Hello,

does the air pump affect the AFR readings?
If yes, how can the OEM ECU controll mixture in cruise area if the the AFRs are leaned out by the air pump?

 

Only is the sensor is plumbed in after the air pump.

 

So if the sensor is placed on the default location the AFRs are not affected of the pump?



this picture shows that also air is blown in the exhaust port before passing the o2 sensor

 

Yes, but keep in mind that when installing a WB 02 sensor, It needs to be at least 2 feet from where the exhaust exits the engine.

 

The air pump directs air into the exhaust manifold at certain times and to the main cat at certain times. At times when the air pump is putting air into the exhaust manifold, it will foul out O2 sensor readings. That's typically at idle and part throttle, though.

Full throttle you will get proper readings, but it is annoying if you're trying to work on low load spots. But, you can also just unplug the air pump electrical connector to turn it off.

Dale

 

We unplug the air pump for dyno tuning, on vehicles that have it functioning. Then when all tuning is complete, plug it back it in.

 

thanks for you answers, but can you explain me how the factory ECU does closed loop at cruising? how does the factory narrowband probe work when air is injected?

 

The stock ECU knows when there is airpump air being injected and can "fudge" what the O2 sensor is telling it the right way so it all runs right. Unplug the airpump with a stock ECU and you'll have a rough idle, harsh on/off throttle, etc. The factory ECU is trying to compensate for air that isn't there, so you get a weird fuel mix.

This is also why you need an airpump with a factory ECU or else the car runs like crap.

Dale

 

the "port air" is only used up to about ~2500rpm OR 25% throttle openings (the actual graphs are in the FSM's Foxed.ca - Mazda RX-7 Manuals).

the closed loop turns on about 1200rpm, and stays on until 3199rpm OR 1psi.

there is an area where both are on at the same time, although its small. the air pump air volume is teeny compared to the engine, so at idle the AFR's are thrown off a lot, at 2500rpm, its not doing much.

as such the ecu just runs in closed loop like every other car. the catalyst sees 14.7:1 AFR's, so its happy, which is the whole point of closed loop anyways

 

ok, now to my problem. I was running a PFC without airpumpt and without o2 feedback for a long time. But I decided to switch back to run with air pump and o2 feedback to pass the german emission tests(please, no vdub jokes )
But my car is running not good in closed loop with the pfc, maybe my basemap is "too far" away to run the desired AFRs. Is the FD running a 14,7 AFR in closed loop? so how should I map my cruise area with disconnected airpump?

 

get a tune

 

the FD is running 14.7 in closed loop. the O2 has enough control to make it 14.7:1 weather or not the air pump is in port air.

you might want to compare the cruising area of your map with the base map, as the base map runs fine with or without the airpump.

 

Ok so I will disconnect my airpump and remap my cruise area to 14,7.
But theres one thing that I don't understand, when I map my cruise area without airpump to 14,7 and reconnect the airpump - why does the o2-sensor of the emission testing device will not read a AFR value thats too lean to pass the emissions-test?

Can you please post a picture of your settings for the Narrowband emulation ?

 

the FD closed loop is more complex to explain than it really is. the simple explanation is that Mazda set the mixture slightly rich, and then they use the 02 sensor to lean the mixture to 14.7:1. the air pump may be on or off during this time, but the 02 sensor has enough control to keep the mixture at 14.7:1