Go Back   Blazer Forum - Chevy Blazer Forums > Mechanical & Maintenance > Engine & Transmission
Sign in using an external account
Register Forgot Password?
Search


Welcome to Blazer Forum!
Welcome to Blazer Forum,

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to start new topics, reply to conversations, privately message other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join Blazer Forum today!


Reply
 
 
 
 
LinkBack Thread Tools Search this Thread
  #1  
Old 08-24-2012, 05:47 PM
xgiovannix12's Avatar
BF Guru
1992 Chevrolet S-10
My Garage
 
Join Date: Oct 2010
Location: Summit Ny
Posts: 5,959
xgiovannix12 will become famous soon enough
Default 4.3 vortec Knock Sensor.

Hey guys

I was wondering if any 1 could explain to me what a knock sensor does and what kind of symptoms would it give if it were bad?

Im thinking mine is on its way out but im not sure.


Thanks guys.
__________________


My Build Thread , April 2012 Rotm ,Differential Electric Locking System DIY
>>>My thoughts and comments should be considered at ones own discretion <<<
Current Project: Still waiting for a spider.
Reply With Quote
  #2  
Old 08-24-2012, 08:05 PM
Starting Member
1998 Chevrolet Blazer
 
Join Date: Nov 2010
Location: Dartmouth, NS
Posts: 127
Jase1979 is on a distinguished road
Default

A knock sensor detects knocking or pinging type noises in a engine ie. spark knock, If it sees excessive noise from an engine it will retard the timing to try to cure the noise, One way to test it is to watch your spark advance on a scanner and see if it dropping off, or a easier way is to unplug it and see if symptoms go away, Also note unplugging it will turn on the engine light
__________________
98 4dr 4x4, 2.5"rc suspension, 2" pa body lift, 31x10.5 BFG mud terrain, 15x8 Camaro wheels with 1.25" spacers
Reply With Quote
  #3  
Old 08-24-2012, 08:14 PM
xgiovannix12's Avatar
BF Guru
1992 Chevrolet S-10
My Garage
 
Join Date: Oct 2010
Location: Summit Ny
Posts: 5,959
xgiovannix12 will become famous soon enough
Default

Well the problem is I dont have an scanner for OBD 1 . The engine is very quiet but runs rough when the code presents its self.

the light comes on when ever it feels like it too.. My dear uncle the previous owner cut the wire for some reason. IM not sure why but the wire was twisted together and taped.

Last night I cut the wire cause of corrosion and Soldered it Then heat shrinked it.

This morning truck ran great. I took it for an other drive the light came on. Then if i leave it off the light goes away.
IM thinking its the connector on the sensor its self. Not sure tho.


Edit: I played with the wire again and the light went away. SO far it has not came on. We will see tomorrow.
__________________


My Build Thread , April 2012 Rotm ,Differential Electric Locking System DIY
>>>My thoughts and comments should be considered at ones own discretion <<<
Current Project: Still waiting for a spider.
Reply With Quote
  #4  
Old 08-24-2012, 09:16 PM
richphotos's Avatar
Moderator
1993 GMC S-15
 
Join Date: Dec 2011
Location: Minneapolis, MN
Posts: 3,926
richphotos is a jewel in the roughrichphotos is a jewel in the roughrichphotos is a jewel in the rough
richphotos1
Send a message via AIM to richphotos Send a message via MSN to richphotos Send a message via Yahoo to richphotos
Default

our trucks have the knock sensor? LOL i had no idea
__________________
1993 GMC Jimmy S15 SLT
4.3L Vortec
Digital Dash, keyless entry, leather and power everything
Reply With Quote
  #5  
Old 08-24-2012, 10:19 PM
Starting Member
1998 Chevrolet Blazer
 
Join Date: Nov 2010
Location: Dartmouth, NS
Posts: 127
Jase1979 is on a distinguished road
Default

LOL richphotos it is on the rear of the engine block sort of hidden by the distributor and other wires/ fuel lines

As for the sensor itself being bad it is not really common but they are not that expensive, and a connector could be tightened or picked up at a junkyard. Just make sure you torque in the new sensor.

Why did he cut the wire I do not know, BUT my wifes previous vehicle a 2000 Chev Malibu had really bad piston slap, it was so bad that the knock sensor would pull the timing back to -30 degrees, I disconnected the knock sensor and we drove that car for 3 years and over 100,000 Kms that way with no problems other then the engine light was always on.
__________________
98 4dr 4x4, 2.5"rc suspension, 2" pa body lift, 31x10.5 BFG mud terrain, 15x8 Camaro wheels with 1.25" spacers
Reply With Quote
  #6  
Old 08-24-2012, 10:24 PM
xgiovannix12's Avatar
BF Guru
1992 Chevrolet S-10
My Garage
 
Join Date: Oct 2010
Location: Summit Ny
Posts: 5,959
xgiovannix12 will become famous soon enough
Default

Im not sure jase but I do believe it got melted by the manifold.

I wont be changing the knock sensor any time soon but I might change the plug.
Im not sure how to tighten the plug but id sure like to try.

Also these motors have 2 knock sensors
One on the rear of the motor on the passenger side and one on the driver side by the spark plugs.
__________________


My Build Thread , April 2012 Rotm ,Differential Electric Locking System DIY
>>>My thoughts and comments should be considered at ones own discretion <<<
Current Project: Still waiting for a spider.
Reply With Quote
  #7  
Old 08-25-2012, 11:48 AM
xgiovannix12's Avatar
BF Guru
1992 Chevrolet S-10
My Garage
 
Join Date: Oct 2010
Location: Summit Ny
Posts: 5,959
xgiovannix12 will become famous soon enough
Default

Did about 40 miles on the truck today and NO ses light . Then the last 5 miles toward going home it came on. I pulled over and took my seat belt off and the light turned off.

This happened twice on the way home.. IM going to be changing a dryrotted vac line on the intake as soon as she cools off.

Forgot to note that the light stayed off the rest of the way home.
__________________


My Build Thread , April 2012 Rotm ,Differential Electric Locking System DIY
>>>My thoughts and comments should be considered at ones own discretion <<<
Current Project: Still waiting for a spider.
Reply With Quote
  #8  
Old 08-25-2012, 02:36 PM
xgiovannix12's Avatar
BF Guru
1992 Chevrolet S-10
My Garage
 
Join Date: Oct 2010
Location: Summit Ny
Posts: 5,959
xgiovannix12 will become famous soon enough
Default

Looks like I have an bad knock sensor. After an hour of reading the GM service manual I found an diagnosis for the knock sensor.

IT says the harness has to have Approximately 5 volts and I had 3.29 volts

then it said to measure the resistance and it has to be between 8,2 .05 ohms and I had 9.31

Im not 100 % sure but i think the Sensors shot. I need Opinions

Edit: crap i just double posted.... Sigh
__________________


My Build Thread , April 2012 Rotm ,Differential Electric Locking System DIY
>>>My thoughts and comments should be considered at ones own discretion <<<
Current Project: Still waiting for a spider.
Reply With Quote
  #9  
Old 08-25-2012, 02:43 PM
richphotos's Avatar
Moderator
1993 GMC S-15
 
Join Date: Dec 2011
Location: Minneapolis, MN
Posts: 3,926
richphotos is a jewel in the roughrichphotos is a jewel in the roughrichphotos is a jewel in the rough
richphotos1
Send a message via AIM to richphotos Send a message via MSN to richphotos Send a message via Yahoo to richphotos
Default

Yeah i would say its shot with readings like that.
__________________
1993 GMC Jimmy S15 SLT
4.3L Vortec
Digital Dash, keyless entry, leather and power everything
Reply With Quote
Old 08-25-2012, 02:43 PM
 
 
 
Reply

Tags
10, 42, 43, 97, bad, chevy, code, engine, knock, liter, pickup, piston, s10, sensor, slap, symptoms, timing


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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
94 s10 blazer vortec 4.3l knock miss and squel Cerpindicular 1st Gen S-series (1983-1994) Tech 8 05-20-2013 01:57 PM
vortec 4.3 knock sensor location VIN W rocknroadie 1st Gen S-series (1983-1994) Tech 5 07-01-2011 06:19 PM
4.3L vortec v6 knock sensor issue! please help! Cdon294 Engine & Transmission 3 12-22-2010 09:23 PM
Knock Sensor TT 2nd Gen S-series (1995-2005) Tech 4 05-08-2008 07:21 AM
knock sensor getblazed00 General Tech Help 3 02-12-2006 11:20 PM

Advertising

Featured Sponsors
Vendor Directory
Our Sponsors

All times are GMT -5. The time now is 12:05 AM.

Internet Brands, Inc.