Engine hunting car runs and the engine will hunt when warm after car standing for a while

wow no year car stated nor a country x10 worse.
welcome to our USA forum!
the country with ZERO, carry cars. not a one. here
and due to that , no books here nor coverage at mitchells. either.
That is a G13 engine, (not m13) is my 1st guess.
Most Suzuki's with tiny engine and run a map sensors, not MAF
so is called SPeed Density system.

if yes, the that means ALL vacuum leaks cause fast idle.,
armed with that juicy fact, we know why it races.
you never said and actual RPM so no Tachometer?
only 2 causes. a huge vacuum leak
or unlikely the ISC stuck wide open with gunk inside, (clean it?)
ISC is idle speed control.
old suzuki's had man killler ISC software, my 91 did it.
and all others like it........
it would hunt idle like mad with any vacuum leak.(of any kind)
today this is very *******, this mode. (hunt)
toyata cost them $1billion in fines for this same deal.

but Clutch drivers have no problems with idle hunt, "skills"
what year/country.?
please showa photo of engine. ?
and win. a win/win
you win and I win not guessing all that.

fact 2 , is that that hunt tells me the ISC is moving fast.
so is not stuck. (99% says R3PO)
unplug ISC see the hunt end? sure.
the ECU has lost its wits. from..... this....
it sees a massive air leak (vacuum map readings ) and then (dumbblly ) hunts it like mad, (bad Firmware code) but real.
i can demo this is seconds hood up.
causes?
1: vacuum hose fell off.
2: same hose cracked.
3: brake booster diaphragm cracked, sucking air big time)
4: lots more,. even gunk under throttle plate blocking it open.
and more. lots more. can cause lots of vacuum leaks.

HOT ENGINE? (ill guess hot)
idle surges.(hunts) (very simple reasons or very hard to find.
the car has 2 engines. G16A and G16B
they work totally opposite, (8valve and 16v)
the vin number tells you the engine type ,digit 8 is engine code
6= G16B 16v
U= G16A 8v
i have factory book. its in chapter 0 these facts.
the cause of idle surge and hunt are:
1: ISC failures. the ISC can stick partially open and then hunts.
clean it and test it . see videos of how.
2: engine running so bad the ISC can nOT regulate idle speeds.

#2 is caused by up to 50 reasons.
8v , air leaks, cause racing idle and iSC goes nuts.
16v , all air leaks cause lean and if too lean the ISC goes nuts.

by nuts , i mean it hunts or gives up.

the list is endless, but the tests are basic,
i cant help you because no engine stated.

http://www.fixkick.com/IDLE-AIR/idle-index-home.html


ISC = IDLES SPEED CONTROLER (a system not just a PART)

no engine type stated, there are 6 engines used.
but bad idle is caused by 2 things.

• misfire.
• or lean AFR, lean fuel mix.. causes HUNTING

the ECU can also cause the hunt if it can not hold hot idle to spec.
most cars is 800rpm.

hunting or surging ilde. name the 2 RPMS, low and high , is it hot or cold engine this issue.? 400rpm or 1000 or 2000 all are diff.causes.
no year, stated. so cant help.
but ill answer in the generic,
1: the ECU (got a carb,? )
the ecu controls idle speed at all times.
if not , there is a problem (you)
A: air leaks in the induction will make motor race at some point the ECU/ISC loses control. and hunts. trying hard to correct it.
b: egr stuck open idle too low, iSC cant correct it,, bad EGR.
c: engine EFI running way too leak starving for fuel so it hunts for 2 reasons < ISC hunting, and lean does that.
lean is gross power loss and opening throttle bogs the engine.
so is double bad. ISC makes it worse,

all this breaks down to 2 reasons.
1: ISC bad. in some way (gummed up. or restricted inside)
2: bad fueling or air leaks. vacuum leaks.

try answers , the hot cold question and the 2 speeds, of the hunt.
lowest rpm and highest of the hunted range of RPM.

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I would try replacing the ignition control module and the distributor pickup as the next most likely cause of this problem. Also I would do the following

This problem can be caused by a dirty automatic idle speed control valve and throttle valve. Buy a can of throttle valve cleaner from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control

what a lovely car -if it was a manual ,i have a diesel manual one and its a flier ,as for this iam not sure so try reading the codes but if this is a gearbox related fault car then its the scrapyard as this car has no value in the UK but if stuck for spares look here in spain as no end of these cars running around and well appreciated here they are as well .This hunting when cold is the puzzle as it could be gearbox related whereby the gearbox computer is operating the engine RPM idle to stop creep but iam just not sure as i never see any autos of rover just manuals

check for a vaccuum leak this is where i would start if it rolled into my shop. possibly a PCV valve sticking or a hole in the hose, this hose should run from the valve cover, or crank case and then to the intake, or carb.

The fuel filter needs to replaced first. If the problem persists then next thing is the fuel pump for a replacement.

does throttle sensor check out correctly???