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Code P1407, Emission problems?

Tiny
BENSJETS8147
  • MEMBER
  • 1994 FORD MUSTANG
  • 3.8L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
I have changed MAF sensor, and all four O2 sensors. Now I am getting a code P1407. Exhaust gas recirculation no flow detected. Is there a way to check the functioning of my EGR valve and the two other related electrical sensors without having a bunch of tools and related scanners. I'm a backyard mechanic with very limited tools. Could I just unplug a sensor at a time to see if it changes the running of the engine, when the engine is warm of course? It seems by my scanner in "live mode", the system is always in "closed loop" Maybe you can steer me to something else that may be wrong. Sorry for the terrible image of my scanner. Thanks in advance.
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Tuesday, July 30th, 2024 AT 9:29 PM

21 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

First, locate the EGR valve. It should have a vacuum hose to it. Confirm the hose is connected and not damaged. You can disconnect it and check to see if there is vacuum from it with the engine running.

If that is good, remove the EGR valve and confirm it and the intake where it mounts isn't blocked with corrosion. Additionally, place vacuum to the hose to see if the pintel moves when vacuum is applied.

As far as testing the O2 sensors, you need a scan tool that can check live data. With the engine running and at operating temperature, you should have voltages from each between .01 and .09v. The voltage should change when the engine speed is changed.

If you don't have a live data scanner, here is a link that explains how to check it with a voltmeter or multimeter:

https://www.2carpros.com/articles/how-to-test-an-oxygen-sensor-02-sensor

Let me know what you find or if you have other questions.

Take care,

joe

See pic below.

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Wednesday, July 31st, 2024 AT 10:50 AM
Tiny
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I know how to clean an EGR and how to pull the hose off to check for vacuum. I am totally confused about the two different solenoids that is mounted beside the EGR, and both solenoids are tied into the EGR via hoses and vacuum lines They both have electric to them, and I'm sure the wires run back to the computer, so how would one go about testing them in a backyard setting? I have never seen a setup like this. It is on a 94 Mustang base model.V6
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Wednesday, July 31st, 2024 AT 6:14 PM
Tiny
JACOBANDNICKOLAS
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Hi,

There is an EGR vacuum regulator solenoid (pic 1 below). It is a simple on or off switch. It should have two wires to it. The PCM regulates the vacuum it allows to reach the EGR valve. If you have vacuum, that isn't the likely cause. As far as testing, disconnect the electrical connector and apply 5v to the connector pins to see if you hear it moving internally or allowing and then stopping vacuum.

If you have a bi-directional scanner, you can actuate the sensor via the scan tool.

Also, there is a differential pressure feedback EGR sensor (DPFE). See pic 2. This sensor converts a varying exhaust pressure signal into an analog voltage which is digitized by the Powertrain Control Module (PCM). That information is then used to determine EGR flow.

If you look at the last pics, it is an exploded view of the system. I copied and pasted how it operates in the very last pic.

Let me know if this helps.

Joe

See pics below.
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Wednesday, July 31st, 2024 AT 8:09 PM
Tiny
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Thanks for the input, and especially the pics. I am working in my backyard with very limited tools, especially no scanners as you spoke of. I am going to remove the EGR valve and see if it needs cleaned and attempt to see if the other solenoids (DPFE) are working as they should. Thanks again.
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Thursday, August 1st, 2024 AT 11:59 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

No problem whatsoever. If I can help, I will. When you have the EGR off, make sure to check in the intake also and apply vacuum to the EGR valve to see if the pintel moves.

Let me know what you find.

Joe
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Thursday, August 1st, 2024 AT 7:12 PM
Tiny
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I have vacuum to the EGR. I unhooked the electrical connector going to the DPFE. When I did this the engine ran smoother with a bit more RPMs. Everything else I left connected. I then drove the car for about 20 miles and it ran great, but still throwing the code p1407, which I thought would be there being I unhooked the electrical connector to the DPFE. I am going to take the EGR off and see if it needs cleaned, and the passageway also as you suggested, as well as hooking vacuum to the EGR to see if the pintel moves. I'm 71 years old, working outside in 90° temperatures, so please bear with me. Thanks again for all your help.
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Saturday, August 3rd, 2024 AT 4:49 PM
Tiny
JACOBANDNICKOLAS
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Hi,

The heat has been excessive. Take your time. There is no hurry whatsoever. I'll be here. The more I think about what you said, I'm questioning if the DPFE is faulty. If it ran better with it disconnected, maybe it is opening the EGR at idle. It shouldn't. Reconnect it and see if that is happening.

Take your time,

Joe
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Saturday, August 3rd, 2024 AT 8:06 PM
Tiny
BENSJETS8147
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Well I plugged everything back up, and just for shits and giggles, I took it for a drive. On my small scanner, I have a green light, an amber light, and a red light. I always plug it in when I am driving and keep it on live Scan to see what is happening. First it went into red mode. Then it went to Amber mode. And finally it went to green mode. My scanner says everything is working, but I do have one question at this time. When I first start it when cold, my scanner says it is in closed loop. I thought it was supposed to start in open loop, and once warmed up, it should then go to closed loop. Any ideas on this? Also, how would I know if the EGR is open or closed when idling?
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Saturday, August 3rd, 2024 AT 9:45 PM
Tiny
JACOBANDNICKOLAS
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Hi,

You are correct. On cold start, the PCM should control things. Once operating temp is reached, then it should go closed. That doesn't make sense.

As far as the EGR, if you remove vacuum from it, it should be closed. You could try that and see if it changes how it idles. Just make sure to plug the vacuum supply.

Joe
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Sunday, August 4th, 2024 AT 7:13 PM
Tiny
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Hello,
Just wanted to keep you updated being you have been so very helpful. After I plugged everything in, it has been running fine. My scanner says everything is working on IM mode, and I still have a green light. It still says it is in closed loop all the time, even on the first start of the day. I'm getting a very high odor of gas, and from the soot around the tailpipe, it is running very rich. I have just recently found out this is a 2001 engine. Someone must have did some rigging to make this run through the computer and other sensors. There may be a lot of troubles coming my way being I do not know what was done. Maybe I need to unload it. Thanks again.
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Saturday, August 10th, 2024 AT 1:22 PM
Tiny
JACOBANDNICKOLAS
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Hi,

That makes things a little different. LOL Tell me, does your scanner provide live data? If it does, what are the short-term fuel trims when the engine is at operating temperature?

Next, have you confirmed that the fuel pressure is within the manufacturer's pressure specifications?

Joe
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Saturday, August 10th, 2024 AT 6:35 PM
Tiny
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Have no way to test the fuel pressure. First start today, started in closed mode. Went about 20 miles and the cats are staying in the INC mode, with a code P1407. Was running great yesterday, just running rich. Now I'm lost again.
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Monday, August 12th, 2024 AT 11:05 AM
Tiny
JACOBANDNICKOLAS
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Hi,

The code indicates there is no EGR flow. Let's do this the long way. I attached step 1 of the diagnostics for the P1407 in pic 1. It indicates test HE70. I skipped test HE71 because it is specific to a P1408 which isn't relevant.

We know the code is present (1407), so pic 2 is test HE72. Perform that test and let me know the results. Once I have them, I will know what test is next,

Let me know.

Joe

See pics below.
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Monday, August 12th, 2024 AT 7:53 PM
Tiny
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Trying to borrow a vacuum tester. AutoZone did not have one at the time. The car is starting in closed loop, and of course I'm only guessing, but that lets me to believe the EGR is always closed. Would it hurt anything to continue to drive this way? I will update you about the two tests you recommended as soon as I can get them performed. Thanks.
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Tuesday, August 13th, 2024 AT 10:12 PM
Tiny
JACOBANDNICKOLAS
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I just read through everything we have discussed, and I have a question regarding the closed loop it is always in. Since you have a live data scan tool, before starting the engine in the morning (cold) connect the scanner and check what the coolant temperature sensor is indicating. It could be off and indicating engine temp is already at operating temp.

As far as driving it, you should be okay. I wouldn't run it hard or take any long trips.

Let me know.

Joe
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Wednesday, August 14th, 2024 AT 12:51 PM
Tiny
BENSJETS8147
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I could not get a complete on my cats, so I unhooked the two sensors that run the EGR, and unplugged vacuum to the EGR and plug the line. Then I drove it for about 30 miles and it ran okay. I pulled over, plugged everything back together, and within a mile I got a complete on the cats. I'm going to try to send you pics of my scanner. Check them out and any thoughts my ears are wide open. Sorry for the bad pics but I'm using a cheap government phone. Yes, I am a very poor person. I think if you blow them up a little you will be able to see them better. Good luck my new friend.
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Wednesday, August 14th, 2024 AT 7:49 PM
Tiny
JACOBANDNICKOLAS
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Hi,

Wealth is not a form of money. It is being a good person. I have a feeling, you are a lot wealthier than you think.

As far as the pics, the fuel trims are all over the place. They should remain between -10 and +10%.

At what point were they at 38%? That tells me the computer is dumping fuel to add for a lean fuel mixture.

Let me know.

Joe
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Wednesday, August 14th, 2024 AT 9:10 PM
Tiny
BENSJETS8147
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You are absolutely right about wealth. It comes in many forms. I'm in my fourth year of remission from having throat cancer, Hallelujah! All the pics were taken when the car was idling, and after about a 30-mile drive. I'm getting between 20 and 23 mpg jumping around town and short drives. Never had it on a trip. As far as deciphering what my scanner is telling me, that is one of those times I speak of, I have enough knowledge just to get myself in trouble. I'm sure you are a very busy person with your own life, and this large task you have taken upon yourself to help other people such as myself, so you are very wealthy in your own right. You take your time trying to help me. I realize I have dumped a lot into your lap. I think when they swapped the motor from a 2001 into a '94 they created a lot of problems. I have no idea where to start. It does run rich all of the time, and I'm not willing to spend a lot of money trying to fix it. If it were something simple, that would be different. I bought the car for $500 thinking it would make me feel young again driving with the top down, and it does that when it is running. Thanks again.
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Wednesday, August 14th, 2024 AT 9:33 PM
Tiny
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First pic is the actual first start of the day. Next two taken before starting.
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Thursday, August 15th, 2024 AT 12:45 PM
Tiny
JACOBANDNICKOLAS
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Hi,

The first two indicate it is in an open loop. Is that correct? Also, were you able to get the ECT reading before starting?

Let me know.

Joe
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Thursday, August 15th, 2024 AT 7:18 PM

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