• Welcome to the Contour Enthusiasts Group, the best resource for the Ford Contour and Mercury Mystique.

    You can register to join the community.

P0171 and idle problems, engine loud

M

Matt R

Hard-core CEG'er
Moderator
Joined
Jun 6, 2004
Messages
2,787
Location
Plattsburgh, NY
So out of the blue, my car started acting funny. With my foot on the brake while in drive, it would shudder and sound like it was stalling, yet the RPMs stayed around 850-ish. It kept getting worse, till finally the CEL came on, and a P0171 came up. Being next to the exhaust pipe, the exhaust was kind of pulseing out. I did the carb cleaner test over the entire engine bay, and didn't notice any change in idle. Then I took out the air filter, and it had a small amount of oil collected in the bottom plastic under the filter. I spun the filter around to the fresher side, and cleaned the MAF with some electrical cleaner, and reset the ECU. This made somewhate of a difference. Now it idles fine in drive, but just as rough in park. The CEL has stayed off.

Also, the engine got much louder once it started doing this. The sound I think is coming from the timing belt cover, or underneath it. Almost like a rattleing noise. It is loud enough to hear in the car, but especially outside.

I'm having no problems with acceleration, gas mileage, etc, just the idle. It stalled only once after reving to 3500 RPMs in park and letting off the gas quick. Right now in idle, in park, it hovers around 750-800, then seems to "cycle" to about 1250, and back down again to a shaky 750ish. Any ideas what else could be causing this?
 
P0171 System Too Lean - Bank No. 1.

Which I am sure you already know...

Most common fix for this is to Clean your MAF.

http://www.contour.org/ceg-vb/showthread.php?t=3046&highlight=P0171

Few other things you can try...

From TSB,
P0171 - System Too Lean (Bank 1)The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The code is set when the adaptive fuel tables reach a rich calibrated limit.

Fuel System:
· Contaminated fuel injectors
· Low fuel pressure or running out of fuel (fuel pump, filter, fuel supply line restrictions)
· Vapor recovery system (VMV)
Induction System:
· MAF contamination
· Air leaks between the MAF and throttle body
· Vacuum leaks
· PCV system concern
· Improperly seated engine oil dipstick
EGR System:
· Leaking gasket
· Stuck EGR valve
· Leaking diaphragm or EVR
Base Engine:
· Exhaust leaks before or near the HO2S
· Secondary air concern
Powertrain Control System:
· PCM concern

Since your "engine is louder" now, it leads me to believe you have a vaccume or exhaust leak of some sort.
 
Last edited:
That is what puzzles me- the MAF being cleaned fixed it part way. But it leads me to believe there is more to the problem. As for the loudness, it isn't exhaust, definately mechanical noise. As I said everything is fine, including all fluids. Just the idle in park is crappy.
 
Matt R said:
That is what puzzles me- the MAF being cleaned fixed it part way. But it leads me to believe there is more to the problem. As for the loudness, it isn't exhaust, definately mechanical noise. As I said everything is fine, including all fluids. Just the idle in park is crappy.
Click to expand...

Mechanical? Can you describe this sound?
 
I'd say like a metallicy, mostly kind of belt-ish noise. Like that tish-click you can hear in some cars ideling, about 1 second apart evenly, but this is much louder.

I don't think there is any kind of vacuum leak because going over the whole engine bay multiple times with carb cleaner didn't do anything.
 
If you have a leak near the O2 sensor, that could cause a P0171 too.
 
Well I've driven the car 2 days now since this all happened, and it is running fine, w/o a CEL, but still shudders once in park, so the CEL must have not really had anything to do with anything. I'm pretty sure the Zetec doesn't have an IAC, so is there anything else that would affect idle?
 
If it sounds like it's coming from the timing belt cover area, have you checked the timing belt?? On Zetec's they usually go at around 60k iirc, although I have 78k on mine and it went out at the end of October. Mine was so bad that it had split in 3 due to one of the idlers breaking down and 1/3 of it had rolled itself over. No rough running or anything though. It just up and quit, although it had been taking longer and longer to start. Pop the top timing belt cover off and check it just to be sure :shrug:
 
Ok, so it has gotten worse. Still code-free. Now about 5 seconds after coming to a stop, it just keeps going up and down between 600 and 900 RPMs. Even or park or neutral, and in drive you can feel the car trying to go against the brakes.

The sound is coming from the timing belt side of the engine, meaning it is the timing belt or something having to do with the serpintine belt (pully?) My '89 Tempo kind of did this before, and it was a MAP sensor. Is that possible on newer cars? And also, what is the quickest and easiest way to pop off the timing belt cover?
 
Well, if you wanna take just the plastic top cover off, if you're careful you can get it past the pass. side motor mount bracket/middle timing cover (a metal piece). Thats what I did to discover that my belt was toast when my SE died on me. The "right" way to do it would be to support the motor and remove the pass. side motor mount and middle timing cover (metal bracket) and then the top cover, which is what I ended up having to do anyways because my timing belt was bad. If your belt is bad, you'll prolly end up having to remove the middle cover anyways
 
The timing belt itself looks great, but a little off center (maybe it is supposed to be like that). Upon more inspection, I'm pretty sure it is a valve that is making all the noise. I have video clip but I can't figure out how to upload it with sound (you can clearly hear the noise). Here is the pic of the timing belt:

1205061457.jpg



Today the CEL came back on again, I'm guessing the same thing from the shuddering. The charging system was checked and is running perfect. Minus the valve noise, which isn't comforting, I'm thinking either a mount (engine or tranny) or Intake Manifold Gasket. Thoughts?
 
Last edited:
Came up again P0171. I'm guessing since the engine is shuddering and not working right, it is running too lean. I'm going to pull the valve cover and look for obvious damage from that noise if it gets any warmer out.

The possible reasons I can think of so far:

Dirty/clogged injectors- maybe pull them and have them pressure cleaned?
Intake manifold gasket (not as likely- no response to carb cleaner blast).
Engine or tranny mount (not as likely, shouldn't affect idle, and engine dosesn't "bang" when accelerating).

Ideas please? It is really starting to irritate me.
 
Last edited:
your cel sounds like a dirty or bad maf. when mine was bad, it would set the code then remove it and maybe not come on for a few days.

now the timing belt on my car lasted anywhere from 65K-100K, i cant be for sure because i was never given the true mileage when i got the motor. my timing belt didnt break or wear out, my pulleys went and belt tension was very loose and with the episode i had with my injector harness coming apart and clutch started it 7 times at 75mph, i figured i better replace it before it blew.

now the noise is hard to say what the problem is. it could be a noise your just really noticing now because of the idle issue. if its a tick/clicking noise, then its probably just the injectors. nothing wrong with them, just noisy. just cant say what it is really though.
 
Well, one other problem that I had during my timing belt project last month was rough idle after I changed the timing belt. It didn't idle rough at all before the belt went, but it ran rough and threw a CEL after we put it back together (I didn't bother getting it scanned). I had to remove the spark plug in the #1 cylinder to get it in time and noticed it was carboned up and out of gap ( I had changed it about 28k ago, but the originals lasted till 50k so I thought I would be ok to let them go till around 35k or so :shrug: ) Anyways, I had corrected that one, but didn't check the others. Well, I decided to replace them all and see what happened and that was the solution to my problem. My car idled so rough that I thought we put the motor mount back on wrong or something, but then I remembered the spark plug looked horrible, so i replaced them. How long ago were your spark plugs done? My suggestion would be to check them out
 
You must log in or register to reply here.
Back
Top