Timing at wot..table is set at 20...datamaster shows 24...

So which one should I go by.....when someone says to run around 26 degrees, are they referring to the table or the timing reported by datamaster? It seems 4 degrees are being added on top of what it’s already in the table…

So which one should I go by.....when someone says to run around 26 degrees, are they referring to the table or the timing reported by datamaster? It seems 4 degrees are being added on top of what it’s already in the table…

There is a constant that increases the whole timing table by a set number of degrees. You might check that.

There is a constant that increases the whole timing table by a set number of degrees. You might check that.

After doing little bit more search i found out that the 2-4 degrees is hardcoded into the pcm and there is no table to control it. Some said that the amount of timing on top of what’s in the table is triggered by the IAT readings.


:confused:

Look at your minimum timing table. If it is set to 24 you will not see less then 24 even though you command 20.

After doing little bit more search i found out that the 2-4 degrees is hardcoded into the pcm and there is no table to control it. Some said that the amount of timing on top of what’s in the table is triggered by the IAT readings.


:confused:

Must be an OBD1 thing. Mine commands exactly whats in the timing table. The IAT and the EGR are the only things that ever add any timing on my car.:)

mine always runs up to 4deg more than what i have commanded for it under wide open throttle. obd1 here also. i have done a search about this also and it seems to be a common thing. still tunning on it now and am just taking the extra 4 deg back out of it to compensate for the extra timing.

Its an obd1 lt1 thing, just go lower than you actually plan to get. And yes the 24 that datamaster shows is correct.

There are several tables that can add timing in the LT1 OBD1 puter. I found one on accident last year with my new huge CAM :eek: it turns out there is a table that will add timing when the PCM is trying to mantain the idle RPM. This added timing will be locked in if you go WOT while its active like i did by setting my T-Brake and mashing the gas to the floor. I ended making a 1/4 mile pass with 4 extra degrees on 22#s of boost and a 100shot :D It felt good but I was lucky nothing popped. Jeff

Must be an OBD1 thing. Mine commands exactly whats in the timing table. The IAT and the EGR are the only things that ever add any timing on my car.:)

I see the added timing on every 96 and 97 I tune.

There are several tables that can add timing in the LT1 OBD1 puter. I found one on accident last year with my new huge CAM :eek: it turns out there is a table that will add timing when the PCM is trying to mantain the idle RPM. This added timing will be locked in if you go WOT while its active like i did by setting my T-Brake and mashing the gas to the floor. I ended making a 1/4 mile pass with 4 extra degrees on 22#s of boost and a 100shot :D It felt good but I was lucky nothing popped. Jeff

whats the name of that table..the only thing that i found but have not verified is the table called Idle Underspeed Spark Advance Vs. RPM Error and it has 4 degrees in there......:confused:

I see the added timing on every 96 and 97 I tune.

At WOT mine commands whatever Rpm and Map(100KPA) combination it is currently at on the "Main spark advance RPM vs MAP" table. However, I do see some additional timing when I'm not WOT. I wonder if it could have something to do with the tuning software. I use Tunercat for OBD2. This computer never ceases to amaze me. :)

At WOT mine commands whatever Rpm and Map(100KPA) combination it is currently at on the "Main spark advance RPM vs MAP" table. However, I do see some additional timing when I'm not WOT. I wonder if it could have something to do with the tuning software. I use Tunercat for OBD2. This computer never ceases to amaze me. :)


using TunerCAt as well...LT1 edit shows the same timing though.


funny thing i noticed is that it only adds 2degrees till around 5k and then it shoots up to 4 degrees.

Just back the timing off.....and bring it in slow on the dyno or track.....the mystry 4* timing has been talked about .......

whats the name of that table..the only thing that i found but have not verified is the table called Idle Underspeed Spark Advance Vs. RPM Error and it has 4 degrees in there......:confused:

That is the one! Just think insted of the mystery 4 you could have mystery 8 :eek:

That is the one! Just think insted of the mystery 4 you could have mystery 8 :eek:

ill zero it out tomorrow and see..i am pretty sure thats it though :p

ill zero it out tomorrow and see..i am pretty sure thats it though :p

You may noy have to worry about this one unless you have a huge CAM and Idle problems. I don't know of anyway to get rid of the mystery 4.