I have the 2.0L 4 cyl. engine (2001 XLS Manual 114k miles). Runs fine when cold but once the engine gets warmed up it starts idling really low. I mean so low that the RPM gauge looks like the engine is turned off, although it hasn't completely stalled (yet). The engine will kind of stumble here and there and occasionally jump up to the normal RPM. Not rough really (in fact it's hard to tell if the engine is on when it's so low) but something is obviously wrong. The check engine light is not on (assume no codes?).

Also when I'm driving I can feel that the RPM's are unstable and erratic. You know, it feels like I'm pushing and releasing the pedal very slightly even though I'm not moving it.

I replaced the spark plugs and fuel filter since they needed to be done anyway. I checked the vacuum lines and they all seem good. I replaced a few deteriorated lines even though they were holding vacuum. None of this changed anything.

So now I'm looking at more expensive stuff like the throttle position sensor, idle air bypass valve, EGR, MAF, etc. Any ideas where I should start? Is there anything that I can actually test to see if it's working or do I just need to start replacing parts until I find the problem? I guess cleaning the MAF and IAC might be starting points that don't cost anything (that IAC looks difficult to remove though).

I'm kind of thinking it's the TPS since it feels erratic at speed. However, I have never had a bad TPS cause a slow idle before. I have had it cause rough idle and such but not slow. Can it do that? What about the MAF sensor?

 

The PCM controls the idle speed.

 

Yeah but there are a ton of things that it uses to determine the correct idle and control the idle. MAF, IAC, EGR, TPS, and vacuum leaks are all known to mess with the idle.

 

Nope, the PCM tries to keep the idle within a certain range. Don't confuse idle with fuel mixture, timing, etc. If it can't, most often it will set a code but not always, at least older Fords didn't always.

Yes, vacuum leaks will affect the idle but the PCM will try to maintain it at a certain speed. I had a '97 Ranger that had a vacuum leak and the idle slowly increased to over 1500rpm. If it wasn't a manual shift, I couldn't have drove it till the day I finally found the leak. It only set a IAC out of range code once. It did set a lean code at idle every time it was driven and maybe it was in limp mode and ignored other codes. Not sure but that's what it did.

 

When my Iac valve went out it didn't throw a code.But I have a V6.I cleaned the on on my Focus it wasn't that hard to pull out.I think there basicly the same engines, Duratec

 

What were your symptoms?

 

My Focus seemed to idle high,the tach would show a bounce in idle from 600-800rpm and shake at a stop.I cleaned the maf and iac and I put in new plugs.The Escape would not idle when you started it up when warm it would rev. all over then stall let it sit for 5-10 minutes would run fine.

 

Welp, cleaning the MAF sensor with MAF cleaner didn't change anything.

I noticed it actually seems to hunt a bit while driving even when cold but that could be normal. Will have to wait a while for the engine to cool so I can clean the IAC. I'm still leaning towards the TPS... Hard to test those since it does work just not perfectly.

I believe all the 4 cyl engines are in the Zetec family, same as the Focus I think. My particular 2.0L should be a Zetec-R (black valve cover).

 

Ugh, that IAC is impossible to get to unless you're Gumby. The axle and exhaust is in the way from the bottom.

I can get to the bottom bolt but the top one seems impossible. Even if I somehow managed to to the top one out, I don't think I could get it back in. Am I missing something?

 

http://www.fordparts.com/Commerce/Ca...=Escape#Search
the iac valve is located on the driver side front of engine I believe I didnt mess with exaust at all

 

On mine it's on the back of the engine (towards the firewall) in between the engine and the intake manifold. It's on the bottom of the intake manifold and you can only see it from under the truck. To reach up to it I have to thread my hand in between the axle, exhaust, and starter. It's really tight up in there and I can't see the top bolt from underneath.

I'm going to try taking off as much stuff as I easily can up top to see if that somehow helps reach that top bolt. I'm not sure if it's accessible from the top though.

I saw on a Focus forum someone mentioned some sort of cap on the throttle body that can crack and leak vacuum. I haven't had any luck finding it but that is another thing I want to check.

 

I put an OBD reader on the truck today and got a P1401 code. Weird thing is, now the check engine light keeps coming on and I keep getting that code. The check engine light wasn't even on until I read the codes, now it won't stay off.

Anyone know if this could be the source of my idle/running problem? P1401 is bad EGR valve? I have had similar problems with EGR on other vehicles (and cleaning it didn't fix it; had to replace). EGR stuff is expensive! $100 for the valve plus there is a control solenoid and pressure sensor (at $35 each). Yikes.

 

P1401

DPF EGR circuit open
VREF short to PWR
Damaged DPF EGR sensor
DPFEGR circuit short to PWR
SIG RTN circuit open
Damaged PCM

 

I think that P1401 was just a loose connection on the DPFE. I gave the sensor a couple of taps and reseated the electrical connection. The error code hasn't popped up again.

Still idling really slow. If I can ever figure out how to get to that top bolt on the IAC I'll clean it out.

 

Does the vehicle have a loss of power when driving on the freeway? Or is it just an idle problem.