shamoo

In pretty much any gear, partial throttle of around 75% or less feels faster and probably does accelerate faster than full throttle.

Why is that? My A/F voltage is perfect thru the entire rpm range.

Tuan

I have the same problem too. The reason why I run half throttle is because i HAVE TO, I lean out when i go full boost. Sad, i need some serious fuel or tuning...

GruvyTune

exactly, tuning should take care of that! Thats how my car felt till it was tuned at open throttle.

dbman96

At part-throttle you're probably not putting it into open-loop mode and therefore the ECU is running you REALLY lean which will feel more powerful until it burns holes in your pistons or snaps a ring land.

echo999

Can someone explain Closed-loop, and open-loop.. and how the ECU detects and treats each condition?

DIRep972

iTrader: (1)

if ur car feels faster at part throttle then u r leaning out at full throttle. make sure your fuel system is functioning correctly.

dustin

Wanna hear my idea/theory?

I bet your car at full boost part throttle is about as fast as it is full throttle. However, you expect it to feel a lot faster when you floor the car down to WOT (like a N/A car)... but it doesn't really do anything.

When you have the car at full boost, regarless of throttle position, it is at maximum load. The restriction of the throttle plate is the only difference, but the motor is getting the air it needs either way.

This is why our cars are so drivable at light throttle on the freeway, almost any gas makes the car go into boost. If your car is at full boost, regarless of throttle position, it is flowing the same amount of air and burning the same amount of fuel as if you had the car floored.

Dustin

xci_ed6

There will be a preassure drop accros the throttle plate, so you will have a less air flow. but if your boost is the sa,e then you are flowing the same. where is your wastegate actuator hooked up? manifold or charge pipe? If in the manifold you will get max boost regardless of throttle posistion, if in the charge pipe max boost will vary with throttle posistion (slightly).

my ? is, is your throttle plate set right? is it starting to close again after 3/4 throttle?

-Dustin

shamoo

Ya know what? I think you're right. I was testing out your theory today when I did some full throttle and partial throttle passes on the highway. They were practically the same.

I'll look into it some more though just to make sure....thanks for the replies.

eh-D

Usually you will run closer to stoich at partial throttle becuase airflow is metered and the correct amount of fuel is delivered to each injector. At wide open throttle the system goes into open loop operation and the injectors deliver the max fuel that the system can provide.

Honda designed cars this way to compensate for the general driving public(ie-pumping 87 octane into an ITR and passing in 5th gear at high altiude up a hill while loaded with enough cargo to stock a small thrift store).

Most cars will see a huge gain from tuning for this exact reason. If you have an EGT watch it, odds are it will be way cooler at WOT than if you were just on the highway at 55.

Hondas aren't the only cars that work this way, I've driven several cars that had more punch at 9/10ths throttle than 10/10.

LsTurbo91

Interesting theory, I'll have to try that at a dyno someday.

Hondata

http://www.hondata.com/techclosed.html

Doug

falcongsr

people with missing links or similar map limiters need to understand that their ECU is in open loop mode whenever they are boosting, regardless of throttle position (and regardless of the throttle position sensor) when the MAP sensor gets near 3V (atmospheric) the ECU goes open loop.

Also, I remember a guy saying that the throttle actuation on small displacement cars tends to be 'cammed' so a little gas pedal movement makes a big difference when you first put your foot down, but the last 1/3 of travel to the floor is almost no difference. The C shaped part of the throttle cable reciever on the throttle body doesnt look like it has a 'cam' shape but it could still be happening just with the geometry of the cable/gas pedal and the cross sectional area of the throttle body.

Joe

JT

I'm very curious how you came up with this conclusion, as many people know the TPS voltage level is what is used to control open loop. Therefore, the reason for the very popular TPS mod by Rafe Jaffey to cure the part throttle detonation problem that many people have experienced. John at J&S has a new Safeguard which also uses the TPS signal to trick the ECU into open loop. Check out this post.. http://forums.clubsi.com/showflat.ph...ts&Main=601687

Additionally, Zip also uses the TPS signal in his EBL for open loop as well.

dbman96

Open loop is triggered by EITHER of two things:

TPS reaching WOT voltage (approx. 4.5V)

OR

MAP sensor reaching "WOT" voltage (approx. 2.8ish V)

TPS trick is useful on JRSC cars because of the way JR located the MAP sensor before the blower, it is almost always seeing some vacuum even when the blower is making boost.

On a turbo car, the missing link or MAP limiter should push the MAP sensor up to open-loop level before it caps, so in theory you should be open loop even at partial throttle. But if you're running a VAFC-hack type install, that doesn't hold true and you really do need to run the TPS mod to force open-loop mode.