower the static time say 2 degrees and then see if PING ends, (if happens at all)
it even states in the FSM to ground out the KS sensor,so static time can be, set, and vacuum advance defeated.
did you miss the free book in the sticky here/ PDF for free /89/90
do not read pages before 8D-29 those are for MPI/TBI engines NOT YOUR,your car is model code 80/81 wrankler, ignore all non Wrangler pages.
the cars hood sticker (under it look up) see EPA tag ,shows spec, static advance. in degree's.

wrangleryjforum.com

STICKY - Jeep Wrangler YJ Factory Service Manuals (FSM) and Part Catalogs

I thought that this might be helpful to fellow YJ owners to make one sticky resource thread with all of the original factory service manuals and parts catalogs for 1987-1995 Jeep Wrangler YJs. If you have anything I'm missing, please feel free to post them in this thread and I'll add them to...
wrangleryjforum.com wrangleryjforum.com

there is no CKP sensor on this car, nor to the engine computer. at all]
the dizzy does it all (and tiny bit via ECU.,,
this distrib is set at 1600 RPM for hood sicker spec, label RPM with a tool called a timing light. vacuum adv. pulled and plugged hose.
page 38 below,
degrees.JPG

the rumor is the KS sensor can retard spark 15 degrees. and is not covered in the FSM. so is unknown.
it's purpose is to run REGULAR gasoline the cheap stuff.
a car this old gee, i'd have already tested the vacuum advance by hand vac,pump and the centrifugal too. they love to rust up and jam and MPG goes to HORRID.

that is about all.(the book covers all tests just told)
 
this sensor loves to make folks angry, ( justified)
it was designed wrong.! 91 is the cure.

on the intake manifold it does not belong there. it hears valve noised and goes nuts (the intake plenum box i bet acts as a nasty echo chamber)!!
one if the tests in the FSM is to ground out its KS output pin, to do dizzy timing tests.

this kinda hints at what to do, (keep it grounded out (jumper) and time the dizzy the old fashioned way to find ping point and the back off a few degrees
like we did from 1920 to 1985, (zero EFI)cars.) did mine that way in 1964, a chevy 1961 283 v8
we had test drive it on a hill , and lug the engine on purpose,then back shop, and lowered the advance,2degr at try.

pick a fuel grade and stick with that and turn the dizzy for max advance and no ping.(we called it the ping point)

the book even warns us, the KS must be set to spec,torque (wrench) or it fails hard. clear as day stated, and now gone it is.forever and ever. gone.
none sold.
that is what I'd do for sure.
 
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