Suzuki Sidekick and Trackers 1.6 Liter.  
IDLE SPEED ADJUSTMENT:

There is none, really the ECU does this automatically, but if the Dutycycle is off, then it must be done.

99% of all idle errors are EFI fueling issues, (wrong) misfire or vacuum leaks.

Idle speed hot is the last to work right, all else must be correct, first.


 

If 1989/90' motor has idle issues, go here.


Setting the Dutycyle on all 1992 and newer Sidekicks. ( if found  off ) (I list all causes, here)

I may call the throttle body,  "TB" as a short hand.


This page covers the location of the bleed screw, for the newer 91'+ 8valve TBI engines.  The above newer side kicks is at above link.

  AIR  Bleed SCREW:  8 valve 91-95 1.6L         The new car has a plactic cap on it, on all Suzuki's
 

The below Throttle plate screw issue:  { not a step but a side issue, that is related }
The Throttle plate adjustment screw (painted white) , that the FSM says never touch. (from 1991 to eternity.)   This stop screw is a FACTORY setting.

As is the ISC side screw (allen hex).  Only fiddle the bleed for 50% dutycycle.

 

If you mess up the throttle stop screw, here is my 8v factory screw measurment. (off 3 spare bodies, still unmolested) 0.250"

The valve is really 99.99% closed, the tiny open , only prevents JAMS and fast wear of bore.  (it's a factory 1991+ setting , leave it be)


This photo is to recover the actions of others.

The above is crude,  and can very by body casting errors.  Today, I'd use the below way.
I'm told in the factory they set it with a flow bench, for very very tiny flows, "miniscule" and is a SECERT.

(Other car makers set this to .0005" gap at the bore to fly valve)   This too may work good. SUZUKI does not help, with facts here.

The 1989 and 1990 engine has a unique TB , throttle body with NO BLEED screw
See here for all early Sidekick ISC checks.

 


Tests:  (out of 91 FSM , factory service manual ) for idle regulation.

With the engine idling, turn the air conditioning system ON and note the engine idle speed rises 200 rpm.
This validates that the ECU, is controlling idle . ( only the A/C does this trick and maybe Power steering overload)

rule 1: If the TPS idle switch is not signaling IDLE, then idle regulation will be dead.

rule 2: The ECU in limphome mode (even  wth CEL not glowing running) will stop idle controls from happening.

In the years 1989/90 there are many fast idle devices , unlike 91+ , and they are Head lights and Defrost, click here for all 89 differences.

The misc. fast idle speed on a 89/90 is 950 RPM.

The A/C idle speed should rise to 1000 rpm, otherwise there may be a malfunction in the A/C ON signal circuit. (from the A/C AMP module.)
Or defective ECU or the ECU is locked in a Limphome fault state, air leaks, advanced ignition timing.

Now turn on the headlights and Heater fan and or defroster, the RPM must hold at 800.!  (89/90 go to 950 RPM)
If  this test fails,  it can be caused by many a thing, Besides a stuck ISC.

The power steering overload switch must NOT be active full time (faulty switch) or idle will be too high.

  Idle control can be dead if the TPS switch (not the variable resistance side) is broken in the open position , or miscalibrated.


ISC Basic functions listed:  IAC is thermal only device, the ISC is electric.
The ISC  , provides extra air with IAC  (opens with more current) at startup. If this doesnt happen starting can be hard and flooding can happen, if IAC or ISC is dead.
The ISC , closes ( low current) the ISC and EGR are used to stop neck snap effect when you you cut the throttle greatly going fast.  (the so called "dash pot effect" )
The ISC does work between shifts of the transmission.
Last the ISC controls the idle ,while at idle, under any load condtions.  Electrical loads  or in PARK or  Drive.


ISC killers :
The ISC, can lose control ,even though , the valve itself is in perfect condition.
  • All illegal induction air leaks any vacuum leaks at all , any where in the induction system and hose and devices. This includes TB gasket leaks or IAC leaks, hot.
  • Any blockages below the throttle plate (TBI) (A loose of factory minimum air will case low idle.)
  • Lastly any bad wiring to the ISC will render it useless.
  • Setting idle speed too fast with  hot motor , will make the ISC lose control  (or the reverse)
  • 8V TBI Dash Pot device, stuck active HOT motor. (or its VSV bad or wires to it CUT)
  • Ignition timing set wrongly advance (more than 8 degrees before TDC)!
  • Timing belt slipped .
  • A Bad engine (seen as, vacuum bouncing or weak vacuum, or compression bad.
  • A melted Cat Converter blocking the Exhaut flow .
  • Limphome active or worse backup mode.
  • TPS idle switch not at near 0 volts.
  • EGR leaks,
  • Bleed screw all the way out or missing or screwed 100% CW in.
  • Check engine light glowing, or  the CEL dead all the time (backup mode)

Rev :12, 12-11-10  simple is  goal


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