Guuuuys, I don't want to be a smartass but you are giving way too much credit to the 02 sensor. Preludes and cars from that time do not have really effective AFR correction.RattyMcClelland wrote:You would just be slapping flaps.
Isn't that right @damon
On a serious note. No o2 sensor would send an engine error code and it won't start. The engine needs to run in closed loop mode to drive which uses the o2 sensor to adjust fuel and timing in real time. When you are caning it or on track it goes to open loop and runs off a specific map at set values.
@RattyMcClelland I'm sorry but most of what you wrote is not correct .
Engine runs the same map all the time (except when in VTEC, then it switches to alternate map).
It is a simple two-dimesnional table of RPM/MAP. Each cell has a value for ignition timing and interval how long injector needs to be open.
That same map/maps are slightly changed on values of IAT and ECT until engine is at operating temperature, then no corrections are used until some of those values drops under or goes above predetermined values.
Closed loop will be active after thermostat has started opening, but even on the slightest hint of condition that could stress the engine, it switches to open loop. Closed loop is actually used by ECU much rarely than one would expect (too much TPS (15% 1st gear, 24% 2nd etc) = no closed loop, MAP sensor value high ( > ~ -0.4bar) = no closed loop, high RPMs (~5k) = no closed loop, engine below working temp (71C) = no closed loop, etc.) Conditions written are from my head, I can extract the values from my map if needed, they are left at default. 02 readings do not affect timing whatsoever.
While in closed loop, ECU will track percentage of AFR that needs to be trimmed since last loss of battery power (long term trim) and the moment it goes to closed loop, it will apply that percentage to all fueling values. Meanwhile, it will also correct values for current cell (called short term trim) and add those values to long term trim percentage. The moment one of conditions for closed loop is not met, all trims are ignored, meaning accelerating anything more than just feathering the pedal will just use plain basemap, no corrections.
Yes, it will throw a CEL, but it will run fine when 02 is not present.
My country is not a wealthy one so most guys can afford D16/B16 just now. They all run on the same (cloned chip) tune for years, pass MOT, etc. That tune has 02 disabled completely, how about that
I tuned mine myself and been doing so for a lot of time now. At first I was also skeptic and thought 02 is a must have, but the truth is a proper open loop map with adjusted IAT temp values can get away without using 02 at all. I do have my wideband plugged in all the time and enabled, but it is not necessary. I also ran open loop for months and had wideband just to keep an eye on the values, with closed loop disabled. Perfect AFR values all the time, just had to adjust IAT corrections now and then if outside temperatures changed and I haven't changed the default IAT correctiong until then. 02 won't save your engine, if catastrophic failure is about to happen, tough luck
