Throttle Body Air Bleed Screw

[Peter Wood]

order matters here, on 16v and 8v.
1: no vacuum leaks. or main induction leaks mAF to TB. air horn.
2: MAF must not be bad and many are now. for sure china clones new, 100% POS, pieces of Squat. those, get CARDON rebuilds.
3: IAC bad  is common now, 2021. 20+ years old. vast things fail.
4: FPR dead. and fuel mixtures way to high. now like this.
5: ISC needs to be cleaned.
6: EGR bad stuck open or love to at ever stop sign. (landing )

unless all  that is good the calibration steps can fail.
and PCM idle up pins at the wrong voltage , any, means those input things are failing like bad PS overload switch etc.
ECT bad, will cause richer running and then add vacuum leaks wow engine screams.

the 97 is obd2, ever do full scans?
see all DTCs
all pending DTC
the look at all sensors to be sure al read correctly for cold and hot engine
is hot RPM 800 not , scanned.
is water them 180?>
is MAF working right scanned
is engine in closed loop status , hot idle?
we check it all first before calibrating anything.

cases in point
TV must  be closed fully and not molested
the do TPS calibration steps.
Bleed screw can not be calibrated until all illegal air leaks are cured. or just  wasted effort.
if the bleed screw is CW max in out, closed, that means PO had hot idle failing hard and this was his nasty fix. (his bogus bandaid)
the ECU sets RPM HOT , not owner of cars and is by EPA laws infact this.
yes we do to Dutycycle calibration say ever 10 years,  to adjust for natural changes in the engine, loser engines make more power for example.
keep in mind the engine even runs at 15,000 feet altitude.  thin air , engine as less power so ISC opens more.
if the bleeds screw is set wrong the engine fail at low or high altitudes.Hot engines,
or super hot days, or more humid days, on humid days engine makes more power and ISC closes a tad
if the cars electric load goes to full Alternator current flow, 50amps. or 700watts or a bit over 1 HP taken off the engine crankshaft and ISC opens
or shifting from park to drive , ISC opens way more. for that load.
the ISC and PCM form a servo loop, closed loop servo. regulating RPM.


Helloo,

Thanks for all your advice.   Here's photo of the offending item, top of Throttle Body view, with the broken up plastic cap? in centre.
If it is just a cap, then I can dig what's left of it out and should find the real adjustment screw below?