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2004 Silverado 175k mi; Spark knock issue #4548641
10/19/17 07:53 PM
10/19/17 07:53 PM
Joined: Sep 2013
Posts: 71
Texas
TexasTea Offline OP
TexasTea  Offline OP
Joined: Sep 2013
Posts: 71
Texas
Hi guys

I've got a 2004 Silverado 5.3L V8 with 175,000 miles that has been having spark knock intermittently since I got the vehicle in 2007 with 65,000 miles. I always use 87 octane fuel

Only in the past 3-4 years have I been actively searching for a resolution but I found that with this cooled down weather here in Houston Texas the spark knock has disappeared and I'm not sure what's the reason

I have an ODBII transmitter with the torque app on my phone tracking the knock retard and timing and the odd thing is that when I actually hear evidence of spark knock occurring, most always under medium to heavy load in gear and at the upper range of RPMs; 3,000-6,000 RPM, no spark knock count is increased nor is the engine computer retarding the timing to compensate

Now all the sudden with the weather cooling off I noticed, again, under the same load conditions mentioned above, the engine started to spark knock only slightly then stopped and all subsequent times I've loaded the engine, when chilly out, the spark knock has disappeared.

Could the heat or hot days be the actual cause of the spark knock? Or does this point to an issue with the gasoline not dealing with high temperatures very well? Perhaps both or something else entirely?

I have done nothing as far as repairs or maintenance to warrant any change in behavior yet now on chilly evenings if I actively attempt to forcefully make the engine spark knock it is not occurring even under the heaviest of loads I'm comfortable putting the engine up to which is pretty high but not stupidly or dangerously high (not maxing it out or anything)

Hoping some of the intelligent and experienced minds on this board can shed some knowledge on this matter so I can better safeguard myself from damaging the engine

Thanks for looking

Last edited by TexasTea; 10/19/17 07:57 PM.
Re: 2004 Silverado 175k mi; Spark knock issue [Re: TexasTea] #4548663
10/19/17 08:16 PM
10/19/17 08:16 PM
Joined: Aug 2005
Posts: 907
dayton oh
kc8adu Offline
kc8adu  Offline
Joined: Aug 2005
Posts: 907
dayton oh
the sensors are in the valley and take on water.
yours are likely beyond dead.

Re: 2004 Silverado 175k mi; Spark knock issue [Re: kc8adu] #4548674
10/19/17 08:26 PM
10/19/17 08:26 PM
Joined: Jun 2003
Posts: 17,371
Deplorable in apple valley, ca
Chris142 Online content
Chris142  Online Content
Joined: Jun 2003
Posts: 17,371
Deplorable in apple valley, ca
Originally Posted By: kc8adu
the sensors are in the valley and take on water.
yours are likely beyond dead.
yep. Just did the ones on the wifes 04 tahoe @160k.


02 Wrangler durablend 10w40
87 F250 traveler 15w40
04 Tahoe super-s 10w30
Z400 castrol T 10w40
Can am maveric edge 5w40
57 case tractor 15w40
Re: 2004 Silverado 175k mi; Spark knock issue [Re: TexasTea] #4548683
10/19/17 08:37 PM
10/19/17 08:37 PM
Joined: Feb 2011
Posts: 6,719
Hudson, NH
LeakySeals Offline
LeakySeals  Offline
Joined: Feb 2011
Posts: 6,719
Hudson, NH
Did mine this spring. The boots are the real problem. Buy a new harness along with new sensors and seal them down to valley pan good with black rtv. You can do the valley pan gasket and its grommets too while its open . Not hard work. Youtube diy.




06 Escalade 6.0L LQ9 AWD 165k M1 5w30
03 Maxima 3.5L POS 152k ST HM 10w30
Re: 2004 Silverado 175k mi; Spark knock issue [Re: TexasTea] #4548688
10/19/17 08:46 PM
10/19/17 08:46 PM
Joined: Sep 2013
Posts: 71
Texas
TexasTea Offline OP
TexasTea  Offline OP
Joined: Sep 2013
Posts: 71
Texas
Thanks for replying I should've mentioned that both knock sensors were changed about 15-25k miles ago. The rear was corroded add throwing a DTC but regarding spark knock the was no change before or after
Issue persisted same as it stays had been

Re: 2004 Silverado 175k mi; Spark knock issue [Re: TexasTea] #4548692
10/19/17 08:49 PM
10/19/17 08:49 PM
Joined: Aug 2008
Posts: 18,701
Ontario, Canada
StevieC Offline
StevieC  Offline
Joined: Aug 2008
Posts: 18,701
Ontario, Canada
What kind of driving patterns and what kind of mileage. Possible that the coolant sensor is the culprit? I had minor pinging in the Journey that I couldn't seem to remedy with higher octane fuel and then the sensor eventually failed and when I replaced it I got better mileage, the pinging went away as well.


'18 Highlander - AMSOIL SS 0w20 / ATF / Severe Gear
'06 Santa Fe - 535,000km AMSOIL SS 0w30 / ATF (R.I.P)
Re: 2004 Silverado 175k mi; Spark knock issue [Re: TexasTea] #4548741
10/19/17 09:46 PM
10/19/17 09:46 PM
Joined: Dec 2013
Posts: 2,201
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline
Joined: Dec 2013
Posts: 2,201
Fort Worth, Texas
Ambient temps have a huge effect on audible spark knock/detonation, I would first suspect incorrect "LOAD" inputs sent to the PCM by the Mass Air Flow Sensor, The Base/Main spark tables are dependent on Cylinder Air Mass Volume calculations derived from the MAF sensor.


2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/Auto
Re: 2004 Silverado 175k mi; Spark knock issue [Re: TexasTea] #4548744
10/19/17 09:50 PM
10/19/17 09:50 PM
Joined: Dec 2013
Posts: 2,201
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline
Joined: Dec 2013
Posts: 2,201
Fort Worth, Texas
The PCM monitors knock sensor voltages, Water intrusion will cause the line voltage to be pulled low & set a trouble code/s.


2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/Auto
Re: 2004 Silverado 175k mi; Spark knock issue [Re: clinebarger] #4548754
10/19/17 10:15 PM
10/19/17 10:15 PM
Joined: Sep 2013
Posts: 71
Texas
TexasTea Offline OP
TexasTea  Offline OP
Joined: Sep 2013
Posts: 71
Texas
Thank you this is very helpful info I'll inspect the MAF sensor and associated components and adjust accordingly.

Right now I'm getting about 12-14 mpg city
Add I get 15-16 highway (maybe more)

This seems on the low side of average compared to other trucks of this year but it's always been consistent if low

Last edited by TexasTea; 10/19/17 10:16 PM.
Re: 2004 Silverado 175k mi; Spark knock issue [Re: TexasTea] #4548765
10/19/17 10:52 PM
10/19/17 10:52 PM
Joined: Dec 2006
Posts: 18,644
Dallas,Tx USA
aquariuscsm Offline
aquariuscsm  Offline
Joined: Dec 2006
Posts: 18,644
Dallas,Tx USA
If you're referring to pinging under acceleration it's probably the [censored] ethanol trash that's forced on us.


1996 Nissan 300ZX 5-speed,Arctic Pearl(#175 of 300)
Quaker State Ultimate Durability 10W30
2012 Honda Accord Coupe EX-L 2.4,auto,San Marino Red
Quaker State Ultimate Durability 5W20

Re: 2004 Silverado 175k mi; Spark knock issue [Re: TexasTea] #4548773
10/19/17 11:16 PM
10/19/17 11:16 PM
Joined: Sep 2004
Posts: 7,532
Marshfield , MA
andyd Offline
andyd  Offline
Joined: Sep 2004
Posts: 7,532
Marshfield , MA
I'm just tossing out ideas that come to me.The combustion chambers may have enough carbon deposits to cause this. So would a cooling system getting marginal,after time and miles, in hot weather. Pressure cap? Worn out O2 sensor?


'16 Camry LE STP synth 0w20 and STP filter. the Fridge

1994 Ranger ,the Rat, 5w30 dino, STP filter

'16 Camry SE, Valvoline HM 0w20 and OEM filter
Thick oil is better grin2
Re: 2004 Silverado 175k mi; Spark knock issue [Re: clinebarger] #4549178
10/20/17 11:28 AM
10/20/17 11:28 AM
Joined: Jan 2017
Posts: 278
Iowa
Iowegian Offline
Iowegian  Offline
Joined: Jan 2017
Posts: 278
Iowa
Originally Posted By: clinebarger
Ambient temps have a huge effect on audible spark knock/detonation, I would first suspect incorrect "LOAD" inputs sent to the PCM by the Mass Air Flow Sensor, The Base/Main spark tables are dependent on Cylinder Air Mass Volume calculations derived from the MAF sensor.


My thought too. MAF and/or Air intake temp sensor may give good readings at one temp but bad ones at another temp.
Do you hace readings on the AIT with your scanner? Compare to ambient temp?


2011 Equinox, 2.4l
2009 Sienna, 3.5l
Re: 2004 Silverado 175k mi; Spark knock issue [Re: andyd] #4549181
10/20/17 11:30 AM
10/20/17 11:30 AM
Joined: Jan 2017
Posts: 278
Iowa
Iowegian Offline
Iowegian  Offline
Joined: Jan 2017
Posts: 278
Iowa
Originally Posted By: andyd
I'm just tossing out ideas that come to me.The combustion chambers may have enough carbon deposits to cause this. So would a cooling system getting marginal,after time and miles, in hot weather. Pressure cap? Worn out O2 sensor?


Another good idea. Carbon holds heat and in hot weather this could cause predetination.
Higher octane may help if this is the case?
Have you experimented with higher octane fuels to see if this still occurs on hot days?

Last edited by Iowegian; 10/20/17 11:31 AM.

2011 Equinox, 2.4l
2009 Sienna, 3.5l
Re: 2004 Silverado 175k mi; Spark knock issue [Re: TexasTea] #4549183
10/20/17 11:33 AM
10/20/17 11:33 AM
Joined: Jan 2017
Posts: 278
Iowa
Iowegian Offline
Iowegian  Offline
Joined: Jan 2017
Posts: 278
Iowa
Also, what is your long term and short term fuel trim like on normal driving?
Would give more insite.


2011 Equinox, 2.4l
2009 Sienna, 3.5l
Re: 2004 Silverado 175k mi; Spark knock issue [Re: TexasTea] #4549259
10/20/17 12:59 PM
10/20/17 12:59 PM
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Merkava_4 Offline
Merkava_4  Offline
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Originally Posted By: TexasTea
I should've mentioned that both knock sensors were changed about 15-25k miles ago.


Did that cure your spark knock back then ? Maybe you need to replace them again.


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