my check engine light.............please help

[kurt5153]

hey guys i followed the FAQ about the Check Engine light. to me it looks like it flashes 8 times the first time and 6 the second time but when i went to the codes theres no 6 but theres an 8 thats the VAF is this right? heres a link to youtube please help!

http://www.youtube.com/watch?v=nfFL87ACcmY" onclick="window.open(this.href);return false;

[PoisonDrop]

Look at the timing. It's 4 seconds between codes. Long flashes are digits in the tens column, short flashes are in the ones column, with 1.2 seconds in between each digit.

To answer your question, I believe you are showing 3 codes. 8, 10, and 16. Those would be the airflow meter, and the intake air thermosensor respectively, but 16 isn't listed in what I have, so I guess I can't help you on that one. Try solving the first two problems (is your airflow meter plugged in?), and then reset the codes. See where that gets you.

[Slammed6]

Yeah, its codes 8, 10, 16

Code 8: Volume Airflow Sensor

Sensor Purpose:
This sensor tells the PCME how much air is entering the engine. Located in the intake tract, it uses a sliding-core that changes position based on changes in airflow. The VAF also contains the intake air temperature sensor (IAT) sensor.

Fault Description:
This code indicates that the voltage on the VAF sensor A/D channel is less than 0.200V. There is no upper limit to the VAF reading although it will never be higher than the +5 volt reference from the PCME. Normal VAF voltages range from 4.00V at engine-off, 3.20V at warm idle, 1.80V at moderate acceleration and 0.35V at the absolute maximum core displacement.

The VAF has a 5-position connector:
Wire Colour
Purpose

R
VAF sensor output

P
+5V reference from PCME

BK/DB
VAF sensor ground

BK/DB
IAT sensor ground

BK/R
IAT sensor output


PCME Fault Control Moding:
When Code 8 is present, the PCME uses the TPS voltage and idle-switch to determine the "basic" fuel injection amount. There are 3 basic conditions:

1. Idle switch ON meaning the throttle is closed.

2. Small throttle angles indicating light load and small airflow amounts.

3. Large throttle angles indicating heavy load and larger airflows.

In these conditions, 3 different airflow readings are "constructed" and substituted for the ailing VAF sensor's reading. The result will be a Probe that will run but which will be very ill tempered.

Memorization:
This code is memorized in the PCME non-volatile memory.

Things To Check When Diagnosing:
1. Check to make sure the connector is tight and clean.

2. Check for the +5 volt reference from the PCME if EGR and TPS codes are also present.

3. Check the condition of all grounds.

4. Make sure the core is not stuck and that the VAF is mounted as close to the horizontal as possible.

5. The VAF itself is not cheap (>$1000CDN) new so if you suspect it's bad, do your best to source one from a wrecking yard (don't tell them how much Ford/Mazda wants for it).





Code 10: Intake Air Temperature Sensor

Sensor Purpose:
This sensor tells the PCME the temperature of the air entering the engine. This information is used to adjust the amount of fuel delivered and is also used to adjust the amount of spark timing. The IAT sensor is located embedded inside the Volume Airflow Sensor housing and is not itself replaceable although a substitute part may be used (see below) since if the IAT goes, it amounts to replacing a $1000CDN part for a $0.39 thermistor. The fix may not be pretty but it's cheap. However, the IAT is a robust part and is not likely to fail - ever.

Fault Description:
This code indicates that the voltage on the IAT A/D channel is lower than 0.136V (indicating a short circuit to ground) or the reading is over 4.844V indicating the connection from the PCME to the sensor is open. The sensor can be checked with an ohmmeter and should fall within the ranges shown in the table:

IAT Sensor/Intake Air Temperature
Reading in Ohms

-20oC (-4oF)
10000 to 20000

20oC (68oF)
2000 to 3000

60oC (140oF)
400 to 700


PCME Fault Control Moding:
When Code 10 is present, the PCME substitutes fixed calibration values for the various representations of intake air temperature used internally. The engine may idle roughly and may be hard to start. Timing and fuel delivery calculations will be skewed somewhat since the air temperature will be only an approximation.

Memorization:
This code is memorized in the PCME non-volatile memory.

Things To Check When Diagnosing:
1. Use the above table to check the intake sensor itself. It is probably the cause of the problem

2. As always, check the connector to make sure there's no corrosion or grease or dirt in it.

3. Disconnect the sensor harness at the VAF (go there to see what each pin is for) and check the BK/R wire for +5V with the ignition on. If it is absent, check the wiring to the PCME and the PCME itself.

If the sensor itself is bad, don't despair. Contact Digi-Key and order up an NTC (Negative Temperature Coefficient) thermistor part number KC017N-ND. This thermistor has a similar characteristic to the OEM part in the VAF near ambient temperatures though it does veer off the OEM characteristic once temperatures begin to get high or low. The car will run quite acceptably with this thermister as a VAF but you might find it runs rich when cold (like below freezing cold). The other problem is that because the thermister reads abnormally high on the "hot" side, the PCM might perceive that the air is hotter than it really is, causing slightly lean conditions during throttle transitions and more importantly, it might start removing spark timing. You decide... I eventually recalibrated my PCM to use the new sensor since I run it with my MAF setup. Clearly, this is not an option to the average Prober.





Code 16: EGR Position Sensor

Sensor Purpose:
Exhaust Gas Recirculation is used to re-route metered amounts of exhaust gases from the exhaust manifold (right side) to the intake tract. Doing this tends to reduce combustion temperatures and reduces the formation of smog- contributing oxides of nitrogen or "NOx".

The PCME uses the EGR vacuum and vent solenoids in conjuntion with the EGR position sensor to determine and modulate how much vacuum is applied to the EGR valve to regulate how much exhaust gas is entering the intake.

The EGR position sensor has a 3-position connector:
Wire Colour
Purpose

P
+5V reference from the PCME

R/BK
EGR position signal to PCME

BK/DB
EGR sensor return (ground)


Fault Description:
Two conditions will result in a Code 16. The first condition is either a short or open condition where the sensor voltage reads below 0.196V or above 4.74V.

The second condition is where the EGR voltage is within the above specified parameters but the valve is not where the PCME thinks it should be. That is, if the sensor reads, say, 0.3V but the PCME is asking for 3.5V worth of EGR, Code 16 will get set.

PCME Fault Control Moding:
When Code 16 is present, zero EGR contribution is commanded. The result may be a proclivity to pinging (spark knock) and increased exhaust emissions.

Memorization:
This code is memorized in the PCME non-volatile memory.

Things To Check When Diagnosing:
1. Check the conectors and wiring between the PCME and the EGR position sensor.

2. Check the condition of the vacuum hoses and wiring at the EGR vent and vacuum solenoids. These solenoids are the release and apply solenoids - any malfunction in these may generate a Code 16.

3. Check the P wire for +5V with the ignition on. If Code 16 is accompanied by Codes 8 (VAF) or 12 (TPS) the PCME or wiring may be at fault.

4. Replace the EGR position sensor if all else checks out.

[PoisonDrop]

Ah...no EGR for me, so I guess that's why it's not listed in my copy of the manual...