No power

Does the car have any codes?


More importantly, have you verified that its lost power? Like your track times have slipped badly or something like that? Over time you get used to things and it may feel like its slowing down when in fact it runs like it always did but your instead just used to it and maybe bored.

If the egr is malfunctioning, it can cause all sorts of issues. The light should come back after enough drive cycles.

When it does, pull the code and check back.

mirage86 said:

I've got an 03 GT 5 spd. Sotck with 84000 miles. Vehicle runs fine except when u go to get on it. When u put the gas to it, rpms climb up but the car does get up and go like it used to. I thought the clutch was slipping and put a new one in. But it does the same thing. Under a load, it doesnt cut out like a missing plug, stopped up exhaust or starving for fuel. R the stangs prone to anything that would cause this? I dont wanna start throwing stuff at it.

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Can you elaborate on the bolded part more? Does the engine RPM flare in response to throttle input, so much so that you thought it was a bad clutch, had it replaced and after that it's still doing the same thing?

squeak93 said:

Does the car have any codes?


More importantly, have you verified that its lost power? Like your track times have slipped badly or something like that? Over time you get used to things and it may feel like its slowing down when in fact it runs like it always did but your instead just used to it and maybe bored.

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What he said.
I have one of those accelerometer units and recently I was fooling around with it. My car hit 100mph in 9.55 seconds, but I have been driving it with the blower on it for so long it doesn't seem that fast anymore. But it be.

Have you replaced the fuel filter lately? Could be reducing the flow to the engine at wot....you could have got some bad gas at some point..when was the last time the spark plugs were changed?

i doubt its all in his head if his gas mileage took a hit. when was the car last serviced?

Check EGR system and DPFE sensor

The P1406 EGR code is one that I am very familiar with. This DTC basically means that the EGR flow is not as expected.

This DTC has several causes.
1. Carbon build up in the throttle body that blocks/restricts the EGR flow.
2. A problem with the EGR valve itself. The valve usually rots out from the corrosive exhaust gases.
3. Bad differential pressure feedback sensor (DPFE). The EGR flow is actually OK but the sensor is giving a false reading.
4. leaky hoses connecting the DPFE to the EGR tube.

The worst thing about this problem is that the DPFE is bad about half the time. This means that you usually have to rule out a blockage in the EGR system itself. When you are sure that the EGR system is clean (usually after the EGR valve has been replaced), you replace the DPFE which solves the problem.

The DPFE throws false DTC’s so much of the time, Ford redesigned the sensor to adjust the allowable range of the signal return. The all Metal DPFE is the worst. The plastic one is not as bad.

If the code is for insufficient EGR flow, this will only affect emissions. If the code is for excessive EGR flow, this will affect drivability.

IMO, if this is the ONLY DTC you are getting, clogged cats is not the cause.

Recommend the first thing is to inspect the hoses leading to/from the DPFE. They are hard to see and are subject to hot exhaust gases. They dry up and leak. This upsets the flow to the DPFE and allows exhaust gases to leak. Because the hoses are so close to the firewall, they are difficult to get to.

If the hoses are fine, next thing is a crap shoot. As stated before, the DPFE sensor is bad about as often as there is a real problem with the EGR system itself. At 84k miles, this is not high enough where I would definitely say to start with the EGR valve.

If you replace the DPFE, go to Ford and get the revised one. Also, replace the hoses. You will hate me while doing the job. But in the end, it will stay fixed longer.

Good luck. This problem has kick my tail more than once.

mirage86 said:

But would 1406 cause a drivability issue? My experience with egr's is that the only monkey with idle.

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Depends. The DTC is because the measured EGR flow is not as expected. Usually this means not enough EGR flow. But it could mean too much EGR.

Bottom line is, too little EGR flow will NOT affect drivability. It will cause a "check engine".

Too much EGR will affect drivability. How much depends on the conditions at the time (idle/power/how much excessive flow there is).

If the EGR flow is way out of wack, it could create all kinds of problems such as what you are experiencing. However, for it to be that far out of wack, one would expect the EGR valve to be rotted out to the point where it is flowing all the time (not likely here).

As I stated in the post, the DTC may be false itself (DPFE). If so, then the DTC has nothing to do with your base complaint.

It could just be a smoke screen to your real problem. At the very least, the DTC would prevent your car from passing inspection.

I would be real surprised if changing the cats made the P1406 problem go away.

I am normally a test first and then replace kind of guy. For this problem, I have changed out more "good" parts in the interest of narrowing down the real cause. Can be frustrating.

Good luck.

PS, if the DTC code had been in the original post, I would have chimed in much sooner.

mirage86 said:

Got the o/r x pipe on and shes alive. Had a collapsed cat. As for the code, I'll figure it out later.

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How did that happen? Pearl02.