I have a 95 Cadilliac DeVille 4.9 high idle , I have changed the ISC and new plugs, wires. Also have cleanded the carburator, what would cause this?

Hi stop buying parts till you do a couple of checks.
The problem is either Spark or fuel.
We are going old school here.
1. Remove a plug wire from spark plug, with a gloved hand or insulated pliers stick the old spark plug or stick a phillips screwdriver about the same size as the top of a spark plug into the wire
2. hold the bottom of the plug or screwdriver about 1/4 inch from metal on engine block anywhere. Have someone try to start it and watch for a good spark to shoot across the 1/4 inch opening. If so you have spark.

3. Fuel D/C a fuel line somewhere on the fuel rail.
Put a rag over the end and have someone give a SHORT crank . Rag covered in fuel it's OK.

Once you find out if it's spark or fuel the you can troubleshoot the right system.

Mike

The usual problems with the ISC motor are
a) one of the two coils goes open circuit ie it burns out.
b) the ISC internal gears chew themselves up, likely causing a).

The issue is therefore why the ISC chews up the internal gears. The usual
reason is that there's a build up of carbon and fuel gum in the throttle
body that stresses and jams the ISC gears. This gunk has to be cleaned out.
Further, most of the carbon comes from the PCV valve that vents hot oil
vapour into the intake from the rocker cover. This oil vapour can become
excessive when the valve stem seals are old and not doing their job
adequately any more. Since your car is a 2000, its not unlikely. Piston rIng
blowby is another source.

At a guess, the dealer tech has just replaced the ISC motor without doing an
adequate check (and clean) of the rest of the throttle body to ensure that
the ISC can adjust the speed freely. It may be that the new ISC is faulty,
but its unlikely. An unexpected failure (esspesially if the ISC gears are
again stripped) should result in a more detailed investigation.

Yes, its a warranty issue. Be polite to the dealer.

You didn't specify year make and model. There may be no problem with IAC valve and have changed it for no reason. There could be something else affecting the idle and causing the computer to store a false code. You may have a vacuum leak resulting in improper IAC operation thus setting a code.

1995 Geo Metro. COLD start or HOT started or BOTH?
Does it ever idle down to 800 HOT? (engine temp)>?

Aka:
Geo Metro (later re-branded the Chevrolet Metro), Pontiac Firefly, and Suzuki Swift
which engine, what country??? I will post for USA only !!!!
Auto or stick tranny???
the USA 1995 was the last car to use TBI injection (throttle body)
the LSI option, then had a 4 cylinder. in 1.3Liters.
and works totally differ. than any 1.0L
answsering for 1.0L

Have you inserted the Diagnostic jumper wire and looked at the
FLASH codes yet?
choke? on 95? what country is this, ours are not carbs. in 1995.
so post country. ours are all EFI in USA.
3 cylinder? 1 liter? or which engine/?
on any USA Metro, 1L , when first started, it has 2 valves. to control IDLE, (cold , is iAC) hot is ISC, The cold start valve opens farther the colder it is (how cold was it). but usually is limited to about 2000 rpm
max.
this engine, TBI, uses a MAP to control fuel mixtures, and
any air leaks (aka; vacuum leaks) what so ever, will cause too fast idle.
so on MAP cars, you get to find out what is leaking AIR.
1995 has the new better , idle control speed motor, (ISC)
this can be stuck open.
that new TPS, did you do the calibration correctly?
it must set right. or idle will never be controlled.
finding the cause, takes hard work, and hands on testing
A/C fast idle broken
A/T transmission fast idle, device, broken.
Air leaks (add huge list of possibles and cracked hoses here)
Throttle stuck
ISC or IAC bad.
very hands on to find this, done many.
TPS on indexed corrrectly or not calibrated.

cold engine idle surge. (problem)
RPM range of surge not stated
300-700 or 800 to 1500? (range is critical to diagnosis)

bad fuel
running summer fuel in winter (running old fuel?)
needs a tune up bad, see the list in the operator guide.
idle speed controller,sticking or EGR valve same. (clean them)
location not stated, so cant guess about local air temps.?
no other symptoms, lack of engine power? etc?
was it ok last week, or better, when was the last time it was OK?
1week, 1year?
surge , causes, on a tuned engine might be:
1: too lean. so lean the ISC can not control idle. rpm low, stalling
2: too rich, flooding, stalling, spark plugs foul (look at them)
3: weak compression in 1 or more cylinders.
4: bad spark.
5: air leaks, in the plenum causing , ISC to lose control.
why high RPM?

especially?
well that means it fails hot too.
and there is a simple tests. for hot surge.
is engine fully hot? 180F and holds solid there?
say rpm is about 800
and you turn on head lights, heater fan and (not AC) and defrost.
the RPM must hold or the ISC is failing.
ISC -= idle speed controls. (all EFI has this function)

can somebody send me a photo on a 1995cadillac sedan devill were is the oil sending unit located

It means that the throttle body is dirty and the deposits in the throttle bores are restricting air flow at idle to the point that the idle speed control has no more authority to maintain the correct idle speed.

Take the air cleaner off, hold the throttle wide open and look down the throttle bores. Spray the throttle bores with carb cleaner and scrub the bores and backside of the throttle blades with an old toothbrush. Cleaning the deposits off the bores and throttle blade backsides it will restore the idle air flow to the correct level. When the throttle body is clean, disconnect the battery negative cable for 60 seconds to reset the idle learn offsets to the "clean throttle body" default values.

While you are in the throttle body and looking down the bores....see the two tubes sticking up at you from the intake manifold floor just below the throttle blades...??? Those are the EGR tubes and they are NOT supposed to be full of carbon and crud. Rod them out thoroughly with a piece of stiff wire to remove the deposits. Go all the way down thru the tubes to the cast passage below and make sure that they are clean and unrestricted so that the proper amount of EGR can flow.

Turning the key to the run position extends the ISC anticipating a restart, so if the setting is incorrect it would not erase a hard code. Just turning the key to run would light up both the service soon and service now lights as a bulb check, in other words, letting you know the bulbs work. Do you have the factory service manual?

The ISC adjustment is simple on this car. With the engine running and at operating temperature, You raise the throttle arm slightly with your right hand and push the shaft of the ISC in to fully retract it with your left hand. With constant pressure on the ISC shaft it will slowly retract. The very second it bottoms, you quickly remove the wiring connector to the ISC. Now you should have a very low idle and a gap between the throttle arm and the tip of the ISC. Approx. 0.060 of an inch. Once you know the gap is correct, shut off the engine, wait 10 seconds and reconnect the ISC wiring. Restart the engine and the ISC is set to spec. The TPS setting must be verified at this time. At minimum idle, ISC not touching the throttle arm, and unplugged, the TPS should be reading approx .0 or .1. Once the ISC is reconnected, you should see a TPS reading of approx. .5 at idle. with the A/C off.

A hard code can be erased but will continue to reset as long as the reason for it has not been corrected. Idle learn procedures were designed into later year engines with multi port fuel injection to adjust idle regardless of the amount of coke build up within the throttle body. Your fuel injection system does not build up coke or deposits because the 2 injectors spray down thru the throttle body, effectively cleaning the throttle body while running. Alot of owners adjust the ISC as if it were a throttle stop screw on a carb. guessing as they go. The ISC and TPS "MUST" be in sync to get the best off throttle response and smoothest idle. Adjusting the ISC without verifying gap or TPS voltage usually results in a surging or too high warm idle. You say the car failed at idle. For what reason? CO or HC? or idle too high?

Tell us news.

no take that ****** out and give it a bath in carb cleaner 20 mins coat with wd 40 reinstall if its better by a new one any way only a temporary fix dont////dont turn any screws

FORD IDLE AIR BYPASS

Ford doesn't use idle air bypass to regulate idle speed on its older throttle body (CFI) applications, but uses a solenoid or vacuum diaphragm instead to open the throttle linkage. Idle air bypass is used only on multipoint injection applications. On older pre-OBD II cars, codes 12, 13, 16, 17 & 19 all indicate idle speed is out of spec (too high or too low). Codes 47 and 48 indicate a fuel mixture problem which could be caused by an air leak. On OBD II vehicles (1996 & newer), codes P505 to P509 indicate a fault with the idle speed control system.

The diagnostic procedure when any of these codes are found is to turn the engine off, unplug the ISC bypass air solenoid connector, then restart the engine to see if the idle rpm drops (it should if the ISC solenoid is working). No change would indicate a problem in the motor or wiring.

The ISC solenoid can be checked by measuring its resistance. With the positive lead of a digital volt/ohm meter on the VPWR pin and the negative lead on the ISC pin, measure the resistance of the solenoid. On many applications, the spec calls for 7.0 to 13.0 ohms. If it is out of specs, the ISC solenoid is bad. Also check for shorts between both ISC solenoid terminals and the case.

If the ISC checks out okay, check for battery voltage between the ISC connector terminals while the key is on. Voltage should also vary when the engine is running. No voltage indicates a wiring or computer problem.

It take a special tool to take the pump off. You can buy one at most auto-parts stores.