Engine Knock with 93 Octane??
06-29-2010, 05:18 PM
#1
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Engine Knock with 93 Octane?? Trying to figure out why i need 100 octane in order for my motor not to knock?
It's pretty much stock minus just a few mod's,like slp air lid,k&n air filter,160 thermostat,superchips handheld tuner <knocks with stock or performance tune> flowmaster muffler,3.73 gears,no cats,descreened mass airflow,coolant bypass,transgo reprograming shift kit....
I have tried amoco ultra sunoco 93 mobil 93 you name it i have tried it,and under wot the car pings pretty badly and i know thats not right.
The car was a 1 owner upto 1 yr ago and Never raced until i bought it and unless i have 100 in the tank it pings.
I have no check engine light on and was hoping someone could point me in the right direction??
Thanks in advance for your time...
It's pretty much stock minus just a few mod's,like slp air lid,k&n air filter,160 thermostat,superchips handheld tuner <knocks with stock or performance tune> flowmaster muffler,3.73 gears,no cats,descreened mass airflow,coolant bypass,transgo reprograming shift kit....
I have tried amoco ultra sunoco 93 mobil 93 you name it i have tried it,and under wot the car pings pretty badly and i know thats not right.
The car was a 1 owner upto 1 yr ago and Never raced until i bought it and unless i have 100 in the tank it pings.
I have no check engine light on and was hoping someone could point me in the right direction??
Thanks in advance for your time...
06-29-2010, 05:39 PM
#2
Could be oil mist from the PCV system getting into the intake and causing the ping. Install a catch can and see if your problem goes away.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
LS1,LS2,LS3,LS7,LT1 Custom Camshaft Specialist For custom camshaft help press here.
Custom LSX tuning in person or via email press here.
06-29-2010, 07:21 PM
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Yep, carboned up from sucking oil... might need to do some topend cleaner (or give it a drink).
Another cause might be the descreened MAF... ever put a wideband on it to see what the fueling looks like?
Another cause might be the descreened MAF... ever put a wideband on it to see what the fueling looks like?
06-29-2010, 09:47 PM
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Not yet,im looking to find a local shop to take the car to but have not found one as of yet.
Where can i purchase a wideband tool that you mentioned in your post?
Thanks again for your time
Where can i purchase a wideband tool that you mentioned in your post?
Thanks again for your time
06-29-2010, 10:00 PM
#6
+1 on the descreened MAF. It's best to re-scale the MAF table after descreening. Can get away without doing it, but, is better to be done.
A wideband 02 sensor is used to measure air/fuel ratio. You need the wideband sensor & the display or controller.
Top end cleaner like Sea-foam
A wideband 02 sensor is used to measure air/fuel ratio. You need the wideband sensor & the display or controller.
Top end cleaner like Sea-foam
06-30-2010, 05:48 AM
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Personally, I like my Innovate LM2 wideband - but if you are going to have it tuned, you don't need to buy your own...
I would get another stock MAF and replace yours - no gains to be had from taking the screen out on a setup like yours... all you do is run the risk of skewing the fueling.
Decarbon the chambers with Sea-foam top end cleaner... or you can use the old-school trick of sucking a glass of water through a drinking straw with the brake booster vacuum line (hold the RPM at around 3k while doing it)...
I would get another stock MAF and replace yours - no gains to be had from taking the screen out on a setup like yours... all you do is run the risk of skewing the fueling.
Decarbon the chambers with Sea-foam top end cleaner... or you can use the old-school trick of sucking a glass of water through a drinking straw with the brake booster vacuum line (hold the RPM at around 3k while doing it)...
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06-30-2010, 08:28 AM
#9
Carbon build up, as others have stated.
Another thing to look out for is oil from you K&N contaminating your MAF hot wires. If the oil from the air cleaner gets on them, it will bake on, and cause an insulating effect, which in turn causes the maf to read very lean, and the fuel trims to shoot way up to compensate.
Another thing to look out for is oil from you K&N contaminating your MAF hot wires. If the oil from the air cleaner gets on them, it will bake on, and cause an insulating effect, which in turn causes the maf to read very lean, and the fuel trims to shoot way up to compensate.
06-30-2010, 09:21 AM
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If you have a scan tool, start looking at the misfire
(current, cylinder mode) counts. See if any holes
are way out of bed with the rest, which might point
to a silted-up injector or two.
Check for cleverness like !EGR without tuning out the
EGR advance; this is a good way to get light-throttle
ping.
(current, cylinder mode) counts. See if any holes
are way out of bed with the rest, which might point
to a silted-up injector or two.
Check for cleverness like !EGR without tuning out the
EGR advance; this is a good way to get light-throttle
ping.
