Could locking the ECU in open loop have any adverse effects?

[DSMTyson]

I'm a little new to tuning but i'm learning rather quick(or at least I like to think so). Right now i've locked my ecu in Open Loop until my o2 sensor gets here. I'm just wondering if theres any side effects from constantly running in open loop(been running like this every day for 2 weeks).

Does it increase or decrease gas milage?

If it causes no adverse effects, then what exactly is the point of running in closed loop?

Thanks,
-Tyson

 

[UofACATS]

Does it increase or decrease gas milage?

If it causes no adverse effects, then what exactly is the point of running in closed loop?

It's perfectly safe to run your car in Open Loop, assuming your airflow and fueling are accurately calculated. Given open loop operation does not use oxygen sensor feedback, it relies on the accuracy of the data entered to calculate the tune. It assumes this data is correct, and operates blindly so to speak. The point here is that it can't alter fuel trims if it's running lean, so a bit of caution is advised.

Closed Loop increases your gas mileage in stock trim because closed loop operation uses instant feedback from the Front o2 sensor to determine optimum air to fuel ratio. In cruise this to be 14.7:1, which we know as stoichiometric ratio. This is the most efficient (or probably highest efficiency with adequate safety precautions considered) air to fuel ratio.

You can achieve a perfect, efficient tune locked in Open Loop, you just need to tune.. May be easier said than done though I wouldn't say I'd recommend it unless there's a major shortcoming with the vehicle that cannot otherwise be addressed. An example would be outdated large injectors that did not respond well to the relatively large percentage swings in fuel during light cruise. This is because a __ % change on 450cc injectors is seamless, while the same % change on 1600's causes a stumble, hesitation, or other undesirable behavior.

 

[DSMTyson]

Thank you for the very informative reply and for answering all my questions. That just wiped some sweat off my brow. I thought that it would be safe staying in open loop, but I was just making sure. And my fuel trims/dead time/airflow adjustments are all accurate, could use a bit of fine tuning though like you mentioned.

Thanks again.