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2001 Ford Mustang v6 stalling when coasting or sometimes braking

4567 Views 7 Replies 2 Participants Last post by  WhiteSnake91
I received a 2001 Ford Mustang v6 with true dual exhaust (sounds nice ;D) in a trade about a week ago but recently have had some trouble with it stalling....first noticed it the other day when I was leaving my house to go to the court house to get the title officially in my name, stopped by the local garage to get a fuel pressure test and they did it and the man told me the fuel pressure isn't low, it's erratic going up and down which is puzzling to me.

I've done my share of reading, although I'm new to cars. I'd really like to get this thing in tip top shape. I've ordered brand new all Motorcraft brand spark plugs, spark plug wires, and ignition coil which are set to come this week. In an older forum post, a man had the same problem with the stalling/hesitation and replacing the ignition coil fixed it for him so hopefully it's an easy fix.

I replaced the fuel filter the other day but that didn't fix the stalling issue sadly, I don't think it had ever been changed before, was very hard to get off like it was almost bonded on, but after an entire afternoon of messing with it, I got it off and replaced it.

I need to solder the instrument cluster to get the odometer to work, it's sporadic, but I've already watched how to do that, and I need to get a new light bulb for the cluster since the check engine light doesn't light up at all. I have several codes I got when I scanned it with my scanner last night. Last night when going to the store and finding a parking space when coasting and braking at a turn in the parking lot, the car acted like it was about to stall again but didn't truly die, but the gas pedal did nothing even pressed down firmly, it sort of sputtered then surged ahead and I had to brake quickly and I parked it. When I was done at the store it cranked right back up though. The problem seems to be when coasting/braking...I saw how to put a fuel pump in, I heard Delphi is a really good brand especially considering the price. I just personally dread dropping the gas tank since getting the fuel filter off the other day took so long.

codes I have: p1233, p1131, p1151. The p1131 and p1151 are for both front o2 sensors, I'm thinking maybe it's just tied to the bad fuel pump, I don't have ANY history on the car so I don't even know if it's been changed before or if it's even the original motor/tranny, the ODO reads ~244k, a little high for a 2001 model, but it actually drives fine, appears to still have a good strong engine and transmission. My gas milage, is, okish. Not gas guzzling, but not the ~17mpg/25mpg highway the online specs say it should have. I'm not sure how much MPG the dual exhaust is supposed to increase it by, I know roughly in trucks it's supposed to give about maybe 4mpg more. So optimally with the dual exhaust I'd get about 21 city and 30 highway. Somebody can correct me on this, I mean again, I admit, I'm new to vehicles PERIOD, but I've done alot of reading/watching videos.

what I'm going to replace this week, all spark plugs, spark plug wires, ignition coil...all OEM Ford Motorcraft brand

What I think is bad: The fuel pump. Although my dad, and from reading up on it, both say if the fuel pump is bad the car will be hard to crank, which isn't true, it always starts right up, one or two times it's taken a second or 2 longer to crank, but it's always cranked right up. Battery says it was made in 9-15 on it, so not even a year old, oil doesn't look bad, the radiator reservior or hose has a small leak if I fill it too high, I'll be looking into fixing that sometime.

what could possible be bad:eek:ld worn out spark plugs, spark plug wires, ignition coil. I have no idea how many miles/how old they are sadly. The IAC could be bad, MAF could be dirty, Fuel Pressure Regulator on the fuel rail could be bad, fuel pump driver module in the trunk could be bad, fuel pump relay could be bad, or obviously again, the fuel pump. But you'd figure if the fuel pump was bad it wouldn't always crank right up and the pressure would be ok would it? The mechanic just said the pressure was erratic like going up and down.

If it IS the fuel pump, it's not the end of the world. I'd just like to not spend a bunch of money on one and that not be the right problem, I live on a tight budget and would feel very sad to throw money on parts I know wouldn't fix it. It did need a tune up the man I got it from said, and reading about ignition problems causing stalling also made me order the Motorcraft spark plugs,wire, and ignition coil.

Hope I was fairly descriptive with the problem and what I've researched on and what I think is the problem or what could be the problem. Thank you for any help.

also another quick question, it's not DIRE but is very annoying...I think the seat belt sensor in my seat is bad too, it's plugged in, I'm always paranoid about having my seatbelt on (which isn't a bad thing...), but, the dashboard light stays on and keeps BEEPING every so often, very annoying...just started doing that last night. Is there anyway to stop it...? Spray cleaner in the seat belt buckle?
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I'm not sure how long it will take to be approved, I'm assuming since I linked to other forum posts where people had the same problem, but my long reply is in limbo. However, just now on a late night munchies run to the store, it did the hesitating/almost stalling thing again and I gave it gas and it took a sec or 2 then it surged ahead when I had stopped at the exit of the road entering the store. Didn't die though. I got out and inspected the suspected worn ground wire but I was wrong, it's just an old piece of ducktape somebody placed there that had come undone and the ductape's fibers were sticking out, the actual wire is fine.

I'm not sure what brand the spark plug wires are, they're grey and say Made in USA in yellow on it, but I know for SURE the ignition coil is some very cheap offbrand, I've seen how the good motorcraft one is supposed to look like, with the purple sticker on front and on the back the yellowish gel, on this one, there's no sticker at all and on the back there's no gel only a big piece of black plastic. So a cheap offbrand ignition coil is definitely a cause of concern to me. Hopefully the new one comes in today. Knowing that, I dread looking at the likely very cheap dollar store brand spark plugs which are probably very worn (lol...)

on the oil level in the car's instrument cluster it shows good right in the middle I believe, I can visibly see the battery meter move a little lower than the middle and then it moves back up to pretty much dead center or a little above center on the battery meter on the instrument cluster when I crank it, the coolant level stays all the way on the left in the COOL range.

edit: you know what? Now that I think about it, these stalling problems started happening (although intermittently a few days later) after I took out the factory radio/cd player which didn't work, and installed an aftermarket XO brand stereo...same kind I had in my previous car, nice little cheap 20 dollar one from walmart for just playing sd cards/usb music mp3's when riding around...same kind worked fine in my previous 2001 nissan sentra, sooo....that really does point to a bad battery or bad alternator if it can't handle a simple stereo playing. For some reason the speakers in the doors don't work either, I read maybe the driver's side AMP behind the back seats could be bad, idk, I don't know much about audio at all besides how to install a stereo. Only the back speakers/bass works in the car. But yeah....definitely sounds like a bad battery/alternator now. Because for the first couple days I had the car and drove it around town the factory one was in the car, but turned off since it was just static and wouldn't pick up anything, then when I installed the new one, the stalling began a few days later, and then now intermittently. I can't say with 100% certainty that the stereo caused the problem, but it is a common denominator. I'd link the cheap stereo from walmart but then it would put my post into limbo like my other one waiting for approval,lol. It's only a 20W x 4 output stereo according to the walmart website spec sheet, and, on the nissan sentra I had before I had another of the same stereo in it for several months with no stalling problem ever.

edit2: the battery light and seatbelt light come up when I turn the key, then the seatbelt will go off sometimes if I unplug and replug it in again, again why I think maybe the sensor in the clip by the seat may be dirty, then when I crank the car the red battery light stays for a second or two then disappears. I'm on youtube right now watching an autozone video, and the guy said if that light comes on when you turn the key the battery is bad? That light used to come on (all of them did actually) on my old 2001 nissan sentra and it never had a battery problem. I mean I know every make is different with little things like that, but I figure all the dash lights were SUPPOSED to come on when you turn the key. So, bad battery indeed it could be or alternator.


I got the battery and alternator tested this morning at autozone by this nice guy, the battery tested bad, and alternator is good...the battery says 9/15 everstart plus...the cheap walmart kind.

Any battery recommendations? I'll spend more if it's truly a quality part, I don't want to be left stranded. I was thinking maybe just the Duralast Gold brand. There used to be a napa in my town but it shut down apparently within the last year. There's walmart, autozone, and oreilly's. There's also still a sear's here in a little strip mall surprisingly, I heard back in the day their brand of batteries was very well regarded but is so so in recent years. There's some place here called auto parts, I'm guessing just a little mom and pop store on the other side of town, never personally been to it yet, they actually set up shop inside the old original napa place before they moved across town then napa went out of business

I'm soooo thankful it's just the battery which is so easy to replace and not the fuel pump, my god I was dreading doing that job

on a side note, I'm sad the napa place here shut down, reading online, the blue napa store brand spark plug wires were like legendarily touted as being extremely well made
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I have about 30 mins to go until they finish testing this everstart plus at walmart, I really feel they're just trying to get out of exchanging it since the warranty goes by serial number and they told me I didn't need a receipt to exchange for another...when I get paid this friday I'm going to just get a good Duralast Gold battery, I've heard very iffy things about the walmart batteries. But back to my reason I feel they're just trying to get out of exchanging it, I saw with my own eyes at autozone the battery failed the test and the alternator passed, at walmart the girl behind the auto center counter hooked their primitive looking tester to it and she claims it said it was good, and that they need to load test it for 1 hour 45 mins. I'm not the first person that has been screwed over trying to exchange a battery at walmart it seems from reading's not the end of the world, I'll have a new battery either way by the end of the's the fact they're not wanting to exchange it when it's infact the battery giving me trouble that irks me. I definitely will NEVER buy a battery from walmart.

If the new battery fixes the issue I'll be sure to update the thread. The ignition coil just came in from amazon so I'll be putting the new spark plugs, coil, and spark plug wires all on whenever the wires come in, last thing I'm waiting on.

for the o2 sensor codes, I'm going to try cleaning the MAF sensor and order the new spectre air filter, solder the Odometer connector to fix it, look around for some antifreeze stop-leak since I know I have at least an antifreeze leak, maybe an oil leak too....although the oil level looks fine on the dipstick, I have a dark spot under the car. I haven't ever personally seen with my own eyes it leaking though, must be a really slow leak if there is an oil leak...then finally get a new CEL bulb since it's out.

I remember for my 01 nissan sentra for cleaning the throttle bottle it had a crazy convoluted idle relearn it very complicated if I clean out the throttle body on the 01 mustang?

I have some bg44k I can put in the fuel tank too to clean out the system....if that's too harsh/strong though, the milder chevron techron is like 5 bucks at the store or buy 1 get 1 free at autozone even I think still on sale.

edit: they just called me and said the battery tested good...sigh...I'll just get a duralast gold this friday and update if that fixes the issue.

edit2: I think the blue power antenna wire from my stereo was draining my battery, I still need to drive more but I disconnected it after calling the wiring harness company and talking to the guy and he said to disconnect it, my car doesn't even have an antenna period nonetheless a power antenna. I put in the spark plugs and wires and ignition coil today too...busted my hands and arms all up, very cramped in there...bad news though, wet oil and crusted burnt oil was on all the spark plugs....needs both valve cover gaskets as well as those spark plug gaskets....the parts are cheap but I'd rather pay a mechanic, I don't ever want to work on that cramped engine again especially in this 100 degree humidity here ha. Unless the guy topped it off before he traded it to me, it doesn't appear to be using much or burning much oil though, the oil level on the dipstick is good and it drives perfectly fine and doesn't overheat

edit3: for whatever reason the pcv valve hose had been disconnected from the intake air tube by the previous owner, it's the oem motorcraft hose and very worn and cracked and brittle....I seriously doubt the pcv valve had ever been changed before as a result of this...I'll try a new motorcraft pcv valve and pcv valve hose and see if that fixes the engine burning oil, I actually don't think the valve cover gaskets are bad at all because the oil and burnt oil was on the electrode side of all the spark plugs and not the other side with the porcelain. I'll update again whenever the parts arrive from amazon this week. I need to drive the car more but when I went to the store after changing the plugs,wires, and coil and unhooking the blue power antenna cable the car didn't die on me or hesitate and surge like it had been doing, I also reconnected the (very worn) pcv valve hose, the owner before, idk why, but he had disconnected it completely...I was thinking WOW that's kinda an important part of the vehicle to just leave disconnected. I was speechless. The person before really neglected the car, it actually has that fancy expensive K&N filter in it but it's completely black and filthy, don't think it's ever been cleaned and the rubber gasket that seals to the MAF box on the bottom of the K&N filter is hanging on by a thread, I think it's too far gone, I can get a brand new Spectre air filter that's reusable too for like 21 bucks at autozone....and according to some research I've done, K&N now actually owns Spectre, I guess they won some lawsuit back in 2011 against them or something,idk. But the contact info for both K&N and Spectre are the same exact address and phone number on their websites. So I think K&N really makes the filters and they're just rebranded for Spectre, or maybe the other way around. But either way, I think buying the K&N cleaning kit for the filter is a waste of money since this one is so far gone. And also I think maybe just a new pcv valve and pcv valve hose might fix the oil burning on the spark plugs, it's only on the electrode side and not the other side at all with the porcelain on it, so I think the valve cover gaskets might be ok after all. Also did more reading online and that p1233 was only caused since I pulled the fuel pump fuse when I changed out the fuel filter and cranked it and let the car die to release the fuel pressure. So the Fuel Pump Driver Module should be ok, I heard if that's bad it'll send a specific code. Going to try cleaning the MAF sensor, the scanner claimed both of my front o2 sensors were bad
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I wanted to update this post asking for more help, the new duralast gold battery didn't help the car dying =/ yesterday leaving my friends I couldn't keep it alive by mashing on the gas like I could before, and just now when I went to get a burger it died leaving my place too and mashing the gas didn't cranked right back up though and drives fine.

What I've done: New fuel filter, new duralast gold good battery, alternator tested fine, new pcv valve and pcv valve hose, both ignition coil, spark plugs and spark plug wires, all motorcraft, new spectre air filter, all fluid levels are good too...when I fixed the pcv valve brittle hose and old valve, it fixed all my CEL codes, both front o2 sensors aren't bad, they were just both reporting lean due to a vacuum leak I guess, but all codes are gone.

What I think it could be: IAC valve, EGR valve?, Throttle position sensor? Fuel pump? You'd imagine if the fuel pump was bad it wouldn't crank right up every time though...and it also drives fine going up hills and going down hills

reading a little online, IAC seems to be a common problem and isn't too expensive...I could also try cleaning the MAF but if there's no lean codes I doubt the MAF is the problem...I had a bad MAF on my old 2001 nissan sentra and that thing wouldn't even crank up with the bad MAF till I replaced it or unplugged the bad one. The throttle body doesn't appear to be gunked up either, a little brown rust(?) by the plate, could be carbon, tried to scrape some off by finger and it wouldn't come up so honestly could be rust, idk. Possible on a 2001 neglected car with 244k miles on it nearly.

When I get some more money there's a very good mechanic here that charges 75 to test literally everything wrong on a car and can tell me what's wrong...I think that would be better rather than buying more parts and it not fixing it. The everstart battery that was previously in the car was dying though and was the wrong size anyway however. Still really sucks to spend 145 bucks and it not fix the problem
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I'll double check all the hoses, I haven't seen any bad ones really. It doesn't idle rough and it drives fine, just randomly (usually when cold) stall out when coasting or after having stopped at a stop sign. What would be considered the correct fuel pressure? I wasn't aware the fuel pressure testers were so pricey looking around online,yikes, I could go get the pressure tested again monday and tell them to give me the exact numbers it's giving me. Looking around online I've seen different numbers thrown around, some say 30psi at idle is good, under load I'm not sure of, nor do I know what the pressure should be with the key turned but engine off.

I wish bad fuel pumps would throw a code, would make this much easier, it sucks since I have no CEL codes at all right now

The stalling out when the engine is cold or has been sitting overnight lead me to believe the IAC is bad, but I'm not 100% on that, I also tried to find a location picture online where the IAC is even at on the v6 2001 model but couldn't find one online that pointed it out. I could try cleaning the IAC out with carb cleaner when I locate it.

Edit: Found the IAC, a small hose running near it looks old and worn but I can't tell where it goes, it connects to another small one then appears to disappear into the firewall in the upper left of the engine bay if you were standing in front of the car facing the engine. Not sure what that hose even does, it's small and comes out of the upper left of the engine. Maybe an air conditioner hose? Not sure. Waiting for the heat to end today then I'll get some carb cleaner later.

there's a picture where I circled the mystery small hose that runs from the top left of the engine next to the IAC and goes into the firewall...not sure what it's called. Found the pic online by searching, found it in some topic where a guy was asking about 99-04 3.8 mustang vacuum lines. For some reason the thumbnail seems to be broken, but if I right click with my mouse and click open image in new tab it opens fine

UPDATE: .... cleaned the MAF sensor and IAC valve earlier and the car hasn't died today. When I get some money I guess I'll order a new motorcraft IAC and gasket off rockauto for like 56 bucks total

on a side note, how long are these cars known to last before having a major breakdown like bad engine and/or transmission going out? With 244k on it, I'm a little wary of how much more life is in the car. It drives fine though, and to be honest I have no history on the car so I don't know if its the original engine/transmission.
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