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Yesterday on the way to work my car started stuttering a little on the freeway in 6th. It was being weird all the way to work and I pulled codes and looked it up. Cleared it, then on the way home I got a Check Engine light.
'01 Base with dual cone dry filters and no mods. I just did the pugs and wires a few weeks ago (ngk ix and MSD 8.5mm).
So far I've checked the plug and connection to the MAF, I cleaned the MAF with approved cleaner, I got another MAF from NAPA, same results.
Vacuum lines look ok. What do I need to check next? Thanks for any help, my searching has resulted in very little.
Let the car idle and wiggle the wires going into the maf. Listen for a change in idle and if so, you have a wiring/connection issue. You can usually lightly bend the pins a little bit and get a better connection
edit. Just saw where you’ve checked the connections. Have you checked voltage to the maf or wiggled the wires?
Common thing on Z06 (especially) cars that get a Vararam. Has the same issues.
My money is on the cone filter setup. For some reason your calibration doesnt like the airflow characteritics of that setup. A tuner can correct the issue or you can change the intake setup. One other thing that helps is if you relocate the maf closer to the throttle body.
I still have my OE air box. I've been running this filter setup for about a year. I will see if putting the stock box back on helps and see about moving the MAF. Thanks a lot for the suggestions. I will try wiggling the connection when running, too, jus in case.
I think the previous owner had an intake on it before I got it. I will put the stock box on today and see if that helps. I don't know anyone in town I trust with it, so I will have to look around and suck it up if I can't figure it out.
Between yellow and ground or yellow and purple, and measured .03V at idle, 2k rpm increased to .04V. That doesn't seem high enough compared to the video I watched on MAF testing.
Between yellow and ground or yellow and purple, and measured .03V at idle, 2k rpm increased to .04V. That doesn't seem high enough compared to the video I watched on MAF testing.
Thoughts.
Between yellow and ground Key ON Engine OFF it should read 5v or real close to that. Try that test. Below I am adding the Service Manual tests for that Code. Should also test ground circuit and the Ignition 1 voltage to that connector as well. Ignition 1 voltage should be 5 volts on the pink wire. The "Go to" answers Yes on top and No on bottom the way this formats here. Added schematics as well as Connector End View at the bottom.
DTC P0102
Circuit Description
The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The powertrain control module (PCM) uses the MAF sensor signal in order to provide the correct fuel delivery for a wide range of engine speeds and engine loads. A small quantity of air entering the engine indicates a deceleration, or an idle. A large quantity of air entering the engine indicates an acceleration, or a high load situation. The MAF sensor has an ignition 1 voltage circuit, a ground circuit, and a signal circuit. The PCM applies a voltage to the sensor on the signal circuit. The sensor uses the voltage in order to produce a frequency based on the inlet air flow through the sensor bore. The frequency will vary within a range of around 2,000 Hertz at idle, to about 12,000 Hertz at the maximum engine load. DTC P0102 will set if the PCM detects a frequency signal lower than the possible range of a normally operating MAF sensor.
Conditions for Running the DTC
The engine is running for greater than 0.5 second.
The engine speed is at least 300 RPM.
The ignition 1 signal is at least 8 volts.
Conditions for Setting the DTC
The MAF sensor frequency signal is less than 10 Hz.
The above condition is present for greater than 1.2 seconds.
Action Taken When the DTC Sets
The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.
Diagnostic Aids
Inspect for the following conditions:
A misrouted harness. Inspect the MAF sensor harness in order to ensure that it is not routed too close to the following sensors or components:
The ignition coils
Any solenoids
Any relays
Any motors
A low minimum air rate may cause this DTC to set during deceleration. Inspect for the following conditions:
A plugged or collapsed intake air duct or a dirty air filter element
Objects blocking the MAF sensor air inlet screen
Throttle bore and throttle plate deposits
A wide open throttle (WOT) acceleration from a stop should cause the MAF display on a scan tool to increase from about 4-7 g/s at idle to about 190 g/s or more at the time of the 1-2 shift. If not, inspect for a restriction.
Any unmetered air entering the engine may cause this DTC to set. Inspect for vacuum leaks anywhere downstream of the MAF sensor.
If you suspect the vehicle condition may be related to aftermarket accessories, refer to Checking Aftermarket Accessories in Wiring Systems.
If an intermittent exists, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
This step verifies the signal circuit from the MAF sensor electrical connector to the PCM. A voltage reading of less than 4 volts or greater than 6 volts indicates a malfunction in the wiring or a poor connection.
This step tests the signal circuit of the MAF sensor for a short to another 5 volt reference circuit.
Step
Action
Values
Yes
No
Schematic Reference: Engine Controls Schematics
1
Did you perform the Diagnostic System Check-Engine Controls?
--
Go to Step 2
Go to Diagnostic System Check - Engine Controls
2
Install a scan tool.
Start the engine.
With a scan tool, observe the MAF sensor frequency parameter.
Does the scan tool indicate that the MAF sensor frequency is less than the specified value?
10 Hz
Go to Step 4
Go to Step 3
3
Observe the Freeze Frame/Failure Records for this DTC.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC or as close to the Freeze Frame/Failure Records that you observed.
Does the DTC fail this ignition?
--
Go to Step 4
Go to Diagnostic Aids
4
Inspect the fuse that supplies the Ignition 1 voltage circuit of the MAF sensor. Refer to Engine Controls Schematics .
Is the fuse open?
--
Go to Step 14
Go to Step 5
5
Turn OFF the ignition.
Disconnect the MAF sensor harness connector.
Turn ON the ignition, with the engine OFF.
Measure the voltage from the signal circuit of the MAF sensor to a good ground. Refer to Circuit Testing in Wiring Systems.
Does the voltage measure near the specified value?
5 V
Go to Step 6
Go to Step 8
6
Connect a 3-amp fused jumper wire between the signal circuit of the MAF sensor and a good ground. Refer to Circuit Testing in Wiring Systems.
Start the engine.
Do any additional DTCs set?
--
Go to Step 16
Go to Step 7
7
Turn OFF the ignition.
Connect a test lamp between the Ignition 1 voltage circuit of the MAF sensor and the ground circuit of the MAF sensor. Refer to Circuit Testing in Wiring Systems.
Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate?
--
Go to Step 18
Go to Step 11
8
Does the voltage measure less than the specified value?
4.5 V
Go to Step 10
Go to Step 9
9
important
Disconnecting the PCM connectors may eliminate the short to voltage if the signal circuit is shorted to another PCM circuit. Refer to Circuit Testing in Wiring Systems.
Turn OFF the ignition.
Disconnect the PCM. Refer to Powertrain Control Module (PCM) Replacement
Turn ON the ignition, with the engine OFF.
Measure the voltage from the signal circuit of the MAF sensor to a good ground.
Does the voltage measure near the specified value?
0 V
Go to Step 12
Go to Step 15
10
Turn OFF the ignition.
Disconnect the PCM. Refer to Powertrain Control Module (PCM) Replacement
Test the signal circuit between the PCM and the MAF sensor for the following conditions:
A high resistance or an open
A short to ground
A short to the ground circuit of the MAF sensor-- Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 22
Go to Step 12
11
Connect a test lamp between the ignition 1 voltage circuit of the MAF sensor and a good ground. Refer to Circuit Testing in Wiring Systems.
Does the test lamp illuminate?
--
Go to Step 13
Go to Step 14
12
Test for continuity at the harness connector of the PCM from the signal circuit of the MAF sensor to all other circuits at both PCM connectors. Refer to Circuit Testing in Wiring Systems.
Does the DMM indicate continuity between any other circuit?
--
Go to Step 17
Go to Step 19
13
Repair the high resistance or an open in the ground circuit of the MAF sensor. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
--
Go to Step 22
--
14
Important
The ignition 1 voltage circuit of the MAF sensor is spliced to other components on the vehicle.
Repair the short to ground or an open in the ignition 1 voltage circuit of the MAF sensor. Refer to Wiring Repairs in Wiring Systems.
Replace the fuse if necessary.
Did you complete the repair?
--
Go to Step 22
Go to Step 20
15
Repair the short to voltage in the signal circuit of the MAF sensor. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
--
Go to Step 22
--
16
Repair the short between the signal circuit of the MAF sensor and the circuit for which the DTC set. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
--
Go to Step 22
--
17
Repair the circuits that are shorted together. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
--
Go to Step 22
--
18
Inspect for poor connections at the harness connector of the MAF sensor. Refer to Testing for Intermittent and Poor Connections and to Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 22
Go to Step 20
19
Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent and Poor Connections and to Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 22
Go to Step 21
20
Replace the MAF sensor. Refer to Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor Replacement
Did you complete the replacement?
--
Go to Step 22
--
21
Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement
Did you complete the replacement?
--
Go to Step 22
--
22
Use the scan tool in order to clear the DTCs.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC run, and pass?
--
Go to Step 23
Go to Step 2
23
With a scan tool, observe the stored information in Capture Info.
Does the scan tool display any DTCs that you have not diagnosed?
--
Go to Diagnostic Trouble Code (DTC) List
System OK
A PPL 719
Low Reference
B TAN 472
IAT Sensor Signal
C BLK/WHT 451
Ground
D PNK 339
Ignition Feed
E YEL 492
Mass Air Flow (MAF) Sensor - Signal
Last edited by RedRiderZR1; 06-03-2018 at 04:46 PM.
All my fuses check out. The pcm doesn't seem to be easy to get to.
Need to take off the passenger front wheel and remove the access panel at the rear of the wheel well. It is under there. Also, here is the connector end view of the PCM to trace the yellow wire.
Ok, I cut the yellow wire 6" from the plug, no 5v and continuity between cut and plug. Damn. I won't pull the wheel today, but now I know what to do next. Thanks again for all the help and info on this. I was hoping for an easy fix, not this time.
Hey !!
Yes, 5 volt ref. on the yellow pic enclosed), ground on the black/white and ignition voltage on pink... IAT wires are the other 2 wires. with engine running (my scan data enclosed) your grams/second should "roughly" be the engine displacement...baro PID (mine was 14.65 and do the conversion) should be near outside barometric pressure...my baro at the time was 29.9 in/hg...frequency at idle is 2,700 Hz !!
Ok, I cut the yellow wire 6" from the plug, no 5v and continuity between cut and plug. Damn. I won't pull the wheel today, but now I know what to do next. Thanks again for all the help and info on this. I was hoping for an easy fix, not this time.
Really NOT a good idea to cut the signal wire to the MAF...you are only setting yourself up for trouble down the road if you were to splice those wires together. They make "piercing probes" for doing this kind of thing...they are pretty cheap on Amazon. When you are done you use liquid electrical tape to cover the very small hole.
I poked it first, I just wanted to make sure I wasn't getting anything and now I know. Still seems like an odd failure.
The 5 volt is a VERY important signal in the car...if that yellow signal wire were shorted to ground the car wouldn't start...you most likely have an open in the circuit...if you do have a 5 volt ref. at the PCM it's time to break down the wiring harness in half and start checking for a break...if no 5 volt at the PCM end "sometimes" a shorted potentiometer (TPS sensor), psi sensor, or a Hall Effect (cam/crank sensor) can "pull down" the entire 5 volt ref. circuit...most of the time you will have another issue....that is when you have to disconnect the sensors and see if the 5 volt ref. returns before calling it a bad PCM... Keep us advised !!
06-03-2018, 12:04 AM
At a loss with P0102 error and Check Engine light
