Throttle Stop Screw Adjustment Help

[drjun]

I bought a Second hand Vitara JLX 1997 model with a 1600 16Valve EFI engine, automatic transmission. The previous owner has tampered with Throttle Position Sensor (TPS) adjustment. However, the previous owner also tampered the throttle stop screw adjustment which is the basis of the 0.65 mm clearance for the TPS. How should I find the optimal setting of the Throttle Stop Screw Adjustment? Anyone, please?

[jtgh]

dang, someone told me 16v dont have screws and that the trottle completely close up.

ok i do now this.
the setting of the idle duty cycle sets that.

the freeze timing jumper is placed.
then analog voltmeter to IAC electric , 7v is 50%
adjust bleed screw and throttle stop at same time
to achieve 50% (7vdc) and 800 rpm at the same time.
97?
i will look that up.

how to set my idle and DC

what you are doing is getting the IAC to the center of its command authority. 50%

[ranger88den]

Jtgh,
Guilty, it was me. I have cleaned two 16v throtttle bodies and although they do have a throttle stop screw(with seal paint intact), both throttle plates closed absolutely tight. In fact, the throttle plates sealed so tight it would hold the cleaning solvent without leaking out. Just my experience. By the way, one was from a 1995 and the other I bought off ebay didn't give a specific date, just late 90's. Hope this clarifies.

[jtgh]

bless you ranger for doing that, having factory settings is great data.
ive measured 2 , 8v TB now.

does 16v TB have a screw adjust throttle plate stop, at all?

here is what I know about this sub.
some car co's (ford did it) let the throttle plates just drop against the walls.
this turns out to be way dumb, it guarantees the quick jamming of the butterfly at it
beds itself in to the bore. (ford saved one 5 cent screw, and eat the warrantee work)

so the throttle stop screw can be for 2 diff things.
1: only holds plate the tiniest distance away from wall bore, stopping above.
2: or as in the 8v this air is the minimum air allowed in , becoming 1/4 contributor to all 4.
(on 16v there are 3 sources of air , TB plate, IAC-T and IAC-E.)

on the 8v it is 1/4 inch , held open, at screw.
This amount of air adds to the other 4 sources of air . (the 4th is fast idle dash pot on 8v only)
so in theory, one could adjust it a tad of the IAC therm is leaking too much , from age.

my 95 fsm , the words after converting from Japanese to English, are mangled.
eg: pg 6e2-c2-9 Idle adj (8v) fails to say what to do if idle is high and dutycycle is low.
16v:6E3-c2-9 , same deal. just says adjust the bleed screw for 50% and 800 rpm.
with ECU freeze idle jumper in place. (DLC jumper)
confounding it is.

No where in any manual does it show or mention that painted throttle stop screw.

My guess is to place the jumper and then set the bleed to 50 duty-cycle.
then release the jumper and pray for 800 rpm.
I think the DC should win over idle. (is there meaning, but the do not say,darn them)

I should play with this, maybe after setting duty cycle the ECU counts rpm clicks and closes down the IAC to get 800RPM.
I am not sure.

for now im sure adjusting the bottom plate screw, only if you have all leaks fixed first.
then are sure the IAC thermal is leaking a tad too much, one can close this plate down and only then
if the bleed screw runs of of steam.

I'd love a photo of the throttle stop screw on 16v , no where is one.
it's a good riddle.
cheers

[ranger88den]

I'll try to get you a picture, but the last time I tried to post a picture the file was too big.

[jtgh]

just email it to me.
click my icon name and "send email to jtgh"
and attach it

or
use photo shop, hit resize 1024 x 768
keep size below 146.5 KB
this is limit on this add reply manage attachments.
but my Gmail above can take huge photos.

my email , is>>>>>" eemail (at ) [gmail] DOT (COM)" remove spam punct.btw
i welcome email. and photos or needs to get car running again, requests.

[jtgh]

ps , i going to play with ECU some more , the idle controls , so i can learn better how it really works.

the 8v has slightly diff , behavior with air leaks, it starts hunting.
If the Dashpot jams the idle open, the IAC keeps cycling over and over trying hard to
dop idle.
the 16v dont do this i hear. (to test this , just unplug evap hose (make a leak)
and watch what your IAC does. (shut down iAC or start hunting)?

i am interested in the diffs between the 2 cars.

cheers.

[drjun]

I will experiment on all your suggestions. My initial adjustment shows idle at 850rpm. However, when the aircon compressor kicks in, the engive revs up to 1050 rpm. Is this just fine for an auto tranny or should I find ways to lower the values some more?

[jtgh]

not cricital. the A/C on button sends a signal to the ECU and the ecu will add 200 rpm
to the current rpm (usually 800 to 1000 jump)

thanks again so very much for the tip on the TB and the plate closing so tight it is
solvent proof. there is no spec on that screw and any real experience is nice to have.

holiday cheers.

[jtgh]

on another post . on guy here fond that if the (8v) TPS switch is calibrated
so that the switch is closed with Dashpot pressing down the thottle (as it does key off)
then the ECU hunts like crazy , an wierd off gas pedal , rpm's and the like.

that is another clue.
as is the vacuum line clogged to the dash pot. (it must retract)

in both cases unplugging the IAC electric. conn. stopped the hunting.
showing that ECU was doing it.

The Ecu has wild , idle control, it starts guessing wildly if it sees a problem.
stupid it is.

all the best ,
happy holiday, and Cheers !