2000 Taurus P0301 Misfire

Daniel Mechanic Congers, New York Posted   Latest  
2000 Ford Taurus SEL 3.0L (S) 4-spd (AX4N)
P0301 - Cylinder 1 Misfire Detected
Cylinder 1 Misfire

i switched coil and plug miss didn't follow. my fuel injectors are spraying good and got the right amount of compression i took the upper intake off to put alittle oil into the cylinder to see if it would bypass the valve and the oil stayed didnt leak pass the valves. need some help from here

Robert Mobile Technician
Newark, Delaware

Can you duplicate the misfire? what scan tools do you have to what scan tools do you have to work with here? If you have Factory Ford or and Alltel have you ran the Power Balance test to verify the misfire? I have I have seen many technicians get burned on these older Ford's by diagnosing the effect and not the cause. I have seen these things shut off fuel to save the cat with just a very slight misfire. Technician would diagnose the misfire as a faulty PCM because it was not commanding the injector. however it however it was just doing its job. The root problem was an engine mechanical issue. I'm not saying that's what you have going on here. Just giving you some input from what i have learned on these things. 

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Daniel Owner
Long Beach, California

Have u check running compression 

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Ray Diagnostician
North York, Ontario

Do you have a scope?

In the first waveform

The blue CH A is a pressure transducer in the tailpipe while cranking and 1 cylinder has a higher exhaust pressure pulse.

The red CH B is the relative compression

The tan CH D is a pressure transducer in the intake manifold and 1 cylinder has a low pressure pulse

In the second waveform,

If you scope the secondary and do a brake torque, you could find lean or rich injectors

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Bob Diagnostician
East Longmeadow, Massachusetts

The first thing I would suggest is to verify that cylinder 1 is really the cylinder that's misfiring. On some of the older stuff, cylinders would sometimes be reported incorrectly. You could be chasing your tail. 

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Patrick Owner
Baxter, Tennessee

Check the valve springs, they break often. Surprisingly they will pass a cranking compression test. 

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Thomas Diagnostician
Saint Petersburg, Florida

exactly. using a lab scope or Vantage to check relative compression with a synch will lead the way, then an in-cylinder test for more information...I have run into broken valve springs as well. A compression gauge may look just fine, meanwhile there is a sealing issue that can be detected with a scope.

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Albin Diagnostician
Leavenworth, Washington

Over the years, I have watched many people struggle finding the cause of a misfire. Back to the basics, we need the proper amount of compression, the proper amount of spark at the proper time, the proper amount of fuel injected, at the proper time, and the ability of the cylinder to pump air.

In reading your post, I don't see where you addressed any of these much needed things, except the compression. Just because an engine has compression (static compression with a manual gauge) doesn't mean the cylinder is pumping air. How did you test for proper fuel injection? Did you pull the injectors and watch them spray as the engine was cranked? If so, there are easier, quicker and more accurate ways to gather this information.

I also see you put some oil on top of the intake valve to see if were leaking. Why? I have a few ideas that should make your misfire problem analysis more accurate, less stressful, and quicker than taking the engine apart looking for problems. A labscope will be needed for this testing.

The reason for using a labscope, instead of a mechanical compression gauge is, the scope and relative compression is testing the engine compression dynamically. The mechanical gauge is doing a static compression test. In the case where an exhaust valve didn't open, your gauge would show good compression. The scope relative compression would show the low compression. Now, let me qualify that. If used properly, the mechanical gauge can be use to test the running compression, which would find that closed exhaust valve, but, on the engine you are working on, this would be very hard to do on the back cylinders (under the intake manifold).

To answer the question on whether all cylinders are pumping air, the quickest way is to use a First look sensor hooked into either the intake manifold, or stuck into the exhaust, and gather the information when doing the relative compression test. Both of these tests can be done at the same time, without having to take the engine apart.

When it comes to qualifying the fuel flow, you can use a scan tool and watch the fuel trims, or if you are blessed with an exhaust analyzer, give the exhaust a sniff and it won't be very hard to tell if there is fuel present. Both ways are very accurate. Now, please keep in mind, this engine might shut the injector off when a misfire is detected, and if this happens, then the gas analyzer won't tell you much. By scoping the injector current, you will know if the injector is being shut off or not.

When it comes to testing the spark, A current probe will tell you if the coil is working properly, although, it will not tell you if the spark is happening inside the combustion chamber. An old fashioned spark tester set to 30KV will answer the question if the coil is producing the proper fuel, but, you can also use your scope to scope either the primary voltage, or use a COP paddle, and get a secondary waveform to display on your scope.

Back to the basics,,,,,, Answer the basic questions, Spark, Fuel, Compression & airflow, and you will be well on your way to coming up with the root of the problem.

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James Owner/Technician
Pike, Pennsylvania

I'm with Daniel here, I would do a running compression test. Best way to check for broken valve spring outside of visual test or using a pressure transducer.

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Ray Diagnostician
North York, Ontario

Daniel, read Albin Moore's post, it is excellent!


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Brin Diagnostician
Melbourne, Florida

I can appreciate you reaching out for help on this one. It can be uncomfortable to do so, but asking for help can be the catalyst for change and bettering yourself. Anyone that knows me knows how passionate I am about training. For me, training helps to remove the pain in the service bays. I found, early on, that there was no tree branch that I could touch after a hard day in the bay that would take away my pain. I needed to attend as much training as possible, read as much as possible and make as many friends as possible. 

We have a challenging career! Isn't it great? We do have a lot of great resources like Diagnostic Network and a ton of great training companies and independent trainers that help to not only take a way the pain but make diagnostics very enjoyable. If, for some reason, you are not in a position to attend traditional, instructor-led training, there are a lot of valuable resources that you can take advantage of. Message me if you're interested. I'd be glad to share some of my favorite resources with you. 

I'd recommend air/fuel management, misfire, diagnostic techniques and strategies, and electrical classes to start. Attending or taking part in classes like these will help you to reason through the current issues that you're faced with pinpointing. 

I'd like to give you an example using your current situation, but it might be difficult to do so. We need a lot more information to help you. I hope that this doesn't sound condescending. Truly, my goal is to help you be the best you can be. 

We need some brief background. What was the clients concern and how did that compare to what you experienced when you test drove the vehicle to verify that concern? What did freeze frame tell you? If you're not familiar with how to interpret scan data at a high level, you can at least use the freeze frame data to determine what conditions that the fault was present. You can use that information to see if it agrees with the clients description and again compare that with your own experience when attempting to duplicate the concern. Heck, knowing those conditions will help you to know how to duplicate the concern. I would then recommend custom building your scan data list, recording that data while test driving the vehicle under several different load conditions but focusing heavily on driving the vehicle under the conditions that the fault occurs. Come back to the shop and analyse that data. By this time, you'd pretty much know what is going on. The next step is proving your suspicions. Don't test something until you're pretty sure that the test will give you the answers you need.

Maybe you did all of this? If so, please share your results. We love this stuff! To a fault at times. We would love to help.

I apologize. I didn't read all of the responses but I can tell you that Robert Pleasanton's and Albin Moore's response's are perfect examples of what I'm referring to. Albin teaches and writes material on just this subject. We call it front seat diagnostics and I wouldn't be surprised if he didn't coin the term. 

Robert has shared some of his case studies and his approach is so dang exciting because it's just logical as heck. 

Please excuse me if I've read this situation wrong. Hopefully my response can be helpful to someone. 



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Brian Diagnostician
Seneca, South Carolina


The points you made are very necessary. If a tech doesn't know how to analyze the data they are seeing, that fine. If they will at least post all the info ( VIN, ALL Codes not just the ones in the module controlling the "problem system", Freeze Frame data , actual results from tests completed eg, voltages, pressures, scan tool used, scan tools available to use), here many top level guys can look at it and walk him and everyone who reads it through their diagnostic process. This way everyone learn something. A short post with no data looking for the fix may or may not result in the silver bullet. Regardless of the outcome no one is any better for it.

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Vince Technical Support Specialist
Commack, New York


are you still at it with this car?

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