it is this screw. at end. of this post
your car is 90, not 91. the 91 has a bleed screw up top. added in 1991.... and very different procedures.
http://www.fixkick.com/IDLE-AIR/89-90-idle-air.html
the top screw is Dash pot screw, that one is never changed,but the calibration is in the FSM... ask, if need it.
the lowest screw, is the TV stop screw. (can be seen to move if you watch the tv) see photo below.
the TV stop screw, opens the TV as you turn the screw in, Clock wise. (right hand tread rules)
in 1991+ the valve is always closed at idle. and the bleed screw adds air, by turning it CCW, (opposite of 89/90) (like a water faucet does)
the reason they did this is easy, the 89/90 everytime you mess with idle stop. you destroy the idle switch calibration. (a royal pain this is)
so Suzuki added the bleed, makes that hassle no longer true.... they mention this in the 91 fsm.
that is correct.
if you turn the TV screw, and the idle doesn't change that means the ISC Servo regulation is working,! as you turn the screw in, and add air the ECU sees you do that, and closes the ISC , negating your fiddling...."seem like nothing changed" is correct action hot. !
600 rpm is Usually the EGR stuck open but if the TV stop screw is closed and the idle switch stuck open the ISC is dead and 600 is possible.
never adjust the TV on a cold engine. that is because the ISC is dead then, the IAC is open below 150F. (the duty cycle is set only HOT)
the idle speeds are all for a hot engine. cold is a totally other ball of wax. (Dash pot, on , then off, the IAC runs most of the air supply cold)
when the head lights were on hot, the idle. was too low. (implies ISC is out of steam) so open the TV a tad, CW on the screw, does the ISC wake up? hot? now?
I suspect your ISC is set to a way high duty cycle. (open too long) and when you selected HL, it could not open more. or enough.
and go to 920 like it does in park?
to correct just that, on a hot engine, with HL on, add more air, by turning the TV stop crew CW. this adds air and the ISC will suddenly wake up
an idle goes to 920 to 950 rpm. from 800 or 850. see?
lets do the whole ball of wax.
1: start engine, Dash pot is extended for 5 to 30second (temp. based) and the sucks back via VSV actions.
2: then the IAC IS THE predominant air supply causing 1200 rpm or more. Temperature dependent.... until 150F (yes the water pipes here must not be clogged)
3: the engine warms (thermostat not bad) and as it crosses 150F the IAC closes (IAC is in the base of the TB) if not?, engine screams like a banshee for ever...
4: engine is now hot. the ISC starts regulating all hot idle speeds, if the TPS idle switch is closed. (calibrated)
5: 800 hot, electrics off, and 920 with any of the IDLE up things a active (HL or park,defrost, blower,p/s overload/ AC ,etc.)
ok so they set your TV wrong, it is never allowed to stick ever, if it did the mech is not aware of how this TBI system works.
lets say the IAC leaks. hot.
so the mech, then closes the TV to correct that leak (bad idea that) now you risk having a sticky throttle (danger of getting rear ended for sure) or?
a dead wrong action.,
there are 3 phases. if step 2 fails, above, all bets off.
the procedure for the idle switch is hard.
if you adjust the TV the idle switch can do 2 things, wrong.
A: fail to close, and ISC is now dead. (unregulated idle)
B: if it stays closed too long the ISC is active as you step on the throttle and it fights you.. (acts very strange. like a hesitation but is not what many think is cuase)
That is why the 89/90 idle setting is so hard, with that screw.
setting duty cycle is no easy.
the cheater duty cycle is here. (no correct tools)
http://www.fixkick.com/IDLE-AIR/89-90-id...s_end-duty
the tps calibration is hard, or impossible if there are idle speed devices , malfunctioning....
http://www.fixkick.com/All-Pdfs/M89/TPS/...ation.html
the 91 air bleed screw, gets rid of most of this hassle. because the TV is 99.9%c closed at all times, driver out of car..
starting in 1991, the TV is closed, so all idle calibrations do not effect the TPS switch at all.. a big improvement.
the real screw on a real 89/90 is here, and added to my 89 page.
![[Image: 89TB-TV-stop-screw.JPG]](http://www.fixkick.com/IDLE-AIR/1989-90/89TB-TV-stop-screw.JPG)
your car is 90, not 91. the 91 has a bleed screw up top. added in 1991.... and very different procedures.
http://www.fixkick.com/IDLE-AIR/89-90-idle-air.html
the top screw is Dash pot screw, that one is never changed,but the calibration is in the FSM... ask, if need it.
the lowest screw, is the TV stop screw. (can be seen to move if you watch the tv) see photo below.
the TV stop screw, opens the TV as you turn the screw in, Clock wise. (right hand tread rules)
in 1991+ the valve is always closed at idle. and the bleed screw adds air, by turning it CCW, (opposite of 89/90) (like a water faucet does)
the reason they did this is easy, the 89/90 everytime you mess with idle stop. you destroy the idle switch calibration. (a royal pain this is)
so Suzuki added the bleed, makes that hassle no longer true.... they mention this in the 91 fsm.
that is correct.
if you turn the TV screw, and the idle doesn't change that means the ISC Servo regulation is working,! as you turn the screw in, and add air the ECU sees you do that, and closes the ISC , negating your fiddling...."seem like nothing changed" is correct action hot. !
600 rpm is Usually the EGR stuck open but if the TV stop screw is closed and the idle switch stuck open the ISC is dead and 600 is possible.
never adjust the TV on a cold engine. that is because the ISC is dead then, the IAC is open below 150F. (the duty cycle is set only HOT)
the idle speeds are all for a hot engine. cold is a totally other ball of wax. (Dash pot, on , then off, the IAC runs most of the air supply cold)
when the head lights were on hot, the idle. was too low. (implies ISC is out of steam) so open the TV a tad, CW on the screw, does the ISC wake up? hot? now?
I suspect your ISC is set to a way high duty cycle. (open too long) and when you selected HL, it could not open more. or enough.
and go to 920 like it does in park?
to correct just that, on a hot engine, with HL on, add more air, by turning the TV stop crew CW. this adds air and the ISC will suddenly wake up
an idle goes to 920 to 950 rpm. from 800 or 850. see?
lets do the whole ball of wax.
1: start engine, Dash pot is extended for 5 to 30second (temp. based) and the sucks back via VSV actions.
2: then the IAC IS THE predominant air supply causing 1200 rpm or more. Temperature dependent.... until 150F (yes the water pipes here must not be clogged)
3: the engine warms (thermostat not bad) and as it crosses 150F the IAC closes (IAC is in the base of the TB) if not?, engine screams like a banshee for ever...
4: engine is now hot. the ISC starts regulating all hot idle speeds, if the TPS idle switch is closed. (calibrated)
5: 800 hot, electrics off, and 920 with any of the IDLE up things a active (HL or park,defrost, blower,p/s overload/ AC ,etc.)
ok so they set your TV wrong, it is never allowed to stick ever, if it did the mech is not aware of how this TBI system works.
lets say the IAC leaks. hot.
so the mech, then closes the TV to correct that leak (bad idea that) now you risk having a sticky throttle (danger of getting rear ended for sure) or?
a dead wrong action.,
there are 3 phases. if step 2 fails, above, all bets off.
the procedure for the idle switch is hard.
if you adjust the TV the idle switch can do 2 things, wrong.
A: fail to close, and ISC is now dead. (unregulated idle)
B: if it stays closed too long the ISC is active as you step on the throttle and it fights you.. (acts very strange. like a hesitation but is not what many think is cuase)
That is why the 89/90 idle setting is so hard, with that screw.
setting duty cycle is no easy.
the cheater duty cycle is here. (no correct tools)
http://www.fixkick.com/IDLE-AIR/89-90-id...s_end-duty
the tps calibration is hard, or impossible if there are idle speed devices , malfunctioning....
http://www.fixkick.com/All-Pdfs/M89/TPS/...ation.html
the 91 air bleed screw, gets rid of most of this hassle. because the TV is 99.9%c closed at all times, driver out of car..
starting in 1991, the TV is closed, so all idle calibrations do not effect the TPS switch at all.. a big improvement.
the real screw on a real 89/90 is here, and added to my 89 page.
http://www.fixkick.com