ok im running the STS turbo @ 5lbs w/o detonation but when i hook up my lap top to datalog it says that the timing is like 20 degrees advanced and when i get in boost it doesnt retard the timing just advances more shouldnt it be retarding timing? the program was done by madz28.com so im sure its right i just need to hear it from others to make me feel better

 

When the engine RPM increases, the advance typically increases to keep the peak cylinder pressure near TDC. The question is, how do you "retard" your timing under boost? Is it programmed into the PCM, or are you using an external boost retard module?

If you're using an external boost retard module, you will not see the affects of that module in your scan data. The scanner is showing you what the PCM is finding when it looks up the advance in a table of RPM vs. MAP. Its not the actual timing, so an external box may still be retarding the timing under boost, you just can't see it on your scanner.

If you have the entire timing map for boost included in the PCM "tune", it would still be normal for the PCM to advance timing with increasing RPM, just to keep peak cylinder pressure correct in relation to TDC. But the programmer will have added less increase in advance with rising RPM, reflecting the fact that he knows you have boost.

 

ok cool that is exactly what i was thinking. all my timing is done through the PCM. now if i decide to go with a MSD BTM will i have to get the PCM reprogramed? or would it be a waste to go to a BTM over what i have now?