throttle body

[lakaiD14]

i have 2 throttle bodies, one stock (d14a3) and anotherone i think D15/16 but that doesn't matter

as the obd1 swap describes best TB is of an D16y7. just because on the D14 TB the iacv? is mounted. and on the D16 IM it's mounted directly to the IM.

the "thing" that is mounted under the opening off the D16 TB is that just the TB heater (don't know the right word in english:P) and just can be sealed of, because it is not needed? because the D14 TB has some electric/magnetic operated valve, and the D16 TB has not.

[mynameisowen]

The "heater thing" on the D14 TB is a RACV Rotary Air Control Valve I believe. The D16 uses a IACV Idle Air Control Valve mounted on the IM, they both do a similar thing. For OBD1 you need to use the IACV on the IM I believe so you can cover the RACV.

Can someone back me up on this?? Also does anyone know whether leaving the RACV on but not plugged in will have negative effects? Id rather leave it on instead of covering it but I will cover if there are problems??

[lakaiD14]

yes i know these things, but i mean the thing that is in place of the RACV on the D16 TB......
and i know also that i can cover the RACV on the D14 TB.


but "the valve" mounted beneath the D16 TB, can i cover that? because iff u cover the RACV on the D14 TB, u also remove the "TB-heater".

because u cut off the cooling system a bit.....

[Dodo Bizar]

My D16Y7 TB did not have this valve underneath (like most D16Z6 / D15B7 etc. do). Though I am not sure it applies to all TB's the same.

Though I still don't get it why my 'said to be D16Y7' TB does not have it. Chance is it aint D16Y7. Anyway the reason I call that one best is since it has hardly any disturbances on the surface.

Now back to your guys discussion:

We have 2 functions:
-idle control (fine control)
-cold engine fast idle control (crude control)

The fine control is always controlled by the ECU. The cold idle can be both ECU or mechanical (coolant driven).

In (most) OBD1 engines you have the IACV for the fine control and the valve under the TB for the cold idle. It just opens up when it is cold and closes when it heates up... this to limit the working area and precision of the fine control.

In the case of EJ9 both functions are combined in the RACV, but there is a double layer to it: when normally activated the RACV will be 100% controlled by the ECU. I think the 3 wires are needed in order to have more precision/range somehow. Now in the case of electrical failure there is still the classic mechanical system behind it. There is still a magnet inside controlled by the temperature of the coolant. Normally it will never work, only when the electrical circuit would fail.

Now there is the problem regarding OBD1 swap on an EJ9: the RACV will not be controlled by the ECU, so the magnet/thermocouple/whatever takes over and probably will scoop in more are than you like for safety. Especially when the coolant is disconnected, the temperature will stay low, and the valve will stay open on a cold fast idle setting! Meaning too high rpm with warm engine. Solve this by closing of the valve enterily. Costing cold idle rpm, but winning on warm idle rpm (low rpm at idle, 1200-1400 rpm instead of initially 2000, in my case it idles just 600-700 cold, climbs to 1200 during warming, ends up 700 warm due to the Skunk2 IM geometry and bad ECU settings).

[lakaiD14]

so iff i get this right, after my obd1 swap (with my D15 TB instead of D16), i can remove my coolant controlled valve. BUT is a advantage when my engine is warm, just for the idling.. right? it does not make this high rpm.


then i have the nest problem (does not matter if my engine is warm or cold. but iff i step my foor of the gas, my rpm dives to almost zero.....

the engine just keeps itself turning....... but with 200 prm or less...

anyone knows what this can be?

[Dodo Bizar]

Yup, that is delayed reaction, the current ECU and valve combi expects a much smaller plenum and needs less air to pass initially. Now the pressure in the plenum builds up too slow and almost stalls your engine.

I have the same problem since I went from OEM to Skunk2 IM which again is a plenum increase.

So getting the OBD1 swap should fix this or at least improve. Your ECU tuner should be able to change the reaction speed of the valve later on (check if this is the case with your aspirations ).

[novaksaotome]

so as i see, here is the possible solution of my idle problem, these valve underneath the d16 tb is calle FITV (fast idle thermo-valve) or something like that, so one side is connected to a coolant hose and the other? a vacum? is it better to take it off and cover it with a metal plate? will my idle stop going up and down all the time?

[lakaiD14]

iff your iddle goes up en down you have to concider to clean your IACV (that was my problem when my ECU gives code 14). but after that my idle problem was not over....

after 2 days of thinking and trying i found the problem, i have used the wrong gasket for the throttlebody, i have used my old gasket that came of my D14 throttlebody. the patern of the gasket is slightly different compared to the one used on a D15/D16 throttlebody. the wrong gasket resulted in a leak where my engine sucked air between the throttlebody and the IM because of the simple fact that on that exact spot there has to be a piece of gasket.

but the geometrie of the throttlebodies is different so if u control the gasket and replace it the problem might be over....

[lumpenst]

I have a similar problem with this but it only happens when the a/c is on. I have the obd1 swap with p08 head, intake manifold and throttle body. I also have the fitv blocked and not connected to any coolant lines.

I believe this problem is caused by my rom i'm using that is done using crome free 1.2. I read on pgmfi forums that in the 1.2 version the iacv duty cycle and idle adjustment parameters don't work right. Newer versions of crome crashes on my laptop with windows vista.

I guess it might also have something to do with one of the plugins which i'm using that adds full throttle launch control. When the a/c button is pushed the full throttle launch is cancelled and when it's off it cuts at some predetermined rpm value in the rom. The logic of the code probably conflicts with the iacv adjustment dependant on a/c load.

[lakaiD14]

i dont know this for sure but i believe eCtune has a fuction u can adjust conditions when A/C is activated.... but why use A/C it only costs hp and a lot of it

15% hp loss when A/C is activated or something i believe