High idle on 89 4runner v6 EFI. Problem started after a leak in the cooling system causing it to loose pressure and get hot. After fixing the leak and changing out the thermostat the issue remains. It's idling at about 2000 and when I put the car in gear it dies. Please help!

old car, very old
this is easy, to find, but can be many things, my tests cut this to 2 reasons. mostly. (leaks and isc failure tests)
1: ISC system is dead, (stuck idle speed contr. valve)
2: throttle cable stuck or set wrong, (must have slack)
3: vacuum leaks, on all cars with map sensors, vacuum leaks make the ISC loose control and RACES fast with full engine power. all MAP based EFI SYSTEMS, "speed density systems:

rocker cover, i edited it for you. (my guess high is over 800rpm)?
hot engine or cold engine or both?
if hot is water temp, 180F? or stuck at 149F"? too low...
are you in neutral or drive? or park.?
which engine?. is it there are many sizes used on Swifts,
one if the largest number of engines on car.
my guess is a "G" engine family.
High idle is usually a vacuum leak,
is this a CARB or EFI engine?, (TBI, throttle body injection:?)
if it is EFI and if TBI
any air leaks will cause too fast hot idle.
here is the list: EFI only ! electronic fuel injected.

1. Vacuum leaks. (hose left off, or now cracked?)
   
2. sticking ISC, idle controller.
3. TPS set wrong, and no longer has a working idle switch.
4. ECU in Limphome (if CEL lamp (dash) glows running , bingo)
5. PVC hose fell off.. sucking in fresh air , and higher idle.

more if you have answers to what your engine and driveline
consist of.




here is the lineup
GEN2 Swifts (the G family used)
1.0 L G10 (LP2) I3
1.0 L G10T (LS3) turbo I3
1.3 L G13A/BA (L72) 8V I4
1.3 L G13B/G13K 16V DOHC I4
1.5 L G15A 16V I4
1.6 L G16 16V I4

older post.

first off no engine stated. so I WILL TELL YOU WRONG!!!
so ill answer in EFI generic form. (pure EFI facts)
engine idle races too fast. HOT ! no cold.
guess #1, you meant hot, engine., (cold racing is normal)
lots of causes.
but here they all are, i can in fact find all causes. in 1hr or less, hands on (i have the magic hands) and EFI sa v v y !

engine never gets hot , never reaches 180F + and holds, vacuum leaks on MAP based engines all race, so.... vacuum...MAF based engines do not race, they run too slow with vacuum leaks. (unless 2 problems, way too rich and leaks of vacuum)ISC valve stuck open (electric idle controller)IAC valve (thermal valve stuck open hot, it must close hot or the engine screams. hot. or the coolant path is BLOCKED to it...spark timing way too advanced. 5min job. to check. not scanning the PCM is the top failure here, why own any car with OBD2 and not have or rent a scan tool.. ? why work totally blind ? scan it and report ALL DTC errors, now.... and WIN.is this the 3.2L V6? (single or twin cam?)

here are all engines in the class car (not all offered in USA)
2.3 L 4ZD1 I4
2.4 L C24SE I4 (GM, Aus)
2.4 L C24NE I4 (Euro)
2.6 L 4ZE1 I4
3.1 L LG6 V6 (GM)
3.2 L 6VD1/6VD1W V6 (Both single and twin cams options)
2.5 L 4JA1 diesel I4 (Cameo, TH)
2.8 L 4JB1-T turbo diesel I4
3.0 L 4JH1-T turbo diesel I4
3.1 L 4JG2 turbo diesel I4

i open the hood and see what?? and engine.
the EPA hood sticker tells you the size.
and the wide valve cover , twin cams.


in most cases, its too much air.
after all it can't race if air supply is low.
one other cause is previous owner hack jobs
hacking .
he screws the throttle body screw that must never be touched, ever.
adding way too much air. that does.

The EFI adds fuel to air (math calcs on the fly)
and cant be blamed for that.

wow , 1977 , we dont get 77 cars here ever, they are relics.

a BLAST FROM the pass, (i have 66 and 68 cars,now, so....)

if the engine is good, compression near spec> x4 150PSI min?

The fsm covers all these numbers, so you look them up. ok?

and spark is good.,!

then the carb is bad. fixing 1977 carbs\' (done 100) are very hard.

lacking kits, and good cleaners (illegal here now).

lacking parts, inside, (toy dont sell em;\')





CARB 101:

Stalls only hot?

choke not going to full open hot? fix it or upgrade to manual.

float level wrong,? fix it. (google that)

JET, nozzles and emulsion paths blocked? or loose?

JET main fell out, and is rolling around in bowl?>

fuel pressure too high?, some shade tree used EFI pump:? oops.

fuel pressure too low 1psi, (read toy spec, get it right)

air leaks at the carb base gaskets, or there in intake.

idle set too low?



(bad carb)

how is that,?

(which engine. ?????)_
as always check all fuses. and scan the ECU for DTCs. first.
there is no need to fix OBD2 cars like 1980 cars (hard rows to hoe)
it can be 2 problems this......
lets fix the easy one first. idle. (and hope for moving issues to fix for free) it idle car is parked, so is 100% safe tests. (not moving)

so it surges at idle.
questions.?
1: hot or cold or both.?
2: low extreme RPM and high at idle.
400 to 800 RPM? surge.
1000 to 2000. what? numbers tell the tale.

first off, idle is the last thing to work right on any engine.

there are many ways to find what is wrong.
fix idle surge way.
i make sure that the engine holds closed LOOP status.
hot idle, if not , i fix that first.
keep in mind if not in closes loop and lean
all lean engine surge and guess what the ISC will add to the surge
because idle is way too slow, so the ECU open the ISC wider
and wider and its still too slow, so the ECU resets the ISC
this cause a worst hunt (surge)
the ECU adjust spark time and the ISC to get 800 rpm. (spec. look up yours)
so say , i see closed loop failed, OBD2 scan page 1
i look at the O2 sensor an its stuck lean.
if stuck lean and it really is (o2 bad?) then its lean and it will surge
.
examples.
1: i find 02 sensor bad, (only effects idle and light steady cruise)
2: i find fuel pressure at 15PSI , hopeless low .
3: i find all injectors clogged. and lean.
4: with MAF EFI, ( i find maf reading too low, (dirty) causing lean.
5: if MAP car, i find the MAP stuck hard high vacuum causing lean.
not knowing what engine you have or the idle hot surge range,
i can not go farther.

the driving bog tells me,
1: scan the ecu ,get DTCs; do that first.
2: clean MAF if car has one, ask how..
3: check fuel pressure.


my guess is engine is lean. and starving for fuel all the time.
cept WOT.

MAF cars starve for fuel if there are any vacuum leaks.
MAP cars do opposite, they race fast with 100% full power.
MAF is air density EFI
MAP is speed density EFI.
apples and oranges diffr. so what engine.

it is a dangerous car to drive like this, "TOYOTA LIKE" dig?
if you are a toyata person the floor mats hit throttle pedal and gee....
is the dash cluster lamp called CEL glowing driving
if yes, scan the ECU/PCM read out the error numbers.
Like P0300 gross misfire. etc.
ever do a full 60k mile tuneup, ? why not, if not?

first tell the symptoms , of a hot and cold engine.
diagnosis takes facts and evidence. you offered some....
you start car cold ,does it idle fast (normal) then you drive
and idle is ok? near 800> until hot. see how that works.? the Fuelng
system works by temperatures of the engine coolant .
my guess your post is all HOT engine.

too fast idle HOT, this means the ISC (hot) is out of control
ISC is a system, not just 1 part. so dont buy an ISC.
The ISC is idle speed controls. and is the first to fail, this control
when there is any problems with,well, anything , under hood.
The ISC can get dirty and jam and may just need to be cleaned.
this is all part of normal turn up service, ask him why idle is high
i promise you , he will tell you. (ASE patch on sleeve)

the first thing to learn, on all EFI is which of the 4 systems yours is.
1999 era was only 2, AD and SD systems.
or MAP or MAF based EFI. (air or speed density systems)
i login to alldata.com and see?
there are 2 engines, a inline 4 and a V6, is MAF.

both engines have the cam timing belt if ignored, both engines
grenade with belt slipped or snapped. dont let that happen.
id never drive any honda , running bad, until the belt is checked 1st.
see why? $3000 new engines are VISA breakers.

OK my easement: (with limited inputs)
too fast hot idle on any MAF engine.
ISC stuck .
ECU in limphome mode, (scan it) and idle controls are shut down on purpose.
air leaks, is not it, if MAF engine, as leaks there cause lean and lean is slow idle (outofcontrol)

tell more, get more.

hot engine ?, cold or both,, EFI runs in 3 modes, cold ,warm and hot.

name it.

which engine option (displacement)??????



there is no idle adjust, that is the PCMs, job 100%, all the time.

Carbs are gone.

here is rule one for all EFI.

idle is the last thing to work correctly.

anything the causes a gross imbalance of engine power to engine load, under idle will cause , idle controls to fail.



low idling causes. (over 50 but, here ar basics)

1: AFR (air fuel mixture too lean) usually surges. (clogged or leaking injectors. or fuel pressure way to high)

2: air leaks, cause racing, so not that. (speed density car ,if is)

3: egr stuck open. low idle and misfire.

4: ISC stuck closed (IAC electric)

5: cam belt slipped, timing retarded, compression at 1/2 spec, and well, valve will bend soon....

6: CEL glowing running? can be in limphome, limp cancels Idle controls (in may cases) RTM read the FSM on DTCs.



if fails hot?, is hot = 180F temp or more? "thermometer time"

if not, the PCM goes , quite nuts.

hot engine
cold
or both
in drive, or park, is this a stick shift car, i dont know.

this is called surging idle. and all EFI love to do that at a drop of hat.
ALL
the hot idle is 800 rpm
bad idle surgine is caused by.
1: EGR leaking.
2: lean combustion for any of many reasons, is EFI holding closed loop status at hot idle, (no , fix that first.
3: ISC is out of control (ISC electric is the ECUs idle controller)
the ISC goes out of control easy.
EG:
a: egr LEAKS.
B. AIR LEAKS.anywhere in the induction path (AIR path)
illegal leaks, MAF engines go lean, MAP engines just race fast.

4: ISC is stuck (clean it)

with all cars. we:
1: check all fuses
2: check the CEL is it glowing running,? yes, then scan it now.
3: check with scan tool for closed loop hot. if fail fix that first.

and lots more..... but i stop here.

check the thermostat first always might be stuck if thats it simple fix

Hi.

If problem is only on startup and when idleing, then the problem is likely IAC system, also a vacuum leak will cause the same problem.

If problem is not only on startup and idle, but also when driving, then MAP sensor and EGR system must be checked.

Check also accelerator cable state and setting.




The first thing to do is pulling out the OBDII fault codes stored in the ECM. This is done connecting a code reader to the ECM diagnostic port. The job can be done for a small fee at any local garage, and it is done for free at AutoZone.

The codes will help locating the problem.

About possible faults:

Problem is stalling when idling and during startup, but engine idling fast all the time. Problem not starting at times it is due to the fact that the wrong mixture is being sprayed, this is probably causing flooding and misfire. Since the CEL is on, one of the codes returned is probably misfire.

Check accelerator.

Check IAC system. This is composed by a valve and a solenoid that check and control amount of extra air air when the engine is idling. The IAC valve is located on top of the throttle body.

Check the vacuum system and try cranking with gas tank cap off. Vacuum system is tested using an hand tool gauge onvacuum lines while spraying card cleaner on the hoses (or heating them with a torch). If there is a leak, pressure will go up. A big leak will also do hissing noise, and will often result in a lean code when doing an OBD code scanning.

This kind of symptoms can also be caused by weak wiring to MAP/MAF sensor (MAP in this engine).

If the car also drives very rough and is revving up and down in a weird way, check the EGR valve.

As first thing I would do a code scanning. This car is OBDII. The scan can be done for free at the nearest Autozone, or for a small fee at any garage.

If you get any OBDII code from the scan, report it here, so that we can individuate the possible reason for the problem.

If you repute my solution helpful, then please take some times to accept the solution. Providing good repair tips requires time and skills, and your feedback is important for us.

Regards.

Ginko.