i had someone burn me a custom chip for my old tpi w/ stock head and comp cam 224/230 cam setup about a year or so ago. now i have dart ie pro 180 heads, 3000 stall, hsr, and a bunch of other crap. my question is this... the base timing on the chip is set at 8. if i set the timing on the car at 12*btdc, would it make a difference in the timing at all, or would the computer still be running on 8*btdc because of the chip? thanks for the help guys

 

Whatever the stock base timing is (be it 6*, 0*, etc.) is what the ECM uses as a reference point.

E.G. My '92 RS has a stock base timing of 0* BTDC. The timing tables in the ECM are based on the base timing being 0* BTDC. If the ECM is supposed to advance the timing 28* at, let's say 2,500 RPM under certain loads, speed, blah blah blah, then it's assuming the base timing is set to 0* BTDC. As far as it knows the timing is 28* BTDC at that time.

If I were to advance my base timing to 2* BTDC, the ECM would still follow the same timing tables under the conditions above, and would advance the timing to 28* BTDC at 2,500. As far as the ECM knows, that's what it's doing. But what's really happening is the timing is being advanced to 30* BTDC (28* from ECM + 2* Base timing).

To a point doing something like that can increase performance as long as the knock sensor doesn't pick up any detonation (read pre-ignition). If it does sense detonation it will tell the ECM to retard the timing until the knock goes away. By doing so the ECM could retard the timing below the amount you advanced the base timing (that 2* I mentioned earlier). It could retard the timing 8* or more. That would put your overall timing at 22* BTDC at 2,500 RPM.

So, the only way to properly do it is to scan for knock counts (how many knocks the knock sensor picks up) and hope for none.

To sum it up, if you were to advance your base timing to 12* BTDC, and the chip you have advances it 8* BTDC, you'll have 20* BTDC base timing at idle. That's an awful lot for most engines.

 

for some reason, the car sounds like it likes a lot of timing at idle. i dunno... im not too familiar with programming though

which brings me to my next question... should the timing be falling off towards the end of the run? i remember logging a run up to 140 mph and seeing the timing slowly dropping down at around 80-100mph or so. i was told the hsr likes a lot more timing and more fuel... but im not sure. is this right though, should the timing be falling off slowly, or start to increase?