1989/90 Bad idle speed, maybe air leaks,
and how to test for this problem.
Little of the the below is in the FSM. (Factory service manual)
Bad idle speed or regulation.
If Idle is bad, you must check to see if the engine is in good condition first, before trying to correct idle problems.
Setting idle on a bad motor is mostly just a waste of time and effort.
BAD THINGS: (that kill curing a bad idle)
A BAD MOTOR (and covers most this first section)
Bad Compression.
Bad Vacuum (the Vac. gage wiggles at idle) If true, bad motor.
Bad Cam timing (timing belt has slipped) Crank key has sheared.
Bad Ignition timing. someone tried to correct the above cam slippage, with the distributor clamp screw, really a bad idea.
I BET IF the IGnition timing was off ( more than 2 degrees) then the Cam has slipped, I bet.!
Bad ECU or bad inputs to ECU. (bad Oxygen sensor, cracked exhaust manifold causing oxy sensor to go nuts)
Leaking Injector or clogged injector.
Clogged air filter.
Bad Gasoline in the tank , and varnish covering all the injection vitals (bad, way bad)
Bad Fuel pressure (must be inside spec. range ) use a real gage , don't guess.
ECU stuck in limphome mode, due to any of the above malfunctions.
ECU dead and operating in BACKUP mode. ( no idle controls, is first thing to go bad)
A/C stuck on. , Defrost or HL stuck on , or a bad or miswired DIODE block causing false A/C/Defrost/HL , on conditions. (unplug diode block to prove this)
Power steering overload switch stuck on.
Bad Diode block, remove it to test it.
These items must be corrected before idle speed can be set.
Only good motors and ECU will idle correctly and regulated, that is a fact.
WE HAVE INDUCTION LEAKS: See graphics below for details.
There are 3 idles modes, on this car and all 8 valve KICKS.
They are:
1- HOT running, 2- Cold Start IAC , 3- fast idle cause by the Dashpot cold start device.
Only #1 and 3 are adjustable !
ALL 8v motors run a real fast cold idle and run even faster for even colder ambient temperatures, 2500 RPM is common.
#2 causing a too fast idle speed, is problematic, because the FSM states no normal cold idle, speed. !
HOT IDLE:
Problem 1, hot idle is too fast. (Motor is known to be tuned and running perfect , per above list)
- 1st try to adjust the idle by screwing on the throttle stop screw. See photo2 , red arrow and the words "The Throttle"
- Unplug
the Diode block. So
electric loads can not raise idle.
- Make sure the dashpot plunger is retracted. It must retract within 2 seconds of starting hot or cold. If not, trouble shoot this failure.
- The Throttle shaft is not closing all the
way,
Kick down or throttle cable jammed.
- Make sure the throttle stop screw is touching the bell crank, stop on throttle shaft. If not, something is holding throttle open, Find it.
- Using an IR gun, measure the temperature of the Thermostat housing, It must be above 160F, the coolant must be 180F MINUMUM.
- Remove inspection port 23 below , hot, and make sure valve is closed, above 150F.
- If you suspect the IAC, then test it in a hot pan of water and just look at what it does.
- Next pinch
all
vacuum lines, skipping the hose 18(FPreg)
(visual inspection here and leakdown test recommended) , skipping
PCV
hoses, but visual inspection of these hoses are critical. All hoses to
the TB and the the Induction Plenum must be checked for leaks
Pinch all
lines. If Idle drops you do have an air leak in this hose.
- All TB gaskets must be checked for cracked or
missing.Same
with the whole manifold. TB = Throttle Body.
- ISC gasket, EGR main gaskets must be perfectly
sealed. (
the EGR valve inside must not leak exhaust at idle or the gasket leak
air)
- If no leaks are found, at this point, then one must pull the ISC and plug both holes to it, in the throttle body, the RPM must drop way below 800.
- IF the RPM don't drop at all ,from above action, then you have a massive leak somewhere.
- Last places to look are Intake gaskets at the head.
- Bad ISC. Clean the ISC and test with 12vdc battery jumper applied, to it, for 1 second ON, , then 10seconds OFF ( to keep it cool) The valve must allow air ON, and must block AIR off. (this test may take cutting 1 of its wires and then resplicing it back).
- THE IAC ( TB base air thermal device) may be bad,
some just
pull the cover and put clay in side to block it , as a test.
As anyone can see, hot idle speed and regulation is hard to achieve. (on a bad motor or one with air leaks, all EFI cars made this is true)
Key testing of this system only requires the mechanic to start blocking off all sources of air leaks one by one and then last block off the ISC ports.
If you block them all , and the hot RPM is above 800 (diode block unpluggged) then you have a bad TB or manifold gasket or a blocked open throttle plate. Some times we get gunk under that TB butterfly plate.
See id #8 , the TB surface has holes that match #8 so plug them with putty or tape.
Find a way to plug up the ISC ports. (many ways there are , tape is one) then the idle MUST go way below 800 RPM hot.
IF this test fails to achieve below 800 rpm (600 is typical) then thre IS an air leak, use propane gas play around to find it. (propane will cause RPM changes if leak is present.)
Find the vacuum air leak and you are on the way to solving hard to find fast idle causes.
This MAP sensor based system raises idle for any leak from any source. (that is how it works) Called a Speed Density System in the Car world.
All air leaks on this system result in an increase of idle speed with FULL POWER !
My contribution to the 20 year old 89/90 kick-o-roos.
Setting the dash pot. speed setting: This is the Cold start temporary fast idle device.
- Hot
motor,running.
( strangly calibrated hot)
- Neutral (park)
- Pull the vacuum hose from Dashpot nipple and block the hose, leave DP device nipple free from any connection to vacuum!
- Idle will rise greatly by action of the spring inside
this
dashpot. ( this occured hot
already and
not as above vacuum line pull)
- Adjust the idle at the dashpot screw to
1700 to 1800
RPM. by adjusting the screw near the end of the dashpot plunger. See
photo 2.
- Return the hoses to the original state and check hot idle again.
Some hackers defeat this device totally because they dont like the super high RPM colds starts. YMMV.
Cold Idle speed:
Cold idle speed is never mentioned in the FSM ! ( they do NOT spec. out what RPMs for what temperatures.)
HOW ever the valve does close at 150F. Between, cold and 150F, he RPMs are NOT spec'd out.
Spec'd out means ,not specified by Suzuki or Geo .
This IDLE SPEED , is a function of the IAC , the coolant temperatures , the air temperature, the ISC modulation via the ECU internal tables .
The colder the air and coolant the faster the idle will be, because of the wax pellet inside the IAC and maybe the ECU actions.
There is a schematic in the FSM showing all the variables that can change cold idle speed.
If all things are perfect with the HOT and Bad things sections, above, then one has only 1 item that can correct a too fast, cold idle.
That item is, the IAC. [ some hackers (love yah!) put clay in this 3 screw port (photo 3) which cures a bad IAC.]
You can or may try to:
- Buy a new or used IAC.
- Adjust the ring inside shown in Photo 3. below, it is threaded and 1 or 2 people have said they were successful fiddling it.
- if you live in warm climates ,some have blocked it , partially or fully. Ok if you like the low cold start RPM'S, use a heavy right foot , LOL.
- Test it in a pan of
hot
water. Pull it and wait for wife to go shopping,
Grin !
The is my contribution to all early Kick owners.
I hope this helps you cure your idle issues. (I'm sure it will)
or post to our forum, search or start a New Post.
Do be shy , and for sure feel WELCOME !
Exhibit drawings to follow: Photo 2 is 1991 but is funcitonally the same (has diff port sizes and injector size so dont swap them)
Drawing 1:
A real 89/90 Throttle Body. Notice ISC has no coolant heat up pipes. (coolant).
Photo 2:
This is my 1991' TB , but is very close to 89/90 Top valve is ISC and sometimes called IAC hot idle valve.(it's electric)
Sorry for Blue words are wrong, due to naming convention in 91 year change. IAC below is ISC ! Send me a real 89 photo and i will use it.
The ISC works the same on all Kicks , they just look a tad different. 89/90 has no external Air piping !
PHOTO 3:
(91' TB but 89's are similar) Left opening is IAC cold start warm up air valve. cold idle primary.
11-18-09