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CEL on constantly and occasionally flashes

 
gerzbek
New User
Posts: 3
Joined: 08/13
Posted: 08/12/13 10:25 PM

First off, Hello everyone and thank you in advance for your help.

I have a 2004 3.8L V6 engine Mustang, automatic, I'm having issues with it having a constant CEL and will occasionally flash when reaching 20-30 MPH and then be constant again after 30MPH.  I've had this problem in the past and changed the spark plugs/coil pack and wires and fixed the issues.  This was only 6 months ago, my worry is that changing these is not the permanent fix and only temporary.  Do you have any suggestions on what this problem could be?

When having it scanned at autozone they told me it was a misfire in cylinder 2.
I do not have the exact trouble codes, I'm heading to autozone in the morning to check what they are.  

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waynep712222
User
Posts: 124
Joined: 03/13
Posted: 08/13/13 07:14 AM

which code numbers.. is important..

a #2 cylinder misfire is a P0302.. but there are thousands of codes...

can you do me a favor... before you go any farther..  do you own a digital volt meter

run this test..

engine running.. headlights on...  set meter to 20 volts DC..

1.   Negative battery Post  to Positive battery Post.. 14.1 volts to 14.8 volts is accepted..

2.   Negative battery Post to the engine block... 0.04 volts DC MAX

3.   Negative battery post to the body... 0.02 volts DC MAX..

4.   Engine block to the Body.. 0.02 volts DC MAX..

why.. i have found so many bad or loose grounds on mustangs.. and the electrons are supplied from the negative side.. loose ground.. broken wire strands at the wire grounds on the core support is a big issue..

this test takes about 2 minutes.. and volt meters are cheep..

post the exact codes if you can..

ignition coils do fail .. spark plug wires come off.. or burn the ends off when a wire is not fully inserted...  

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waynep712222
User
Posts: 124
Joined: 03/13
Posted: 08/13/13 07:31 AM

i pasted together a picture of the ground locations to start cleaning..

1992Mustang50batterycablegrounds

flashing usually indicates an intermittent connection... but please post all the codes.. by number..  

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gerzbek
New User
Posts: 3
Joined: 08/13
Posted: 08/15/13 04:10 PM

Alright I got the codes

P0302
P0133
P0316  

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gerzbek
New User
Posts: 3
Joined: 08/13
Posted: 08/15/13 04:10 PM

Alright I got the codes

P0302
P0133
P0316  

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waynep712222
User
Posts: 124
Joined: 03/13
Posted: 08/15/13 10:15 PM

P0133 - O2 Circuit Slow Response (Bank 1, Sensor 1)
Description: The powertrain control module (PCM) monitors oxygen sensor response time by
commanding a calibrated fuel control routine. This routine sets the air fuel ratio to a
calibrated limit to produce a predictable oxygen sensor signal amplitude. For vehicles with
universal heated oxygen sensors (HO2S), the test fails if the oxygen sensor signal does not
reach the predicted amplitude within a predetermined response time. For vehicles with
heated oxygen sensors (HO2S), the test fails when the oxygen sensor amplitude is less than
the predicted minimum amplitude limit.
Possible Causes: • Contaminated HO2S
• Exhaust leaks
• Incorrect fueling
• Mass air flow (MAF) sensor
• Deteriorating HO2S
• Inlet air leaks
Diagnostic Aids: Access the HO2S test results from the scan tool to verify the DTC.



P0300 - Random Misfire Detected
Description: The random misfire DTC indicates multiple cylinders are misfiring or the powertrain control
module (PCM) cannot identify which cylinder is misfiring.
Possible Causes: • Camshaft position (CMP) sensor
• Low fuel (less than 1/8 tank)
• Stuck open exhaust gas recirculation (EGR) valve
• Blocked EGR passages
• Misfire monitor neutral profile correction has not been relearned since the last mechanical
repair
Diagnostic Aids: One or more EGR passages may be blocked or partially blocked.
Application Key On Engine Off Key On Engine Running Continuous Memory
All GO to Pinpoint Test HD.



P0301, P0302, P0303, P0304   ect...
P030x - Cylinder x Misfire Detected
Description: NOTE: x represents cylinder numbers 1 through 9.
The misfire detection monitor is designed to monitor engine misfire and identify the specific
cylinder in which the misfire has occurred. Misfire is defined as lack of combustion in a
cylinder due to absence of spark, incorrect fuel metering, low compression, or any other
cause.
Possible Causes: • Ignition system
• Fuel injectors
• Running out of fuel
• Evaporative emission (EVAP) canister purge valve
• Fuel pressure
• Evaporative emission system
• Exhaust gas recirculation (EGR) system
• Base engine
• Misfire monitor neutral profile correction has not been relearned since the last mechanical
repair
Diagnostic Aids: The malfunction indicator lamp (MIL) blinks once per second when a misfire severe enough
to cause catalyst damage is detected. If the MIL is on steady state due to a misfire, this
indicates the threshold for emissions was exceeded and caused the vehicle to fail an
inspection and maintenance tailpipe test.



P0316 - Misfire Detected On Startup (First 1000 Revolutions)
Description: DTC P0316 sets in addition to any type B misfire DTC which occurs in the first 1,000
revolution test interval following engine start.
Possible Causes: • Damaged crankshaft position (CKP) sensor
• Ignition system
• Fuel injectors
• Running out of fuel
• Fuel quality
• Base engine
• Damaged powertrain control module (PCM)
Diagnostic Aids: Freeze frame data and the DTC P03xx are also stored, indicating which cylinder the misfire
occurred.  

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waynep712222
User
Posts: 124
Joined: 03/13
Posted: 08/15/13 10:26 PM

there is a chance the coil failed.

there is a chance there is a vacuum leak...

there is a chance there is some other failure.. including blown head gaskets..

it takes a digital scope to spot a bad coil...

you can OHM the spark plug wires with a digital volt meter..   set to 200K and read the wires directly..  the meter should display less than the length of wire in inches at that setting..

a 24 inch wire should ohm out between 10K and 16K ohms  1,000 ohms per inch max..

a 14 inch wire should ohm out between 6K and 10K ohms.. you get the idea..

you may want to run a compression test..

please check that the cooling system is actually totally full.. most of the V6 motors have a bleeder screw above the thermostat area on the top of the hex shaped tube with heater hoses out the side.. and a warning.. you will want to remove the screw.. clean out the passage.. pick up a proper NYLON oil drain plug gasket for it.. toss the white plastic device.. they leak sometimes... allowing tiny amounts of coolant out.. where it gets evaporated.. but when the engine cools off.. it allows air back into the engine.. messing up the amount of coolant thats actually in the engine.. causing intermittent overheating..


how did the ground cleaning come out.. visual inspection of the ground wires on the radiator core ends.. i have found many of those loose.. and most of them frayed.. down to only a few strands of wire out of an 8 gauge wire..  

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waynep712222
User
Posts: 124
Joined: 03/13
Posted: 08/15/13 10:31 PM

with the scan tool plugged in.. and looking at live data stream.. looking at the short term and long term fuel trims.. see if they are within 10% at idle and at a steady 2500 RPMs...

this is what a decent oxygen sensor voltage graph should look like at 2500 RPMs..

O2B2S1 Zps69fd0fbd  

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