Please Help!!! Fuel Mixture Problem...

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

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

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!

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

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.

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.

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.

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

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.

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.

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.

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!

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.

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".

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.

OK,
This is what I did in the past when I have problems. I would try QuikMechanic at:
http://www.ineed1.com/quikmechanic.html

I used them before, and they helped alot. It's alot cheaper than going to the shop and they don't fix it, but charge me $68 or more per hour. It's just $1 anyway, so you can't go wrong.

Chutch

Yep... starting to see a trend here. I just duct taped the same elbow that kidgrok was talking about on my 2000 Focus. Of course, it was Sunday, so I couldn't go get the part. Something so simple after replacing fuel filter, spark plugs and wires (which didn't help the stalling during idle). Word to the wise -- check for vacuum leaks before ANYTHING else at all if you have an idling problem.

I have a 2003 focus with 11 k miles. I was driving home tonight and it stalled at a stop light, and then continued to stall whenever i stop. It seems that the car will not idle once I let go of the gas. There are no engine lights on, i have gas, and the car does not seem to sound any different when I drive. I have noticed that there seems to be alot of issues that could cause the car to stall like this. I have also seen that focus' have had recalls in the past 2000-2002 for stalling problems. I was wondering if anyone had any advice for me?

Welcome, Ukai, to the "Focus-On-Surviving-In-Your-Stalled-Ford- At-A-Busy-Intersection" thread; or "101 Ways to Pamper Your Focus With New Parts It Doesn't Need," or maybe "The Chugging and Dying Support Group." From your request for help I can see you belong to the exclusive and elite group consisting of Every Ford Focus Owner in the World. I don't know if we can help you fix your car, but we can definitely rescue you from any feeling of aloneness while trying.

The symptoms you describe sounds exactly like those caused by the vacuum leak that must have afflicted the head of the engineers who designed the Focus' emission control system and/or the managers who increased Ford's profit margin 25 cents per vehicle by approving the use of parts made out of recycled Hubba Bubba. What I'm saying is, before you spend too much time and money looking for a really complicated, costly cause for the car problems you're experiencing, open the hood and stick your head under it while someone starts the car. No, I'm not suggesting taking the easy way out--at least not yet. Besides, you'll have to do that at the car's other end. Instead, listen for the telltale "hiss" of air entering the engine via an "unauthorized portal," bypassing the many sensor "tollbooths" designed to render your vehicle undriveable if any air is not paying the proper "toll." In the car mechanic's vernacular, this is known as an IBP ("Instant Boat Payment") or, more classically, a "vacuum leak."

I'm fairly convinced that most of the time, when your Ford Focus exhibits the sudden failure to idle properly but seems to run fine when getting sufficient gas, it has fallen victim to a simple vacuum hose failure. In any case, as bskriva states, "check for vacuum leaks before ANYTHING else at all if you have an idling problem"--that is, if you can trust anything from someone named "bskriva." But I'll back that statement and add to it, "if you believe you MUST throw away your money, please just make out a cashier's check in my name and forward it to me." Good luck!

I had suffered through the same problem with my 01 Focus Zx3. At 20k, with the car still under warranty, it exhibited the stumbling idle and just generally poor throttle response and fuel economy. I let it go for a while until the CE light came on.

The dealer replaced the EGR valve under a TSB the first time. It fixed the problem but now it has occured again at 38k. I replaced the EGR valve this time because the syptoms were the same but no CE light. ( I didn't feel like paying the dealer or anyone else $60 to diagnose the car and finding nothing wrong. You know how it is, no CE light, nothing is wrong when the tech looks at it :) )

Car seems to run OK now, stumbling is gone and throttle response is improved. If mileage doesn't improve during this tank, then its something else.

Incidentally, the EGR valve for US Focus Zetec 2.0 engines is $100 and you can only get it from the Ford dealer.

Also, I stupidly forgot to connect the MAF sensor when I put the car back and now I have a CE light. Anyway to fix this without going to the dealer or buying an OBD II computer? Can you borrow an OBD II computer?

Thanks for the replys. I am going to check the vac. tommarrow hopefully its just that. I'm so pissed its only been 11k miles, my last car was a honda and it went 150k without any problems but brakes tires oil etc. I wasn't expecting anything so soon. I'll have to send ford a thank you letter.

Thanks so much to kidgrok and others that posted about checking for vacuum leaks... I have a 99 ford focus and I had the same problems as others.. rough idling ending in the car stalling... It would do fine when driving however. It was just when I was sitting idle it would get really rough and then cut off. I started to go get spark plugs, then went to autozone and got the p0171 code, too lean thing, then i searched on google and found this page.. I listened under the hood and i heard the famous hissing and found this hose coming out of the back of the intake manifold with a rubber elbow like kidgrok described. I stuck my finger back there and felt it trying to be sucked into the hose.. The hose had somehow developed a round hole in it. When I covered it up with ducttape, it fixed the stalling problems. It still sounds like its idling a little bit low, but no more rough idling and stalls. I probably need to get a new hose, because I think its restricting the air flow. Thanks so much, I would have taken it to a dealership and probably gotten charged mega bucks. Just wanted to emphazise you all try and check this before doing anything expensive.

Hello all! A week ago or so, my 2000 Ford Focus began to idle rough and stalled at every stop sign and light that I came across. The engine light eventually made a quick appearance so I had the code pulled and behold it was P0171. I checked these boards and thanks to Kidgrok and others I discovered the very same hose with the vacuum leak. I slapped some duct tape on it in the middle of a Wal-Mart parking lot and holy smoke, it stopped stalling and no more rough idle. Now, I have absolutely no experience with cars except for a few basics. I can't afford to pay someone to fix it and I don't have any male or female friends that have any idea how to fix it. Well, I have Dad but I can't run to him everytime his little girl breaks something. Could someone give me a crash course in the best way to get this little elbow out so I can replace it? Ya'll rock!! Thanks for helping me with the quick fix instead of me spending money (that I don't have) on things that aren't broken.

Thanks,

Neph

I just had to post this to say, wow...I'd spent a good bit of money trying to get my car's idle problem fixed, nobody had any ideas how to fix it. I'd changed both (due to stupidity on the part of the people checking the codes) Oxygen sensors and as I listened to the rough idle I decided to check the Internet and sure enough as mentioned several times in this thread, there was a small lead in a vacuum hose at the back side of the intake manifold...

After spending so much time and money trying to get it fixed, I'm glad I could finally find somewhere I could get to the bottom of things.

Thanks all.

I am definitely going to give kidgrok his due. Same issue, rough idle, P0171 code, but fortunately, I checked this forum before taking the car to a dealer. Reading kidgrok's advice, quote...

"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!" Unquote.

I found EXACTLY the same issue. Big ol' hole in the outside bend of the elbow. I'll buy a part this week, but duct tape once again clears the issue! Thanks everyone, and especially kidgrok!

My 2000 Focus (70K) also started having the same problem and I followed kidgrog's advice. The only difference was that the rubber tubbing connecting to the elbow on the side futhest from the manifold was totally perrished right at the elbow. So much so that the air was actually sucking the pipe inwardsand in so doing it created a hole. Luckily the pipe was long enough so that I could cut a piece off and reconnect the pipe. Walla, problem solved.... thanks kidgrod.

I'm not sure if this will help you, but I had an 89 Mustang that I loaded up with a 301 Cleveland and a C4 transmission. I had the same faults that you Focus people are talking about. After a few "Fire in the hole" close calls, we found that it was the stud nuts holding down the carberator. They were loose.
After tightening, there was no stall and no hesitation.
That was one fine Pony!!!
What I'm saying is, check the intake manifold studs. The nuts may be a wee tad loose.

Greg

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!

Kidgrok (or anyone else): My son's 2000 Focus LX has the same rough idle/stalling problem. It has the 2.0 L Single Port engine. I looked behind the engine at the intake manifold area, but can't seem to find this magical rubber elbow you all are talking about. Can you be more specific about where it is located, or can you send me a part#, picture, or drawing to [email protected]?
Thanks,
Jim

Ahh yes, the good 'ole P0171. The MOST common cause of this is a vacuum leak. For the Zetec 2.0L, the most probable cause is the PCV hose on the bottom front of the intake manifold. You can't buy the elbow seperately, you have to buy the whole hose, which is only about $15-20. Its not very difficult to replace, just disconnect from intake (best way to get to it is from underneath the car), follow the hose to the front of the engine just in front of the t-stat housing next to the exhaust manifold, disconnect and remove and replace. The reason your car(s) run rough and/or stall is because your computer relies heavily upon the Mass Air Flow sensor to tell the PCM how much air is actually going into the engine. When air finds another way of getting into the engine (ie: vacuum leak, intake leak), the PCM sees less air going into the engine and gives it less fuel, causing rough idling and/or stalling. Hope this helps anyone out there.

I had suffered through the same problem with my 01 Focus Zx3. At 20k, with the car still under warranty, it exhibited the stumbling idle and just generally poor throttle response and fuel economy. I let it go for a while until the CE light came on.

The dealer replaced the EGR valve under a TSB the first time. It fixed the problem but now it has occured again at 38k. I replaced the EGR valve this time because the syptoms were the same but no CE light. ( I didn't feel like paying the dealer or anyone else $60 to diagnose the car and finding nothing wrong. You know how it is, no CE light, nothing is wrong when the tech looks at it :) )

Car seems to run OK now, stumbling is gone and throttle response is improved. If mileage doesn't improve during this tank, then its something else.

Incidentally, the EGR valve for US Focus Zetec 2.0 engines is $100 and you can only get it from the Ford dealer.

Also, I stupidly forgot to connect the MAF sensor when I put the car back and now I have a CE light. Anyway to fix this without going to the dealer or buying an OBD II computer? Can you borrow an OBD II computer?

Here is something you can do to get your CE light off. Disconnect both your battery cables from your battery... wait about an hour (just to be sure) and then connect them again... the light will be off and if you connect a computer to the car, it won't show any codes. Hope this works for you... it worked for me.

Stop Bringing Up Old Posts!!!!!!!!!!!

Just wanted to add my thanks to this forum & kidgrok. my daughters 2000 Focus SE recently passed 80k and started to rough idle & throw P0171 codes. after doing the basics, searching for vacuum leaks, that engine is noisey, hard to hear vacuum hiss. but checked the standard hoses no leak. changed both Upstream & downstream O2 sensors and even swapped in a know good DPFE, nothing changed. Found this thread and located the hose that kidgrok mentioned, BINGO the back end near the block on the backside has a hole. wrapped with duct tape, everything is good again. Will be ordering the part this week. Thanks all!!!

It's always nice to know this information is still available and helping people; so chill please, AltecZX2. New threads would not necessarily convey that message.

Anyway, gotta love this Internet thang!!

:)KIDGROK ...PLEASE HELP!

My 2000 Focus LX has the same rough idle/stalling problem. It has the 2.0 L Single Port engine. I looked behind the engine at the intake manifold area, but can't seem to find this magical rubber elbow you all are talking about. Can you be more specific about where it is located, a better explanation, picture, or drawing to [email protected]?
Thanks,
Liz

Wow. Glad I found this. Six years from first post, and I'm having the same problem with a 2001 Ford Focus. Like others have said, right now it's more of an annoyance than a problem. The car will go, and it will restart if it goes dead. I will look for the vacuum leak but I doubt I could replace the elbow myself. Anybody know how much a mechanic would charge?

By the way, I learned the hard way to always check the Internet first when you're having Ford problems. Taking it to the dealership can cost you dearly. A few years back, I paid for a new alternator plus other fixes before the dealer told me that my problem was a bad fuel pump. Then he was going to charge me to replace it when the part was a recalled part! When I found that on the Internet, he fixed it for free, of course. But wonder what the dealer would have done if I hadn't seen it online.