Mercury Mountaineer Start Stall Idle Problems

mnpaulmnpaul Member Posts: 11
edited October 2021 in Mercury
Hi all...Frustrated Mountaineer owner here--My 2002 Mountaineer has been stalling at 70 MPH on the freeway. It staills at slow speeds, at stop signs etc. Dealer CANNOT get it to fail of course. It appears to be fuel related. I have seen "Fuel error" message on the display. It will restart immediately. It can run fine for a couple of trips, then it will fail. I put a can of Gummout cleaner in the fuel and it's working through that now. Any ideas?


  • oluade76oluade76 Member Posts: 6
    Hmm..... if its fuel related... EGR?

    Why not try this......
    Use gas until nearly empty and fill-up at a brandname station like chevron/texaco

    Take it to a different dealership and perform - throttle service (combustion camber) change fuel filter etc.

    Using gumout might not be good for a classy SUV like Mountaineer. Instead try Techron system cleaner

    Just my 2 cent
  • mnpaulmnpaul Member Posts: 11
    Hi oluade76, thank you so much for your input. I use Mobil gas all the time, so that's a constant (as constant as it can be) Additionally in fact, I did use Gummout Professional cleaner this past weekend. It got worse, (more stalling), but it could be cleaning--who knows.---it's been parked since Sunday as I am out of town. The dealership called me this week (after bad feedback from me on a phone survey) and of course they want it back in when they can attach the "black box" to trap the error codes when it fails for me. I will see what that brings. Thanks again.
  • djanthenedjanthene Member Posts: 1
    I have a 2004 Mercury Mountaineer and I am having the same issues. The vehicle is stalling on me at 50 MPH. I have had it in to the dealership twice this week. They still have it, since Saturday. They replaced the fuel pump and it stalled 20 minutes down the road after I picked it up. So, there it sits at the dealership till they can figure it out. They have no idea what is wrong. When they went to bring it into the shop after I dropped it wouldn't start, now I guess my battery is dead and needs to be replaced, I never had trouble with it before. So, after talking to the tech today for 20 minutes I decided to call Mercury, and report this to them. Please do the same so that they can start researching it. The more they hear from us the better off we are with them trying to find out what is wrong. Here is the website: I called 1-800-521-4140. They are escalating it to their escalations group and I should hear back from them in 2-3 days. I love my vehicle but I am NOT willing to endanger myself or my family because they can't figure out what is wrong with it. If anyone figures it out before they do please share. :confuse:
  • mnpaulmnpaul Member Posts: 11
    Hi all,

    Well I wanted to update everyone on my vehicle status. I have been out of town for the last couple of weeks since adding the "Gumout Regane Complete Fuel System Cleaner" (purchased at Target. I did some drving yesterday for the first time in 2 weeks and the vehicle stalled twice on the freeway. On my return trip (about 20 miles) and today with a 40 mile or so trip--NO stalling occured. Of course I am not 100% convinced this issue is resolved, but it's good new nontheless. The symptoms keeps pointing to a fuel issue and something being clogged. The stalling became worse when the Gumout was hitting the engine, but it appears that it has passed it (like Draino) and hopefully has cleared the issue. I am going to try to drive the vehicle as much as I can this weekend, as I have an appt at the Ford Dealership on Monday am and of course I would LOVE to cancel it.

    I will update everyone on my progress the rest of the weekend.

    Just be advised if you do have the same issue as I indicate above (frequent stalling at high speeds) becareful when/where you add the Gumout. The instructions say to get to a really low gas tank, add the Gumout and fill it up with fresh gas. I did this and once the Gumout hit the engine & fuel system it stalled many times. Stay on local streets unitl it works it through. The Saturday I added the Gumout, was the worst ever, it must have stalled at least 6 times in a couple mile radius before I parked it for a couple of weeks.

    Good Luck

    I'd love to hear other stories relating to this issue.
  • mnpaulmnpaul Member Posts: 11
    Hi all, just an update--several hundred miles and NO more stalling. I am convinced the Gumout solved the problem. Give it a try.

    Good luck
  • mnpaulmnpaul Member Posts: 11

    Did you ever get a resolution? My issues are back after a sucessful 4-5 full tanks of gas and now the stalling started this past weekend. I put a bottle of Heet in the gas tank and had less stalls (1 at 50 mph in a 200 mile trip home yesterday)

    Any updates would be appreciated. I am thinkiing about changing the Air Control Valve (from a previous poster), but I am not sure if that's my exact problem, since its stallling at high speed (not just at idle)

  • melvyn_cincymelvyn_cincy Member Posts: 2
    Amazing I have a 2002 Mountaineer V8 with the same issue, started 3 yrs ago. Mercury/Ford claims they have never seen this before. Mainly stalls when car comes to a stop sign in the mornings, never had a high speed stall. I have replaced fuel filter and air control valve. Knock on wood, car has not stalled in the last 6 months.
  • mnpaulmnpaul Member Posts: 11

    The stalling came back this winter. I then decided to add a bottle of HEET to each gas tank when I fill up (live in MN) and it solved the problem. The car is stored in a warm garage, is not run often (live in the city) I am thinking that it is some type of condensation build up that that HEET resolves.

    I will continue to add HEET to every fill up regardless of the outside temp. It appears to fix whatever is causing this annoying & unsafe problem.

    Good luck!
  • droid1droid1 Member Posts: 1
    greetings We have an 02 mercury mountianeer that seems not to like spring weather.
    the problem stated April 07 thru June 07, my wife would take short trips maybe 10 to 20 miles, on a hot or warmer than normal day time temp in Minnesota during the time shown. The car would run fine, she would turn it off do whatever errand she was doing and then car would not start. we tried several remidities including user a higher octane gas and even replacing the battery ( first thought the battery was at a minimum 5 years old). Of course when the car was at the dealer they could not get the problem to repeat.
    We took the Mountaineer to another dealer and they replaced the DPFE sensor in July of 07. Until then to now the problem went away.
    Now to today ( April 21 08) and once again Minneapolis had the warm est day of the year so far a whopping 76 degrees. the morning stated out cool not cold so when my wife went to work the car ran fine when she went to start the car in the afternoon after having sat out all day it did not want to start. after several attempts she decided to let it sit. We waited to approx 8 PM to try and start the car and of course it started.
    My question is are we expierencing a vapor lock issue or is there something else at hand?
  • melvyn_cincymelvyn_cincy Member Posts: 2
    Similar stall issues, not sure if it related but dealership just replace my "vent soleniod" as part of evaporative emission system. I also had issues refueling the truck, the pump at gas stations would keep tripping the auto-shut off. They has to drop the fuel tank to get at the vent soleniod. Good luck.
  • mnpaulmnpaul Member Posts: 11
    Very good idea to explore. I am still putting in HEET into the gas tank every fill up and when it's 90, it's hard to find stock till the winter sets in again. Water in the gas line seems to be the your idea could be something that would work. I am sure it would be expensive and my warranty is up...Ughh! Thanks again!
  • kmmbrenizerkmmbrenizer Member Posts: 2
    I have a 2004 Mercury Mountaineer that has been stalling at stop signs, stop lights, and any other time I slow down to turn. It's so scary! First, the battery light comes on (I think cause the engine dies) then the a light comes on that says High temp/low pressure. It wills start right back up. I just bought this truck in March. It's so frusterating. Do you guys thinks it's the same thing thats happening to your Mountaineers?

    I live in MN as well and had no problems until it started warming up outisde.

  • mnpaulmnpaul Member Posts: 11
    Sure sounds like the same thing --but mine dies on the freeway at 60 mph and slow speeds, so it's not very specific.

    Try HEET and see what happens.

    The post last week is interesting, as it all seeem to be related to condensation in the fuel line...

    Let us know...
  • bh2000bh2000 Member Posts: 1
    I highly recommend an induction cleaning service. On many ford/mercury SUV's I have seen similar stalling problems and have chased them one by one, including cleaning the injectors, fuel filter, etc., depending on the codes. However the one thing that seemed to resolve the most frequent problem of stalling at a stop sign, whenever you take your foot off the gas pedal, was an induction service.

    It is very important to keep your air filter clean, once carbon builds up in the intake manifold, your vehicle will begin to stall. The codes may not always point to the exact problem.

    I recommend a BG Induction service if you have never had this done and your vehilce is over 65,000 miles.
  • chasanthonychasanthony Member Posts: 4
    Mercury Mountaineer 2004, AWD, V8.
    Bought this used with 40k miles on it.
    The engine dies (dead) when using the cruise control.
    Example, you are driving down the road at 40 mph and set the cruise
    control, several minutes pass by and suddenly the engine is dead.
    Most of the warning lights in the instrument cluster come on.
    Naturally you have to slip it into neutral or struggle to the side of the road, without
    power steering, put it in park and restart. It restarts everytime.
    This problem happens randomly however only when using the cruise control.
    It does not appear to be mileage or time related, in other words the engine can die
    after 5 miles of 10 miles of cruising, or it can die after 1 minute or 10 minutes of cruising. Outside temperature does not seem to matter, it could be cold or hot outside and it could die.

    I've tried adding "gumout" and "fuel injector" fuel and tank cleaners. I don't sense
    the problem is fuel related but rather a gremlin in the engine management system that involves the cruise control.

    I stopped at a local autoparts store that offers a free service where they will scan your OBII or whatever port that is with their scanner. NO codes showed up.
    I thought about borrowing or buying something I could hook up to the port to try to catch a code but don't know what to buy or borrow or whether the cars computer will be savvy enough to catch or remember the fault.

    I have seen the same problem posted on the NHTSA website however can't find any recommendations.

    Anybody else out there having an engine dies with cruise control problem?
  • pgskal31pgskal31 Member Posts: 1
    I changed the battery on my 2004 Mountaineer and it hasn't been running good since then. It stalls at times when starting, at a stop sign, or in reverse. I've changed the air & fuel filters and spark plugs. Nothing comes up on the computer at the service station. I've tried Gumout but still have the same issue. Any ideas on what the problem might be?
  • Randy_74Randy_74 Member Posts: 2
    2004 Explorer 4.6Liter V8 doing the same thing. Any luck solving this problem?
  • chasanthonychasanthony Member Posts: 4
    Nope. The engine still dies with cruise at slow speeds. I've never resolved the problem. However, I have been able to make it happen more often:
    Simply put it in cruise.
    Then go down a hill.
    As the engine rpms drop they keep dropping until somewhere under 500 rpms the engine will die, not all the time but very often.

    I read a post where someone suggesting having the computer reflashed may fix the problem but my local Ford dealer closed up shop and I'd have to drive a distance,
    I think the other dealer quoted something under $100.00 to reflash the computer but would not guarantee a fix.
  • qbnqbn Member Posts: 1
    I had this problem happened to me last week in the shopping mall parking lot. The car stalled and the signal displayed High Temp / Low Oil pressure like veryone stated here. The car started within seconds without any issues and I have been driving for a week now without noticing anything odd with the car. I have been buying regular 87 octane gas as suggested and buying from a very reputable station (BP).

    This is my very first time encountered such odd problem with my Mountaineer. I bought this SUV used at 25K 3 years ago and now I have 83K on the odometer. I've been very pleased with the vehicle so far, well, besides the gas sipping happy.

    I called the dealership and told them about the issue and they told me that they never heard of this symptom before. Of course, they suggested that I bring my vehicle in for inspection (-:

    I will head down to my local Autozone to have them pull the code of the vehicle and see what type of codes they can pull from the vehicle. By the way, this is a free service provided by Autozone.

    The other tging I can think of is, when did I replaced my fuel filter??? Not exactly sure, but I am going to have it replaced this Saturday for sure.

    I really like the vehicle and I am not ready for any car payments at this time yet. So, I am going to find out what I can do before trading it in for some else.

    Thanks for reading my post.

    Have an awesome New Year everyone!!

  • kcardwellkcardwell Member Posts: 1
    Just broke 90k wants to stall when not under acceleration. Fuel pump was replace 6months ago . Sounds like intake may have leak ? Thought someone might know seeing how my MC is off until Monday!!
  • gkaygkay Member Posts: 2
    No body that I see has found a cure for it yet.
    I have had this issue for about 3 months now. I have put enough Gumout and tektron in the tank to build a refinery.

    I brought it to my mechanic today and he says it is my "MASS FLOW" sensor on the air intake/filter gizmo. He says its 250 or so. Last year I paid about 600 for him to clear the error light messages so I could pass inspection. $600 because he changed all air sensors one at a time!

    Okay back to symptoms: The stalling comes and goes. Some times I am ready to have the SUV towed and then it may disappear for weeks.
    Always happens when you hold a steady pedal. That is why it dies when using Cruise Control.

    Anyone else add to this?
  • kmmbrenizerkmmbrenizer Member Posts: 2
    We finally figured out why my 2004 Mercury Mountaineer was stalling. This was happening when I slowed down, it would just shut off and say low oil pressure. sometimes it would go into engine fail safe mode. My husband found a posting online. We brought it into Ford last fall 08 and they did 1500 worth of work but it started doing it again.

    We brought it again with the bulletin he found online and they replaced the THROTTLE POSITION SENSOR. It has NOT happened in two months!!!! IF YOU ARE HAVING THESE ISSUES-get this checked! IT was $200 with parts and labor!!!
  • gkaygkay Member Posts: 2
    Thank for the info.
    Wow, isn't the internet great!
  • bballengeebballengee Member Posts: 1
    I'm not sure if this will help, but I ran into a similar problem with my 2000 Mountaineer (30K miles). Every thing fine until one morning I tried to start it for a minor errand. Wouldn't start - starter spun the engine, but nothing happened. I squirted some starting fluid into the intake and tried to start - engine fired on a couple of cylinders. Checked the fuel pump relays - both checked ok. Figured bad fuel pump. Had the car towed to dealer who confirmed bad pump. Dealer replaced pump assembly and everything was fine. Next, ran into problems when gas tank got down to about 3/8 full or less. Going down a slight incline for about 30 seconds, the gas gauge would drop from 3/8 to empty and the engine would shut off - not fun on the interstate. Took it back to dealer - couldn't duplicate the problem - no codes showing. Picked the car up from dealer and drove it to the back of his lot and drove it down an incline to the street - it stalled. Dealer said OOPs, we'll check it out. Dealer found that it always stalled on an incline and would restart when you coasted to a level area and let it sit for 5 - 10 seconds. Still no codes showing, but dealer said Ford recommended upgrading to a newer model fuel pump assembly at higher cost. I said fine - it's on your dime. Dealer replaced pump assembly with another original OEM part - no problems since.

    My guess is there is something flaky with the pump or sending unit with these cars and Ford doesn't want to fix it with a recall. A fuel pump shouldn't go out at 30K miles, much less die on the interstate at 60 - 70 MPH when you happen to be going down a long incline.
  • chasanthonychasanthony Member Posts: 4
    2004 Merc Mountaineer Premier with V8

    The plug on the driver's side closest to the firewall fouled. When I remove the coil and spark plug boot there was lots of water and rust inside and around the boot. I had to replace the coil and plug. Just plain water, no antifreeze. Anyone else have this problem? Is there a problem with the way water (rain or car wash) spills across the top of the engine?
  • tpr1tpr1 Member Posts: 1
    did you replace the IAC, Idle air control? my 2002 mountaineer was stalling on me and thats what the mechanic replaced. it worked fine afterwords for about a year, and not it is idling to fast. time to get rid of it.

    good luck

  • fitz123fitz123 Member Posts: 2
    It seems like many of you have had the same problem. I hadn't had many problems with my car in the years I've owned it- I bought it with about 15K miles and it has 73K now. About three months ago my car stalled while I was driving about 35 mph. It started up again after a couple of minutes. A couple of weeks later I shut the car off after doing errands and after about 30 minutes tried to go back out, but the car was unresponsive (made a clicking sound when I tried to start it, but nothing else). I had it jumped and it was fine for another two weeks or so. Then, while parked out on a beach, it was dead when I tried to start it. I had it jumped again and the next day had a new battery was put in. The following week the car stalled again (at 35mph). It wouldn't start back up for me, but once it was towed to a garage, it did start (about an hour and a half after it died). The garage had it for the day and found nothing wrong. I then brought it to a dealer, who kept it for 2 days, found no codes and nothing wrong. They changed the oil and filter. It stalled again two nights ago (again while driving 35 mph) and did start back up after about a minute. The dash lights all lit up as it died. The dealer had it the entire next day again, found no codes and NOTHING wrong. They suggest they keep it for several days to see if it will happen while they are driving it. It's my only means of transportation, so I don't want to do that. It is extremely frustrating and I feel like it's not safe to drive (I often have a child in the car) and worry about it happening on the highway. After reading all of the blogs about this I am not sure if anyone has found a true solution. Can you let me know if you have done something that has completely stopped the stalling???
  • defectivemntnrdefectivemntnr Member Posts: 1
    I leased this mountaineer at the end of 2007. It was great until April of 09 when it began randomly not starting. By then it was just outside of the lemon law, too bad because it's really a :lemon: The vehicle continuously has this problem even after taking it to 3 different dealerships. The first two times they couldn't find anything wrong. The third time they replaced the alternator. When the problem continued and became worse-everyday there was a point when it wouldn't start-I took it to a different dealership and they replaced the starter. Still the problem continued. So I brought it it back and they had it for FOUR weeks before determining it was a bad relay, which they repaired. Less than a week later the problem continued, on the fourth of July, my 3 yr-old and I were stranded in a hot parking lot waiting for over an hour for roadside assistance because the mountaineer would not start. Next I took it to a third dealership, this time Ford sent a Secial Ford Engineer to inspect the vehicle. They determined that it was a bad battery, replaced it and happily sent me home. That very night it wouldn't start. It continues to have these episodes of not starting and all Ford can say is to have it repaired. This is totally ridiculous since six attempts at repair and even the special ford engineer can't seem to fix it. Has anyone else had this problem? Ford is losing a loyal customer because this is the third mountaineer that I've had and the last, I can't wait to get rid of it.
  • chasanthonychasanthony Member Posts: 4
    Its been several months since I had the "stalling with cruise control" issue.
    That's because I have not used the cruise control in several months.
    This evening I was cruisin on a road and set the cruise control.
    When I started to go down a hill naturally the cruise control should
    back off the throttle and it did. However when the rpm's dropped below
    500 the engine died and it was just as i was going around a corner.
    Do you know what it feels like to lose your power assist going around
    a corner, its like suddenly trying to steer an 18 wheeler if you are not prepared for it.

    So I have been reading all the posts here about my stalling issuing and many of you have a different problem than I. It seems your cars die randomly. Either they don't start or they simply die whenever. That is not my problem.

    If you can imagine the engine management system (ECU or whatever we call it today), trying to keep the engine at giving running condition. This may include adjust the timing, injecting more or less fuel depending if its trying to create power or keep the emissions in the happy range. I was thinking what engine computer code might say something like "if the cruise control is on and the poor son of b is suddenly driving down a hill, then don't let the rpms drop below 'idle". You know what I'm saying. I can't think of any engine component other than the computer that would monitor such a situation.

    So engine guru's do you think this is a code problem or component problem?
  • jenerisjeneris Member Posts: 1
    I have a 2004 Mercury Mountaineer....bought it brand new.

    1) The cruise control....failed before the warranty was up. Would do what everyone else is saying....shut the engine down & have to pull over to the side of the road to restart. It would always restart just fine. Took it in to Ford/Mercury dealer & they claimed to have fixed it...the next time I used it, it did the exact same thing. This was happening back when the Ford trucks were mysteriously starting on fire while parked in the garage. Some theories out there were the electrical system or cruise I figured I'm just better off not using the cruise control. No big deal.

    2) The past 6 months it has randomly been stalling or wanting to stall while idle in traffic or at very slow speeds. Doesn't happen all the time, sometimes I can go a week or so with no problem & then it just shows up again. Restarts just fine, no real issues than the nervousness of stalling on a busy street. Check engine light had been on prior to this ever happening & I took it to my mechanic back when the light came on. He said it was just a faulty sensor & it would be approx $300 to replace. He assured me nothing was wrong, so I opted not to have it fixed at that time.

    Since it's been stalling a little more frequently (but luckily not at high speeds), I took it to my mechanic yesterday. I'm not really sure what the deal is, he said he had to order some parts. He fixed my SUV & I picked it up today, but he's behind on his paperwork so I'll go in on Monday to settle up the bill & see what he replaced. I drove it around a little bit tonight and it was fine. Seemed to have more power than ever, but we'll see how it handles over the weekend .
  • 3csunshine3csunshine Member Posts: 1
    Are you as fustrated as me? Mine is randomly stalling going at 20-35 mph. I put it in N and it turns right back over.
  • bellenbellen Member Posts: 1
    I have had this same problem with my 2007 Mountaineer. Just today I had to replace the plug, coil, and boot for the third time.... still no recall though!
  • neversaynoneversayno Member Posts: 1
    What did you ever find out? im having the same issue
  • fitz123fitz123 Member Posts: 2
    I brought it to a dealership a couple of times... The last thing they did seemed to make a difference, which was basically clean the throttle. I'm not a car person so I honestly don't even know what that means, but they said it was very dirty (I bring it oversand a lot, so that may have contributed?). Anyway, I have not had an issue since, although I still don't trust it 100%. Good luck!
  • abel10abel10 Member Posts: 1
    My 2002 Mercury Mountaineer will start, but immediately (slowly) turn back off. It will only stay on if I hold down gas pedal (accelerate). My friend's mechanic looked at it, not sure if he's good mechanic , but i'm broke so I let him. He told me it might have something to do with throttle body. Said he cleaned it and washed air filter. It ran good for about 1 week, but it's started doing same thing this morning. Jiffy Lube also suggested I change air filter. Check engine light is NOT on. Once in a while it makes a noise when I turn on. Similar noise when car is already on, and you try turning ignition or overturning. They told me I'll probably need starter soon. Might be seperate issue. Don't want to throw money away.. Please help. Thanks
  • judiannejudianne Member Posts: 1
    Hi there - well, I do love my mountaineer. It is a 2003 V8 AWD. I bought new with 6 miles in 10/2003 and have since then driven quite a bit. The odometer now reads 279,864 (thats miles). Same engine, same transmission, even the same starter. I guess mine was built on a very good day! The body is 100%. The leather on my drivers seat is cracking a bit though, but oh well.

    Anyway, I just started having this really bizarre problem that three mechanics have looked at and nobody can answer. There is some little cap on the back of the engine that keeps blowing off and anti-freeze pours out everywhere. The man who owns the garage that is working on my car has know it since it was a baby, so obviously, he has done gone by my car, and me. But this one is kind of a stumper. I'm hoping to get another 100,000 out of it since I have childen in college, so if anyone has any suggestions, please let me know! I don't know if this is just some oddity...or if it could indicate a problem that can possibly be fixed before it is a disaster!

    thank you so much!
  • sulemasulema Member Posts: 1
    This just happened to me!!! What was your outcome? What did it turn out to be?
  • fpa4ufpa4u Member Posts: 1
    On my way home from KY to NJ I broke down in PA. The truck stalled at 70mph. The only code was a crack sensor issue. I replaced it and got back on the road again. Light came back on but no more stalling at speed. Now I took it to one guy and he said I had blow heads. So I did a little research and found that the intake manifolds fail often. Well sure enough the manifold was leaking into the injectors plugs etc...So we replaced the manifold on Sat but now it stalls like crazy so we are going to clean the injectors this weekend. I will update and let you know. Also have a noise that sounds like a diesel when in gear. I just had the trans checked today and it is fine. We are also replacing the fly wheel this weekend as the trans guy said the noise is coming from there but he wanted $1,000 bucks to replace a $62 not happening...
  • 1aucoin1aucoin Member Posts: 1
    please help.3 days ago i replaced the manifold gaskets to stop coolant leak. now its running very rough,it also has a knocking sound from the oil sounds like the motor is bogging out, rpm will not get over 1500 ,cataylic converter was glowing red hot last night. at first i thought it was just a vaccum leak, guess not. before i replace gaskets it did run hot and i had to tow home. could i have messed up my motor. i have no coolant or oil leak now, though. if any one has an idea that would be GREAT, THANKS
  • locannislocannis Member Posts: 1
    has anyone found a solution for this issue? Starts then shuts off unless holding gas pedal.
  • dkt2dkt2 Member Posts: 1

    Has anyone found the reason for this? I have a 2004 Mercury Mountaineer SUV and it is going dead when I slow down to about 30 or stop at lights. Very bad when on a busy street for this to happen. Was hoping to keep it for a while longer because wife is having lots of health problems and doctor bills.

  • ckg3ckg3 Member Posts: 1

    Hoping this is of help to some folks. I had very similiar issues to what is mentioned in this thread. I had a Mazda MPV with a Ford Duratec V6 (2004). The issue turned out to be related to a few things. 1) I changed out my ignition coil packs. This engine gets water on the coil pack which causes a misfire due to the short circuit intermittently when the spark plugs fire and the moisture accumulate under the boot. 2) I also had the throttle body cleaned for carbon from the misfires I just mentioned. The 3rd and most important thing I believe is I replaced the Idle Air control valve. This adjusts the air for the engine at idle and can stick when there is carbon buildup in the intake manifold giving your engine too much or too little air at idle and when accelerating and cause a stall. This thing was like $50 or less at Autozone and super easy to change just 1 nut and 15 minutes. About the same work/complexity as changing a air filter.

  • buckeye_amgbuckeye_amg Member Posts: 1
    I have the same stalling at low idle problem (under 500 RPM) with my 2003 Mountaineer 4.6L V8 AWD. I have searched many forums and spent 3 weekends on this problem.
    I think I may have solved it with worldwide help.
    1. Weekend one - Replaced Crankshaft Position Sensor & Serpentine Belt (No change with problem)
    2. Weekend two - Throttle Position Sensor & Mass Air Flow Sensor (No change with problem)
    3. Weekend three - Idle Air Control Valve with Gasket ( Major IMPROVEMENT!!!!!)

    I think weekend 3 did the trick. And it was the easy one to replace. $75.00 from Autozone with a lifetime warranty. Easy removal and install. Remove Negative battery terminal. Carefully remove IAC Valve electrical connector. Remove 2 8mm bolts. Remove old gasket. Install by reverse order these instructions.

    Now after racing the engine to 2500 RPM while in park then letting off the gas pedal. The computer auto revs when the RPMs hit 600.

    I hope this helps someone.

    Good Luck
  • jd688jd688 Member Posts: 4
    Your description sounded similar to what I'm going through with my 2008 Mountaineer, problem is, I don't have an IAC with mine. My computer is telling the engine to rev at a high RPM on startup, then keeps it above 1100. Then when I shift into R or D it kills the engine. Engine starts right back up, but the only way to get going is to apply the gas while shifting into Drive. Tell me THAT's good for the transmission. My mechanic can't determine what's going on because the computer isn't throwing any codes. I think the computer's sick, but doesn't know it. I'm driving with HAL from 2001 Space Odyssey.
  • clint355clint355 Member Posts: 1
    edited October 2017
    Hi fellow mountaineers. i have a 2004 4.6L mountaineer with the same problems" won't idle or accelerate no power at all. So i disconnected the exhaust line from the EGR valve, and my engine idle was good. I took it around the block and it ran fine, when i got back home, i took off the two o2 sensors at the bottom of the upper catalytic converter. My engine power was good and it ran normal. To solve the problem I realize it was the lower catalytic converter, it was blocked to capacity. I really don't know how the car was running, I used a direct fit system I bought on line and now it run"s great.......i hope this helps some one
  • EliseElise Member Posts: 1
    When you say stalling do you mean it's actually cutting off or trying to cut off running power as you're driving or do you mean it's not shifting gears efficiently when trying to gain speed in that feed range? Because if you're talkin about it's not shifting efficiently I call it bucking and I've done a lot of research on it because my Mountaineer does the same thing and has right around when we hit a hundred and fifty thousand mile marker shortly after buying it used one owner previous. Makes a quite dangerous when trying to merge with traffic on the highway therefore I never drive on the highway anymore unless I have to also becomes quite annoying when you're trying to cross roads from a stop sign and your kind of stalling out there in the middle of the street diagonally trying to cross over a road with oncoming traffic coming at you. I've done a ton of research best I could find is that this is a common issue some recalls ride on but leaving out owners from 2000 through 2008 of the Mercury Mountaineer at least to my knowledge there could be older other vehicles as well because I know this was Associated to two other vehicles having the same issue as well including the Third vehicle with this issue being the Mountaineer between 2002 to 2012 or 2014 owners submitting these complaints about this issue for the Mountaineer. Those recalls that were issued on the newer models where is you'd quite a few years ago about five or six I think maybe even more so it's looking like they're probably just going to neglect the older vehicles still having issues and owners submitted complaints...
  • @mnpaul said:
    Hi all...Frustrated Mountaineer owner here--My 2002 Mountaineer has been stalling at 70 MPH on the freeway. It staills at slow speeds, at stop signs etc. Dealer CANNOT get it to fail of course. It appears to be fuel related. I have seen "Fuel error" message on the display. It will restart immediately. It can run fine for a couple of trips, then it will fail. I put a can of Gummout cleaner in the fuel and it's working through that now. Any ideas?

  • JWrightJWright Member Posts: 1
    I have a 1994 Mercery Sable SW that stalled only going around corners and at stop lights. I finally fixed the problem by cleaning the IAC (Idle Air Control Valve). It's just two screws to remove and carbon cleaner with a q-tip. MAGIC. I need to do this about once a year and it runs beautifully now.
    Here's a video that helped me do this:
    (It's so easy that I am someone who NEVER works on cars and could do it).
    Of course, remember I have an old car with not so many computerized equipment that gets in the way of fixing things. So if you are in doubt yourself, have your mechanic check this first.

  • crumblingcookiecrumblingcookie Member Posts: 1
    2008 Mountaineer survivor here-Engine stalls out at the most inconvenient times (i.e. going up a hill at 10 miles and hour, during 5pm traffic in the city, etc.) It starts right back up though. My mechanic has no idea what it could be; no codes came up on the computer. I'm about to try cleaning the idol air control valve though, just because I'm at my whits end. Daily driver. Sending thoughts out to anyone else stuck with this blasted thing. Anyone else plagued out there?
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