Question about Chevrolet Silverado 1500

2 Answers

Ok Guys good luck with this one. 2004 Silverado 4.3 V6 VORTEC Has miss on cylinders 2,3,4, According to the misfire counter on my scan tool. Have Done Complete tune up. plugs, wires, cap, rotor, fuel filter, air filter, and pcv valve. Still had same miss. Also ran compression test and fuel pressure test numbers are Cylinder #1 167 lbs. #2 171lbs #3 171lbs #4 168lbs #5 170lbs #6 171lbs. Fuel pressure pressure KOEO 63lbs and with Key off held at 28 Lbs Idle pressure 60 lbs. Have replaced Mass Air Flow Meter, Throttle Position Sensor, Map Sensor, Injectors #2 #3 #4, Ignition Coil And Ignition Module. Also replaced PCM Had dealer Flash new one. Still have same miss. Checked grounds all ok Battery Volts at 14.2 when at idle, 12.6 when not running. Have done crank relearn twice no help. Only misses when throttle is just off idle in park about 1000 rpm or right at cruising speeds. No miss at idle or about 20 percent throttle or higher. Have had this vehicle to 2 different dealers with no luck. Randy Marion Mooresville NC and Park Chevrolet Charlotte NC. Neither Can determine what is wrong. NEED HELP THROWING GOOD MONEY IN A PIT Have Spent well over $1000 on this truck doing 90 percent of the labor myself. Just Stumped.

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  • Martin Lanstra May 29, 2011

    Havent gotten any luck at the dealer other than spending money for nothing I have looked every where I know to look and just looking for ideas. As far as a sticking valve I forgot to mention that if you unplug throttle position switch all misses go away. So a sticking valve isn't likely . but without throttle position will not pass An IM inspection. also trans doesn't shift correctly. Just stumped as I said. I also have worked as mechanic for 20 yrs and just cant figure this one out. Being a 45 year mechanic I am sure you have been stumped on a few yourself. Have checked wiring and found nothing. pinned out throttle position back to PCM Checked ok also pinned 2,3,4, injectors back to pcm all ok

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  • Master
  • 1,915 Answers

It's on 2 different banks, but not all cylinders-but they are up front of the engine, so maybe a vacuum leak up front?-spray throttle body cleaner at hoses, gaskets, the base of the EGR maybe...My only other guess is possibly a damaged reluctor inside at the crank sensor, that might account for those cylinders when you consider the firing order is 1-6-5-4-3-2...

Posted on May 29, 2011

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  • Chevrolet Master
  • 75,822 Answers

Hello
Sure sounds like you have a problem either with a sticking valve or a problem in the engine wiring harness, that is about all that is left. I would lean towards a valve problem as my first choice and the next would be a fault in the wiring to number four injector. But seriously do you really expect to fix this over the Internet? This is absolutely a hands on type of problem. I speak from 45 years of being a professional technician with a 25 year specialization in electronic engine control problems like yours.

Posted on May 29, 2011

  • yadayada
    yadayada May 29, 2011

    A FEW IDEA'S AND QUESTIONS, has the dealer ever recorded this misfire event with an OBD2 flight recorder while on a test drive? Has the dealer confirmed the code being set while in the shop? Are you sure you don't have a valve that is sticking or a weak valve spring? Have you done a test on the compression force required to collapse the valve springs? Remember this is not necessarily a electronic problem, DO NOT IGNORE THE MECHANICAL POSSIBILITIES.

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3 Answers

What are the probable causes of DTC P0300?


Most usually a P0300 random misfire on multiple cylinders code is caused by a vacuum leak or low fuel pressure an volume ! Do a fuel pressure an volume test . Also I would do a compression test an a cylinder leak down test .How many miles does the vehicle have , a lot ?
Diagnostic Aids
If the Misfire Index indicates that one bank of the engine is experiencing misfire, the HO2S for that bank may be malfunctioning (i.e. Bank 1 Sensor 1 or Bank 2 Sensor 1). If the Misfire Index indicates that paired cylinders (i.e. cylinders 1-4, 6-3 and 5-2 for V6 applications and 1-6, 8-5, 4-7 and 3-2 for V8 applications) are experiencing misfire, inspect the CKP sensor reluctor ring for damage.
The Misfire Index counts the number of misfires. The scan tool can monitor the Misfire Index. There is a current and history misfire counter for each cylinder. Use the current misfire counter in order to determine which cylinder is misfiring.
Many different conditions could cause an intermittent misfire.
Check for the following conditions:
  1. Check the spark plug wires and the coil wire for the following conditions:
  2. ?€¢
    Ensure that the spark plug wires are securely attached to the spark plugs and the distributor cap.


    ?€¢
    Check the wire routing in order to ensure that crossfiring is not occurring.


    ?€¢
    If the misfire occurs when the weather is damp, the problem could be due to worn plug wires.


    ?€¢
    In order to test for this condition, spray the wires with water. With the engine running, watch for a spark to jump from the wires. If a spark is visible, replace the wires.

  3. Check for contaminated and a low fuel level and the following conditions:
?€¢
Check the fuel condition and quality. Dirty or contaminated fuel could cause a misfire condition.


?€¢
If the fuel level is low, contaminants in the bottom of the fuel tank could enter into the fuel metering system.


?€¢
For more information, refer to Fuel Supply System.


Step
Action
Value(s)
Yes
No

1

Important: Before clearing the DTCs, use the scan tool to record the Freeze Frame and the Failure Records for reference. This data will be lost when the Clear Info function is used.
Was the Powertrain On-Board Diagnostic (OBD) System Check performed?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check

2
Review Failure Records data.
Are there any other DTCs stored?
--
Go to Applicable DTC Table
Go to Step 3

3

  1. Install a scan tool.
  2. With engine idling, monitor the MAP sensor voltage on the scan tool.
Is the MAP sensor voltage greater than the specified value?
4.0V
Go to DTC P0108 Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage
Go to Step 4

4
Duplicate the conditions during which the misfire occurred.
Is the DTC active at the ignition cycle?
--
Go to Step 5
Go to Step 10

5
Using a scan tool, review the Misfire Index. Is the Misfire Index increasing for more than one cylinder?
--
Go to Diagnostic Aids
Go to Step 6

6

  1. Install the spark plug tester J 26792 on number 1 spark plug wire.
  2. Disconnect the fuel injector harness at the intake manifold.
  3. Crank the engine, spark should jump the tester gap.
  4. Repeat for each spark plug wire.
Was the spark adequate on all of the spark plug wires?
--
Go to Step 7
Go to Step 11

7
Inspect the spark plugs for wear, excessive air gaps, cracks, or fouling.
Are the spark plugs OK?
--
Go to Step 8
Go to Step 12

8

Perform a cyclinder compression test. Refer to Engine Machanical.
Was a problem found?
--
Go to Step 14
Go to Step 9

9

Refer to Fuel System Pressure Test .
Is the fuel system OK?
--
Go to Step 10
Go to Step 13

10

Misfire is intermittent and is currently not active.
Go to the Diagnostic Aids
--
--
--

11

Refer to Enhanced Ignition System Diagnosis .
--
--
--

12

Replace the spark plugs.
Is the action complete?
--
Go to Step 14
--

13

Make repairs as indicated by the Fuel System Diagnosis. Refer to Fuel System Pressure Test .
--
Go to Step 14
--

14

  1. Using the scan tool, select the DTC and the Clear Info.
  2. Start the engine.
  3. Idle at the normal operating temperature.
  4. Select the DTC and the Specific.
  5. Enter the DTC number which was set.
  6. Operate the vehicle within the conditions for setting this DTC as specified in the supporting text.
Does the scan tool indicate that this diagnostic ran and passed?
--
Go to Step 15
Go to Step 2

15

Using the scan tool, select Capture Info and Review Info.
Are any DTCs displayed that have not been diagnosed?
--
Go to the applicable DTC table
System OK
This is GM factory service info

Sep 28, 2015 | 1997 Oldsmobile Bravada

1 Answer

I'm trying to locate the cylinders on a 2006


On top of the intake manifold you'll find the number for each cylinder at its respected position.

Sep 23, 2014 | 2006 Honda Accord

1 Answer

What is p0306 with ev error from a 2000 toyota 4 runner


misfire. is it a v6 , if so cylinder 6 has a misfire , plug,coil pack will need checking through

May 01, 2014 | 2004 Chevrolet Silverado

1 Answer

Random misfire cylinder 3


Smoke test entire vehicle for vacuum leaks

You don't have any idea where the misfire
is from, at this point,find out

You installed parts

That is not what you do,you diagnose & find
the cause of the misfire,no parts involved there

You don't have the professional tools or software
at home, to diagnose without wasting time & getting
no where

Could have a bad intake gasket or mechanical problem
in one cylinder

Apr 04, 2013 | 2001 Chevrolet Silverado 1500

1 Answer

1996 5.7 vortec misfire cyliner 4 and 6


have you cleared the codes between fault reads
clean the maf first .....replace the maf if faulty
coil packs ?
injectors

Apr 16, 2017 | 1996 Chevrolet Tahoe

1 Answer

RE: Johnny brown- 2003 Sebring multiple cylinder misfire 3.0 New distributor new crankshaft sensor new plugs new wires good compression injectors good... Installed new EGR started with cold engine and


ENGINE MISFIRE

There are few possibilities that can cause engine misfire issues. It can be issue with spark plugs or faulty spark plugs. Also get the compression test done for cylinders. If any of cylinder shows low compression then required, then that particular cylinder will cause misfire.

Also get obd codes scanned, the error code will let you know which cylinder is misfiring or all cylinders are misfiring.

-----------

For your trouble shooting I suggest you to refer the help oinks below. It has step by step details for many engine misfire issues.

----------


Click the link below:-----


Ford Explorer Cylinder Misfire?

http://whoisbyme.blogspot.in/2012/06/ford-explorer-cylinder-misfire.html

---------

Engine Misfire codes on Chevrolet Malibu?

http://schematicsdiagram.blogspot.com/2011/12/engine-misfire-codes-on-chevrolet.html

---------

Cylinder 6 Misfire?

http://howtobyme.blogspot.com/2011/12/cylinder-6-misfire.html

------------

Misfire on cylinder 4?

http://schematicsdiagram.blogspot.com/2011/12/misfire-on-cylinder-4.html

-----

While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

----------

Ford Explorer 5.0L: Engine Miss?

http://whoisbyme.blogspot.in/2012/06/ford-explorer-50l-engine-miss.html

-----------

Oil on spark plugs and car misfires?

http://technoanswers.blogspot.in/2012/02/oil-on-spark-plugs-and-car-misfires.html

------------

Can cylinder misfire Damage the Catalytic converter?

http://schematicsdiagram.blogspot.in/2012/02/can-cylinder-misfire-damage-catalytic.html

------------

Car misfires and error code P0306 and P0303 is shown?

http://technoanswers.blogspot.com/2012/01/car-misfires-and-error-code-p0306-and.html

-----------

Chevrolet K1500 No spark, random misfire

http://repairhelpcenter.blogspot.com/2012/11/chevrolet-k1500-no-sparkrandom-misfire.html

-------------

2004 Ford F150: Engine Misfire and Lean Code?

http://whatisbyme.blogspot.in/2012/05/2004-ford-f150-engine-misfire-and-lean.html

-----------

1995 Toyota LS: Misfire at idle or low RPM

http://whatisbyme.blogspot.in/2012/04/1995-toyota-ls-misfire-at-idle-or-low.html

--------------

Toyota Corolla: Random Misfire?

http://technoanswers.blogspot.in/2012/04/toyota-corolla-random-misfire.html

----------

2006 Ford Freestar: Misfire on Cylinder Number 2?

http://whatisbyme.blogspot.in/2012/06/2006-ford-freestar-misfire-on-cylinder.html

-----------------------------


This will help.

Thanks.

Dec 09, 2012 | Cars & Trucks

1 Answer

Engine is misfiring


There are few possibilities that can cause engine misfire issues. It can be issue with spark plugs or faulty spark plugs. Also get the compression test done for cylinders. If any of cylinder shows low compression then required, then that particular cylinder will cause misfire.

Also get obd codes scanned, the error code will let you know which cylinder is misfiring or all cylinders are misfiring.

-----------

For your trouble shooting I suggest you to refer the help oinks below. It has step by step details for many engine misfire issues.

----------


Click the link below:-----


Ford Explorer Cylinder Misfire?

http://whoisbyme.blogspot.in/2012/06/ford-explorer-cylinder-misfire.html

---------

Engine Misfire codes on Chevrolet Malibu?

http://schematicsdiagram.blogspot.com/2011/12/engine-misfire-codes-on-chevrolet.html

---------

Cylinder 6 Misfire?

http://howtobyme.blogspot.com/2011/12/cylinder-6-misfire.html

------------

Misfire on cylinder 4?

http://schematicsdiagram.blogspot.com/2011/12/misfire-on-cylinder-4.html

-----

While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

----------

Ford Explorer 5.0L: Engine Miss?

http://whoisbyme.blogspot.in/2012/06/ford-explorer-50l-engine-miss.html

-----------

Oil on spark plugs and car misfires?

http://technoanswers.blogspot.in/2012/02/oil-on-spark-plugs-and-car-misfires.html

------------

Can cylinder misfire Damage the Catalytic converter?

http://schematicsdiagram.blogspot.in/2012/02/can-cylinder-misfire-damage-catalytic.html

------------

Car misfires and error code P0306 and P0303 is shown?

http://technoanswers.blogspot.com/2012/01/car-misfires-and-error-code-p0306-and.html

-----------

Chevrolet K1500 No spark, random misfire

http://repairhelpcenter.blogspot.com/2012/11/chevrolet-k1500-no-sparkrandom-misfire.html

-------------

2004 Ford F150: Engine Misfire and Lean Code?

http://whatisbyme.blogspot.in/2012/05/2004-ford-f150-engine-misfire-and-lean.html

-----------

1995 Toyota LS: Misfire at idle or low RPM

http://whatisbyme.blogspot.in/2012/04/1995-toyota-ls-misfire-at-idle-or-low.html

--------------

Toyota Corolla: Random Misfire?

http://technoanswers.blogspot.in/2012/04/toyota-corolla-random-misfire.html

----------

2006 Ford Freestar: Misfire on Cylinder Number 2?

http://whatisbyme.blogspot.in/2012/06/2006-ford-freestar-misfire-on-cylinder.html

-----------------------------


This will help.

Thanks.

Nov 28, 2012 | 2004 Honda CR-V

1 Answer

2004 Ford Escape 3.0 V6 - I had the spark plugs replaced when first experienced misfiring, and code said misfire on #4 cylinder. Right after replacement, things were fine. About a month later, starting...


If you had a scan tool you would be able to see the cylinder misfiring, i would try replacing the coil boots on the coil, there like replacing sparkplug wires but there small boots that pop on the end of coil with steel spring inside them, run truck and if misfire continues then you have a coil thats going bad,hope this helps. note if you could find out which cylinder it was you could swap coil with another cylinder and if skip move to that cylinder then you would know if its a coil this is after replacing boots.

Aug 25, 2010 | 2004 Ford Escape

2 Answers

4.3 vortec runs OK cold, runs rough or dies warm


replace the CKP and the truck will need to go to a shop and have the "crankshaft variation relearn" performed. the misfire may or may not go away, and that will need to be addressed also.

Oct 01, 2009 | 2002 Chevrolet Silverado

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