Honda D Series Forum banner

1 - 15 of 15 Posts

·
Registered
Joined
·
9 Posts
ITB only for NA that wack

ITB's can be us in a turbo application turbo but fabrication of a air box for the 4 throttle bodies which i have seen in many 4age 20v in Hawaii and Cali, but itbs need a modified ecu because the high amount of air so air/fuel maps need to be change. Go Hondata chipping your ecu can help....Its a honda have faith...not a AE86 turbo 4age 20v
 

·
Registered
Joined
·
1,987 Posts
The spark timing and fuel maps for ITBs look different than a manifold intake. Tuning is the only way to extract power from ITBs, just slapping a set on there will actually hurt performance.

Look at these two default calibrations that come with Hondata SManager.

ITB spark table- it reaches full timing advace quicker and holds it longer through the RPM range - it's hard to read but if you look closely in the upper left corner of the pic notice this is a TPS based map


Stock P28 spark table- kPa based map


ITB fuel table


Stock P28 fuel table


You can actually "see" that the two 3d maps have different shapes. Every car has unique airflow properties. With a different intake or exhaust the "shape" of maximum performance will change as you add or take away fuel or spark advance searching for more power.
 

·
FAMILY MEMBER #316
Joined
·
2,955 Posts
more air means it need more fuel. plus, the idle will be all fucked up and theres usually not a lot of vacuum for the motor to work off of.
 

·
Registered
Joined
·
2,406 Posts
Its not the air flow is how the air flows, normal manifolds have a slow map transition. ITB's have a violent very fast MAP signal on a off throttle so a stock ECU just dumps way too much fuel on throttle tip in. A good ECU will have a throttle/Map blend and or a MAP adjustable transfer rate.

Also ITB's have a very waivy MAP signal from each runner having a seperate MAP pulse, a after market ECU can use a MAP filter to take the adverage of the MAP signal compare to a stock ECU which will constantly adjust the fuel curve with every on and off cycle of each intake runners air pulse.

ITB= Adjustable ECU
 

·
Registered
Joined
·
873 Posts
Does Crome Pro have this cycle issue covered?

OT:
I dont see people use their IACVs anymore with their ITB setups...
So what does one do to get idle to compensate for a/c?
 

·
Registered
Joined
·
2,406 Posts
I only use Electromotive Tec 2, which has a multiple ways to deal with the MAP issues of ITBS. As for the AC issue you can run a factory IAC you just need to be creative with the plumbing. Some people build a vacuum log and pipe the IAC into it so the idle air is fed equally to each runner. I personally dont use a IAC, my tuner can get the car to idle with out one so its one less thing in the engine bay.
 

·
Registered
Joined
·
944 Posts
Discussion Starter #11
ah its hard to understand, and those diagram looks like rocketscince for me^^
but i think i get it
in simpel words

the ecu are too slow to react on the fast itb airflow---->right?
 

·
Registered
Joined
·
5,511 Posts
No, they just can't compensate for the irregular MAP readings. Crome's ITB Tools(which uses the stock ECU), uses the MAP only for idle/low vac, then switches to TPS only.
 

·
Registered
Joined
·
5,511 Posts
No, Crome(free) still has it. There should be a version already installed under Plug-ins. If not, check the sourceforge directory for Crome or go through the Crome Development section on forum.pgmfi.org (there's an ITB thread).
 
1 - 15 of 15 Posts
Top