Vacume line under map sensor leading to throttle body unit side

the service manual OEM 120 pages, said this, did VECI fall off?
VACUUM SCHEMATICS
A vacuum schematic for emission related items can
be found on the Vehicle Emission Control Informa-
tion (VECI) label. For label location, refer to Vehicle
Emission Control Information (VECI) Label" << federal laws here EPA.


engine starts (sure) but does it have FULL POWER hot and cold????????????
throttle cable jammed?
is it automatic tranny>? and Kick down cable jammed?
got cruise. and cruise to TB cable jammed.
scans show this:
"P1299 Vacuum Leak Found (IAC Fully
Seated)
MAP Sensor signal does not correlate to Throttle Position
Sensor signal. Possible vacuum leak!"



FAST IDLE HAS MEANY CAUSES!
THE Primary case is the IAC fails or vacuum leaks cause the IAC to go out of control. IAC is bolted to the TB. and is weak, then.

I have the service manual, so can be exacting
as you may know this jeep uses MAP Sensors fuel then engine.
called Speed Density system. jeep (as in NO MAF sensor)
that means any vacuum leak, cause fast RPM even your right foot does.
the 2.5 is cut down 4.0L:
and is MPI 4 injectors injecting it.
we can pinch all vacuum lines, (not PCV) and see if RPM hot drops from 2k to 800 rpm,. bingo that line leaks if it drops RPM large.
easy no? ,just pinch a line. or pull the end point and cork it, up.
the car is 1999 and all 99 cars USA (is it) have OBD2 port. why not just scan the PCM first.? see errors called DTC. and can really help cut down time. and buying useless parts not needed at all.
I owned for years a 1999 cherokee, 4.0L near same drive line. 5sp,m/t box.

here are some very very common caused, seen on all ;my jeeps back to 1988.
this is not guess, it is all jeeps fail here. every one,owned long enough and not serviced correctly
THE IAC is simply clogged up., so clean it? all; mine loved to clog until my newer jeeps are TBW,throttle by wire. no IAC , now, gone.

The the Throttle body TV throttle valve plate is gunked up and sticking open
again, clean it. (PULL TB off)

that is 2 thing things and to be frank , vast places go get vacuum leaks
even old cracked injector cushion seals( at base) sucking air.
we use a smoke machine on the hard nut cases. just like EVAP side.


more, Brake booster leaks, called a huge vacuum leaks
I bet EVAP hoses do not race the engine ever.
map vac hose cracked
egr hoses cracked. vac.
HVAC dash heater controls vac hose cracked and sucking air./
canister evap purge valve hose cracked, sucking air
it has a distributor vacuum advance hose. plug them to see if they leak.
the map sensor quote SM.
"INSTALLATION
(1) Install rubber L-shaped fitting to MAP sensor.
(2) Position sensor to throttle body while guiding
rubber fitting over throttle body vacuum nipple.
(3) Install MAP sensor mounting bolts (screws).
Tighten screws to 3 N·m (25 in. lbs.) torque.
(4) Install air cleaner intake tube"

see that word rubber there, what if that leaks air.
the under hood HVAC parts there have vacuum tank to hold vacuum in reserve and it too can leak air .

I have cured vast vacuum leaks. on engines.
nature abhors a vacuum (on earth)
the end point sucks air. (like diaphragm devices and HVAC lots)
to see all vacuum things in my OEM SM
I had t type F3 100 times to find them all. find.F3 command.
PDF reader.
no single diagram is there in the book, , its on the VECI lable on car.
look under hood and up and under hood yet?


the PCM can go to limp home
and doing so can force the IAC to dead, OFF LINE,
so not scanning the PCM first is really bad idea. knowing just that.
good luck, !

Test the map and tps. If the throttle is controlled electronically, also test the accelerator position sensor. Make sure the tps signal changes smoothly as the throttle is opened.

Manifold Absolute Pressure (MAP) Sensor
OPERATION The Manifold Absolute Pressure (MAP) sensor is a device which monitors manifold vacuum. It is either mounted on the firewall or throttle body and is linked electrically to the on-board computer. The MAP transmits information on manifold vacuum conditions to the computer. This data determines engine load and is used with data from other sensors to adjust the air/fuel mixture.
On the 2.5L engine, the MAP sensor is mounted in the right rear side of the engine compartment. It is connected to the throttle body by vacuum line. The MAP sensor on V6 and V8 engines is mounted to the throttle body. It is connected by an L-shaped rubber fitting. The V10 MAP sensor is found on the right side of the intake manifold and senses vacuum in the manifold.
TESTING See Figure 1
To completely test this sensor and its circuitry, you will need a DRBII scan tool, or equivalent. This is a test of the MAP sensor only. This test is for all engines except the 4-cylinder.
On the V6 and V8 engines: inspect the rubber fitting from the MAP sensor to the throttle body. Repair if necessary.On the V6 and V8 engines: test the MAP sensor output voltage at the connector between terminals A and B (see drawing). With the ignition ONand the engine OFF , the output voltage should be 4-5 volts.Test the engine controller terminal No. 1 for the same voltage to confirm that the wiring is in good shape. Repair if necessary.Test the MAP sensor voltage at the sensor connector between terminals A and C with the ignition ON . The voltage should be 4.5-5.5 volts. Also check terminal No. 6 of the engine controller wiring harness for the same voltage. Repair or replace the wiring as necessary.Test the engine controller pin-1 for the same voltage to verify the wire harness condition.
Fig. 1: Terminal connections for testing the MAP sensor


Throttle Position Sensor (TPS)
The Throttle Position Sensor (TPS) is located on the throttle body and tells the computer when the engine is at idle, off-idle, or at Wide-Open Throttle (WOT). At idle, the computer cancels the spark advance. Idle speed is computer-controlled through the automatic idle speed motor.
TESTING To completely test this sensor and circuitry, you need the DRBII scan tool, or equivalent. This is a test of the sensor only. This test applies only to V6, V8 and V10 engines.
This test requires a digital voltmeter. The sensor must be checked on the vehicle with its 3-wire connector engaged to the sensor. The center terminal wire of the sensor connector is the output terminal.
Remove the air cleaner housing.Attach the positive lead of the voltmeter to the center terminal of the sensor harness.Attach the negative lead of the voltmeter to a good ground.With the ignition key in the ON position and engine not running, check the sensor output voltage at the center terminal wire of the connector. Check this at idle (throttle plate closed) and at Wide Open Throttle (WOT). At idle, the sensor output voltage should be greater than 200 millivolts. At WOT, the sensor output voltage should be less than 4.8 volts. The output voltage should increase gradually as the throttle plate is slowly opened from idle to WOT.If the sensor does not meet specifications, replace it.

Fig. 1: Common TPS mounting-V6 and V8 engines




Fig. Fig. 2: Common TPS mounting-V10 engine

The three lines hanging under the truck connect to a valve on top of the 4x4 transfer case, this is why the 4wd does not work. As for the throttle body lines there should be a diagram on the radiator support that explains that. You should have one large line that goes to the PCV valve, a small line going to the air cleaner, a small line connected to the MAP sensor and possibly another connected to a valve that controls the EGR valve. Your fifth line should connect to a port on the manifold that supplies vacuum to a tank that is the vacuum source for the HVAC control doors and the front axle engagement system. The axle engagement system is what the line hanging by the transmission under the truck is for.

it has a throttle position sensor is right on the throttle body some trucks in this model came with electronic throttle is a two part throttle one is in the pedal the second in throttle body you have to use a scanner to find if it is the problem i had couple of experiences where the vacum lines next to the battery were broken they're made of hard plastic also look in the intake for cracked rubber hoses or spitted ends most likely that's the case hoping you find this helpful i thank you for your time

I would recommend that you replace the TPS (throttle position sensor), as it will cause this issue. You might try cleaning the throttle body itself, if the butterfly is corroded, or the throttle body is dirty it can cause this as well. I had one doing the same thing, and yesterday I used a can of throttle body cleaner and it cured it.

map sensors or manifold air pressure sensors are mounted either on the intake manifold or the throttle body. in some cases they are monted on the firewall with a vacume line running to them from the manifold. they have a three wire connector plugged into them.

throttle position sensor, or check to make sure you have vacume going to the map sensor. Alot of times the outlet on the throttle body gets plugged and there is no vacume at the map--causes it to die. unplug the throttle position sensor and then rev it up and see if its better.

map sensor located on firewall right side of vehicle..3 wire connector..small black sensor..with a vacuum hose leading to it..throttle position sensor on right side of throttle body unit..3 wire sensor..iac located on front of throttle body..4 wire sensor

Hello,it sounds to me that you have a vacume leak.Check a vacume tube that is under the throttle body right in the middle of the firewall and the intake manifold.This vacume tube has a rubber elbow shaped connector at the end of it on the engine side.They regularly fail.

What size engine?

If it's rear wheel drive the the MAP sensor is located on passenger side by the throttle body it's a little black box with three wires and a vaccum line connected to it.

If it's front wheel drive, then the map sensor should be behind the throttle body close to the firewall on the passenger side.same discription