Knock Sensor - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Reply
 
 
 
Thread Tools Search this Thread
Old 09-26-2005, 02:03 AM   #1
Senior Member
Posts like a Turbo
Thread Starter
 
Join Date: Jan 2005
Location: Pawtucket, RI
Posts: 333
Thanks: 0
Thanked 0 Times in 0 Posts
LuxuriesPremier is on a distinguished road
Default Knock Sensor

Where is this device located and how can you tell if it is bad? Can your car run without it? Pictures are good....
LuxuriesPremier is offline   Reply With Quote
Old 09-26-2005, 02:48 AM   #2
Senior Member
True Car Nut
 
Join Date: Mar 2004
Location: Ames, Iowa
Posts: 3,066
Thanks: 0
Thanked 1 Time in 1 Post
bill buttermore is on a distinguished road
Default

My Factory service manual for '95 shows the L67 knock sensor on the back of the engine to the left and above the oil pressure sender. The single wire for the knock sensor comes out of the same sheath that runs to the vehicle speed sensor on the transaxle. The knock sensor is threaded into the engine block, with its face immersed in coolant. If you disconnect the wiring to the sensor, the PCM will set a check engine light, (code P0325) and will retard the ignition timing of the engine by 10 degrees to help prevent damage from detonation that it can no longer detect.

The car will run if the sensor is broken or disconnected, but should set a check engine light and will be very sluggish, especially noticeable when you try to accelerate rapidly.

Check the wiring to the sensor first to make sure it is OK. Squeeze the oval-shaped connector into a circle to remove it from the sensor.

Resistance measured from the output pin of the sensor to ground should be around 3.9Kohm. You need sealant on part of the threads to keep the coolant from leaking and the sensor from rattling, but the threads must be able to make an electrical ground with the block, and the end or face of the sensor must be clean to "hear" the knocks clearly.

Without a scan tool, you can unplug the wire to the sensor, and connect a voltmeter set to measure a couple of volts AC on the output pin and ground. Tap on the engine block and watch the meter, it voltage is produced, the sensor is probably OK.

If you have a scan tool, set it to show KS count and strike the engine lifting ring - this should cause the sensor to register a knock shown as an increase of one count on the tool.

The face of the sensor immersed in coolant can get covered with sludge and become less sensitive, and they can just fail. They should be torqued to no more than 14 ft-lb if you replace it. Overtorquing makes them oversensitive and can destroy them.
bill buttermore is offline   Reply With Quote
Old 09-26-2005, 03:07 AM   #3
Senior Member
Certified Car Nut
 
Join Date: Oct 2003
Posts: 19,756
Thanks: 0
Thanked 0 Times in 0 Posts
1993 SLE is on a distinguished road
Default

there are 2 one in the front of the engine and one in the back....some one will chime in with a pic im sure
1993 SLE is offline   Reply With Quote
Old 09-26-2005, 10:25 AM   #4
Senior Member
Certified Car Nut
 
Join Date: Mar 2003
Posts: 12,432
Thanks: 0
Thanked 0 Times in 0 Posts
J Wikoff is on a distinguished road
Default

I'm starting to think knock sensor location depends on who put it together. Some say on the back near the oil filter, some say on the front above the starter. My 92 L67 has one on the rear, the 93 SE parts L27 has one above the starter. It goes back and forth from year to year.
J Wikoff is offline   Reply With Quote
Old 09-26-2005, 11:04 AM   #5
Senior Member
True Car Nut
 
Join Date: Mar 2004
Location: Ames, Iowa
Posts: 3,066
Thanks: 0
Thanked 1 Time in 1 Post
bill buttermore is on a distinguished road
Default

Quote:
Originally Posted by jwikoff99
I'm starting to think knock sensor location depends on who put it together. Some say on the back near the oil filter, some say on the front above the starter. My 92 L67 has one on the rear, the 93 SE parts L27 has one above the starter. It goes back and forth from year to year.
Yeah, it can be confusing. My '95 FSM shows:

Series I L67 with one sensor in the back near the oil sender; threads in parallel to ground.
Series I L27 with one sensor in the front towards the middle of the water jacket; threads in parallel to ground.
Series II L36 with two sensors front and back middle of water jacket; thread in perpendicular to ground.

And if I remember correctly from my '97 SSEi,

Series II L67 same as L36

I'm hoping someone will correct me if I am wrong.
bill buttermore is offline   Reply With Quote
Old 09-26-2005, 02:32 PM   #6
DINOSAURUS BOOSTUS

Expert Gearhead
 
BillBoost37's Avatar
 
Join Date: Mar 2005
Location: Enfield, CT
Posts: 41,391
Thanks: 0
Thanked 0 Times in 0 Posts
BillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of light
Default

Jay...

You believe you have an exhaust leak in the front manifold, possibly catalytic converter etc.

Please address these first. A plugged cat will rob you of power. Once you get the cat straightened out and have fixed any other leaks, then testing the sensor(*) would be a good idea.
BillBoost37 is offline   Reply With Quote
Old 09-26-2005, 05:42 PM   #7
Junior Member
Posts like a Ricer Type-R
 
Join Date: Aug 2002
Posts: 10
Thanks: 0
Thanked 0 Times in 0 Posts
willwren is on a distinguished road
Default

Fix all known problems first. And confirm them before spending any money. Do NOT shotgun parts. You'll pay through the nose.

And take that pulley OFF the car until it'* running correctly. It has a GOOD chance of making this worse considering the problems you currently have.
willwren is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
knock knock knock L27Buick 1992-1999 7 09-17-2004 04:23 PM
Knock Knock continued (spun bearing) Spiral 1992-1999 5 05-25-2004 09:57 AM
Knock Knock, engine knock? Spiral 1992-1999 5 05-23-2004 10:08 PM
KR without Knock> Not even false knock? streetracer Performance, Brainstorming & Tuning 1 08-18-2003 02:08 PM
Knock Knock Tamara 1992-1999 11 01-31-2003 05:26 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 06:42 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.