Timing problem
Thread Starter
Racer
Joined: Nov 2006
Posts: 430
Likes: 1
From: Savannah Georiga
Timing problem
Hey guys I recently went to get dyno tuned and car looked great made 375ish with long tubes and CAI. but after looking at everything its running only 16-18 degrees of timing after 4200. What is causing it to knock almost 10 degrees out?? any possible solutions that i can try to look at before taking it to a shop.
Could it be:
exhaust leak?
knock sensor? (but no codes have been thrown)
bad fuel?
We took intake off cleaned a little oil out of it and put a catch can on thinking thats why maybe. But still wouldnt hold timing.
Motor is stock, never taken heads or anything off (except intake now)
07 z51 with around 65k miles
Car runs awesome no problem at all, but def has a lot more potential.
Could it be:
exhaust leak?
knock sensor? (but no codes have been thrown)
bad fuel?
We took intake off cleaned a little oil out of it and put a catch can on thinking thats why maybe. But still wouldnt hold timing.
Motor is stock, never taken heads or anything off (except intake now)
07 z51 with around 65k miles
Car runs awesome no problem at all, but def has a lot more potential.
Safety Car
Joined: Aug 2010
Posts: 3,600
Likes: 118
From: F'burg VA
St. Jude Donor '13 thru '20,'22,'24 thru '26
I was going to post about this exact same thing. Dynoed my LS3 yesterday and we only saw 9 degrees of timing. Are they just sending them out detuned on purpose? Or are they just padding a huge margin of safety?
It did put down 377hp (SAE Corrected)
It did put down 377hp (SAE Corrected)
Burning Brakes
Joined: Aug 2008
Posts: 802
Likes: 6
From: Oro Valley AZ
Hey guys I recently went to get dyno tuned and car looked great made 375ish with long tubes and CAI. but after looking at everything its running only 16-18 degrees of timing after 4200. What is causing it to knock almost 10 degrees out?? any possible solutions that i can try to look at before taking it to a shop.
Could it be:
exhaust leak?
knock sensor? (but no codes have been thrown)
bad fuel?
We took intake off cleaned a little oil out of it and put a catch can on thinking thats why maybe. But still wouldnt hold timing.
Motor is stock, never taken heads or anything off (except intake now)
07 z51 with around 65k miles
Car runs awesome no problem at all, but def has a lot more potential.
Could it be:
exhaust leak?
knock sensor? (but no codes have been thrown)
bad fuel?
We took intake off cleaned a little oil out of it and put a catch can on thinking thats why maybe. But still wouldnt hold timing.
Motor is stock, never taken heads or anything off (except intake now)
07 z51 with around 65k miles
Car runs awesome no problem at all, but def has a lot more potential.
Thread Starter
Racer
Joined: Nov 2006
Posts: 430
Likes: 1
From: Savannah Georiga
yeah it was scanned on efi live. and we logged it on the dyno and on street and went back and looked at the entire runs and saw an avg of 16-18 degrees. like i said the car runs awsome just doesnt have full power for some reason. my a/f is 12.6-12.8
Supporting Vendor
Joined: Sep 2010
Posts: 470
Likes: 6
From: Southeast Florida Florida
Hey guys I recently went to get dyno tuned and car looked great made 375ish with long tubes and CAI. but after looking at everything its running only 16-18 degrees of timing after 4200. What is causing it to knock almost 10 degrees out?? any possible solutions that i can try to look at before taking it to a shop.
Could it be:
exhaust leak?
knock sensor? (but no codes have been thrown)
bad fuel?
We took intake off cleaned a little oil out of it and put a catch can on thinking thats why maybe. But still wouldnt hold timing.
Motor is stock, never taken heads or anything off (except intake now)
07 z51 with around 65k miles
Car runs awesome no problem at all, but def has a lot more potential.
Could it be:
exhaust leak?
knock sensor? (but no codes have been thrown)
bad fuel?
We took intake off cleaned a little oil out of it and put a catch can on thinking thats why maybe. But still wouldnt hold timing.
Motor is stock, never taken heads or anything off (except intake now)
07 z51 with around 65k miles
Car runs awesome no problem at all, but def has a lot more potential.
Did you tune the timing table? What was the IAT/ECT? You used the word "knock off"...was there knock retard?
Once the AFR is set, the timing should be moved about by the tuner to give you the most torque through the timing table. What did the torque curve look like?
Ed M
Melting Slicks
Joined: Jun 2005
Posts: 2,396
Likes: 52
From: Sicamous BC
I fought the KR battle with my LS2.....I'm not finished as winter is setting in & everything is parked. It seems the LS2 & 3 engines are overly sensitive in this area.
Three things worked very well for me....this was all on a Mustang dyno.
#1 Changed the plugs out to NGK TR6, this allowed timing to go back to stock, otherwise KR was pulling timing by major amounts.
#2 Richer AFR's, 12.6 to 13 is to lean, made better power richer
#3 Changes to Knock Retard Attack & Decay rate.
Here is a link to my post in HPT showing the dyno run after installing the TR6 plugs, going back to the stock timing. Also included is shot showing how much timing had been removed to stop the knock prior to installing the colder plugs.
http://www.hptuners.com/forum/showthread.php?t=31017
Three things worked very well for me....this was all on a Mustang dyno.
#1 Changed the plugs out to NGK TR6, this allowed timing to go back to stock, otherwise KR was pulling timing by major amounts.
#2 Richer AFR's, 12.6 to 13 is to lean, made better power richer
#3 Changes to Knock Retard Attack & Decay rate.
Here is a link to my post in HPT showing the dyno run after installing the TR6 plugs, going back to the stock timing. Also included is shot showing how much timing had been removed to stop the knock prior to installing the colder plugs.
http://www.hptuners.com/forum/showthread.php?t=31017
Last edited by CTD; Nov 14, 2010 at 02:02 PM.
Safety Car
Joined: Jun 1999
Posts: 3,570
Likes: 3
From: Austin, Singapore, Kuala Lumpur, Houston, Dallas, Hong Kong, Elgin, etc.. Texas
Once the PCM sees knock, it pulls timing out according to a preset table. Often times, it pulls out more than necessary.
For example, the knock sensor senses knock and looks up on a table how much timing to pull at that particular RPM, MAP, and IAT. In this example, its programed to pull 5 degrees. If you drop the timing on your High Octane table by 2 degrees at that RPM and Load, the KR goes away.
So you see, your PCM may be pulling more that is really needed because its programed to pull xx degrees at that RPM, Load, and temp for a xx seconds. You want to adjust the timing table to stop it from doing KR.
For example, the knock sensor senses knock and looks up on a table how much timing to pull at that particular RPM, MAP, and IAT. In this example, its programed to pull 5 degrees. If you drop the timing on your High Octane table by 2 degrees at that RPM and Load, the KR goes away.
So you see, your PCM may be pulling more that is really needed because its programed to pull xx degrees at that RPM, Load, and temp for a xx seconds. You want to adjust the timing table to stop it from doing KR.
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