Engine fires but stops, holding accelerator will idle

HI
first I would like to tell you, do this procedure only if the 5th digit of your VIN is C or K.

Description

The engine control module (ECM) learns the idle position of the throttle plate to ensure the correct idle. Anytime the throttle body is cleaned or replaced, the ECM must learn the new throttle position. The idle may be unstable or a DTC may set if the throttle position is not learned.

Conditions for Running the Throttle Learn Procedure

• DTCs P0101, P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0506, and P0507 are not set.

• The engine speed is between 450-4,000 RPM.

• The manifold absolute pressure (MAP) is greater than 5 kPa.

• The mass air flow (MAF) is greater than 2 g/s.

• The ignition 1 voltage is greater than 10 volts.

Throttle Learn

Important: Do NOT perform this procedure if DTCs are set. Refer to Diagnostic Trouble Code

(DTC) List - Vehicle.

1. Start and idle the engine in PARK for 3 minutes.

2. With a scan tool, monitor desired and actual RPM.

3. The ECM will start to learn the new idle cells and Desired RPM should start to decrease.

4. Ignition OFF for 60 seconds.

5. Start and idle the engine in PARK for 3 minutes.

6. After the 3 minute run time the engine should be idling normal.

Important: During the drive cycle the check engine light may come on with idle speed DTCs. If idle speed codes are set, clear codes so the ECM can continue to learn.

* If the engine idle speed has not been learned the vehicle will need to be driven at

speeds above 70 km/h (44 mph) with several decelerations and extended idles.

7. After the drive cycle, the engine should be idling normally.

* If the engine idle speed has not been learned, turn OFF the ignition for 60 seconds

and repeat step 6.
8. Once the engine speed has returned to normal, clear DTCs.
Good Luck

Your car has a bad ground or electrical connection. With electricity especially in cars and more so the older they get. Start at battery and work your way to the end of all ground wires first. Many times i have seen the battery terminals cleaned at battery to terminal connection but the wire to terminal connection are worn or.dirty.look at all.ground from engine to body they often corrode or melt as they are braided aluminum. If all else fails your low idle speed is a vacuum leak listen for a hiss when engine is.running or if u.can seal.the air intake and exhaust pipe.and use compressor to pump air into engine through a vacuum line on intake.manifold keep it.under

Before you could adjust the mixture, make sure that the spark plug gaps, ignition timing and valve clearance are all OK.
- Start the engine and bring it at operating temperature.
- Adjust the throttle stop screw to bring it at the stable rpm.
- Turn in the idle mixture screw while observing the engine speed till the engine starts to stall. At this point turn out the idle mixture screw and keep on opening slowly till the engine acquire the most stable rpm. Finally adjust the throttle stop screw to obtain the desired idle speed.

could be numerous reasons. this is your best bet take it in to a mechanic and have your engine codes scanned. it is a minimal charge, some even do it for nothing it only takes 10 minutes.this will point you in the right direction.

My quest 2004 idle below 500, start up then off, have to start couple times when the engine is cold. when i pushed the gas pedal, it smells gas.

Here is the common cause of surges, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

From the service manual:

Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment
NGEC0549
PREPARATION
NGEC0549S01
1) Make sure that the following parts are in good order.
I Battery
I Ignition system
I Engine oil and coolant levels
I Fuses
I ECM harness connector
I Vacuum hoses
I Air intake system
(Oil filler cap, oil level gauge, etc.)
I Fuel pressure
I Engine compression
I EGR valve operation (If so equipped)
I Throttle valve
I Evaporative emission system
2) On air conditioner equipped models, checks should be carried out while the air conditioner is OFF.
3) On automatic transmission equipped models, when checking idle rpm, ignition timing and mixture ratio,
checks should be carried out while shift lever is in “N” position.
4) When measuring “CO” percentage, insert probe more than 40 cm (15.7 in) into tail pipe.
5) Turn off headlamps, heater blower, rear defogger.
6) Keep front wheels pointed straight ahead.
7) Make the check after the cooling fan has stopped.

SEF976U
3. Open engine hood and run engine at about 2,000 rpm for about 2 minutes under no-load.
SEF977U
4. Perform diagnostic test mode II (Self-diagnostic results). Refer to EC-644.
SEF217U
OK or NG
OK ' GO TO 2.
NG ' 1. Repair or replace components as necessary.
2. GO TO 2.
BASIC SERVICE PROCEDURE VG33E
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont’d)
EC-616
2 CHECK IGNITION TIMING
1. Run engine at about 2,000 rpm for about 2 minutes under no-load.
2. Rev engine (2,000 to 3,000 rpm) two or three times under no-load, then run engine at idle speed.
SEF978U
3. Turn off engine and disconnect throttle position sensor harness connector.
SEF975R
4. Start and rev engine (2,000 - 3,000 rpm) two or three times under no-load, then run at idle speed.
5. Check ignition timing with a timing light.
SEF371S
15°±2° BTDC (in “P” or “N” position)
OK or NG
OK ' GO TO 4.
NG ' GO TO 3.
GI
MA
EM
LC
FE
CL
MT
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
BASIC SERVICE PROCEDURE VG33E
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont’d)
EC-617
3 ADJUST IGNITION TIMING
1. Adjust ignition timing by turning distributor after loosening securing bolts.
2. Turn off engine and connect throttle position sensor harness connector to throttle position sensor.
SEF972R
' GO TO 2.
4 CHECK BASE IDLE SPEED
With CONSULT-II
1. Read idle speed in “DATA MONITOR” mode with CONSULT-II.
PEF356V
700±50 rpm (in “P” or “N” position)
Without CONSULT-II
1. Check idle speed.
700±50 rpm (in “P” or “N” position)
OK or NG
OK ' GO TO 6.
NG ' GO TO 5.

Josh, Did you output the car's diagnostic codes before you reset the computer?
Just to confirm: your car has the "FS" engine - 1991cc double overhead cams?
built on the Mazda "GE" platform?
does your car have an "engine check light" or "MIL" on the dashboard? if so where and what does it look like and what does do ? ie: comes on when ignition is turned on & goes out after engine starts. or comes & goes out after x seconds. etc etc
are you 5sp manual or auto trans?

does your car have a diagnostic plug with a flip open lid just behind the battery near the front left suspension tower?

Common issue at the shop (i'm a ford technician), here is what I do to correct it.
Here is the most common cause of surges and stalls at stops and low erratic idle speed and rough idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

)The fact that thge engine idle fluctuates when it is cold indicates that the Fast Idle THermo Valve is out of adjustment.
This valve is located ot the front of the intake manifold on the driver's side just below the accelerator cable. To adjust it, wait until the engine is cold (best to do it first thing in the morning).
Remove the two screws holding the cover on and start the engine. There is a brass needle sticking up through a plastic ring that has two slots in it. With the engine idle fluctuating, use a thin flat blade screwdriver to SLOWLY turn the ring CLOCKWISE
until the idle stabilizes. Once done. put the cover back on withg the two screws and you should be done.