P59 ECU jumping between idle and normal ignition tables when driving

[vwnut8392]

having this problem with my 6.0L swapped 1981 C10 where when driving it jumps between the idle ignition table and the main ignition table which causes this jerking and bucking. basically i have a 4WD colorado transmission thats converted to 2WD which does not have a VSS sensor in it by default. i got creative with some 4L60E parts like the 40 tooth trigger wheel from one which is welded to the output shaft inside the rear case. im using a VSS sensor from a 2000 silverado transfer case. i modified the rear AR-5 case to have a spot that that silverado sensor mounts in and holds it around .025-.030 from the trigger wheel. it does not read 100% accurate in the data logs. now, occassionally when driving the VSS signal will spike up and down for reasons unknown which make the ECU think its going to decel or idle. im literally jumping between 28-30 degrees down to 5-6 degrees of ignition timing so you can imagine the havoc this is causing when driving. is there a map or constant that i can get rid of this problem? there has to be values somewhere that dictate when it reads that table and when to read the main table. thanks everyone.

[hsv08]

Are you using Hptuners or tunerpro? There is some tables which dictates the speed and tps at which the timing leaves the idle tables and resorts to the main tables. You can force it to stay in one or the other, if the VSS is all over the show.