01 Escape, V6 4WD has a very rough idle from surging. Typical lean codes exist as well as a low voltage code, which I belive will go away when the idle problem is fixed. The lights dim when the idle surges down.
What are typical vacuum leak points? It is most affected by the cold weather and sometimes the problem goes away when the car is warmed up.
On two seperate occasions, the car has had no power brakes first thing on a cold morning leading me to theorize that perhaps the booster is bad or its checkvalve is bad. Are the boosters common to fail? What other vacuum items could leak?
Fuel economy is down a little.

 

I did "test" the booster theory and found that the engine shows no change when operating with the booster inline or with that vacuum hose plugged off. I'll be testing the intake gasket/pcv theory and getting both of them at the same time. Hope that does it. Dash lights up like a Christmas Tree. Scanner shows a bunch of codes.
P1131, P1151, P0171, P0174, P0301. I may test the temperature sender if that doesn't fix the problem.

 

I was getting P0171 and P0174 on my 97 Ranger 4.0L. I could clear the codes at a constant speed but as soon as the throttle was let up, you could watch fuel trims going rich till the CEL came ON!

It turned out to be the gasket under the fuel rail. I knew about a TB about the gasket but ruled it out thinking that it would have happened much sooner.

I used a can of Quick Start and sprayed it about the only open spot on that engine where the gasket is. The engine reved up when I sprayed.

You don't mention idle speed. I drove it for several months with this problem. At first the idle speed was slightly higher than 750 RPM but just before the repair it was 1800 RPM. Lucliky it was a 5-speed manual because I had to downshift to drive at 25 MPH!

Sounds like you have a massive vacuum leak. Is that only on a cold engine? If so, that's odd! You might want to try spraying with Quick Start.

 

You might want to try using carb cleaner as a spray detector which will cause your engine to stumble if it is ingested by the leak area..... it might not be as "explosive"... :-) but care should be taken either way.

 

Idle surges between apparently 0 and 900 or so. Looks like the tach is bottoming out but it doesn't die. I like the idea of the vacuum leak. It sounds reasonable. I will also try this because this article seems valid:
Ford Mass Air Flow Sensors

He reports the mass air sensors need to be cleaned at about 100K. Makes sense to me. I'll report back.

 

What's the MAF got to do with your loss of vacuum to your power brakes?? The MAF is sealed up for the most part. If it's like the older ones, a small plate can be removed to get a closer shot with some carb cleaner.

 

have check the vacum tree in the back also check the pvc elbow there are 2 one in the front which u can see uless u take off the plastic engine cover the could be leaking .just trying to help ihave a 02 esape

 

The issue was completely resolved by changing the intake gasket. Took about one hour working slowly. I changed the upper and lower and every other gasket that came in the Felpro kit. The kit was cheap. I cleaned the maf just for kicks, but the car runs like brand new. It idles fine and started perfect when the temperature dropped down into the single digits last week. Nice to have such instant gratification. No codes present in the ECM over one week after doing the minor surgery. The problem seems common enough since the orings used for gaskets eventually will break down on all of these engines. Good luck to future searchers.

 

Were they "O" rings or actually Quad rings or square? They've used rubber rings for years. Did they fall apart when removed? The rings are static or not a friction seal like a moving piston rod, so they should last for many years unless they were made of the wrong type of material.

Did you detect a vacuum leak at the intake by some test? You had to have a heck of a leak that would affect your power brakes!!

 

I didn't test the vacuum leak other than observing the way it was running. The computer was hunting around and couldn't compensate for the extra air. I don't know how the booster was involved, but when the temperature dipped into the single digits here, the booster worked fine. It would always fail first thing in the morning.
Based on the code cocktail, I thought it would make sense to change the gasket first since it's so cheap.
The Orings just looked all flattened out, old and used. They were flat even with the surface of the intake at the top of the groove. I am confident that the problem is fixed. The car already had a new IAC from the PO and fuel injection service too.
It was a cheap and easy fix and now, the car is reliable and the wife is officially satisfied with the repair.

 

The same job on the older V6, 4.0L is a different story. My vacuum leak was under the fuel rail but I replaced the upper rings also on the 97 Ranger. The 96's had a actual gasket plus rings on the upper. The gasket was eliminated for 97. I had tried retorquing the upper intake earlier which didn't help.

You did use a torque wrench, correct?

 

[quote=bluestang65;6868039]01 Escape, V6 4WD has a very rough idle from surging. Typical lean codes exist as well as a low voltage code, which I belive will go away when the idle problem is fixed. The lights dim when the idle surges down.
What are typical vacuum leak points? It is most affected by the cold weather and sometimes the problem goes away when the car is warmed up.
On two seperate occasions, the car has had no power brakes first thing on a cold morning leading me to theorize that perhaps the booster is bad or its checkvalve is bad. Are the boosters common to fail? What other vacuum items could leak?
Fuel economy is down a little. [quote]

My 2004 Escape had had the same issue, no power brakes on two separate occasions, today being one of them! I have also had performance and drivability issues. Just seems to run like a POS, not the fun spunky vehicle it once was. Sluggish. Blah.