Mapping - Basic understanding behind mapping

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Rishi

Still waiting on some shims!
Note - My replies apply mostly to piggyback mapping.




What afr's are acceptable and where throughout the rev range do you tune to target afr's?
Anything that is an off load or partial load under approx 0.2 bar boost at almost any rpm you want to aim for around stoich (14.7). The standard ecu providing the stock lambda sensor is functioning correctly will do this anyway in many of these areas and so youll be fighting against a closed loop map if you try to change some of these areas.
Higher RPM's it you may wish to add a little more fuel as this helps keeping things cool, but its not vital. From 0.2 bar to 0.8 bar I would progressivly get richer and by 0.8 I would be aiming for mid 11:1 afr. I never go into the 10's some people get carried away and over do the fuel getting terrible MPG and a loss of power.




What do you keep egt's to?
On many of the Pulsars I map they rarely have EGT gauges. They definately are not as popular as they should be, and its not convienent to fit one just to map. Provided you fuel correctly the EGT will remain safe on a pulsar even in excess of 1.5bar provided that you have a decent intercooler system and you are not trying too hard with the ignition.




Tuning with det cans or off the stock knock sensor, what are you listening for, what do you do when you do sense knock and what do you look for on egt's when knock occurs? How to balance deciding whether to add more fuel (watching afr's) or whether to knock base timing back?
Again this applies to piggy back mapping where you are at all times in a closed loop ignition feedback from the standard ecu.
Provided you have already covered your fuel and that is safe you should then pull (depending on engine) some ignition around the max torque limit at higher boosts - before you actually test these areas. Also I generally take back the ignition at these higher boosts a degree or so depending on the engine and spec. I find each engine is very slightly different but usually since I'm dealing with other peoples cars I err on the cautious side. DET however is very noticable. The main thing to remember is that you have gone really wrong if you get det or there are other problems causing this, which would usually show up by now anyway (incorrect load sensing, MAF, running too hot, unstable hard to maintain AFR's etc. You should never need to knock the base timing back, the last thing you want to do is pull the whole map back a few degrees simply because you have one cell somewhere that is causing the problem. This is de-tuning, not tuning!!




When changing base timing, what effect does it have on egt's?
Depends how far you go. Often retarding the ignition can result in higher EGT's and in some cases even burn valves out and over heat engines. However going to advanced will cause extreme cylinder pressures and result in DET, with extreme EGT and everything else that comes with it.





Fusion Ed
 
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