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David H
David H, Cadillac Technician
Category: Cadillac
Satisfied Customers: 2675
Experience:  18 years cadillac dealer.ase master certified.gm master certified
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Cadillac Deville 00 deville bank one only miss fire but on

Customer Question

00 deville bank one only miss fire but on timed intervilles
Submitted: 3 years ago.
Category: Cadillac
Expert:  David H replied 3 years ago.
How many cylinders are misfiring?
Customer: replied 3 years ago.
Like I said all on bank one only
Expert:  David H replied 3 years ago.

Have you checked the fuel trim readings for bank 1 with a scan tool?This can be helpful for misfire diagnosis.

Customer: replied 3 years ago.
when i reset fuel trim with scan tool when the missfire is happining, it clears but only for about 6 seconds then back to timed missfires. when I say times its like there is a times set to 1.5min between missfire for the one bank. they did clear for a long interville with out any warning, enough time to do a 10min road test and i thaught is was just comp delay on the cks relearn since i tried that a few times. Maybe o2 sensor?
Expert:  David H replied 3 years ago.
I would check for vacuum leaks around the intake manifold.Spray down the engine with water while it is running.I have never seen an O2 sensor cause misfires on the 2000 deville northstar engine.But they all develop vacuum leaks eventually.Other than that you may have an intermittent engine wiring harness issue that is rare.Try moving the engine harness around while monitoring misfires.
Customer: replied 3 years ago.
i sprayed around rear throttle boot and vac port at front of intake also at injector section of intake to head and no change did think a wire connection problem but did a one section at a time while missfire was active but could not get a responce but why did the fuel trim fix it but only for a few sec?
Expert:  David H replied 3 years ago.
The computer is trying to compensate for an air/fuel mixture problem.When you reset the fuel trim back to 0 the engine is reacting normally without adjustments from the computer for a few seconds.You need to find what is causing the air/fuel mixture problem.I would do a fuel injector pressure drop test to see if all injectors are spraying th same amount of fuel/
Customer: replied 3 years ago.
the odds of all 4 injectors to be bad and only intermitint are next to one in a billion but since the problem is cycling thats why i was thinking the o2 sensor since they tell ecm to add or remove fuel and maybe bank one is very lazy and only after running the car for a while and reseting fuel trime several times it finaly caught up and was stable enought for the good road test but after sitting over night i had to relearn again but couldnt since i was not forcing the fuel trim to reset.
Expert:  David H replied 3 years ago.
The O2 sensor diagnostics on that model would set an O2 sensor code for a lazy O2 sensor.I would not think 4 injectors would fail but the wiring for those injectors could be a problem.And last but not least would be an ECM problem.
Customer: replied 3 years ago.
yea the ecm is a possible since the problem is in a cycle and could clear up when up to temp, harnes would be more of a random or more active when going over bumps driving and so on. what would be a ecm test procedure also never done a fuel psi drop test. But reseting fuel trim was the only possitive test i got, is there any other way to testing fuel trim circuit when engine is running?
Expert:  David H replied 3 years ago.

The only way to test an ECM is to replace it unfortunately,basically eliminate everything else first.Here is the procedure to balance test the fuel injector's.

 

 


Fuel Injector Balance Test with Tech 2

Circuit Description

The scan tool first energizes the fuel pump and then the injectors for a precise amount of time allowing a measured amount of fuel into the manifold. This causes a drop in system fuel pressure that can be recorded and used to compare each injector.

Test Description

Caution: Wrap a shop towel around the fuel pressure connection in order to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gauge. Place the towel in an approved container when the connection of the fuel pressure gauge is complete.

  1. The engine coolant temperature must be below the operating temperature in order to avoid irregular fuel pressure readings due to Hot Soak fuel boiling.

  2. The fuel pressure should be within the specified range. If the fuel pressure is not within the specified range, go to Fuel System Diagnosis.

  3. The fuel pressure should reach a steady value. If the fuel pressure does not reach a steady value, go to Fuel System Diagnosis.

  4. If the pressure drop value for each fuel injector is within 10 kPa (1.5 psi) of the average pressure drop value, the fuel injectors are flowing properly. Calculate the pressure drop value for each fuel injector by subtracting the second pressure reading from the first pressure reading.

Fuel Injector Balance Test Procedure

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Did you perform the Fuel Injector Coil Test Procedure?

--

Go to Step 3

Go to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) or Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Outside 10-35 Degrees C (50-95 Degrees F)

3

Is the engine coolant temperature above the specified value?

94°C (201°F)

Go to Step 4

Go to Step 5

4

Allow the engine to cool below the specified value.

Is the engine coolant temperature below the specified value?

94°C (201°F)

Go to Step 5

--

5

Caution: Wrap a shop towel around the fuel pressure connection in order to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gauge. Place the towel in an approved container when the connection of the fuel pressure gauge is complete.

  1. Turn OFF the ignition.
  2. Connect the J 34730-1A fuel pressure gauge to the fuel pressure test port.
  3. Turn ON the ignition, with the engine OFF.
  4. Install the scan tool.
  5. Energize the fuel pump using the scan tool.
  6. Place the bleed hose of the fuel pressure gauge into an approved gasoline container.
  7. Bleed the air out of the fuel pressure gauge.
  8. Again energize the fuel pump using the scan tool.
  9. Wait for the fuel pressure to build.

    Important: The fuel pump will run for approximately 2 seconds. Repeat step 8 as necessary in order to achieve the highest possible fuel pressure.

  10. Observe the reading on the fuel pressure gauge while the fuel pump is running.

Is the fuel pressure within the specified limits?

284-325 kPa (41-47 psi)

Go to Step 6

Go to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Outside 10-35 Degrees C (50-95 Degrees F)

6

After the fuel pump stops, the fuel pressure may vary slightly, then should hold steady.

Does the fuel pressure remain constant within the specified value?

284-325 kPa (41-47 psi)

Go to Step 7

Go to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Outside 10-35 Degrees C (50-95 Degrees F)

7

  1. Turn OFF the ignition.
  2. Turn ON the ignition, with the engine OFF.
  3. Select Special Functions from the scan tool menu.
  4. Select Fuel Systems.
  5. Select Injector Balance Test.
  6. Select an injector to be tested.
  7. Press Enter. This will prime the fuel pump.
  8. Record the fuel pressure indicated by the fuel pressure gauge after the fuel pressure stabilizes. This is the 1st pressure reading.
  9. Energize the fuel injector by depressing the Pulse Injector button on the scan tool. This will energize the injector and decrease the fuel pressure.
  10. Record the fuel pressure indicated by the fuel pressure gauge after the fuel pressure gauge needle has stopped moving. This is the 2nd pressure reading.
  11. Press Enter again to bring you back to the Select Injector screen.
  12. Repeat steps 6 through 11 for each fuel injector.
  13. Subtract the 2nd pressure reading from the 1st pressure reading for one fuel injector. The result is the pressure drop value.
  14. Obtain a pressure drop value for each fuel injector.
  15. Add all of the individual pressure drop values. This is the total pressure drop.
  16. Divide the total pressure drop by the number of fuel injectors. This is the average pressure drop.

Does any fuel injector have a pressure drop value that is either higher than the average pressure drop or lower than the average pressure drop by the specified value?

10 kPa (1.5 psi)

Go to Step 8

Go to Symptoms

8

Notice: Do not repeat any portion of this test before running the engine in order to prevent the engine from flooding.

Re-test any fuel injector that does not meet the specification. Refer to the procedure in step 7.

Does any fuel injector still have a pressure drop value that is either higher than the average pressure drop or lower than the average pressure drop by the specified value?

10 kPa (1.5 psi)

Go to Step 9

Go to Symptoms

9

Replace the faulty fuel injectors. Refer to Fuel Injector Replacement .

Is the replacement complete?

--

System OK

Customer: replied 3 years ago.
but this is more likely if one injecter or two in random places. 1,3,5,7 miss in order and at a exact time line, when the engine isfirst started its fine then after iac had moved idelt to 600ish rpms then at the 1.5 or les time line the missfiring starts and for about 45sec's then clears up for 1.5 min and repeat. I take it you have never seen this also no tsb's are out? what controls the fuel trim value for each bank?
Expert:  David H replied 3 years ago.

No I have never seen this type complaint and I have lots of experience on that model.I had one strange intermittent northstar misfire that ended up being very small pieces of the plastic intake manifold coming apart inside the intake plenum hanging up the valves.That one ended up costing me an engine.Here is the only TSB related to your problem.

 

 

PI01748A: 4.6L LD8 , L37 and 4.0L , L47 Engine Rough Idle - kw body calibration camshaft code DTC EGR intake leak lean manifold MIL miss misfire PCM - (Feb 20, 2004)

Subject:4.6L LD8, L37 and 4.0L, L47 Engine Rough Idle

Models:.

 


When servicing the vehicle with the VIN you entered, the following diagnosis might be helpful if the vehicle exhibits the described symptoms.

Condition/Concern:

Some 2000 and early built 2001 model year Cadillac Deville, Eldorado, Seville with 4.6L (LD8, L37) engines or 2001 Oldsmobile Aurora with 4.0L (L47) engine, may exhibit a condition of rough idle with no PCM DTC and no driveability complaints

Recommendation/Instructions:

The camshafts must be replaced (part numbers are listed below) on all 2000 vehicles with 4.6L (LD8) (L37) Engines and the early built 2001 vehicles (see broadcast codes listed below) with 4.0L (L47) OR 4.6L (LD8) (L37) Engines. For a 2001 vehicle, you must verify that it has the early cam profile by reading the 3 alpha characters of the broadcast code listed on the tag attached to the passengers side of the engine's rear cam cover. The Broadcast Codes for early 2001 engines are:

Seville, Deville Applications:

ENGINE VIN CODE Y KMA

ENGINE VIN CODE 9 KKA

.

Eldorado Applications:

ENGINE VIN CODE Y KCA

ENGINE VIN CODE 9 KBA

.

Aurora Application:

ENGINE VIN CODE C KYA

.

Camshaft Service Part Numbers:

.

4.6L (LD8) VIN CODE Y AND 4.0L (L47) VIN CODE C CAMSHAFT SERVICE PART NUMBERS;

12570331 RH EXH

12570332 LH INT

12570333 RH INT

12570334 LH EXH

.

4.6 (L37) VIN CODE 9 CAMSHAFT SERVICE PART NUMBERS;

12570335 RH INT

12570336 LH INT

12570337 RH EXH

12570338 LH EXH

NOTE: the Camshaft Service Part Number information can also be found on page 7 of the July 2001 GM Tech Link Volume, No. 7

SPECIAL NOTE: If you are having difficulty setting the mechanical timing on the rear bank exhaust camshaft. SI and the Service Manual instructs you to set the exhaust camshaft gear so that the stamping "RE" is in the 12 o' clock position. It has been found the "RE" stamping is located in the incorrect position on the exhaust camshaft gear. The correct positioning of the Exhaust Camshaft is when the camshaft dowel pin is in the 12 o' clock position. and the Exhaust Camshaft gear "RE" stamping is in the 9 o' clock position .

Once all 4 camshafts have been installed, the calibration must be updated. The dealer must contact TECHLINE and tell them that the camshafts on the vehicle have been replaced, and they will give the Dealer a VCI number to install the correct calibration. Techline must be contacted each time so that they have a record of when a camshaft change occurred on each vehicle. This will ensure that future calibration for that vehicle will be correct.

.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance. This diagnostic approach was developed for the vehicle with the VIN you entered and should not be automatically be used for other vehicles with similar symptoms.

Models:

(00 01 CADILLAC DEVILLE, SEVILLE, KB, ELDORADO, EB, 4.6L (LD8 , L37) ENGINE) and 01 OLDSMOBILE AURORA 4.0L (L47) ENGINE)

.

Customer: replied 3 years ago.

hope get a chance to do some testing on the car this weekend and will keep you posted

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