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Username Post: Spark Knock - Silverado 4.3 V6        (Topic#157365)
TXChevy 
Senior Member
Posts: 179
TXChevy
Loc: Republic of Texas
Reg: 05-10-04
04-18-07 12:12 PM - Post#1145886    

Is spark knock common with the 4.3 V6? I usually run regular (87 octane) in my 2004 Silverado but I have run mid-grade (89) and premium (92) in the past and it always knocks under acceleration (though the knock does seem less pronounced with premium fuel). The local Chevy dealer has told me that this is a "normal condition" with this engine.

 
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redvett01 
Senior Member
Posts: 1153

Loc: Grayling, MI
Reg: 10-23-03
04-18-07 02:16 PM - Post#1145979    
    In response to TXChevy

You should not have a problem if the knock sensor is working right. Have they changed the sensor?
K1500 04 Silverado EXT


 
elcamino 
Valued Contributor
Posts: 4987
elcamino
Loc: Lake Superior-Michigan US...
Reg: 03-30-00
04-18-07 04:11 PM - Post#1146043    
    In response to redvett01

Carbon, carbon, carbon is a big problem from using cheap fuel.

Look at the tailpipe, rub you finger in there and see if its turns black. If so, thats your problem and there is not a lot you can do about it if you use cheap fuel. Have to use Top Tier gas from the get go. Last summer when gas was high I was buying all my gas at Wal-Mart's Murphy, it was cheaper that the rest. My Cadi started pinging badly, took it to the dealer with 10,000 miles on it. They said, its carboned, what brand of fuel are you using? So I don't use Wal-Mart anymore and pay 7 cents more for Shell. Took a month or so but the knocking has subsided. I also ran some good fuel additive to and that helped. My pipes were black but now they are not.

This product worked for me. P.I. Gasoline Additive
Mike
2009 Cadillac CTS4 AWD Performance Sedan
2012 GMC Sierra AWD Denali 6.2L


 
redvett01 
Senior Member
Posts: 1153

Loc: Grayling, MI
Reg: 10-23-03
04-18-07 06:29 PM - Post#1146141    
    In response to elcamino

Why vdo you think GM says to use Top Tier Fuel.
K1500 04 Silverado EXT


 
Squasher 
Very Senior Member
Posts: 1726
Squasher
Loc: Northern California
Reg: 07-05-02
04-18-07 06:44 PM - Post#1146161    
    In response to TXChevy

  • TXChevy Said:
Is spark knock common with the 4.3 V6? I usually run regular (87 octane) in my 2004 Silverado but I have run mid-grade (89) and premium (92) in the past and it always knocks under acceleration (though the knock does seem less pronounced with premium fuel). The local Chevy dealer has told me that this is a "normal condition" with this engine.



My 2001 5.3 motor doesn't knock on (chevron) 87 octane fuel regardless of how hard I work the motor. Your 2004 shouldn't have a problem if everything is working right. There is no way it can be "normal" for your motor. If it was normal, GM would have a TSB fix for your engines computer.

I dont know whats wrong, but the first thing I would check is the knock sensor. Then maybe run some "seafoam" through the motor, clean the MAF sensor and the throttle body.

Also check if the computer is showing any error codes
2001 GMC Sierra K1500 Z71 x/cab SLT 5.3L


 
elcamino 
Valued Contributor
Posts: 4987
elcamino
Loc: Lake Superior-Michigan US...
Reg: 03-30-00
04-19-07 05:42 AM - Post#1146427    
    In response to Squasher

Its a common complaint the dealers see and there is no easy fix.

Stick with brand names like Chevron, Shell, Shell, Mobil. GM has a TSB which identifies the brands that are Top Tier or use fuel additives such as my example.

But, a vehicle that has had a constant diet of low grade fuel is going to take some time to clean up depending on how strong the additive. With my CTS, it took a couple thousand miles. Cheaper cost fuel additives mean they are weaker.

04-06-04-047D IB Info - Top Tier Detergent Gasoline (Deposits, Fuel Economy, No Start, Power, Performance, Stall Concerns)


Although a certain level of detergent additive is required by law to be formulated into gasoline, cost restrictions cause refineries to use low quality additives in the lowest additive concentration (LAC), a level insufficient to prevent deposit accumulation. As a result, deposits accumulate on fuel injectors, intake valves and combustion chambers, often within just a few thousand miles, disrupting spray patterns, affecting electronic sensors and causing a multitude of problems.
Mike
2009 Cadillac CTS4 AWD Performance Sedan
2012 GMC Sierra AWD Denali 6.2L


 
TXChevy 
Senior Member
Posts: 179
TXChevy
Loc: Republic of Texas
Reg: 05-10-04
04-19-07 06:44 AM - Post#1146455    
    In response to redvett01

  • redvett01 Said:
You should not have a problem if the knock sensor is working right. Have they changed the sensor?



Just took it to the dealer yesterday. They supposedly ran a diagnostic and it did not throw any codes, knock sensor or otherwise. I will start using a better brand of fuel and see what happens.


 
mwright1 
Senior Member
Posts: 656

Loc: Naperville, IL
Reg: 04-05-04
04-19-07 07:06 AM - Post#1146471    
    In response to elcamino

FIW.... I always thought Amaco or BP was a top tier gas.. Apparently I was wrong?


TOP TIER Detergent Gasoline Retailers

Gasoline retailers must meet the high TOP TIER standards with all grades of gasoline to be approved by the automakers as providing TOP TIER Detergent Gasoline.

In addition, all gasoline outlets carrying the brand of the approved retailer must meet the TOP TIER standards.

Additional gasoline retailers are added to the TOP TIER list as they meet the standards. The retailers known to be on the TOP TIER list are shown below.

TOP TIER Gasoline Retailers:

QuikTrip
Chevron
Conoco
Phillips
76
Shell
Entec Stations
MFA Oil Company
Kwik Trip/Kwik Star
The Somerset Refinery, Inc.
Chevron-Canada
Aloha Petroleum
Tri-Par Oil Company
Shell-Canada
Texaco
Petro-Canada
Sunoco-Canada

If it ain't broke open it up and make it better 03 Silverado 5.3 Z71


 
redvett01 
Senior Member
Posts: 1153

Loc: Grayling, MI
Reg: 10-23-03
04-19-07 02:13 PM - Post#1146752    
    In response to TXChevy

Did they drive the vehicle and read knock data to see if the PCM is getting knock counts? If not they didnt check it out properly.
K1500 04 Silverado EXT


 
TXChevy 
Senior Member
Posts: 179
TXChevy
Loc: Republic of Texas
Reg: 05-10-04
04-20-07 08:52 AM - Post#1147222    
    In response to redvett01

  • redvett01 Said:
Did they drive the vehicle and read knock data to see if the PCM is getting knock counts? If not they didnt check it out properly.



I doubt that they drove it, but after reading the responses I think the problem is the cheap gas that I have been using (not "Top Tier"). I also noticed that there is a significant black carbon buildup on the tailpipe, so I am going to try the Seafoam treatment and start using a Top Tier brand of gas.


 
rbarrios 
Old as Dirt Member
Posts: 6223
rbarrios
Loc: West Covina,CA
Reg: 03-29-00
04-20-07 02:10 PM - Post#1147451    
    In response to TXChevy

you can also run a bottle of Chevron Techron for a tankfull. then start using the top tier fuel.
2010 Traverse
2008 Buick Lucerne CXL
2007 Impala 3LT
2003 Trailblazer-152,500 miles
1970 Monte Carlo
1964 C20
1967 Nova


 
TXChevy 
Senior Member
Posts: 179
TXChevy
Loc: Republic of Texas
Reg: 05-10-04
04-23-07 06:00 AM - Post#1148892    
    In response to rbarrios

I ran a can of Seafoam through the PCV line yesterday and it smoked like a chimney for about 5 or 10 minutes. It seems to have smoothed the idle and helped the spark knock a little.

 
Bad Bowtie 
Valued Contributor
Posts: 4552
Bad Bowtie
Age: 42
Loc: TX
Reg: 07-04-03
04-23-07 06:50 AM - Post#1148925    
    In response to TXChevy

Good 'ol Sea Foam.
GMC. We are Professional Grade.

http://www.cardomain.com/id/2004VHO


 
CaptainK 
Senior Member
Posts: 8242
CaptainK
Loc: Maryland
Reg: 02-25-02
04-24-07 04:07 AM - Post#1149740    
    In response to TXChevy

  • TXChevy Said:
I ran a can of Seafoam through the PCV line yesterday and it smoked like a chimney for about 5 or 10 minutes. It seems to have smoothed the idle and helped the spark knock a little.



Nice, gotta love that stuff


'99 Silverado (NBS)


 
Low priced Genuine GM Auto Parts
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