Hi Guys,
Girlfriend and I went on vacation in her 2005 escape. We get to a moderate grade, and the thing has no guts. Had it floored and was struggling to maintain 25 mph, even if I kept it in a lower gear. The rig has 138k on it, and besides oil changes, she hasn't had anything done. I changed the air filter (which was filthy), replaced the spark plugs (which looked awful) with autolite iridiums, and replaced the fuel filter (which was nasty). I also ran some fuel injector cleaner through it. There was a check engine light on, but I disconnected a terminal before changing the plugs. I also checked compression. I got 175 on 4 cylinders, 160 on one, and 185 on another.

The problem was not fixed. It's still running terribly. It fires right up when started cold, and the high idle is fine. When it drops to the low idle, however it starts running really rough. It still has no power and if the engine is warm, it starts rough. It does not overheat at all. Also, when I'm at really low RPMs, it occasionally feels like the power brakes don't function properly--the brakes work, but the pedal is less smooth and harder to press. To me, when this happens it feels like the soft, consistent, pneumatic resistance from the pedal is no longer there.

After doing some research I thought one or three of the cat converters were shot from driving it so long with crummy plugs and fuel filter. Then the check engine light came back on. P0402- Exhaust gas recirculation flow excessive detected.
Could a fouled component of the EGR be causing this? I pulled the vacuum line from the top of the EGR valve and the idle improved. I hooked a pump onto it, and the rough idle returned when I gave it vacuum. The pressure did not remain steady--the vacuum quickly dropped. I took this to mean that the valve was getting a vacuum at idle, which it shouldn't be. This is probably due to a fouled solenoid or sensor. When it does get vacuum, the valve can't hold it. That probably means that the diaphragm in the valve is shot. I thought, "great...i'm going to have buy a new valve, and still have to find out what else is wrong, and fix that."

I reconnected the vacuum line to the top of the EGR valve, and headed to the auto part store for the valve. Somehow the car drives MUCH better. While changing the plugs, fuel filter, and air filter had no noticeable effect, simply unhooking the vacuum line from the EGR valve, hooking a gauge and pump up to it, and then reattaching the vacuum line seems to have solved the vast majority of the problem, if not all of it. It seems to me like the car should have a bit more power, but I have no idea what it drove like before the problem started. That being said, for a 10 year old suv with almost 140k miles on a v6, it's now climbing the hill up to our house fairly decently.

I'm completely confused by this, and not sure how to proceed. Any input you all could provide would be really appreciated. Thanks!

 

The brakes will act like this will a rough idle because there is not enough vacuum for them to function properly

If I remember correctly there is vacuum to the valve all the time but there is a circuit that opens and closes to allow more or less vacuum through when needed. I just fixed a connection issue on this in my 2004. It had a bad ground so signal was not making it to the switch.

You may see if there are any pending codes that may lead you in the right direction.

 

I'll head in to see about pending codes. Does it make any sense to you, why simply unhooking/testing/reattaching the line to the EGR valve would cause such a drastic improvement? Am I correct in thinking I should replace the valve because it wasn't holding the pressure? Since everything seems to be functioning normally now, should I even bother with the sensor or solenoid that control/provide vacuum to the valve?
Thanks!