Misfire with no codes

If you have a Ford 5. Late model Ford 5. The VVT systems work by pulsing oil pressure into an hydraulic mechanism that advances and retards the camshaft. The pulsing is performed by a solenoid which is commanded by the PCM. The entire VVT system is calibrated to the recommended oil viscosity. If you use a thicker or thinner viscosity, the VVT system will over or under advance, causing camshaft related trouble codes, lean or rich condition trouble codes and cylinder misfires.

The oil pressure test port is behind the power steering pump. Remove the plug and install a mechanical oil pressure gauge.

No codes misfire interactive Diagnoses - Primary Ignition Part 1

With the engine at operating temperature, you should see psi at idle speed. Neglecting oil changes will cause wear on the camshaft and camshaft journals and a corresponding drop in oil pressure. If your engine passes the oil pressure test, move on to the valve cover inspection. Look for accumulation of thick black pudding-like buildup.

This one will never work properly even if you clean out the sludge—the damage has already been done. If the oil pressure is good and the engine is clean, move on to the VCT solenoid test. Remove the electrical connector and provide brief power and ground to each solenoid while the engine is running. The solenoid should make an audible click. If you notice the engine smoothing out, the solenoid was probably stuck and should be replaced.

Remove the solenoid and check for debris in the passages. The computer commands a certain amount of advance or retard to the VVT system. Then the PCM checks the camshaft position sensors to see if the commands return the expected results. This all starts with the VVT system. Unlike the cheaper Haynes and Chilton manuals that cover multiple year models, leaving the exact information you need to fix your car, these professional manuals cover your exact year, make, model.

Plus, they contain full trouble code descriptions and troubleshooting instructions. Pricing: Eautorepair.

misfire with no codes

So you have to refer to the factory legends to learn the identification symbols and then refer back to circuit diagrams to find the splice and ground locations. However, Alldatadiy. If you need to dig into your doors, dash or console, Alldatadiy. Ford Variable Valve Timing Mechanism. Sludge buildup.

Oil pressure test gauge. New cam phaser.Forums New posts Search forums. What's New New posts. Members Registered members Current visitors. Site Rules.

How to Fix a Misfire

Log in Register. Search titles only. Search Advanced search…. New posts. Search forums. Log in. JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding. Rough idle and misfiring, but no codes. Thread starter Blckshdw Start date Mar 16, Blckshdw Moderator. About 5 minutes into my morning commute, my TB started to idle funny.

Accelerating from the stop light was responsive, but shaky until about 30mph, CEL began to flash around 40mph. Next stop light, checked the Scangauge I've got about 73K miles, had my spark plugs replaced once since I bought it.

I had noticed for the past couple of months, it would idle high between and when cold, first thing in the morning before I got onto the main road. I plan to check the coil packs, and wire connections when I get home, but if there are still no codes, what other items should I take a look at?

Small update, went outside during lunch and let it idle for a bit, after sitting there for a couple minutes, a steady CEL came on, and threw a P So at least I've got a better troubleshooting point after work. RayVoy Well-Known Member. May be a bad plug, may be a water problem, but probably a bad coil.Automotive Forums. On a 97 a eclipse, the engine will misfire and misfires.

But this doesn't produce any CEL, any check engine light, or any code or any codes.

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That's right! NO CELs, no check engine, and no codes. Has anyone seen this before? You probably need new plugs, maybe some plug wires or even a coil pack! A misfire could be a lot of things, not something a computer has control of could be one, like the plugs or plug wires. I suggest getting a new set of each. If that doesnt help test the coil, dont automatically think its the ECU when your engine misfires.

Yes the CEL comes on when the computer senses something is wrong. The computer cant sense bad plugs or wires! Hey Jake Nice crankwalk! Hey 'rocks Yes. But the misfires don't light it up. The computer is not going to tell if the misfire happens after the coil pack! If you think it will, go outside right now, pull off one of the spark plug wires while your car is running How is the ECU going to see that? There is no sensors hooked to the spark plug or spark plug wires.

There for if you are getting a misfire and you have no CEL, then it is usually in the spark plug wires or spark plugs itself. I have never had a CEL come on and tell me I have a bad spark plug wire I wish it would, make life a whole hell of a lot easier, but it doesnt.

Same goes with spark plugs. Yeah a lot of people like that, luckily I have yet to get it! I was misfiring like a weak ago, i changed the plug wires and it fixed the problem. Does it miss under WOT? Thats what mine did. But still no CEL or P Hey 'RocksHave you ever worked on misfires without seeing any codes? Hey ScottHaven't washed her. Too cold out there now. I never got a CEL even though i was missing. Exactly like I said You will not get a CEL with bad plugs or plug wires.

Rob - If you got a Misfire code it was not from bad plugs or wiresOne of the most common problems you're gonna' experience on your 4. Although quite a few things can cause a misfire code or codes to pop up and light up the check engine light CEL That's right, it's not hard.

There's a method to the madness of troubleshooting a misfire on your 4. In this article, I'll go into the basics of what causes a misfire condition and I'll also offer you a basic diagnostic strategy to get to the bottom of what's causing the misfire problem. The basic symptom of a misfire is a light to severe rough idle that's felt when the engine is idling and a light to severe engine miss hesitation when the engine is under load for example: your Ford vehicle moving from a stop.

Although the misfire codes don't tell you what exactly is the cause of the misfire or rough idle condition, there is a way to find out exactly what is causing it. An engine misfire condition occurs when one or more engine cylinders on are not producing power. Let's take a look at some of the specific components, that when they fail, provoke a misfire or a rough idle condition.

Ignition System: The majority of misfire codes have their root cause in a failed ignition system component that isn't creating or delivering spark to the affected cylinder.

Testing all of the ignition system components is not hard and it doesn't require expensive tools or expensive diagnostic equipment. Fuel System: The Fuel System is responsible for the delivery of fuel. If fuel is missing from any one specific engine cylinder, it will misfire. Engine Mechanical Condition: The pistons and valves are the ones that draw air into the engine. Usually all cylinders wear out evenly but every now and then, either thru' lack of maintenance or some mechanical problem, you'll have one or more wear out at an accelerated pace.

To make the long story short, those cylinders with accelerated wear and tear to produce a less than average compression value that will cause a misfire condition. Page 1 Page 2.

Contents of this tutorial:. All Articles: 4. Applies To:. Ford Vehicles:. Do NOT follow this link or you will be banned from the site!Home Articles Misfire How to Fix a Misfire Easy step by step guide on how to troubleshoot and repair an automotive engine cylinder misfire P, P, P, P, P, P, P, P and P, though appearances may vary, the process is similar for most vehicles.

Begin with the vehicle on level ground engine "OFF" and the parking brake set, wear protective gloves and clothing for safety. Step 1 - There are several combinations of misfire conditions, steady or random, at idle or under power, which may or may not be detected by the computer and trigger a check engine or service engine soon light, read trouble codes to help pinpoint the cylinder s in question and follow the repair guide below.

Check Engine Light Step 2 - If no service light is triggered with a steady misfire, use an infrared thermo gun to test the exhaust temperature of each cylinder. Infrared Temperature Meter Step 3 - Start the engine cold, quickly take a reading at the front of each cylinder's exhaust port on the manifold while maintaining similar placement of the beam over each individual port, a misfiring cylinder will be considerably colder than the remaining cylinders.

Example: Three of the exhaust ports test at degrees while one is at 81 degrees, the cylinder at 81 degrees is misfiring. Exhaust Temperature Step 4 - If no results are yet gleaned, start the engine and allow to idle, remove the fuel injector electrical connector on each cylinder one at a time while observing the engine performance, if no change is observed at a particular cylinder, the misfiring cylinder has been located.

Remove Ignition Coil Connector Step 6 - Once the misfiring cylinder has been located, remove the spark plug for inspection, before removing the spark plugs, mark the plug wires if equipped to identify their positions in the firing order, this will help for proper reassembly.

Remove Spark Plug Step 7 - When a cylinder s runs rich it will carbon foul the spark plug causing it to short circuit. Malfunctions for this condition include partially plugged fuel injector or catalytic converterlow compressionfailed fuel pressure regulator and excessive fuel mixture.

Carbon Fouled Spark Plug Step 8 - A wet spark plug with gas or oil can mean a fuel injector is stuck open, fuel regulator has failed, no cylinder compression, broken piston oil control ring, blown head gasket or excessive leakage from the valve stem seals.

How to Fix a Misfire

Spark Plug Fouled with Gas or Oil Step 9 - A spark plug must be properly gapped with a specific measurement from the electrode, a misadjusted air gap can result in a misfire.

Misadjusted Air Gap Step 10 - Using a proper spark plug with a correct air gap will help ensure operation of the ignition system. Correct Spark Plug Step 11 - If the spark plug is wet with fuel or carbon fouled upon removal, a compression check is needed, perform a cylinder compression test to locate a mechanical failure.

If compression is low, it could mean worn out or broken piston rings, flat camshaft, broken valve spring, burnt or leaking intake or exhaust valves, dropped valve seat or blown head gasket. Compression Test Step 12 - If the compression test is okay along with a wet spark plug, the ignition coil needs to be tested.

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Test Ignition Coil Output Step 13 - Spark plug wires are designed to transfer an electrical charge from the coil to the spark plug, when these cables wear, they can short circuit causing a misfire.

Shorted Spark Plug Wires Step 14 - A fuel injector regulates the amount of fuel which is consumed by the engine, if the injector operation has failed the cylinder will misfire.

Test Fuel Injector Operation Step 15 - A random misfire is can be associated with broken or dilapidated vacuum hoses or tubes on and around the engine causing a vacuum leakthese hoses are typically connected to the engine intake manifold and supply engine vacuum to various accessories such as the brake system.

If an intake gasket fails or a vacuum line that is close to an intake port it will cause a steady misfire. Repair Vacuum Leak Step 16 - Fuel pressure must maintain a constant pressure, if this flow is impeded by a clogged fuel filter or weak fuel pump the engine can produce a random misfire.

Fuel Pump Pressure Check Step 17 - A mass air flow sensor sends feedback information to the computer, as this sensor wears it can produce false data causing a misfire.

Mass Air Flow Sensor Step 18 - Each intake and exhaust valve utilizes a spring which will return the valve to its original position closed.

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If a valve spring has broken or a cam lobe has worn down, it will cause the engine to misfire and run rough due to the loss of compression.

These conditions don't always show up in a compression testbecause a compression test is performed at engine cranking speed. If a camshaft lobe is halfway worn down, it will show up only when the engine is running and under load. Flat Camshaft Lobe Step 19 - In some conditions a broken valve spring can effect different aspects of engine performance for example: If just a small part of a coil breaks off, the spring can still close the valve but only at low RPM's, causing a high RPM misfire.

If the spring breaks somewhere in the middle it will affect both idle and power conditions. To test for this condition, remove ignition coil connector or ignition system or fuel pump fuse to disable the engine from starting. Remove valve cover s to gain access to visually inspect the valve train. Inspect the condition of the valve springs, use a flashlight and small mirror to aid in the inspection.Leaving work today after car had been sitting for 7 hours, I started it and pulled up to the light, about a couple hundred feet away from my parking space.

I'm sitting there and all of a sudden the car starts to kind of shake, so I look down at the tach thinking it's stalling, however it wasn't. It felt like it was stumbling, going down to almost stalling, then coming back After no longer than 10 seconds, it came back around and drove completely normal for the rest of the day.

I don't know if it was a misfire or not, i've never experienced one and this has never happened before. Anyone have any insight to this? The car has had a somewhat uneven idle for a while now, especially on cold engine in gear leaving my driveway in the mornings.

I can feel it in the brake pedals and clearly hear it and see it on the tach. It's not terrible, but still. I would remove the front 3 coils and examine them for hairline fractures. Unfortunately, to check the rear 3 you have to take off the UIM.

Similar issue, except it was doing it all the time. Found a coil on plug that looked like something melted or got to hot internally.

misfire with no codes

I cleaned it 2 months ago, as well as testing a brand new replacement on it, did not change idle at all with new one so I returned it. Plugs could still be bad. It may have only 52K but those plugs are at least 8 years old, too. I agree with the Geek of Bulls: Take a look at them coils. I honestly have no idea, i don't even know what you would call what I experienced. You call it a Duratec. What he said A one time event could be water in the gas. Since they no longer use a fuel reuturn which stirrs the gas up really well in the tank, it could come though in a lump, especially when left sitting and the water settled to the bottom of the tank.

A misfire will not always set a code. I had idle misfire on my '03 DOHC for at least 6 months and no codes, no pending. Still makes no sense.Finding the exact cause of a misfire can sometimes be a challenge that can have you pulling out your hair and spending money on parts that don't solve the problem. Well, troubleshooting and solving a misfire doesn't have to be hard. Armed with the knowledge of what can cause a misfire, rough idle condition and a specific testing strategy, you can easily find out what component is the one that has failed.

In this article, I'll talk about the most common causes of a misfire and I'll show you a specific diagnostic strategy that'll help you track down and solve the issue. The core symptom of a misfire is rough idle. A misfire will always be caused by a failed component in one of the three basic systems of your vehicle. These are:. Getting down to the bare essentials that the engine, in your vehicle, needs to start and stay running, the engine needs: Air, Fuel and spark.

When things are running optimally, each engine cylinder gets its full dose of air, fuel and spark. It's when one of these three air, fuel or spark are missing from the mix that the engine in your GM pickup, van or SUV starts to misbehave and misfire. A misfire condition that sets a diagnostic trouble code P, P, P, P, P, P, P, P and thus illuminates the check engine light is one that is usually easy to diagnose and repair.

Knowing which specific cylinder is the one that's dead or missing, is a time saver!

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What sucks is that the diagnostic trouble code doesn't tell you what exactly has failed. That's right, the misfire could be caused by a BAD COP Coil the usual culpritor a bad fuel injector, or low compression in one or several cylinders. The hard-to-diagnose misfires are usually the ones that set a P Random Misfire Code or ones that don't set a diagnostic trouble code at all. I don't mean to give you the idea that it's all a hopeless matter!

Rough idle and misfiring, but no codes

Let's turn the page and we'll take a look at what you'll need to do to pinpoint and resolve the issue causing the misfire. All Tutorials: 4. So I stole a bike and asked for forgiveness. This material may not be reproduced without the author's consent. Page 1 Page 2 Page 3.

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misfire with no codes

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Rough idle and misfiring, but no codes

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