If you lock open loop, so that the car doesn't enter closed loop, and heat it up to stock 02 operating range, is the 02 doing any "Switching" at all, or just reading voltage as a direct result of 02 in the exhaust?

 

I think it would switch so long as your open loop AFRs happen to fall right around 14.7:1.

 

I can only assume any "Switching" would have to be ECM induced, with the ECM taking no considerations of the 02 in open loop, where does "Switching" come into play, granted it will never stay at a constant voltage due to endless exhaust variables, but non the less shouldn't it make for a better 14.7:1 tuning in locked open loop

 

There is some jitter since the sensor reads full time and slugs of exhaust from the engine pass with voids between them, and do to the sample rate of whatever scanner you have you'll see some variances.

The closed loop strategy is dilibertely changing the PWs to toggle the AFR across stoich.

So you'll see some wondering as opposed to toggling.

 

Grumpy given a situation where a WB just will not happen, is it reasonable to force a "Warmed up" open loop state, and tune for .450v 02 reading as close as you can everywhere (except wot), then get back to closed loop (and fix any areas if necessary) and then control WOT on a more broader scale with PE and so on ?

This is in lue of tuning BLMs

 

Why would you want to tune that way? If the goal is stoich, just run closed loop and let the ECM tell you how far to scale...am I missing something here?

 

Just an alternative mode of attack no real reason

 

So how bad was the damage to your VE scales with th LT1 swap roc?

U also prolly gonna get alot out of reworking the timing tables now too
Later
Jeremy

 

Oddly enough the tune was pretty fair overall

Same amount of knock (maybe one count getting on it hard out of 3 runs)

And 128ish untill about 5k rpms where it really leaned the hell out :P

Only got 2 scans, but both were identical results on WOT runs

 

Some of the issues with the oem sensors are operating temp, and backpressure.

Using a heated sensor fairly close to the engine takes care of one, but if you've done something to change the backpressure, that'll still throw wrenches at you.

You can get sort of close trying to hoover at .44/.45/.5 but personally I wouldn't just go on blind faith about it.

And while 15.5 might be great for lean cruise, I'm having a whole lot of nicer oil pressure at 13.8 and backing the timing down some.

Once you start getting all of it to what the engine wants the plugs will color stain alot easier, and reading WOT gets better since the insulator is just a tad cooler.

 

The exhaust is completely aftermarket but with shortie headers so the 02 is in about the stock location. It swings enough to wake up after a few minutes, so it is operational, will i get a better accuracy/consistancy with a heated 02 ?


I can afford that, just not a WB

 

This one's got me curious...Grumpy could you elaborate on the relationship between AFR, Timing and Oil Pressure.

 

I think he meant oil temp, not pressure. Pressure is RPM dependent.

 

tpep-

I'm not Grumpy, but if you ever worked at an autoparts store in wintertime, admiring the diamond ring that a lady is wearing and wondering why the hell it is you pouring engine oil into her car and not her husband, you would stumble upon the relationship.

Cool oil is thicker than warm oil, assuming you are comparing the same oil.

Running leaner than you (need/want) can elevate temps.

Edit: Kevm, we posted at the same time...but in my car, if I idle from cold start til fully warmed up, my oil pressure will decrease.

 

So will mine, but for the sake of the argument, I think it would be a LOT more useful to monitor oil temp via an aftermarket setup than trying to compare oil pressure in various conditions using the stock guage. Even with an aftermarket oil pressure setup, I think temp is a lot better way to make sure the burn is not getting too hot. Oil pressure should vary directly by rpm, scaled by temperature. Only when pressure exceeds that of the relief spring in the pump will the psi stabilize.

So, to summarize, while I guess pressures would theoretically decrease with leaner AFRs and more spark advance, it would be a lot harder to use that data (even assuming you can get it precisely) than oil temp...

 

The best place to gather data is in the combustion chamber, and folks are working on doing that.

Next best is right up close to the intake valve. Which is not to difficult.

While Baro might have some effect on vac readings it's only slight. Temp has a huge effect on fuel and timing demands. The advantage to sampling by the intake valve is that it takes into account oil temp, air temp, coolant temp., intake valve temp, etc.

While each element would be nice in a way to be able to compensate for, it would moreover be a case of feature creep, IMO.

At low speeds, and throttle openings, in my car, the MAT closely tracks the CT by about 40dF. When in boost, it goes up to 200dF. And even in a drive thru line on a hot day 180dF. At a MAT of 100dF which is by fair the average MAT, I have 0 corrections, but at 160 they start to make some. And at over 200 it's huge. Same thing with cold weather, once you get into below freezing temps they can be rather large. And in no small part is how the gas is brewed, I can actually detect a difference in some brews of gas in how the car acts at different MAT temps..