Stumble issue

[Joeffr]

Would this cause the car to stumble? code P0243, P0720
The EGR system is deleted and the auto-meter speedometer is connect directly to the trans.
The 1st time was about 5 days after it was dyno tuned, 1/2 hour into the ride 5th gear about 70 mph 2,500 rpms. No loss of vacuum and all the gauges seemed normal. I did wash the motor down the night before but I ran it right after that until it was dry.
Then 2 days after that in 2nd gear about 3,000 rpms and then 5 days later about 1hour into the ride. It happen about 6 times that day, it was a very foggy day.
Now 2 days later as soon as you jump on it it stumbles.
would these codes put the computer into a limp mode or would it be a moisture issue?
It's my daily driver on nice days, before this it ran great.
it's an 03 cobra motor with a 2.9 whipple in a FFR cobra
Thanks

 

[MalcolmV8]

You some more data to figure out what's going on. When you jump on it now and it stumbles is it just a momentary thing and gone or stumbles bad and you have to let out of it?

Have you data logged the car to see what's happening? Look at things like fuel pump duty cycle, fuel rail pressure, spark advance etc.

Have you pulled the plugs to see what they look like? could your stumble be fouled plugs? What plugs are you running and what gap?

Also what fuel are you on? I see 684/748 in your sig. Pretty stout.

 

[Joeffr]

When it stumbles now I have to get out of it or it backfires.

This Monday I should have it back at the tuner to get it logged.
Fuel system is a lethal 850 hp return

The plugs looked clean, TR 7 gap .028
Running 92 octane

 

[MalcolmV8]

Since the problem has slowly been deteriorating have you tried a fresh set of plugs? It sounds like something slowly going worse over time. Be interesting to see what your tuner finds when he data logs for you.

 

[Joeffr]

I just talked to the tuner he can get me in on Tuesday, I'll post what we find.

 

[hotcobra03]

Would this cause the car to stumble? code P0243, P0720
The EGR system is deleted and the auto-meter speedometer is connect directly to the trans.
The 1st time was about 5 days after it was dyno tuned, 1/2 hour into the ride 5th gear about 70 mph 2,500 rpms. No loss of vacuum and all the gauges seemed normal. I did wash the motor down the night before but I ran it right after that until it was dry.
Then 2 days after that in 2nd gear about 3,000 rpms and then 5 days later about 1hour into the ride. It happen about 6 times that day, it was a very foggy day.
Now 2 days later as soon as you jump on it it stumbles.
would these codes put the computer into a limp mode or would it be a moisture issue?
It's my daily driver on nice days, before this it ran great.
it's an 03 cobra motor with a 2.9 whipple in a FFR cobra
Thanks

P0243 - Supercharger (Boost) Bypass Solenoid Circuit Malfunction The PCM monitors the supercharger (boost) bypass (SCB) solenoid circuit for an electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified SCB solenoid duty cycle (100% or 0%) by PCM command.

• VPWR circuit open to SCB solenoid
• SCB solenoid circuit shorted to PWR GND or CHASSIS GND
• Damaged SCB solenoid
• SCB solenoid circuit open
• SCB solenoid circuit shorted to VPWR
• Damaged PCM

Disconnect SCB solenoid. Connect test lamp to SCB solenoid harness connector. Cycle SCB driver in PCM by Output Test Mode. Test lamp cycle on and off - SCB solenoid is suspect. Test lamp always on - SCB signal short in harness or PCM. Test always off - SCB signal or VPWR open in harness or PCM.

P0720 - Insufficient input from Output Shaft Speed sensor The output shaft speed sensor inputs a signal to the PCM, based on the speed of the output shaft of the transmission. The PCM compares this signal with the signal of the VSS or TCSS and determines correct tire size and axle gear ratio.

• OSS sensor circuit short to GND
• OSS sensor circuit short to PWR
• OSS sensor circuit open
• Damaged OSS sensor
• Damaged PCM

Verify sensor signal output varies with vehicle speed.


po243 start at step 6



2003 PCED OBD
SECTION 5: Pinpoint Tests
Procedure revision date: 08/19/2002

KJ: Supercharge Bypass Control

KJ: Introduction

KJ1 DTC P0234: CHECK FOR OTHER DTCS

• Note: The supercharger will be bypassed when the brake is on and the throttle is depressed in the wide open throttle position. This is called brake torque and the engine torque is too high.
• Check that the engine has not been subjected to brake torque causing the P0234.
• Drive the vehicle for 10 to 15 minutes with the engine exceeding 2,000 rpm and the engine temperature stabilizing.
  • No Starts:
    • GO to A1 .
  • For Stalls:
    • Return to Section 3 , Symptom Charts.
• Return to repair area and check that upper radiator hose is hot and pressurized.
• Rerun Quick Test and retrieve KOER and continuous and retrieve DTCs.

Are any other KOEO, KOER and Continuous Memory DTCs present with the KOER or Continuous Memory P0234?
Yes No KEY OFF. GO to Section 4, Powertrain Diagnostic Trouble Code (DTC) Charts , for Pinpoint Test direction and REPAIR DTCs. GO to KJ2 .
KJ2 CHECK SCAN TOOL PIDS FOR CAUSES OF OVERBOOST CONDITION

• Key on, engine running.
• Access IAT2, TFT (5.4L SC only) and RPM PIDs.
• Observe the PIDs for values exceeding the following limits:
  • Intake air temperature (downstream), IAT2 PID greater than 230°F.
  • Transmission fluid temperature, TFT PID greater than 275°F (5.4L SC only).

Do any of the above PIDs exceed the limit?
Yes No For IAT2:

CHECK for low fluid level in Intercooler System. CHECK for cracked intercooler lines. REPAIR as necessary.

For TFT (5.4L only):

CHECK for low transmission fluid level. REFER to Automatic Transmission Section 307 in the Workshop Manual for fluid changes. GO to KJ3 .
KJ3 CHECK FOR LOW SPEED FUEL PUMP RELAY NOT SWITCHING

• Key on, engine running.
• Access LFPF PID.

Is a fault indicated on the low speed fuel pump (FP) output?
Yes No KEY OFF. GO to Section 4, Powertrain Diagnostic Trouble Code (DTC) Charts for diagnostic direction following DTC P1232. CHECK for indications of engine knock while driving the vehicle. REPAIR as necessary. If OK, indicate to vehicle owner that transmission damage will occur upon brake torque (reference: GO to KJ1 ). Otherwise, unable to determine cause of overboost condition at this time.
KJ6 DTC P0243: CHECK SUPERCHARGER (BOOST) BYPASS SOLENOID OUTPUT

• Key off.
• Disconnect supercharger (boost) bypass (SCB) solenoid.
• Connect a non-powered test lamp between SCB and VPWR circuits at the SCB solenoid harness connector.
• Key on, engine off.
• Attempt to close and open SCB solenoid driver in PCM by accessing Output Test Mode or scan tool.
• While observing the test lamp, command the PCM outputs on and off.

Does the test lamp cycle on and off (light up and turn off)?
Yes No KEY OFF. GO to KJ7 . For test lamp always off :

GO to KJ8 .

For test lamp always on :

KEY OFF. GO to KJ11 .
KJ7 CHECK SCB SOLENOID RESISTANCE

• Measure SCB solenoid resistance.

Is resistance between 68 and 78 ohms?
Yes No CHECK for damaged vacuum hoses between engine intake manifold and SCB solenoid. CHECK for vacuum reservoir assembly leaks. REPAIR or REPLACE as necessary. If OK, GO to Z1 for intermittent diagnosis. REPLACE damaged SCB solenoid.
KJ8 CHECK FOR OPEN VPWR CIRCUIT BETWEEN SCB SOLENOID AND POWER RELAY

• Measure voltage between VPWR circuit at the SCB solenoid harness connector and battery negative post.

Is voltage greater than 10.5 volts?
Yes No KEY OFF. GO to KJ10 . KEY OFF. GO to KJ9
KJ9 CHECK VPWR CIRCUIT FOR OPEN IN HARNESS

• Note: Refer to the PCM connector pin number chart in the beginning of the pinpoint test.
• Disconnect PCM.
• Measure resistance of VPWR circuit between PCM harness connector pin and SCB solenoid harness connector.

Is resistance less than 5.0 ohms?
Yes No GO to KJ10 . REPAIR open circuit.
KJ10 CHECK SCB CIRCUIT FOR OPEN IN HARNESS

• Measure resistance of SCB circuit between PCM harness connector pin and SCB solenoid harness connector.

Is resistance less than 5.0 ohms?
Yes No REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). REPAIR open circuit.
KJ11 CHECK SCB CIRCUIT FOR SHORT TO PWR GND IN HARNESS

• Note: Refer to the PCM connector pin number chart in the beginning of this pinpoint test.
• Disconnect PCM.
• Disconnect scan tool from DLC.
• Measure resistance between SCB circuit and multiple PWR GND circuits at the PCM harness connector.

Are all resistances greater than 10,000 ohms?
Yes No RECONNECT scan tool. GO to KJ12 . REPAIR short circuit.
KJ12 CHECK SCB CIRCUIT FOR SHORT TO PWR OR CHASSIS GND IN HARNESS

• Key on, engine off.
• Measure voltage between SCB circuit at the PCM harness connector and chassis ground.

Is voltage less than 1.0 volts?
Yes No KEY OFF. REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). KEY OFF. REPAIR short circuit to VPWR, VREF or chassis ground.
KJ13 LACK OF POWER (LOW BOOST) - CHECK VACUUM HOSES

• Note: For vehicle specific vacuum hose routing, refer to the vehicle information decal located in the front of the engine compartment.
• Check for holes or cracks in the vacuum hose/tube between the supercharger bypass actuator and the supercharger bypass solenoid.
• Check for holes or cracks in the vacuum hose/tube between the supercharger bypass solenoid and vacuum reservoir assembly.
• Check for bends or kinks in the vacuum hose/tube between the supercharger bypass actuator and the supercharger bypass solenoid.
• Check for bends or kinks in the vacuum hose/tube between the supercharger bypass solenoid and vacuum reservoir assembly.
• Check for disconnect hose(s) between the supercharger bypass actuator, supercharger bypass solenoid and vacuum reservior assembly.

Are any leaks (holes or cracks) or restrictions (bends or kinks) in the vacuum hose(s) present?
Yes No REPAIR or REPLACE vacuum hose(s)/tube as necessary. RETURN to Section 3 , Symptom Chart 8 for Lack/Loss of Power.



po720 start at step 1

2003 PCED OBD
SECTION 5: Pinpoint Tests
Procedure revision date: 08/19/2002

TJ: Output Shaft Speed (OSS) Sensor

TJ: Introduction
TJ1 DTC P0720, P0721, P0722, P0723, AND P1900: VERIFY DRIVE CYCLE

• Access the OSS PID.
• Drive vehicle.
• Through all gear ranges, shift up and down.

Does PID reading increase and decrease with engine and vehicle speed?

Yes No OSS performed as expected. GO to TJ2 . For Hall Effect Type OSS:

KEY OFF. GO to TJ3 .

For VR Type OSS:

GO to TJ5 . TJ2 VISUAL INSPECTION

• Disconnect OSS sensor.
• Inspect OSS harness for damage. Inspect OSS vehicle harness connector for damage and proper seating.
• If possible, complete wiggle test.

Have any problems been found?

Yes No REPAIR fault. GO to Z1 for intermittent fault diagnosis. TJ3 CHECK VPWR TO OSS SENSOR

• Key on.
• Disconnect OSS sensor.
• Measure VPWR circuit voltage at OSS sensor harness connector.

Is voltage greater than 10.5 volts?

Yes No KEY OFF. GO to TJ4 . KEY OFF. Repair open circuit. TJ4 CHECK VPWR GND TO OSS SENSOR

• Measure resistance of PWR GND circuit between OSS sensor harness connector and negative battery post.

Is resistance less than 5.0 ohms?

Yes No GO to TJ5 . Repair open circuit. TJ5 CHECK HARNESS FOR SHORT TO PWR

• Key on.
• Disconnect OSS sensor.
• Measure voltage between the OSS signal circuit at the OSS sensor harness connector and ground.

Is voltage less than 1.0 volt?

Yes No KEY OFF. GO to TJ6 . KEY OFF. REPAIR short circuit. TJ6 CHECK HARNESS FOR OPEN

• Disconnect PCM.
• Measure resistance of the OSS signal circuit between the OSS sensor harness connector and the PCM harness connector.
• Measure resistance of the OSS SIG RTN circuit between the OSS sensor harness connector and the PCM harness connector.

Is each resistance less than 5.0 ohms?

Yes No GO to TJ7 . REPAIR open circuit. TJ7 CHECK HARNESS FOR SHORT TO GROUND

• Measure resistance between OSS signal and SIG RTN circuits at the OSS sensor harness connector.
• Measure resistance between the OSS signal at the the OSS sensor harness connector and chassis ground.

Is each resistance greater than 10,000 ohms?

Yes No For VR Type OSS:

GO to TJ8 .

For Hall Effect Type OSS:

GO to TJ9 . REPAIR short circuit. TJ8 CHECK RESISTANCE OF OSS SENSOR

• Measure resistance of the OSS sensor between the pins of the OSS sensor.

Is resistance between 400 and 1.25K ohms?

Yes No REPLACE PCM (REFER to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). REPLACE OSS sensor. TJ9 CHECK OSS SIGNAL OUTPUT TO PCM, HALL TYPE OSS

• Disconnect PCM.
• Raise vehicle to allow rotation of the front drive wheel.
• Key on, transmission in neutral.
• Measure voltage between OSS+ and PWR GND circuits at the PCM harness connector while slowly rotating the drive wheel. Note: Opposite wheel must be held stationary.
• The voltage should rise above 5.0 volts and fall below 1.0 volts in a regular cycle. Observe several cycles.

Does the OSS output voltage rise and fall as specified?

Yes No REPLACE PCM (REFER to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) ). REPLACE OSS sensor. REFER to the workshop manual group for manual transmissions.

 

[Jensanity]

I had similar issue with my '03 after washing out my engine bay. Found water pooled in my #3 & #4 spark plug holes. Changed plugs and dried out the water. Two days later the stumble returned. I replaced my coil packs and it fixed my issue. Thinking the water fried a COP or two

 

[Joeffr]

The tuner rescheduled for this coming Monday so no log info yet.

After looking at the last post I rechecked the cop's.

I noticed there was a little discoloration on one of the rubber boots,
I replaced it an it seemed to work.

I'll take it out tomorrow and see how she runs.

 

[hotcobra03]

The tuner rescheduled for this coming Monday so no log info yet.

After looking at the last post I rechecked the cop's.

I noticed there was a little discoloration on one of the rubber boots,
I replaced it an it seemed to work.

I'll take it out tomorrow and see how she runs.

As to coils..mine wore out with no code...mine would jerk spit spudder backfire.

I found it hard to drive easy..like 45 in 6th..it would come and go untill it got to where you couldnt accelerate on hwy...

I found a member close by to swap out all 8 and test..night and day differance instantly

I can go as low as 20 in 6th now and still accelerate without bog

 

[R.D.P.]

Are you running that level of setup on stock coils? I thought people upgrade coils typically when running that level of mods.

 

[Joeffr]

Changing the one COP fixed it.

The tuner said I should just use the stock one's

 

[hotcobra03]

Changing the one COP fixed it.

The tuner said I should just use the stock one's

Thats like changing 1 sock..

Frpp has set of 8 oem..cheap list is 300..than discount on where you buy it..

I paid 215..thru ford

 

[Joeffr]

If I knew for sure it was the cop I would have swap all 8,
It was a $42.00 hunch that worked. I'm sure I'll be changing them
All over the wintertime.

 

[hotcobra03]

If I knew for sure it was the cop I would have swap all 8,
It was a $42.00 hunch that worked. I'm sure I'll be changing them
All over the wintertime.

What brand was that? For cheap china coils under 100 for 8

 

[MalcolmV8]

Thats like changing 1 sock..

Not really. Unless it was a high mileage car that has worn coils. It sounds like he just had one go bad.