Idle adjustment?

[alia176]

Just an uneducated guess here...does our SVXs have an IAC valve (idle air control valve)? If so, is it possible to unplug it then set the base idle using the set screw. Perhaps, set the base idle a tad higher?

[Phast SVX]

once again, the idle is computer controlled, there is no BISS screw.
phil

[SubaSteevo]

There is an idle air control valve. My car actually shows this error code (needs to be cleaned?) and I'd clean it if I knew where exactly it was. Since your car is a 92 try self diagnosing the engine and see if it shows an IAC error (sorry, I forget the code, might be 24). If so, find out where it is and clean it. Let me know if you find out where it is

I adjusted the idle using the screw under the cover overtop of the intake throttle body. Its the cover that says H-6 and sits over the back of engine.
There's a set screw (hex), that you have to loosen a nut to turn.

My was idling around 500 and stalling when I parked it since the P/S puts strain on idle.

I've never seen an intake without an idle adj screw somewhere...

[mbtoloczko]

The purpose of that screw is only to keep the butterflies from bottoming out on the throttle body. They are not for adjusting idle.

[want-a-fast-svx]

Just wondering if anyone had a chance to try this yet??

Originally posted by BurgundyBeast
If you haven't already, try disconnecting the resistor so that the car always "thinks" its in power mode. Might or might not do anything,

[rmjjensen]

first off - I love alldata ...if u ever need any information just PM me and I can always help.

Here's the deal - the IDLE is 100% computer controlled and there's nothing you can do about it (well shouldn't say that). The Idle Control Valve is a solenoid (like everything else) and therefore acts on the same principle of everything else in the SVX. It's a function of the duty cycle that the ECU sends to it. Depending on the duration of the full voltage applied to it will either raise of lower the idle. In order to change it you would have to build a pulse width modulator circuit to manually control the valve.

But there might be some hope. There's an Auxilary Air Valve that is used to raise the idle when the engine is cold. This valve does not act on a PWM'd signal but just a varied voltage ....something your basic adjustable voltage regulator should be able to handle.

SVX Specifications:
...No Load Idle Speed: 610rpm (+/- 100rpm)
...A/C On Trans in N: 800rpm (+/- 50rpm)
...A/C On Trans in D: 700rpm (+/- 50rpm)

Here's an ECU pinout if you want to just toy around EASILY because all the controls can be accessed without taking anything apart.



Hope this helps. Oh yeah - and the Aux Air Valve is NOT monitored by the ECU and WILL NOT trigger a Check Engine Light.

Does ALLDATA talk about installing Indigo gauges ?

[mbtoloczko]

Nice description of the idle control system and the aic. I need to clarify a bit on your notes about pins 9 and 10. Both of those pins represent pull-down style inputs. That is, if nothing is connected to the pins, the pins will automatically hold high (+8 V). So, the ecu will automatically assume that the car is neither in D or in N if the pins not grounded. The tcu tells the ecu that the car is either in N or D by grounding those inputs.

i dont get it, if your car is idling within spec why change it?

[want-a-fast-svx]

Because its extremely annoying and frustrating every time i come to a stop that i have to keep feathering the throttle b/c I don't know if its going to stall and give me problems trying to start. So to prevent this now i try to turn the air on if i see I'm coming up to a red light.

[SVXRide]

Have you tried Chike's "tighten the throttle cable and cruise control cable" trick? My idle is 100-200 rpms higher since it did it (around 750 now).
-Bill

[Beav]

Sounds to me as if you just need to pull the t-body off and clean the IAC. Raising the idle with the throttle stop screw is not the answer. It is factory set on a flow bench. Besides, one would have to go beyond the IAC's ability to reduce idle speed to make a difference - not good either. You need a repair, not an alteration.

Other realities:

TPS has nothing to do with the idle speed. Period.

Fuel is cut, not spark, in order to control over-revving. Nobody wants raw fuel dumped into a hot exhaust - melted cats, explosion in exhaust, etc. Duh.

Since 'power' mode is only reached when the rate of pedal depression exceeds a specific threshold, and you hopefully have reached that at least a time or two without observing the light coming on, it may be due to some sort of programming interface between the ECU and the TCU. I would suggest sending a PM to Longassname and ask if he has any input on that issue.

I do believe the POWER light is only controlled by the tcu. So it would make sense that it wouldn't come on if you dont have a TCU. But how can you go into power mode if you don't have a TCU? Are you just meaning pressing the accellerator quickly? The engine has nothing to do with power mode.

[oab_au]

The trans signals N and P positions to the ECU. If neither is pulled low, the trans must be in gear. It uses this to select a different idle program, to handle the drag of the torque converter.

Trying to control the Aux Air valve would be difficult. The valve is controlled by a bi-metal spring. When cold it is open, when the ignition is on, an electrical element is turned on to heat the bi_metal spring to rotate the valve to the closed position.

The Idle Air control should pick the idle speed up ok, if it is working. As it is mounted under the throttle body, it collects all the sludge that settles down there.

Maintaining the idle speed is shared by the IAC valve and the spark timing, which is varied to quickly return the idle to the set speed, once the IAC valve catches up, to take over, the spark timing returns to specs.

Harvey.