Please Help!!! Fuel Mixture Problem...

[kaiost]

Hello all,

Am currently having a great deal of headache from my 2000 Ford Focus. I moved to Switzerland from the USA 6 months ago and brought the car along with me.

About one month ago when my wife started the car, it would not idle - meaning without gas it would stall right away. The ford mechanics here changed two parts (soupape de ralenti and senseur d'air - exaust recirculation sensor and O2 valve as far as I understood with my limited french). The car then ran for about 50 miles without problems, but then the following problem surfaced:

The check engine light comes on and the car idles very roughly. After two more trips back to the garage in the last week, the computer diagnosis is always FUEL MIXTURE TOO POOR. The first visit the garage reset the onboard computer, yet the problem resurfaced after about 10 miles driving. They then replaced the O2 sensor, yet after 10 miles or so the same issue. The troubling issue is that they told me this morning they don't know what the problem is, and their only solution is to change piece by piece until it runs without problem again. Maybe this would normally be acceptable, but car service in Switzerland is VERY expensive! So the question is, has anyone experienced a similar problem with this model? Could this have something to do with the fuel pump issue posted on this page? Any advise at all would be greatly appreciated!

Many thanks!
Kai

[cougarsvt1]

First check the injectors!!Then fuel pump...MAF sensor....What does poor fuel mixture mean anyways, does that mean rich or lean?

[kaiost]

I went back to the mechanic this morning - the fault code is PO171PCM. As far as I understand the dearer it is running too lean, but he speaks only french, which I'm still having problems with.

Again, any ideas would be greatly appreciated!

[rabi2209]

I am having the same problem. My car will idle really hard and almost dies. I am really confused I dont know what to do. I thought is was bad gas but that doesnt seem to be it. I am glad to see I am not the only one.

rabi2209

[rrinaudo]

I have a Mondeo 1996 with a brand new zetec motor 2.0. I´m having the same problem, but I don´t get any error on the computer... So my mechanic said it could be a fuel computer problem.

[rrinaudo]

After reading the fuel pump issue.... It looks that it should be the problem. I told this to my mechanic and he will check this. I´ll let you know if it was the fuel pump or anything else.... I replaced EGR valves... ignition cables and much more and did´t fix it.
If you turn off and start the engine again when it´s failing... fix the problem for some miles?
The Ford Mondeo engine and much more are the same to the ones in ford focus.

[fordesigner]

Your code -
P0171 - System to Lean (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. For lean and rich DTCs:
Fuel system:
Excessive fuel pressure.
Leaking/contaminated fuel injectors.
Leaking fuel pressure regulator.
Low fuel pressure or running out of fuel.
Vapor recovery system.
Induction system:
Air leaks after the MAF.
Vacuum Leaks.
PCV system.
Improperly seated engine oil dipstick.
EGR system:
Leaking gasket.
Stuck EGR valve.
Leaking diaphragm or EVR.
Base Engine:
Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2Ss.
A SHRTFT-1,2 PID value between -25% to +35% and a LONGFT-1,2 PID value between -35% to +35% is acceptable. Reading beyond these values indicate a failure.

[rrinaudo]

my Mondeo 1996, 3 months ago the engine started to hesitate very roughly, and when i stop at any red light it stall. Then i turn it on and it looks like nothing happens for 20 or 30 km, the starts hesitating again. Then i turn it off and then on again while driving, and hesitation stops for the next few km. If RPM are over 3000... hesitation also stops. If RPM are lower than 2000 the engine stalls. It seems like it is running out of fuel, or dirty fuel, but it is not. My mechanic changed EGR valve, Ignition cables, fuel, oil and air filters, but it did´t fix the problem.
It has been connected 10 times to the computer and no problem appear.
I changed the exaust a year ago, and the engine 6 months ago (my father melt the old one.) with a brand new zetec 2.0 16 v. 3 months after changing the engine this fault appear.

Could be the fuel pump? since it´s similar to the cases of the ford focus. The only diferrence, is when I´m over 3000 RPMs, works fine, between 2000 and 3000 RPMs, hesitation and lurching everywhere.
Lower 2000 RPM, the engines stops. This failure appears every 10/20 km, restarting the engine everithing is normal again

[biggen]

Ford Recalled the fule pump on the focus. not enough pressure to punch through a clogged filter. anywho. i have the same problem with my 2000 focus LX. after 80,000 mile the Check engine light came on. the 02 Sensor was all fowled up so i replaced it. ran great from 12/2/03 to 12/25/03 or approximatly 1000 miles, then i made the mistake of putting in cheep gas. light is back on now. my recomendation is to change the fuel filter. according to the last filter i bough it's only good for 15000 miles.

[maat333]

Of course one should check the easy inexpensive possibilities first, like fuel and air filter, plugs, temperature sensors, etc.
Then more difficult things like fuel pump pressure, air mass sensor, O2 sensor, etc.

But the O2 system is an attempt at a feedback loop that simply can never work exactly right.
You can use a variable resistor in series and one in parallel, to try increasing or decreasing the O2 sensor resistence slightly, to see if that helps temporarily.
That will help determine if it is too rich or too lean and give you better performance while you try to firgure it out.

[maat333]

If you want to use variable resisters to modify the 02 sensor for better idle and more power, start with the resistor in parallel set to infinite ohms, and the one in series set to 0 ohms. That starts you with the same condition you had without the variable resisiters.
Then if you want to increase resistence slightly, adjust the series resistor. To decrease resistence slightly, adjust the parrallel one.

[kidgrok]

I noticed this thread...dead thread?...and found it interesting since my own 2K Ford Focus wagon has exhibited a similar problem for the past three months since reaching approx. 78,000 miles--rough idling followed inevitably by stalling and accompanied by the yellow "check engine" light. The latter didn't come on until after the first month or so, but has stayed on ever since. I didn't take the time to fix the problem because it was really more an inconvenience than a debilitating issue--that is, until the missus stalled out in slow traffic on the interstate. So then I got serious with my troubleshooting skills.

To my credit I'd already replace the worn spark plugs immediately after the first signs of poor idling. Didn't change anything but I felt better anyway. So I thought the next step would be cleaning the fuel injectors or having Ford replace the recalled fuel pump mentioned herein. Either of these steps was too time consuming to fit easily into my schedule so I procrastinated. My recent awakening as to the importance of fixing the problem motivated me to do a web search and I found this thread. After reading the comments contained herein I decided to replace the fuel filter--a step that was easily and cheaply accomplished, even on a Sunday. Yes, there was a lot of discolored crap in the old filter (I don't think it had ever been replaced), but no, changing it didn't solve my problem.

That's when I first really paid attention to the engine's noises and remembered one of the first suggested steps in my Ford Escort manual for troubleshooting an idling problem--listen for a vacuum leak. Sure enough, I could hear what seemed like an unduly loud hissing sound which seemed to originate from somewhere behind the intake manifold. After a few minutes of feeling around for a hose of connection that might be the source of the sound, I discovered a deteriorated rubber elbow connected between a hose coming off the right rear side of the rocker cover and an unidentified manifold connected to the rear side of the cylinder head. The rubber had become soft and too pliable and the force of suction had created a hole in the side of the elbow. Although it is a dealer part and one which I will not be able to replace until after Labor Day, a careful application of duct tape has temporarily cured the problem and my Focus now idles perfectly again. Total time of repair (not including unnecessary measures taken): 15 minutes; total cost of necessary parts/mat's: $0.25. Not bad for an amateur!

Anyway, the main reason for my reply to this thread is to inform other Focus owners that this rubber elbow is highly suspect as an 80K maintenance item since I believe it's deterioration is due to poor design and inadequate materials. Moral: if you hear the hiss, heed this heads up!

[TwistedFocus]

i had a similar problem with my car...change your fuel filter just to be on the safe side..wont cost you much..but definetly CHECK your injectors...im willing to bet that its your injectors...also check for vaccum leaks and the fuel pump as well...the pumps are known to be faulty.

[TwistedFocus]

oh and one more thing..if it is your injectors...dont purchase new ones..you can easily clean them with some cleaner and some electric current. They'll be as good as new once you clean them. that goes for anyone else thats thinking of buying new injectors cuz the old ones are dirty or "BAD".

[icthys]

I had the same fuel to lean problem. I found close to the exact same thing as kidgrok found. The difference was mine was completely disconnected. AFter I connected it I have had no problems 20,000 miles later. A very easy fix after I did all of the other recommendations.