Well, so far I am very much 0 for 2 (at the VERY least!) in getting to the problem with my car's stalling. I know this much: it has nothing to do with the car's major sensors (crank, cam, TPS, MAF) and it has nothing to do with the intake manifold, CAI or stock. Also, leaks between the MAF and the TB are NOT responsible.

Yesterday, After it stalled on my four times after I left the restaurant, I hit the closest Ford dealer I could find (Don Chalmers in Rio Rancho, NM). This time, I actually got VERY lucky. I happened to start talking to one of the senior techs (John). He (and everyone else) was too busy to look at it that day, but we did spend 1/2 an hour talking about what it was doing, how it was doing it, and what I had done.

Most importantly, he told me to bring it back Saturday morning as he was working that day and he should have more time to look into it.

So I did.

After he finished up what he was working on, he plugged in the IDS and promptly found TWO DTCs! That REALLY pisses me off as the XCAL2 does NOT find any! Both of them are related, P0689 and P0690. One basically says the PATS think the ignition key is off but the PCM thinks it is on and the other one is the reverse of that.

He did some digging in the sevice information and pretty quickly came up with three things to test and a couple of different outcomes:

1) Test VPWR at pins 35 and 36. These are the power from the ECM relays from a couple of different paths. If I get a drop in voltage on either of these pins when the car stalls (you have to LOVE datalogging multimeters!), then I know which path to trouble shoot up (ECM relay on one and SMJ run signal on the other one).

2) Stick a meter on the batter in AC mode and look to see if I get a shot of AC power on the battery when the car stalls. Again, dataloggin DMMs are VERY handy for this, especially when they have a min/max function.

He felt if I tested the two power sources and for AC on the battery and they were NOT the problem, then the problem resides inside the PCM.

Take a WILD guess which three tests "passed" with flying colors this afternoon/evening???

So, does anyone know what is involved with chaning the PCM? I KNOW the new PCM has to be programmed by dealer, but does anyone know a good place to get the PCM cheaper than dealer list?

**** I was hopping it was going to be the alternator. One, I might actually be able to get to the rectifier board and find and fix the cold/loose solder joint or cracked PCB and have a free fix. The PCM is solidily silicone potted, so you can't even get the cover off it (at least I couldn't when I tried this evening!). Plus, if it WAS the alternator, it would be a great excuse to buy a high output PA alternator.

I actually got real lucky with John. Not only is he a senior tech, but he is also an instructor at one of the local tech schools, so he was willing to take me under his wing and point me in the right direction on troubleshooting this beast. I definitely know who I am going to have install the new PCM.

 

I don't know if this is related or not , but I had a similar problem where the computer thought that the ignition key was on , even if the key wasn't in the ignition. This didn't cause my car to stall like yours, it caused the starter to engage if you pushed the clutch in. The dealer ship tracked it to an aftermarket alarm I had installed , these computers are very sensitive to any voltage changes and will do strange things. They completely removed the alarm system and everything was OK. It turned out it was also causing another problem I had been having. A couple of months after having my S/C installed , the computer started randomly throwing my car into forced shut down mode without any DTCs. Steeda tried everything to figure it out and couldn't. After the alarm was removed , I checked my records and found that I had installed the alarm 2 days before the first time I had the problem. It hasn't happened again , so I have to assume it too was caused by the alarm. The only similarity is that the computer thinks the ignition is on , so I don't know if they're related , just though I throw it out there ...

 

I previously worked at a Ford dealer, very rarely encountered a bad PCM, if it was a PATS problem it was usually the transponder at the ignition switch. Replacing that also requires reprogramming the keys. I think PCM replacement requires reprogramming the keys as well.

I wouldn't get the PCM from anywhere other than the dealer though, especially for these newer high tech cars, you never know what could go wrong if you get a part elsewhere.

 

It's a pain. The codes are PATS related, but PATS can NOT cause the car to stall (it only prevents the starter from operating, it does not lock out the fuel or ignition). The power coming into the PCM is smooth and stable and does not fluctuate during the stall events (datalogged VPWR at pins 35 and 36 on C175b with my Fluke 87). The alternator does not appear to be dumping AC onto the battery (again, datalogged with the Fluke and general had about 50mVAC on the battery and it didn't change during the stall).

The other part is the behavior of the stall events: they follow a definite "cycle" that runs like this:

1) Car has to be fired up and driven for 10 to 15 miles to fully heat it up.
2) Car sits for 30 minutes to a couple of hours. Less than 30 minutes and it won't always have stall problems, more than that and it won't always have stall problems.
3) Start car up and go for a drive. Stall normally starts a couple of minutes after startup.
4) Stalling gets worse and worse for a couple of minutes (some times to the point where I am on the side of the road)
5) As I restart the car (which usually starts instantly) and TRY to drive more, the stalling starts to get less and less frequent, until after about five minutes of the first stall, it won't stall anymore.
6) Car will not have any stall issues until it has been allowed to sit for 30 minutes to a couple of hours.

Other notes:

1) Air temperature appears to play in this. As Summer has given away to fall, I am seeing it take LONGER to start stalling after it is started (say 5 to 10 minutes instead of 1 to 2 minutes during a hot day). It also gets worse (more stalling, stalls for a longer period of time before it quits, etc.) before it gets better on cooler days.
2) When the car stalls, the engine flat *** DIES. No hesitation. No surging. No rough running. Nothing. One second it is running perfectly fine (accelerating, decellerating, coasting, cruise set, up hill, down hill, etc.). The next, the engine is OFF.
3) When the car stalls, a few seconds later, the vehicle security icon usually lights up. But I don't remember it ALWAYS lighting up.
4) The condition is definitely getting worse. It first started random stalling over a year ago. But at that time, it was one stall in a blue moon. It has progressed to the point I can clearly and cleanly identify a pattern to it.
5) The stalls are NORMALLY associated with hitting a bump or rough spot in the road. BUT! During the "peak" of the stall cycle, it might restart, then stall a couple of seconds later when the car is not even moving.
6) When it starts stalling, I can normally pull off the road and let the engine idel for 5 minutes or so (about the duration of the normal "stall cycle") and the engine will sit there and idle perfectly fine for the duration. If I wait long enough, it will ususally get past the stall cycle and be fine until the engine cools off again.

So, at this point it looks like it MIGHT be one of three things:

1) PCM. I REALLY don't want to replace this unless I have to. It's expensive and it cost money to install due to PATS. Thankfully, my Mom works for a Ford dealer in another town, so I can get the PCM for $585 direct from the dealer. That beats full retail!

2) Alternator. Even though I was not able to log any AC events, there are a couple of other folks that had P0690 codes and the cause turned out to be alternator. Not sure if they had stalling issues as well.

3) PATS module. But I really doubt it as the problem is the car stalling, not failing to start. But I do have a PATS code AND I am seeing the vehicle security icon light up when the car stalls, so...

Lord I am tired of fighting this problem!

 

Oh, and yes, the first thing the tech asked about was an aftermarket alarm system. It has the factory alarm system only. I specifically went that way because I DIDN'T want the problems with interfacing the alarm to a very high tech electronic beast.

Of course, I'm having strange electronic problems anyway...

 

check the bone yards for a used pcm. Hope you get your problem fixed soon. Good luck

 

That's a good idea Gleen. I hadn't even thought of it actually...

 

Well, some progress has been made.

I talked to a Ford Master Technician at another dealer (where my Mom works) for a while. He had a couple of other tests to perform (mainly at the PATS module) and his conclusion was if these tests proved negative (along with all the other negative tests!), then the problem is definitely inside the PCM.

Initially, that sort of sucked, even though I had already pretty much come to that conclusion. His next sentence REALLY made my day: "But, the PCM is covered by the 8/80,000 emissions warranty."

Nice!!!!

I took the car down to local Ford dealer and talked to John again. After explaining the results of the testing he had suggested on Saturday and the results from Tom's suggestion, he simply stated we need to replace the PCM. We then flagged down the service writer and he told him we need to order a PCM for my car and it is covered by the 8/80,000 emissions warranty.

It went that smoothly. No hassles. No arguments. No "well, we will have to keep your car for a week and redo all your trouble shooting before we can order the PCM". No issues at all.

I know that Ford has been getting a lot of negative press lately for poor service, but these technicians have really taken care of me.

Now if that PCM can FINALLY fix my car's stalling problem, then I will be REALLY happy!

 

More progress.... I guess... It definitely IS NOT the PCM. That was replaced under warranty (along with the two ECM relays) today. It's stalling behavior is EXACTLY the same as before.

The tech is going to get a hold of a ford engineer and see if they can shine any light on the subject. There is no pin point testing for a P0689 code for 2005 cars and the testing for 2006 is not applicable because there are wiring harness changes between 2005 and 2006 PCMs body harness. Hopefully, the engineer might have some ideas.

At this point, I'm warming up to the idea of trading it in on an 2009...

 

You're getting closer the fix man. Hang in there!!

At least your issue make for some good reading and Ford is treating you well so far.

Good luck!

 

Absolutely! John has gone way beyond the call of duty helping on this. At this point, I think he is as frustrated as I am.

Nothing is making sense with this issue. More and more, it is starting to feeling like a curse instead of a mechanical problem!

Right now, there are a couple of "maybes" on the list:

1) Alternator is dumping AC on the battery causing the PCM to freak. This is actually my number one theory as this is acting like an electronic issue (cold solder joint, cracked PCB, etc.) given the way it comes and goes under specific circumstances and the way the outside air temperature is affecting it. If I could just swap out the regulator on the alternator for a new one, I would in a heart beat.

2) ignition switch. It is possible that the run signal is dropping out for a split second. This would explain the PATS codes earlier, but I have a hard time understanding how the behavior pattern would fit for a mechanical switch. Usually, they are making contact or they are not.

I think I might build a circuit to allow me to datalog a bit better. What ever is happening appears to be happening VERY quickly. It's possible my Fluke 87 just isn't fast enough to record the even and show something on the min/max. I could build something that monitors a 12V signal (VPWR at pins 35/36 or the 12V run signal for example) and turn on an LED if the power drops below a certain thresshold (say 11V). I should be able to build something that can catch VERY fast transients (say around 1/100,000 of a secod or even faster). It would not tell me WHAT it dropped to, just that it DID drop. I could probably come up with something similar to see if I am getting micro second dumps of AC on the battery as well.

On the bright side, I have learned a LOT about how this car is wired together and what does what!!! That's GOT to count for something, right???

 

Geez, what a nightmare. You are fortunate that you have the knowledge/capability to investigate and datalog the symptoms. Otherwise it might be a 30 day stay at the dealer. Keep us posted.

 

Wow, that's crazy stuff. At least they warrantied the computer even though that wasn't the problem. I did not think it was the problem when I read your first post, since pcm's very rarely go out.

 

Trust me, that has pretty much been the same statement from everyone involved, even me. But at the bottom of just about every pin point test we ran, it end up with something along the lines of "if problem persists, replace PCM".

Now, we have replaced the PCM and the problem persists, but there IS no next step in the Ford service manual! Hopefully, John will find something out when he chats with the engineer.

One other interesting thing that probably ISN'T related to this problem, but the Ford IDS (Integrated Diagnostic System) COULD read the P0689/P0670 power train codes, but neither my XCal 2 nor John's other standalone code reader could read them. Just weird all the way around.

 

I have a 05 mustang with exactly the same problem, replaced PCM, sensors, checked voltage on all pins and wires throughout car. We are also thinking it is the ignition switch. Did you ever find out what the problem was gave you the p0689 code

 

WOW, I feel a lot better about my minor stalling issue now...

But come to think of it, it does sound familiar...

I drove it to the store, parked it, came back out, started it and drove a couple blocks to the near by dealer and when I pulled into the lot, it died.. I started it right back up, moved maybe 20 yards, pushed in the clutch and it died again. I was gonna let it sit a couple minutes, but someone was following me in. so I started it right back up. I pulled up maybe another 20 yards, set the brake and got out to look at the new stangs sittin in the snow (dealership closed for the day) and while I was away from the car it just up and died again... 3 times within 5 minutes.

It ran like crap on the way home, but didnt kill, nor has it killed or ran like crap since.

A few days later I brought the car into advance auto, they couldnt find any codes. And when I was having warranty work done on it, I had ford also check. They too found nothing.

I might note that my car is titled as an 06, but check my signature for build dates.

 

couple questions/thoughts...

1) Does it stall only at idle or opening the throttle from idle or releasing the throttle to idle?
if its dying under load, forget these ideas...but if its dying around low throttle/no load, then I gotta wonder if these cars still have a "air idle control valve" or something similar- guessing they still do, but with servo throttle maybe not...my old camaro and my lincoln mark vii both had air idle valve issues, both acted up- but only somewhere around idle...both just needed cleaned/lubed every year or two to keep them going. cant help but think its a AIC (or throttle servo) not keeping mixture correct as engine warms back up...

2) can you just hook up a test light to the 'run' signal(or your logging meter) to be certain it aint dropping out? seems doubtful to me though as you always see the same 'pattern'...

3) I dont think pats will do anything- ive got schematics here somewhere, and if i remember right it ONLY interrupted the start solenoid if a matching keycode is not read, and ONLY when the key is turned to 'start'.

4)on the possibility of throttle servo...some reputable folks say 'no way', but it sure seems to affect my car- try the pedal calibration thing: turn key to run, wait till airbag/whatnot lights go out, then smoothly press pedal to the floor and smoothly release, turn key off ten seconds and fire it up to see if you notice any difference...a few times mine got real 'balky' off idle, seemed to want to load up or stall out(like flooding) on startup- think it might have been due to stepping on the pedal inadvertently when turning key on before strarting maybe confusing the pedal input values or something...i swear though every time mines got sloppy, this perked it right up...like i said, some pretty smart folks swear this is bs, wont do a thing, but if only psychological- it works for me I do know some chryslers are calibrated the exact same way from what ive read, but lot of folks say it dont do anything on a ford, and a lot of folks say it does make a big difference- so who knows...

good luck!

 

For the record, I DID find the root cause of my problems. It had NOTHING to do with the PCM or any sensors. Heck, event the wiring harness gets off scott free.

The root cause of the problem was the connector block (rear one in this case) that is bolted up to the BEC (bused electrical center) was not 100% seated. It was allowing the fuel pump relay contact(s) to get loose under the "right" conditions.

Here is a more detailed post from another forum with a lot more details on the troubleshooting that FINALLY got to the bottom of this:

DarthStang,

Can you believe it? I think I FINALLY found the root cause of my stalling problem that has been going on for the last year!!!!

Your suggesting about the fuel pump relay pointed me in the right direction. Right after Thanksgiving, I was doing some driving and it started to stall REALLY bad. When I finally got the car off the interstate to someplace I could safely open the hood, it was running so bad that I almost couldn't get the ***** to start. Just the engine shaking as it fired up was enough to kill it.

So, I popped open the BEC and swapped the AC and fuel pump relay.

Needless to say, it started right up like nothing had happened. I immediately drove her over to the Ford dealer that I had been working with (on the other side of town of course!) and it made it there with no issue. I ordered a new relay on the spot...

At this point, I THOUGHT I had this problem licked. But, of course, it died again on me a few days later. Thankfully, it only stalled once that day (instead of thirty or forty freaking times!), so I had to drop the fuel pump RELAY theory, but I was definitely looking closely at the BEC.

The car basically behaved itself for the next several weeks with only the occasional stall (maybe once a week or so). Today, it was a COMPLETELY different story! I was heading back home on I-40 when it started to stall. And it kept getting worse and worse as the minutes ticked by. Fairly quickly, I was over on the side of the road because I couldn't even keep it up to speed.

My first attempt at a "get the b#$&$ home" repair was to swap out the fuel pump relay (no, I didn't really expect it to help, but hope springs eternal...). It made a TINY bit of difference and I tried to get going again.

I made it another half mile down the road before I was on the side of the road again. Cussing...

Now to the meat: As the car was totally hosed, I decided I would never have a better chance to dig around under the hood and track down what was causing this. If I didn't get killed by rush hour traffic on I-40, that is...

My first attempt at stalling it was to wiggle each of the three cable bundles coming in and seeing if the car died. The BEC sits kind of loose (it's only latched on with two plastic latches), so I placed my hand on the top of it to hold it in place before I started wiggling the cables.

And the car stone died!

I restarted it and this time I VERY carefully and slowly placed my hand on the BEC and pressed it down to hold it firmly in place. It was still running, so I started to wiggle the cable bundles to see which one would cause it to stall.

To my surprise, NONE of the cable bundles seemed to have any problems!

There were only two more cables going into the BEC: the main cable from the batter and a 10 awg wire that feeds my driving lights. It is bolted down right on top of the main power cable. When I wiggled the light wire, it died.

That surprised me because I only moved the cable about 1/8" and I was holding it about 5" from the end, so I wasn't putting very much pressure on the connector at all, not with a multistrand 10 awg wire... The wire has a fuse in it just up from where I wiggled it, so I pulled the fuse and restarted the car. A small wiggle on the wire STILL caused the car to stall, so it wasn't a short in my wiring!

At this point, I pulled the cover off and looked at the terminal plate when I wiggled the light wire. It BARELY moved as expected. I fired the car up and then slightly wiggled the main power cable as well. Once more, it stalled.

The next step was very interesting (not the least of which that it FINALLY got me back on the road!): I unsnapped the BEC from the bottom plate and then used my hands (on on top and one on bottom) to press the whole BEC/terminal block assemblies tightly together. After firing it back up, I did the tug and pull thing and the car did NOT die.

About freaking time! I now know EXACTLY where the problem lies in my car! After having a conversation with the cop who pulled up behind me right about this time, I was able to get home with no more stalling.

Once home, I pulled the whole BEC completely apart (unbolted the four connector blocks and power cable and completely removed it from the car). I dug into the rear most connector block to make sure the fuel pump connectors where still in good shape as I had soldered a wire lead to the relay output connector to power my wideband, so I thought maybe the problem was there. It wasn't. All the connectors and wires in each of the connector blocks looked perfect.

Of course, then I realized that the car stalled when the POWER distribution was wiggled and THAT bit is totally contained in the upper BEC itself. So, I made an attempt at disassembling the BEC (and failed). Each relay and every fuse came out before I realized that I had NO way to actually break that thing open without literally breaking it...

So, I restuffed the fuses and relays, bolted the car back together (yes, it DID start on the first time) and then called my Ford dealer to order a new BEC. $220 is VERY cheap money to keep this ***** from ever stalling on me again!


....

Update. That was the 19th of December. As of now (8th January), it has not stalled ONCE. I still have the new BEC sitting in it's box in the garage and it will go in if it ever stalls again.

What I THINK originally caused all of this is the installation of my LC-1 wideband. I had to remove the rear most connector block from the BEC so I could get power for the LC-1 from the fuel pump relay. I HATE hacking wiring, so I went into the connector block and soldered the wire directly to the connector pin in the block itself.

It looks like when I reinstalled everything, I did not get that connector block 100% seated. The bolt was tight, but if that block was every so slightly cocked, it could still tighten up WITHOUT pulling all the pins 100% together.

Time, vibration and heat all worked together to loosen things up until the stalling started, then went about getting worse and worse.

On thing to watch out for if you data log the fuel pressure: if you DO lose power to the fuel pump at the fuel pump relay, you STILL won't see a drop in fuel pressure!

Why?

Because the fuel injectors are ALSO powered by that same relay and we have returnless systems (and there is a check valve in the fuel system), so there is no were for the fuel to go!

 

Nope! These are "modern" engines. Fully drive by wire, so the IAC (idle air control) is all done with the main throttle blade.

 

Holy crap! That's a lot of deep digging and F'ing around with your electrical system...you are a brave man

Glad I could provide some small level of assistance. I remember how bad I felt with my new stang on the side of the road, so I just try to remind everyone, often the problem that is killing your 30 thousand dollar car is a 2 dollar part made in China.

Darth