Can anyone tell me under what engine loads the ECU switches from closed loop to open loop? I've noticed from monitoring my wideband display that under steady state driving conditions, the A/F ratio is always 14.7. However under any amount of acceleration the A/F is determined by the Greddy eManage settings.

 

If somebody could plot a 4 dimensional map using the variables the ECU is using... yes. Or should I say no?

What is the real problem that you are trying to address?

 

In other words, he doesn't know.

Let's talk about the variables that would be used to trigger a change between open and closed loop. I guess throttle position would be one. Perhaps intake manifold pressure?

What else.

 

I'm pretty sure it's just throttle position. Nothing else. The only question I have is "At what throttle position does it switch?"

Fperra, your car is doing exactly what it should be doing.

 

I'm not trying to address any specific problem. Just curious. My guess is TPS or MAP. By the way Wes, I solved my problem with the CEL "MAP lower than expected". UR had set the ratio for old injector/new injector too low (.48). I changed it to .58 and the problem went away. The car is running great now. The eManage does not appear to have any problem driving the 600 cc injectors.

 

VTEC engagement relies on more than one variable. What makes you think the transition from the closed loop algorithym to the open loop static map is different?

 

Because that's the way it is. It's a well-known fact.

 

Usually Honda ECU's transition to closed loop based upon load level - approximately 790 mbar of manifold pressure to be exact. Some older cars also used TPS as a check on that. Not sure if the latest ECUs use load, or a combination of load and TPS, but load is what I'd be looking at.

Oh, I forgot, actually, the latest ECUs in the RSX, etc. will actually run closed loop even at full throttle for short periods (couple of seconds), so there is a time dependent factor in there as well. The primary O2 sensor is a low grade wideband.

UL

 

I have a question about that. During tuning of my car we were doing some street tuning and we were tuning all different scenarios. One was part throttle - full boost. There was a significant difference between how the car reacted, fuel-wise, when we made 6 PSI at 30%-50% (about) throttle and when we made 6 PSI at 50%-100% throttle. And the eManage was not using TPS, but boost / RPM, for it's fuel decisions. The car would always run real lean during the light throttle full boost scenarios. Would light throttle - full boost not create 790 mbar of manifold pressure, or is there some other explaination?

 

Were you making that boost at the same rpm level for each throttle position?

790 mbar of absolute manifold pressure is about 6" of vacuum, so you should have been in open loop.

I would look to the operation of the Emanage for your answers on that one.

UL