check engine light came on?

I need the exact code numbers this guide can help us get the codes.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run down this guide and report back.

5.4L an the code were p0171 an p0174

Have you checked for a vacuum leak yet? That's where i would start. This guide can help.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Please run down this guide and report back.

Thanks for the guide I found the PCV hose had a big hole in it si I got a new one and cleared the codes and it has not come back. Thank you this site is amazing!

Use 2CarPros anytime, we are here to help. Please tell a friend.

I will thanks for your help

just to add, there is a vacuum behind the throttle body on the pcv line that is common for collapsing and causing the lean codes, is this the one you replaced?

Roy

yes that was the first thing i checked and replaced

Good to hear, please use 2CarPros anytime we are here to help.

Im trying to get my check engine light to turn back on so i can replace one of the bad coil packs. I went to the shop and they told me which one it was. I replaced it and not even a week later another was bad. How do i get the light to turn on in order to find out which one it is without going to a shop?

HI there the ECU must recognize a fault with in the parameters of the engine management system before a check light can be set, trying to induce a code will not give you a true indication as to what the problem is.

Mark (mhpautos)

My alternator went bad and I replaced it two weeks ago, a few days later check engine light came on got the code p0306. it started chugging while idling, wipers have slowed down, shaking when accelerating.
Have changed thermostat due to it was slightly leaking, replaced cylinder six plug, plug boot, ignition coil, PCV valve, EGR sensor, EGR connector, replaced vacuum lines that were bad.
I'm at my whits end here!

Good evening,

You covered most of it except for compression and the injector.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Do you have a noid light to see if the injector is commanded on from the PCM? You can rent one at a parts store if you do not have one.

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

I would definitely check the compression.

https://www.2carpros.com/articles/how-to-test-engine-compression



Roy

Common failures on these trucks is the intake leaking coolant into the plug holes. I would remove the other coils and inspect for coolant contamination. If the concern is only while accelerating, this is where I would start looking.

We have a multi-meter and we will test that tomorrow. headed out soon to do the screwdriver test.

Please be careful. There is a lot of spark from the coil.

Roy

Husband is an electrician and a mechanic best of both worlds.

Okay, let us know the results.

Roy

4.6L engine will start to sputter when engine comes up to operating temperature. Check engine light never came on. Vehicle never stalls.

most likely plugs and coils.

ford has expanded there parameters to not have the light come on till it is a dead miss for a while

Roy

Thanks for answering my question. I had moisture on one of the ignition coils. Fixed it and it runs great!

At about 1700 rpm acceleration is nearly unresponsive. It appears that the acceleration has to "catch up" to the throttle advancement. From 0-1770 acceleration seems fine, even very responsive. No idle or load misses, no engine lights.
When the engine is cold, it seems that the problem does not exist or is very minimal. Fuel additives or 93 octane does not seem to change anything.

Have you checked to see if the catylatic converter is starting to plug? Also, have you checked fuel pressure?

Let me know.

My truck has been driving sluggish, changing gears a little harder than usual and today my "service engine soon" light came on. Anything I need to know before I take it to the mechanic?

Before taking it to a mechanic, take it to a nationally recognized parts store and have them scan the computer for you. Most will do it for free. After you do that, let me know what they tell you and maybe you can fix it yourself or at least I can tell you what to expect.

Do that and let me know what you find.

Joe

I have a 2001 ford expedition xlt. The check engine light came on and the car started running really rought .When you came to a stop it felt like it was going to quit.My mechanic is having a hard time diagnosing this. Can you help me?

so what did the check engine lite say?

it ssid service engine

check engine light came on simultaneously with radio going out. Tried to replace fuse and blew again immediately. Code pulled says EVAP small leak/ no flow condition. Gas cap is good, no vacuum leak either. Is it possible a ground wire is loose that may be for radio and evap system sensor? If so where is it located?

A loose ground wire breaks the circuit which causes a reduction in current flow. Fuses blow because of too much current. The fault code is not related. It has to do with the evaporative emissions recovery system, not vacuum hoses. If there's a small leak, you usually need a smoke machine to inject a white smoke at 2 psi, then you look for where it's sneaking out.

A simple trick to finding a short is to replace the blown fuse with a pair of spade terminals, then use small jumper wires to connect them to a 12 volt light bulb. A brake light bulb works well. When the circuit is live and the short is present, the bulb will be full brightness and hot so be sure it's not laying on the carpet or against a plastic door panel. Now you can unplug electrical connectors and move things around to see what makes the short go away. When it does, the bulb will get dim or go out.

Engine Mechanical problem
2001 Ford Expedition 6 cyl Automatic

My check engine light just came on and now my truck shakes until I accelerate around 50mph. What can be causing this problem. The oil and radiator was just flushed a week ago.

Hi:
If the check engine light is on, chances are the computer has stored a code which will identify the problem. Chances are it is a coil pack. Take the vehicle to a nationally recognized parts store and have them scan it for codes. Most will do it for free. Let me know what they tell you.
Joe

I have a P171 left bank lean code. I had a fuel injection cleaning done and that worked for about 3 days and the light is back on Service Engine Soon. The code is the same. Could you tell me what it could be before I start paying for things I don't need. I have been told it is most likely an O2 sensor. Just looking for a good answer before I take it back to the mechanic.

Hello,

Here are the possibilities....

A lean fuel condition may exist if the engine is sucking in too much air and/or the fuel system is not delivering enough fuel. If bad enough, a lean fuel condition may cause lean misfire, a rough idle, hesitation or stumble when accelerating, and/or poor engine performance.

Unmetered air can enter the engine through a vacuum leak, a dirty airflow sensor that is not reading airflow accurately, an EGR valve is not closing and is leaking exhaust into the intake manifold, an EGR valve that is allowing too much flow (because the EGR differential pressure sensor that monitors EGR flow is faulty and is under-reporting EGR flow).

If the problem is not enough fuel, the underling cause may be a weak fuel pump, restricted fuel filter, leaky fuel pressure regulator or dirty fuel injectors.

DIRTY MAF SENSOR

One of the most common causes of Ford P0171 and P0174 lean codes is a dirty mass airflow (MAF) sensor. The MAF sensor is located in the air inlet tube
just ahead of the throttle body. The MAF sensor should be protected from outside dust and debris by the air filter, but sometimes the air filter doesn't fit real tight inside the housing and allows unfiltered air into the engine. Dirt can stick to the MAF sensor wire and form a coating that slows the response of the sensor to changes in airflow. The MAF sensor can also be contaminated by fuel vapors that back up through the intake manifold and throttle body when the engine is shut off. The vapors can leave a waxy coating on the sensor wire. This causes the MAF sensor to under report airflow, which in turn misleads the powertrain control module (PCM) so it doesn't add enough fuel to maintain a properly balanced air/fuel ratio. As a result, the engine runs lean and sets a P0171 and/or P0174 code (see Ford TSB 98-23-10 for details).

If the MAF is dirty, the fix is easy enough: just clean or replace the MAF sensor. In many instances, the MAF sensor can be successfully cleaned by spraying the sensor element with electronics cleaner. Do not use any other type of cleaner as this may damage the sensor.

Disconnect the air inlet tube just ahead of the sensor, and then spray the electronics cleaner through the screen at the wire element in the center of the little MAF sensor. Let the cleaner soak in for several minutes, then give it another shot of cleaner. Let it sit another five minutes, then reconnect the air inlet tubing and start the engine.

If the lean codes keep coming back, the MAF sensor may have to be replaced if the engine does not have a vacuum leak or fuel delivery problem.

VACUUM LEAKS

Another common cause of Ford P0171 and P0174 ean codes is an engine vacuum leak. Ford TSB 04-17-4 details procedures for checking fuel trim and looking for vacuum leaks.

On 3.8L Fords with a split-plenum intake manifold, the port gaskets and isolator bolt assemblies for the upper plenum can deteriorate over time and leak air, often as a result of oil being sucked into the intake manifold through the PCV system. Also the vacuum hose that connects the fuel pressure regulator to the intake manifold can swell and leak vacuum where the hose connects to the manifold. Ford TSB 03-16-1 says the fix involves several steps: remove the upper manifold plenum and replace the original gaskets and bolts with revised ones, replace the front valve cover with a revised valve cover that reduces the amount of oil vapor sucked into the PCV system, inspect and replace the fuel pressure regulator hose, and finally, reflash the PCM so it is less sensitive to lean fuel conditions.




BAD DPFE SENSOR

Ford p0171 AND p0174 lean codes can also be set by a bad EGR differential pressure sensor. These sensors have a very high failure rate once a vehicle has more than about 60,000 miles on the odometer or is more than five or six years old.

The DPFE sensor is mounted on the engine, and is attached with two rubber hoses to the tube that routes exhaust gas to the EGR valve. The original equipment sensor has an rectangular aluminum housing about three inches long. Corrosion inside the sensor reduces its sensitivity to EGR flow, causing it to under-report EGR flow. The PCM responds by increasing EGR flow, which may keep the EGR valve open longer than usual creating a lean condition in the engine. Thus, a bad sensor may set a P0401 code (insufficient EGR flow), or it may not set an EGR code but a P0171 and/or P0174 lean code instead.

The cause of the P0401 code in most cases turns out to be a bad DPFE sensor, not an EGR valve problem or an EGR valve that is plugged up with carbon (though this can also set a P0401 code). An aftermarket replacement DPFE sensor costs less than $50 and usually gets rid of not only the P0401 code, but also the P0171 and P0174 codes, too.



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My Expedition has a check engine light on.

If the light is on, there is a trouble code stored in the computer. We need to know what code it is. Take the vehicle to a nationally recognized parts store. Most of them will scan it for free. Have that done and let me know what code they find.

Joe

Here is a guide that will help with this but we need to find out what codes are causing the light to come on. There are hundreds of codes that could cause the light to come on so we need to start with this.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Let us know what the codes are and we can figure out next steps. Thanks