Any increase in FC after OBIT
- Thread starter SMYUEN
- Start date
There is a definite increase in fuel consumption as I noticed it in my ride after installiig obit. I track every tank of fuel I pumped in and with obit my consumption went from 13.6L/100km to 14.5L/100Km. My driving habit hasn't changed much since I installed obit 2 months ago. So I can say it definitely has increased FC.
galant1688
Well-Known Member
so who is correct?? FC increase or remains
Re: Any increase in FC after OBIT
Woops, thanks for the correction.
Woops, thanks for the correction.
Shaun said:ryan said:
Ryan brother, E-manage (by Greddy) is a piggyback system as well but is a totally different make from Obit. Just thought I'd mention since "aka" suggests they are the same
just got back from PRI man. talk soon !
yendor
Well-Known Member
The main difference between the OBIT and the E-manage is the way in which they interface with the ECU. Both the E-manage and OBIT goes into the incoming MAF or MAP signal to alter the injector pulse width. This is where the similarity ends.
For the E-manage, the ignition changes are made from the ECU outputs to the ignition amplifiers.
For the OBIT, the inputs to the ECU from the crank sensor are changed to effect the ignition advance or retard. In addition, the OBIT offers Lambda modification which further alters the way in whuch the ECU sees the oxygen content in the exhaust. That is how it modifies the closed loop running. As to the fuel ratios there, the common problem with the new E46s is that they run 2 exhaust sensors and if the ECU sees a differing value in the sensors, they may chose to take the safer value and hence the leaner value to enrichen the mixture. I am not sure if the 2 sensors can be wired in parallel to trick the ECU though.... :roll:
For the E-manage, the ignition changes are made from the ECU outputs to the ignition amplifiers.
For the OBIT, the inputs to the ECU from the crank sensor are changed to effect the ignition advance or retard. In addition, the OBIT offers Lambda modification which further alters the way in whuch the ECU sees the oxygen content in the exhaust. That is how it modifies the closed loop running. As to the fuel ratios there, the common problem with the new E46s is that they run 2 exhaust sensors and if the ECU sees a differing value in the sensors, they may chose to take the safer value and hence the leaner value to enrichen the mixture. I am not sure if the 2 sensors can be wired in parallel to trick the ECU though.... :roll:
Racebred
Core Group Members
fuel consumption will increase if you code in for more power. Obit can also be used to maximise fuel consumption. if you want more power, you definitely have to burn more fuel.
Increment of FC is not a "negative trait" of the Obit mod. It is an understanding that when the owner wants more power, you have to have higher consumption, generally. i've never heard of anyone complaining of fuel consumption when one goes for a power mod.
Increment of FC is not a "negative trait" of the Obit mod. It is an understanding that when the owner wants more power, you have to have higher consumption, generally. i've never heard of anyone complaining of fuel consumption when one goes for a power mod.
yendor said:
rodney, you're the man
can you explain a little more about how obit carries out lambda modification and defeats potential test cycles while being one of the cheaper piggybacks on the market?
been wondering for a long time but never found any literature on obit or official obit guy willing to talk
In general FC goes up with power, but when looking at a gain in power, always look at whether it came from increased efficiency (friction reduction, combustion chamber and port optimization, accuracy and closeness to the limit of AFR and ignition timing, cam timing optimization, intake/exh. tract optimization etc. - basically anything that does not change, but makes better use of inducted air and fuel masses). The rise in FC accompanies rise in power only when that power has come about by increasing inducted air mass and burning the required fuel.
There is no real limit to increasing power through efficiency. But there are limits to increasing power by burning more mass... detonation, component strength/thermal resistance/capacity.
Gains from piggybacks can be made from increasing efficiency.. so the associated FC gains do not necessarily exist. It has been done many times before.
There is no real limit to increasing power through efficiency. But there are limits to increasing power by burning more mass... detonation, component strength/thermal resistance/capacity.
Gains from piggybacks can be made from increasing efficiency.. so the associated FC gains do not necessarily exist. It has been done many times before.
yendor
Well-Known Member
Shaun, sent you a PM.
Actually, most cars run a little less rich nowadays to meet stricter emission standards. The mixtures are run in closed loop to ensure that under normal operating conditions the car goes about its business. In the case of poor maintenance (owner never change oil, filters, poor fuel.....), the ECU will look after the car by altering operating parameters and usually this means retaring ignition and increasing fueling. Thus to err in the side of caution, manufacturers tune cars to run at a ration of 13.8 -14.2 at WOT at closed loop. Thus after the CAT, one can expect a reading of around 14.3-14.7.
If I is tuning the car for economy, then the ratios can be kept as such. But in the interest of greatest power, a ratio of 12.7 will the greatest oomph. The balance lies with what you, the owner, want. At the molecule level, 14.7 parts of air to 1 part of fuel yields complete combustion and super emission standards. The problem with this is that it is impossible to get every molecule of fuel to be exposed for the combustion. With an aftermarket ECU, the tuner, with a suitably equipped car, can change the WOT combustion ratios as well as keep the ratios lean enough for cruising. The trick about tuning is that you can optimise the car for fuels that we get here as well as lean out any rich areas in the rev range. With advances in ignition timings bringing about greater power (at the cost of costilier petrol), one can actually extract out more power than stock.
If the car goes through the same driving profile then the economy of the car is increased by virtue that the driver can back off the throttle sooner and lesser throttle inputs are required to get the car moving.
Most of the time the power is addictive and the driver just drives harder and this gives the poorer mileage. :twisted:
You can make the engine slightly more efficient by tuning to reduce the "just in case" parameters and optimise it for the fuels. Most importantly, if there are any hard core mods, the piggyback ECU can top up those important short fall areas and optimise the setup.
Thanks for reading....
Actually, most cars run a little less rich nowadays to meet stricter emission standards. The mixtures are run in closed loop to ensure that under normal operating conditions the car goes about its business. In the case of poor maintenance (owner never change oil, filters, poor fuel.....), the ECU will look after the car by altering operating parameters and usually this means retaring ignition and increasing fueling. Thus to err in the side of caution, manufacturers tune cars to run at a ration of 13.8 -14.2 at WOT at closed loop. Thus after the CAT, one can expect a reading of around 14.3-14.7.
If I is tuning the car for economy, then the ratios can be kept as such. But in the interest of greatest power, a ratio of 12.7 will the greatest oomph. The balance lies with what you, the owner, want. At the molecule level, 14.7 parts of air to 1 part of fuel yields complete combustion and super emission standards. The problem with this is that it is impossible to get every molecule of fuel to be exposed for the combustion. With an aftermarket ECU, the tuner, with a suitably equipped car, can change the WOT combustion ratios as well as keep the ratios lean enough for cruising. The trick about tuning is that you can optimise the car for fuels that we get here as well as lean out any rich areas in the rev range. With advances in ignition timings bringing about greater power (at the cost of costilier petrol), one can actually extract out more power than stock.
If the car goes through the same driving profile then the economy of the car is increased by virtue that the driver can back off the throttle sooner and lesser throttle inputs are required to get the car moving.
Most of the time the power is addictive and the driver just drives harder and this gives the poorer mileage. :twisted:
You can make the engine slightly more efficient by tuning to reduce the "just in case" parameters and optimise it for the fuels. Most importantly, if there are any hard core mods, the piggyback ECU can top up those important short fall areas and optimise the setup.
Thanks for reading....
Thanks Rodney! I am familiar with the AFR ranges and what they do in terms of power, egt, burn speed.
you mention
Isn't it true that all cars except the very latest ones go to open loop at WOT? how can there be closed loop WOT? I understand that some new volvos hold closed loop up to a max of about 4000rpm even at WOT, but I know of no other car that does it. Can share? Really appreciate it man Never mentioned it before, but I really respect the way you handle yourself in real life and on the forums. Thanks for the informative PM. I just got back from a trip this afternoon and now it is really late. Will reply to PM tomorrow.
cheers man!
you mention
Isn't it true that all cars except the very latest ones go to open loop at WOT? how can there be closed loop WOT? I understand that some new volvos hold closed loop up to a max of about 4000rpm even at WOT, but I know of no other car that does it. Can share? Really appreciate it man
Never mentioned it before, but I really respect the way you handle yourself in real life and on the forums. Thanks for the informative PM. I just got back from a trip this afternoon and now it is really late. Will reply to PM tomorrow. cheers man!
yendor
Well-Known Member
No worries, as for an example, my X-trail is one.... Corolla G9 is another. They run to about 3500rpm in closed loop regardless of WOT. Thereafter they switch to conventional metering and that is where my x-trail clocks in at a AFR of 12.5 after the CAT..... shocking.
The corolla does better. Running at 14.3 after CAT all to way to about 3000rpm before the mixtures riched to about 13.7 thereabouts..
The corolla does better. Running at 14.3 after CAT all to way to about 3000rpm before the mixtures riched to about 13.7 thereabouts..
Crufty Dusty
Well-Known Member
Shaun said:
Shaun,
Closed loop just means that the error between the input reference and the feedback signal is used to modify the former based on the previous results of the controlled variable (in this case the AFR). There strictly is no reason why a car cannot run in closed loop throughout the entire rev range, even under WOT, although I can think of some disadvantages:
1) Overreliance on sensors
2) Overreliance on closed loop control algorithms
Cheers
I know they can run closed, but didn't think that they did but from what rodney says they do run to 3500rpm closed loop regardless. sweet.. learn something everyday.
does anyone know if there was a time when manufacturers made the switch over to more closed loop situations? was it a time when a new emissions standard was enforced? was there a specific year? Also, what is a good way to identify whether or not a stock ECU is operating in closed or open loop when not relying on an OBD scanner? Like what basic instruments would you use and what would you look for on what wire?
thanks guys!
Rodney, IIRC the BMWs go to about 13:1, max load, high end of the RPM range too. sweet that cars in general not so pig rich nowadays
but from what rodney says they do run to 3500rpm closed loop regardless. sweet.. learn something everyday.does anyone know if there was a time when manufacturers made the switch over to more closed loop situations? was it a time when a new emissions standard was enforced? was there a specific year? Also, what is a good way to identify whether or not a stock ECU is operating in closed or open loop when not relying on an OBD scanner? Like what basic instruments would you use and what would you look for on what wire?
thanks guys!
Rodney, IIRC the BMWs go to about 13:1, max load, high end of the RPM range too. sweet that cars in general not so pig rich nowadays
yendor
Well-Known Member
Wah... this kind of question very hard to answer... the best bet is to monitor the output from the lambda sensor. For me, I just stuff my O2 sensor up the tail pipe and start driving.... sure can see the transistion point. From that point start adjusting the parameters on the piggyback... Anything lower and it is a waste of time if just adjusting MAP/ MASS sensor....
aren't you supposed to be sleepy????
aren't you supposed to be sleepy????
