Closed loop issues

[Corey872]

Still seem to be having issues with nitrous control 'fighting' with closed loop.

First, let me say that the base cal runs fine. The problem happens when I set up nitrous control to pull out fuel under very light throttle cruise. This seems to save 2-3 MPG when it works. But as I posted with previous versions, the nitrous control 'fights' with closed loop for control of the fuel.

In the attached data log, nitrous control is active and I am going up a small hill at 20% TPS. Nitrous is pulling out fuel, but STFT is dumping in 15% to compensate, closed loop is winning and AFR is pretty steady at 14.5 - 14.7.

As I top the hill at about 17 seconds into the datalog, TPS drops to 12%, STFT maxes out to the preset 25% and the nitrous control finally starts to win out and AFR goes to 16.6-16.8. The cruising at 16.8 AFR is fine, it saves gas and runs smooth, but the switching back and forth between closed loop control and nitrous control makes for quite a bit of surging and throws the fuel trims out of line.

Is there any way to get an option to go into open loop when the nitrous control is active to eliminate this surging? How about a minimum coolant temp to keep from activating when the engine is too cold as well?

[Spunkster]

Change the minimum map for closed loop.

[Corey872]

Thanks for the quick reply - I had thought about that, but because this is already dealing with light throttle / low load conditions (ie 40 kPa), and we only have MAP to control closed loop, it would have to be shut off at some very low pressure like ~30kPa or less, meaning most of the driving range is in open loop.

It winds up wasting more fuel by not having closed loop control over most of the driving range than is gained by being able to lean out the light throttle cruise.

With E85 pushing $2.70 a gallon and most everyone else burning premium at $3.50+ a gallon, I'm just looking to squeeze out every possible MPG!