My New STF project...
- Thread starter Andres3165
- Start date
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- 2012 Touring MT
Font Motorsports
Member
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- 2012 Mazda 2
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- 2012 Touring MT
CAI is in ...
...and I am very pleased with the gain:
5.34 HP Total: 101.80
4.35 LBS. Torque Total: 99.42
Andres
...and I am very pleased with the gain:
5.34 HP Total: 101.80
4.35 LBS. Torque Total: 99.42
Andres
- :
- 2012 Touring MT
My own design + _ $ 40
will post pics later
No just the intake.
Andres
Racebrewer
Member
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- Mazda, Mazda 2 Touring MT
Nice. Looking forward to more info on your CAI. Looks like you nailed it just right.
Also looking forweard to the header info. Please, please,,,,,,,,,,,,,
John
Also looking forweard to the header info. Please, please,,,,,,,,,,,,,
John
Andy Hollis
Member
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- 2012 Mazda 2 Sport
Something odd is going on in that dyno comparison. Notice the AFR chart. It looks like the ECU is going from closed to open loop at completely different speeds in the two plots. The old one goes from 14.7 down to 13 at 55mph and the new one does that at 70 mph. In each case, there is a corresponding power bump when the AFR goes to 13 (which is appropriate since that is typical for best power).
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- 2012 Touring MT
I am not really knowledgeable when it comes to tuning and stuff. Could you be more explicit? Doesn't the air/fuel ratio change with different air flows?
Did you see the readings on the factory set up? two runs are similar 2 & 3 , the first one looks different ???
Thanks
Andres
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Andy Hollis
Member
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- 2012 Mazda 2 Sport
Yep, that first graph has the same thing going on. Motor obviously likes to run at 13:1 AFR for best power (which is fairly typical). For some reason, the AFR step on that first graph changes from run 1 to runs 2 and 3. I'm going to guess that the engine was still warming up to some degree.
ECU's run in two modes, closed loop and open loop. Closed loop is typical operation and has target AFRs that are used to control the injectors based on output readings from the O2 sensor. The target is 14.7:1, which is best emissions (most complete burn). Best power is usually around 13:1, though. No matter what you do with exhaust or intake breathing changes, the closed loop fueling will adjust for the changes and produce 14.7:1 while in closed loop operation.
The only time you see something other than 14.7:1 is when the ECU goes into open loop operation. There, specific fuel amounts are used which are tuned at the factory for the OE configuration. This is primarily used for WOT only, where best power is desired. Why not just change the target to 13:1 and stay closed loop? In the past, the narrow-band O2 sensors used cannot accurately measure in that range. Now, though, wide-band O2 sensors are finding their way into some modern cars which can support closed loop operation with targets other than 14.7:1. So those cars can run closed loop always. The 2 may be one of them.
Anybody know if the 2 has a wide-band or narrow band for the front O2 sensor?
Either way, the comparison shows something else besides simply the CAI addition. It would useful to figure out why the AFR is changing in a single large step mid-run and why it is not consistent as to RPM.
Dyno testing is really hard to do consistently.
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It could be that the wideband is not getting enough airflow, did you have the stock muffler in place, or were you running the DJ "Special" exhaust? Could be that the wideband probe is not being inserted far enough in and is getting some readings from open air, causing lean mixtures until the exhaust flow is enough to overcome the lean mix at the probe.
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- 2012 Touring MT
Andy Hollis
Member
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- 2012 Mazda 2 Sport
Which makes sense...except for the power bump which coincides each tme with the AFR change to 13.
I'm thinking the AFR is really changing.
I was not looking at the whole picture, sorry. It does look like there is a difference in when the ECU goes closed loop, which not being fully warm would explain. The other variable is the throttle plate on the newer cars. Drive by wire systems can have funky things going on, like the throttle pedal and throttle plate relation not being 1:1. I have seen some plots where the plate opens more than expected at partial throttle and less than expected at full throttle.
Take for example the drive by wire system on the Mazdaspeed 6, above 5,000 rpm's the throttle plate starts to close regardless of the position of the pedal. This is done to save motors, and the partial throttle example given above is to make the car feel punchier at low spots in the torque curve.
Take for example the drive by wire system on the Mazdaspeed 6, above 5,000 rpm's the throttle plate starts to close regardless of the position of the pedal. This is done to save motors, and the partial throttle example given above is to make the car feel punchier at low spots in the torque curve.
zoomerang2
Member
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- 2012 Madza2 Touring
One thing I noticed in looking at these graphs, it is interesting to note that the slight bumps in HP were seen 400-500 RPM before the AFR started dropping, not sure what that shows other than that the power bump may not be triggered by the AFR change itself but maybe the throttle finally opens all the way, maybe due to the drive-by-wire throttle programming, and when it does reach 100% open, it triggers the Open Loop condition which then lets the AFR change due to switching over to the open loop map. Interesting... (uhm)
Andy Hollis
Member
- :
- 2012 Mazda 2 Sport
One thing I noticed in looking at these graphs, it is interesting to note that the slight bumps in HP were seen 400-500 RPM before the AFR started dropping, not sure what that shows other than that the power bump may not be triggered by the AFR change itself but maybe the throttle finally opens all the way, maybe due to the drive-by-wire throttle programming, and when it does reach 100% open, it triggers the Open Loop condition which then lets the AFR change due to switching over to the open loop map. Interesting... (uhm)
A delay of approx 500 RPM is typical for a tailpipe sniffer AFR probe. Put it in the header and you'll get closer to 1:1.
You can really chase your tail if you go strictly by the RPM on the tailpipe probe when tuning. Have to account for the delay for the gases to make it out all the way out the tailpipe.
