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Drew, Super Mazda Tech.
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Experience:  19 yrs. experience. Mazda Senior Certified Tech, with Ford, Linc. & Merc. experience. ASE L1 Advanced Certified Master Tech.
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Mazda Millenia S: 98 Mazda Millenia S miller cycle engine

Customer Question

98 Mazda Millenia S miller cycle engine ... rough erratic idle rpm goes up and down (when down it almost stalls), runs good under higher rpm's, currently no codes but 4 monitors are not completed and I have been driving it for two weeks. Uses too much gas, I hooked it up to obd scanner and fuel trims are in open loop (why it uses too much gas) even though temperature goes between 194 and 205 F. Suddenly went to closed loop for 10 seconds and went back to open loop. No activity from two O2 sensor (voltage at 0) which makes me think the reason why in open loop, but why no O2 sensors codes? Help please....
I also replaced EGR valve, cleaned and tested idle control valve.
Submitted: 3 years ago.
Category: Mazda
Expert:  Drew replied 3 years ago.

Welcome to Just Answer. My name is XXXXX XXXXX I will be glad to assist you.

I suspect that you have a vacuum leak causing your concern. There are several vacuum hoses under the intake that crack and leak.You can try to use starting fluid to spray on the engine, with it running and when the vacuum leaks sucks up the additional fuel, idle rpms will change and the engine may run rough.

You can also monitor the short term fuel trim on your scan tool. With the engine running, the should be around 0 (+3-)

Here is some additional information>

Please let me know if you have any additional questions.

Thanks
Drew

ALL MODELS/OBD MONITORS NOT COMPLETED

Applicable Models



























ModelStarting S/N Ending S/NModel Spec
Miata 1996-1997 000000 ZZZZZZ
Millenia 1996-2002 000000 ZZZZZZ
MPV 1996-1998 000000 ZZZZZZ
Protege 1996-2002 000000 ZZZZZZ

Related Category/Subcategory/Symptoms

Engine / Fuel System / Failed Emissions Test/Exceeded Emissions Standards

Engine / Fuel System / Does Not Turn-Off/Warning Light
Engine / Fuel
System / Improper Operation

MTOL - 3870 Dealer Repair Information

Symptom and Conditions

During vehicle inspection at state emissions (smog) certification
or
during normal diagnosis, it is determined that almost all OBD
monitors
are incomplete except O2 sensor heater monitor after performing
the OBD
drive
mode.

NOTE:
Vehicles
will fail the OBD emission inspection if 3 or more OBD monitors
have not
completed. (in most OBD certification states).

Repair Procedure



  1. Check base idle speed and ignition timing after engine warm
    up.
    If not within the specification, adjust them to
    specification.


  2. Monitor RPM PID and LONGFT PID using NGS or WDS.


  3. Start engine and check that the "LONGFT" PID has changed from 0
    to
    another value at idle. Rev engine at 1000rpm, at 2000rpm, at
    3000rpm
    at 4000rpm and at 5000rpm (hold approximately 30 secs.-1 minute
    at
    each RPM level) If the LONGFT PID does not change on the
    first
    attempt, retry running the engine at the different RPM levels 1
    more
    time as indicated above until the "LONGFT" PID value
    changes
    to a value other than 0. (If LONGFT remains at 0 after the
    second
    attempt, then something (a component) is broken or not
    working
    correctly which is preventing the "LONGFT" from learning.
    This is
    preventing the monitors (RFC's)from clearing. Should this be the
    case,
    a complete inspection of all the emission components and PCM
    inputs
    will be needed. (Expample, PS Pressure Switch, Fuel Tank
    Pressure
    Sensor, MAF Sensor, TP Sensor,
    Ect.)

    If the "LONGFT" changes to
    another value than 0, proceed immediately
    to step 4.


  4. Then perform the OBD drive mode(s) as necessary, and then
    check
    the monitors to verify they have completed.

KJ) IDLE SURGE W/AC ON DECEL,HESTATION,LOW POWER

Applicable Models












ModelStarting S/N Ending S/NModel Spec
Millenia 1995-2001 000000 ZZZZZZ

Related Category/Subcategory/Symptoms

Engine / Fuel System / Rough Idle
Engine / Fuel System / Engine Stalls
Driving - Will Restart
Engine / Fuel System / Lack of Power
Engine /
Fuel System / Does Not Turn-Off/Warning Light
Engine / Fuel System /
Improper Operation

MTOL - 3154 Dealer Repair Information

Symptom and Conditions

Customer may complain of an intermittant lack of power, hesitation during
acceleration, and a rapid up and down idle surge after decel and coming to a
stop with a/c on (RPM varies from(NNN) NNN-NNNNRPM). This condition may be caused by
a improperly positioned Cam Position sensor.

* Verify idle surge. * Monitor PIDs for ignition timing, injector pulse
width and RPM. If large fluctuations are noted in these PIDs, follow below
procedure:

1. Make an index mark on the Cam Position Sensor and cylinder head. 2.
Rotate the Cam Position Sensor 1-2 mm clockwise. 3. Drive vehicle and verify
condition. 4. If condition still exists, rotate Cam Position Sensor back to the
index marks and rotate the sensor 1-2 mm counter-clockwise. 5. Road test vehicle
and verify repair.

NOTE: In some extreme cases the Cam Position Sensor bolt can be removed
and the Cam Position Sensor rotated more than 2 mm. If the engine idle
stabilizes and condition improves, check the cam timing, belt stretch condition.

Repair Procedure

Drew, Super Mazda Tech.
Category: Mazda
Satisfied Customers: 2518
Experience: 19 yrs. experience. Mazda Senior Certified Tech, with Ford, Linc. & Merc. experience. ASE L1 Advanced Certified Master Tech.
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Customer: replied 3 years ago.
I checked the hoses maybe not thoroughly so I will do it again, that was my first concern. I am finally getting codes, actually pending codes P1170 and P1173. It seems PCM is not getting feedback from O2 sensors. Do you think bad sensors or just some loose/ bad wiring ?
I am not sure this can cause rough idle, can it ?
And also pre-code for multiple cylinder misfire which again makes me think and verify what you said - vacuum leak. Thanks
Expert:  Drew replied 3 years ago.

There are no common repairs for those codes.

Here is the diagnosis pinpoint test that you will have to perform step-by-step to determine the root cause for your concern.

A vacuum leak will cause this code and a long list of other possibilities listed below.

Thanks
Drew

1998 - Millenia - Workshop Manual - Engine


DTC P1173 - HO2S 21-INVERSION






























































































































































































































































































DTC P1173


HO2S 21-INVERSION


DETECTION


CONDITION


Heated oxygen sensor (front LH) signal stays above 0.45 V for 42 seconds
after the engine has reached normal operating temperature and running at 1,150
rpm or more


POSSIBLE


CAUSE


Heated oxygen sensor (front LH) deterioration



Heated oxygen sensor heater (front LH) malfunction



Fuel injector malfunction



PRC solenoid malfunction



Pressure regulator malfunction



Fuel pump malfunction



Fuel filter clogged



Fuel delivery hose clogged or leakage



Fuel return hose clogged



Leakage intake‐air system



Leakage exhaust system



PCV valve malfunction



Purge solenoid malfunction



Purge solenoid hoses hooked up incorrectly



Ignition coil malfunction



Ignition control module malfunction



Distributor malfunction



Insufficient compression



Mass air flow sensor malfunction



Engine coolant temperature malfunction



Throttle position sensor malfunction



Closed throttle position switch malfunction



EGR system malfunction



Open or short circuit in wiring harness



Poor connection of connector



Vacuum hoses damaged or loose



STEP


INSPECTION


ACTION


1


Have FREEZE FRAME PID DATA been recorded?


Yes


Go to next step.


No


Record FREEZE FRAME PID DATA on repair order, then go to next
step.


2


Verify stored DTC. Have the DTCs P0100, P0115, P0120, P0443, P0510, P1250,
P1402, P1485 and/or P1486 been stored?


Yes


Inspect and repair DTC P0100, P0115, P0120, P0443, P0510, P1250, P1402, P1485
or P1486, then go to step 33.


No


Go to next step.


3


Is DTC P1169, P1170, or P1173 on FREEZE FRAME PID DATA?


Yes


Go to next step.


No


Inspect and repair DTC on FREEZE FRAME PID DATA, then go to step
33.


4


Temporarily clear DTC. Verify RPM, LOAD, ECT and VSS on FREEZE FRAME PID
DATA. Drive for approx. 1 minute under same condition. Is P1169, P1170, or P1173
stored on PENDING TROUBLE CODE?


Yes


Trouble is in process. Go to next step.


No


Go to "01-01A ENGINE SYMPTOM TROUBLESHOOTING,
INTERMITTENT CONCERNS
".


5


Implement PID/DATA MONITOR AND RECORD (MAFV, ECTV, TPV, CTP SW) from
DIAGNOSTIC DATA LINK by using the NGS. Is there any signal that is far out of
specification when ignition switch is at ON, and at idle?


Yes


Implement " 01-01A ENGINE DIAGNOSTIC INSPECTION,
Input System Investigation Procedure
and repair or replace, then go to step
33.


No


Go to next step.


6


Continue monitoring items on the previous step. Is there any input signal
which causes drastic changes when it is set to be in trouble condition?


Yes


Implement " 01-01A ENGINE DIAGNOSTIC INSPECTION,
Input System Investigation Procedure
and repair or replace, then go to step
34.


No


Go to next step.


7


Are both P1170 and P1173 stored to DTC which are verified at step 2?


Yes


Go to step 14.


No


Go to next step.


8


Inspect exhaust system, upstream from heated oxygen sensor (front LH). Is
there any gas leak?


Yes


Repair or replace faulty exhaust parts, then go to step 33.


No


Go to next step.


9


Inspect installation of heated oxygen sensor (front LH). Is it okay?


Yes


Go to next step.


No


Install heated oxygen sensor properly, then go to step 34.


10


Implement PID/DATA MONITOR AND RECORD (FHO2S L) from DIAGNOSTIC DATA LINK by
using the NGS. Is voltage on heated oxygen sensor as follows while racing the
engine (in neutral)?


More than 0.45V when accelerator pedal is suddenly pressed: rich
condition.



Less than 0.45V during fuel cut: lean condition.



Yes


Go to next step.


No


Inspect and repair or replace faulty heated oxygen sensor (front LH),
harness, connector or terminal (refer to "01-40A HEATED
OXYGEN SENSOR INSPECTION
"), then go to step 33.


11


Inspect heated oxygen sensor heater (front LH) and related harness, connector
and terminal (refer to "01-40A HEATED OXYGEN SENSOR
INSPECTION
" ).


Is it okay?


Yes


Go to next step.


No


Repair or replace faulty heated oxygen sensor (front LH), harness, connector
or terminal, then go to step 33.


12


Inspect for open, poor connection and other problems on the following
harnesses, connectors and terminals for fuel injector at left bank cylinder:


From main relay to fuel injector.



From fuel injector to PCM.



Is there any trouble?


Yes


Repair or replace faulty harness, connector or terminal, then go to step
33.


No


Go to next step.


13


Inspect injection amount of each injector on left bank cylinder (refer to "01-14A FUEL INJECTOR INSPECTION, Volume Test" ). Is
there any injector in abnormal condition for amount or condition of
injection?


Yes


Replace faulty fuel injector, then go to step 33.


No


Go to next step.


14


Inspect LONGFT2 and SHRTFT2 on FREEZE FRAME PID DATA which are verified at
step 1. Does it shift to negative side: lean side?


Yes


Go to next step.


No


Go to step 19.


15


Inspect purge control system (refer to "01-01A ENGINE
SYSTEM INSPECTION, Purge Control Inspection
" ). Is it okay?


Yes


Go to next step.


No


By following system inspection, repair or replace faulty parts, then go to
step 33.


16


Inspect PCV operation (refer to "01-16A PCV VALVE
INSPECTION
" ). Is it okay?


Yes


Go to next step.


No


Replace PCV valve then go to step 33.


17


Inspect fuel line pressure under trouble condition (refer to "01-14A FUEL PUMP INSPECTION, Fuel Pump Maximum
Pressure
" ).


Is fuel line pressure okay?


Yes


Inspect on fuel leakage and injection amount (refer to "01-14A FUEL INJECTOR INSPECTION" ). Replace faulty fuel
injector, then go to step 33.


No


Go to next step.


18


Inspect pressure regulator control (refer to "01-01A
ENGINE SYSTEM INSPECTION, Pressure Regulator Control Inspection
" ). Is it
okay?


Yes


Inspect and repair clogged fuel return hose, then go to step
33.


No


By following system inspection, repair faulty parts, then go to step
33.


19


Inspect for air suction at followings:


From air cleaner to throttle body



From throttle body to dynamic chamber



From dynamic chamber to intake manifold



Visually inspect cracks, and damages, and check fluctuation after spraying
rust penetrating agent, then select air suction area. Can air suction be
confirmed?


Yes


Repair or replace source of air suction, then go to step 33.


No


Go to next step.


20


Inspect for air suction on vacuum hose which has negative pressure on intake
manifold, same way as the previous step. Can air suction be confirmed?


Yes


Repair or replace source of air suction, then go to step 33.


No


Go to next step.


21


Inspect fuel line pressure under trouble condition (refer to "001-14A FUEL PUMP INSPECTION, Fuel Pump Maximum
Pressure
" ). Is fuel line pressure okay?


Yes


Go to step 26.


No


Go to next step.


22


Inspect fuel pump maximum pressure (refer to "01-14A
FUEL PUMP INSPECTION, Fuel Pump Maximum Pressure
" ). Is it okay?


Yes


Go to next step.


No


Replace fuel pump, then go to step 33.


23


Inspect clogging on fuel filter (high pressure side). Is there foreign
material in fuel on fuel pump side of filter?


Yes


Go to next step.


No


Go to step 25.


24


Inspect inside of fuel tank for foreign materials and stain. Is inside of
fuel tank okay?


Yes


Replace the fuel filter (high pressure side), then go to step
33.


No


Clean inside of fuel tank and fuel filter (low pressure side). Replace fuel
filter (high pressure side), then go to step 33.


25


Inspect for leaks and clogging in fuel line from fuel distributor to fuel
pump. Is it okay?


Yes


Replace pressure regulator, then go to step 33.


No


Repair or replace source of fuel leaks or clogging, then go to step
33.


26


Verify blinking condition on each cylinders by setting timing light on
high‐tension lead under trouble condition. Does it blink regularly and
stable?


Yes


Go to step 30.


No


Go to next step.


27


Inspect distributor for cracks on cap, eccentricity rotor and worn center
spring. Is it okay?


Yes


Go to next step.


No


Repair or replace faulty parts, then go to step 33.


28


Inspect resistance of ignition coil (refer to "01-18
IGNITION COIL INSPECTION
" ). Is it okay?


Yes


Go to next step.


No


Replace distributor, then go to step 33.


29


Inspect ignition control module (refer to "01-18
IGNITION CONTROL MODULE INSPECTION
" ). Is it okay?


Yes


Inspect harness for poor connection, contacting body and wear from ignition
control module to PCM.


Repair faulty area, then go to step 33.


No


Replace distributor, then go to step 33.


30


Inspect EGR control system (refer to "01-01A ENGINE
SYSTEM INSPECTION, EGR Control Inspection
" ). Is it okay?


Yes


Go to next step.


No


By following system inspection, repair or replace faulty parts, then go to
step 33.


31


Remove radiator cap. Implement procedure to bleed air from engine coolant,
then run the engine at idle. Is there any small bubble which makes engine
coolant white at filling opening?


NOTE:


Large bubbles are normal since they are remaining air coming out from engine
coolant passage.



Yes


Air gets in from poor sealing on head gasket or other areas between
combustion chamber and engine coolant passage. Repair or replace faulty parts,
then go to step 33.


No


Go to next step.


32


Inspect engine compression (refer to "01-10A
COMPRESSION INSPECTION
" ). Is it okay?


Yes


Go to next step.


No


Implement engine overhaul, then go to next step.


33


Temporarily clear DTC. Verify stored PENDING TROUBLE CODE and DTC, after
running under DRIVE MODE. Is there any PENDING TROUBLE CODE and/or DTC
stored?


Yes


Go to applicable DTC inspection.


NOTE:


If the malfunction remains even though all inspections have been performed,
get assistance from Technical Hotline.



No


Troubleshooting completed.



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Drew
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