: Advancing or Retarding Timing?
02-02-2009, 01:33 PM
I came across a question in another thread and it seemed to peak more interest than i thought so i decided to make a thread about it...im gunna do some copy and pasting because im lazy...what started the convo is
on my old tune i made more hp cuz he advanced the timing (at a local dyno), but due to his lack of his duratec experience that caused a couple hiccups i had to go back to my base tune which now i know i basically just wasted my money...
so i wanted to know is can we safely adjust the timing ourselves? if so how?
now im gunna add some quotes from other users that kept this progressing
02-02-2009, 01:35 PM
There is a way through the xcal. You have certain RPM ranged you can choose to advance or retard timing. I forget how many degrees you have either way. I believe its 10? Not sure.
hmmm certain rpm range you say...how is it broken up??
or do u mean it just gives you a specific range that you can adjust?
remember, tho, the pcm already advances/retards the timing too.
No. I believe it adds the advancement or retardation (lol) to the base numbers of your tune.
and one more
02-02-2009, 01:36 PM
I have the SCT pro Racer package similar to what the Vendors use to create/sell tune. (I don't have the package to create tunes for sale, but I can create my own)
Anyway, you can create a cal with XYZ timing tables to do all sorts of custom calibrations, the ECU does a bunch of calcualtions and comes up with an "optimum" spark based on operating conditions and the parameters programed into the CAL.
Now when the cal is sent from their SW package to the flasher, X2 or X3 in my case, there are "options" that can be added for selection at the time you reflash your car. So a "spark adder/subtractor" can be selected that will modify the "calculated" spark at any given time. These are arranged into RPM ranges, 0-2000 2000-4000 & 4000-8000.
So if you add 2 deg to the 4000-8000 you get and extra 2 degrees above 4000 on top of what the calibration is programmed to do. Or -2 degress, and you get a retard to the calculated timing. The Min Max values for these options are limited by the calibrator when the cal is loaded into the flasher so you can't get out of control with the options.
There are also options for Idle RPM, cooling fan switch points, Tire and Rear Diff Ratios, AF/Ratio @ WOT, and a few others, I can't remember all of them.. For ATX versions you can change shift points too.
But vendors will charge extra for these options since they allow you more flexibility and no need to get them to redo your cal if you want to make minor adjustments. Like if I were building an ATX drag racer, I would definitly want some control over my shift points without needing a new cal!
which got me to wondering....
02-02-2009, 01:37 PM
yea i have those options...now with the original tune that i made more power on, he just simply said he advanced my timing a bit...so if i were to attempt this would it be safer to add 2 degrees to all 3 ranges of just 2 out of the 3, or just stick with one?
driving the car i felt a lot more oomph in the 2000 to 4000 range...so shoudl i go with what i felt?
and whats the negative effects if i added too much? my car would just start misfiring?
02-02-2009, 02:28 PM
Well if you get too crazy with adding timing you can get deto, probably not as much now when it's very cool around here (what octane are you running?) but during the summer, under load, you want to be careful not to add too much timing, it can lead to preignition and possibly damage the engine.
And to clarify we are talking about spark timing here, not cam timing
02-02-2009, 03:04 PM
right spark timing...and im running 93 octane
so those are the effects of under or over timing...
so is this done by trial and error?? there has to be some logistics on how to advance it or what spark range to advance it in...
02-02-2009, 04:27 PM
NO you should NOT be ading timing to your engines once you get a tune , VERY DANGERIOUS
02-02-2009, 04:40 PM
i think this stuff should be left to the experts
02-02-2009, 08:46 PM
What does 91, and 93 octane add?
kind of off topic but you stated you are running, or were, 93 octane.
02-02-2009, 11:03 PM
It allows you to safely advance the timing. The gas burns slower.
02-02-2009, 11:04 PM
So you can get more tq/hp out of it?
02-03-2009, 01:27 AM
if you get the itch so bad and you just have to try this, just be sure to datalog your knock sensor afterward. if its knocking, pull back at least 4 degrees.
can the ignition timing be changed without an xcal or some other flasher? could i just take my stock car to a mechanic/performance shop and ask them to advance my timing?
02-03-2009, 09:49 AM