Cobb AccessPORT Discussion
05-09-2008, 11:40 AM
#2453
Registered
iTrader: (1)
Join Date: May 2003
Location: PA
Posts: 3,754
Likes: 0
Received 0 Likes
on
0 Posts
I actually just remembered yesterday that I did that airbox "mod" a few years back where you remove the baffles inside the airbox... I might log some data tomorrow and then put the baffles back in and see how the maf readings compare.
05-09-2008, 01:19 PM
#2456
B.I.G
iTrader: (4)
Join Date: Aug 2007
Location: AT---EIL
Posts: 1,401
Likes: 0
Received 0 Likes
on
0 Posts
HEY MM I got a quick question..
my STFT is at -6
and STFT is at -0
when im crusing its at like 14.7
under WOT in lower RPMS its 14.1
once RPMS HIT 5.5K it goes to 12.1-13.1 all the way to redline
but when its not WOT and its just crusing in those high RPM its running at 11.1
and another thing concerning me is that when im at idle and i rev it up at about 6.5RPM it makes weird poping noises like backfire POP POP POP and the AFR is at 11.1 and after it hits 7K RPM it stops adn the AFR go to 12.1
is that normal?
my STFT is at -6
and STFT is at -0
when im crusing its at like 14.7
under WOT in lower RPMS its 14.1
once RPMS HIT 5.5K it goes to 12.1-13.1 all the way to redline
but when its not WOT and its just crusing in those high RPM its running at 11.1
and another thing concerning me is that when im at idle and i rev it up at about 6.5RPM it makes weird poping noises like backfire POP POP POP and the AFR is at 11.1 and after it hits 7K RPM it stops adn the AFR go to 12.1
is that normal?
05-09-2008, 02:51 PM
#2460
B.I.G
iTrader: (4)
Join Date: Aug 2007
Location: AT---EIL
Posts: 1,401
Likes: 0
Received 0 Likes
on
0 Posts
05-10-2008, 09:23 AM
#2467
Registered User
Join Date: Jul 2007
Posts: 205
Likes: 0
Received 0 Likes
on
0 Posts
Okay, had the night to sleep on this stuff. I'm seeing clues to a couple things I've wondered about. Lots of questions for Jeff.
Topic 1: Fuel injector variation.
I've wondered a lot about car to car variation in output. I've heard a Mazda engineer admit to about 8hp in new, properly broken-in cars; he attributes the 18-ish hp range you see on the internet to dyno procedure variation.
Earlier in the thread, you talk about injector variation, giving an example of a 290cc injector ranging from 276 to 312, if I remember right. We could expect the PCM to account for this variation in closed-loop operation. Does it learn around this with the LTFT? Does it operate open-loop or closed-loop at WOT? If it operates open-loop, and doesn't learn out the injector variation, then the variation in cars might be injectors. Lower-flowing injectors = faster car?
And just for my own understanding: The initial STFT check has been described as dialing in for a MAF calibration. Is it just that, or is it really the relationship between MAF cal and injector flow?
Does the PCM figure out variation in injector capacity between front and rear rotors? Would there be benefit in sorting/blueprinting injectors to make sure the pairs are matched? If all the injectors on a car were flowed, would you be able to dial in the maps to better accommodate the variations?
Topic 2: Cruise economy.
My buddy who had an RX-8 for awhile said his gf got about 10% better fuel economy driving up I-5 than he did. There is discussion that AF ratios drop in highway cruise around 4200 rpm, due to the PCM transitioning to open-loop operation. Calculating the gearing, that makes the transition around 85 mph. I suspect that my buddy just drove a little deeper into that than his gf did. Could this function safely be delayed in the high-gear maps to clear 90 mph in 6th with optimized fuel economy? Would that really make a difference? Does anyone run EGTs to know what would be happening to the cat? What % throttle is required to run 90 mph on straight level road?
I look forward to learning more when you get a chance, and appreciate what you're doing for the community.
Topic 1: Fuel injector variation.
I've wondered a lot about car to car variation in output. I've heard a Mazda engineer admit to about 8hp in new, properly broken-in cars; he attributes the 18-ish hp range you see on the internet to dyno procedure variation.
Earlier in the thread, you talk about injector variation, giving an example of a 290cc injector ranging from 276 to 312, if I remember right. We could expect the PCM to account for this variation in closed-loop operation. Does it learn around this with the LTFT? Does it operate open-loop or closed-loop at WOT? If it operates open-loop, and doesn't learn out the injector variation, then the variation in cars might be injectors. Lower-flowing injectors = faster car?
And just for my own understanding: The initial STFT check has been described as dialing in for a MAF calibration. Is it just that, or is it really the relationship between MAF cal and injector flow?
Does the PCM figure out variation in injector capacity between front and rear rotors? Would there be benefit in sorting/blueprinting injectors to make sure the pairs are matched? If all the injectors on a car were flowed, would you be able to dial in the maps to better accommodate the variations?
Topic 2: Cruise economy.
My buddy who had an RX-8 for awhile said his gf got about 10% better fuel economy driving up I-5 than he did. There is discussion that AF ratios drop in highway cruise around 4200 rpm, due to the PCM transitioning to open-loop operation. Calculating the gearing, that makes the transition around 85 mph. I suspect that my buddy just drove a little deeper into that than his gf did. Could this function safely be delayed in the high-gear maps to clear 90 mph in 6th with optimized fuel economy? Would that really make a difference? Does anyone run EGTs to know what would be happening to the cat? What % throttle is required to run 90 mph on straight level road?
I look forward to learning more when you get a chance, and appreciate what you're doing for the community.
05-10-2008, 11:16 AM
#2468
Earlier in the thread, you talk about injector variation, giving an example of a 290cc injector ranging from 276 to 312, if I remember right. We could expect the PCM to account for this variation in closed-loop operation. Does it learn around this with the LTFT? Does it operate open-loop or closed-loop at WOT? If it operates open-loop, and doesn't learn out the injector variation, then the variation in cars might be injectors. Lower-flowing injectors = faster car?
Originally Posted by SolarYellow510
And just for my own understanding: The initial STFT check has been described as dialing in for a MAF calibration. Is it just that, or is it really the relationship between MAF cal and injector flow?
Originally Posted by SolarYellow510
Does the PCM figure out variation in injector capacity between front and rear rotors?
Originally Posted by SolarYellow510
Would there be benefit in sorting/blueprinting injectors to make sure the pairs are matched? If all the injectors on a car were flowed, would you be able to dial in the maps to better accommodate the variations?
Originally Posted by SolarYellow510
Topic 2: Cruise economy.
My buddy who had an RX-8 for awhile said his gf got about 10% better fuel economy driving up I-5 than he did. There is discussion that AF ratios drop in highway cruise around 4200 rpm, due to the PCM transitioning to open-loop operation. Calculating the gearing, that makes the transition around 85 mph. I suspect that my buddy just drove a little deeper into that than his gf did. Could this function safely be delayed in the high-gear maps to clear 90 mph in 6th with optimized fuel economy? Would that really make a difference?
My buddy who had an RX-8 for awhile said his gf got about 10% better fuel economy driving up I-5 than he did. There is discussion that AF ratios drop in highway cruise around 4200 rpm, due to the PCM transitioning to open-loop operation. Calculating the gearing, that makes the transition around 85 mph. I suspect that my buddy just drove a little deeper into that than his gf did. Could this function safely be delayed in the high-gear maps to clear 90 mph in 6th with optimized fuel economy? Would that really make a difference?
In essence, I simply turn this feature off.
Originally Posted by SolarYellow510
Does anyone run EGTs to know what would be happening to the cat?
Originally Posted by SolarYellow510
What % throttle is required to run 90 mph on straight level road?
The above cruise economy situation is not based on throttle position directly.
05-10-2008, 02:09 PM
#2469
Registered User
Join Date: Jul 2007
Posts: 205
Likes: 0
Received 0 Likes
on
0 Posts
https://www.rx8club.com/showpost.php...1&postcount=10
So the long-run choice is between
1. spend a ton of money on gas
2. buy new stock cats with regularity
3. buy a ~$1000 Euro race cat that will live forever
4. have TeamRX8 impound and crush your car because you are going catless
(Which I support. I like to breathe and see the mountains - in both directions.)I wonder if #1, #2 or #3 would come out cheapest?
If someone wanted to go that way, would you issue a flash that offered all the other benefits but retained the cat protection strategy for cruising?
05-10-2008, 02:56 PM
#2470
04 and still lovin it
Join Date: Jun 2004
Location: Toronto
Posts: 297
Likes: 0
Received 0 Likes
on
0 Posts
Just curious
With all the things the AccessPort and tuning software can see and do, Is it possible to display oil pressure or indicate oil level?
If possible could that be the first thing that is displayed as an opening screen? It would make sence for a rotary
Possible?
With all the things the AccessPort and tuning software can see and do, Is it possible to display oil pressure or indicate oil level?
If possible could that be the first thing that is displayed as an opening screen? It would make sence for a rotary
Possible?
05-10-2008, 06:10 PM
#2474
Power!!
Just curious
With all the things the AccessPort and tuning software can see and do, Is it possible to display oil pressure or indicate oil level?
If possible could that be the first thing that is displayed as an opening screen? It would make sence for a rotary
Possible?
With all the things the AccessPort and tuning software can see and do, Is it possible to display oil pressure or indicate oil level?
If possible could that be the first thing that is displayed as an opening screen? It would make sence for a rotary
Possible?