No one else (including two dealers) have any freaking idea what is going on, so it's time to ask help from all of you! Warning, this first post is going to be long as I have done a LOT to this damn car trying to diagnose the problem!
Summary: The car will stall. Usually, it will stall when you hit a bump or crack in the road. "Sharper" jolts TEND to cause it to stall more often than softer jolts. But, it won't do it when the car is cold, nor if it was cold and you just start it up and drive. You have to drive it for a while (10, 15 minutes) and THEN let it sit for 1/2 and hour or more. When you get back in, it will run perfectly fine for anywhere from a minute (hot days) to 10 minutes (colder fall days) before it first stalls.
Normally, the car will start right back up like nothing happened by either pushing the clutch in and hitting the starter (no need to turn the key off first), OR you can just push the clutch in, wait for the engine speed to drop below about 300 rpm (when the oil pressure light and check engine lights come one), then let the clutch out and it will start right up.
It will start stalling more and more frequent until it almost wont run (I'm been on the side of the road trying to get the engine restarted more times than I want to admit), then the stalling will get better and better until it goes away completely. During the hot days of summer, the time between first and last stall was about 10 minutes. Now that the high is only in the fifties, it can take up to 25 minutes or so before it clears out and runs right.
Other indicators: The vehicle security icon will USUALLY (but not always) come on right after a stall event. It will USUALLY stay on for a couple of seconds then go out. The car will turn over but NOT start so long as the vehicle security icon is lit. Occasionally, it doesn't come on at all (maybe it came on and went off so fast it didn't light up the icon?) and occasionally it will stay on for five seconds or so.
ODBII codes: My XCAL2 has NEVER found a single code related to this problem. At the dealer, there MATCO scanner also did NOT find any codes. BUT, the IDS system DID find two codes, P0689 and P0670. One code is because PCM thinks the ignition is on and PATS does not and the other one is just the reverse of that. More on ODBII codes later...
What has been done to date:
Let's see if I can make sense out of this list. The problem started out at about 38,000 miles with a VERY occasional stall. Maybe once every couple of months, and it pretty much went away completely last winter. This spring, it came back and has been getting worse and worse.
So, my first attempt at "fixing" this problem was fairly well shotgun: what sensors did I think COULD possibly cause the problem, then replace them. Most of those sensors are pretty cheap and I don't mind having them around in case it turns out the original sensors where still good. I started with the crank sensor (the most obvious cause), then went to cam sensor (but I REALLY didn't think they would cause it as they are generally only used to sync the engine during startup).
During my trouble shooting, it SEEMED like the problem would go away for a few days to a week when I messed around with the MAF or CAI (JLT2). I tried returning the car to stock (that sucks by the way) and the problem DID go away for about a week. I decided I was ON TO THE PROBLEM(!!!), so I went ahead and replaced the MAF ($130, so I wasn't quite as fast to replace this sensor!). No dice. I actually replaced this one in the parking lot of the parts house so I wouldn't have to bring the core back. The car stalled on me not 150 feet from their drive way!
That led me to buy and replace the MAF sensor connector. And that REALLY hurt as I had been trying to keep all my wiring as intact as possible, but you have to cut and splice to replace the connector.
At this point, I decided I just had to get some professional help (of the automotive kind!!!) and the next time it started stalling on my, I headed straight for the nearest Ford dealer. I was able to talk their senior tech (their "electronics" guy) into plugging in the IDS system and going for a test drive with me (actually, it was the $100 they where going to charge me for test drive that convinced them, but still...).
This drive was a bust. One, half way through the ride, his laptop battery died and he didn't have the car charger with him. Two, the car never stalled once during the test drive, so he didn't get to see what was happening. I had explained in detail what was happening and what I had done so far and he did have another suggestion: swap the PCM relays with other relays in the BEC. It's free troubleshooting. It also didn't do shit to fix the problem. On the bright side, because his laptop died, I didn't get charged for the test drive either...
His other suggestion (based on seeing similar problems on a few older Mustangs) was to replace the TPS sensor. Again, no change at all.
My next visit was a few weeks later and to a different dealer. One of their senior techs had me bring the car in on a Saturday morning and he spent about three hours "off the clock" going over it with me. This one started out VERY promissing as he found two ODBII codes as soon as he hooked up the IDS: P0689 and P0670. Unfortunately, there are no Pin Point Tests for these codes for 2005 Mustangs. They ARE in the 2006/2007 service manuals, but there is a change in wiring between 2005 and 2006, so 80% of the actual PPTs where not able to be performed on my car.
He did go through the schematics and identify what the PPTs where TRYING to do on the 2006 and then came up with some tests that we could do on my car. This mainly resolved around verifying that we had constant power at pins 35 and 36 (VPWR from two different sources) during the stall events by data logging the voltages here. Needless to say, like everything else, these tests proved there was NO issues with power coming into the PCM during the stall.
His other suggestion as a possible cause was to data log the AC voltage at the battery. He had seen past cases where the alternator was dumping AC onto the battery (and then the PCM) because the rectifier was going back and the diodes where intermittently shorting out. Once more, data logging showed there wasn't an issue. I had a max of 110mV (0.110V) of AC AT THE WORSE CASE and normally had around 50mV of AC at the battery. This didn't change during the stalls.
My next attempt at getting help on this was a call to a Master Technician who is a service manager at a Ford dealership my mom works for. After discussing the issue in depth with him, he wanted to do some more testing on the PATS module, even though we both agreed that PATS can not kill the car when it is running (it is only a starter interrupter). The PPT on the PATS module all passed and I found myself once more staring at the "if all other tests fail, replace the PCM" line.
So, it was back to the dealer and they did replace the PCM. Under warranty actually as the PCM is part of the emission system... Of course, the very next day after the PCM was replaced, it stalled about 10 minutes after I left the restaurant where I had lunch...
Since then, the tech has talked to two different Ford engineers about the problem, but neither one has gotten back to him with a possible solution.
I talked to another tech at the same dealer and he suggested I test VREF (the reference voltage used by pretty much all the switches and many of the sensors) to see if it is being shorted out during the stall events. This was datalogged on the MAF and there was no real change during the stall event. Plus, every single place where VREF leaves the PCM, it is behind a pull up resistor. So even if a specific sensor gets shorted, it won't affect any of the other sensors or switches.
Other Thoughts: The PCM is not losing power during the stall event. I say this because the dash does not go through it's power up cycle with the idiot lights being turned on, etc. I even tested it by starting the car and then quickly turning the key to accessory and then back to run. The car did die, but the PCM was obviously reset as well. It's almost like the PCM is fooled into thinking the engine should be shut down.
Questions On Active Security: My car does have the factory installed active security system (aka: alarm system). I specifically get the factory system because I did NOT want some aftermarket alarm installer screwing around with my electrical system and causing issues down the road...
Does anyone know if the active alarm system CAN kill the engine while it is running versus the PATS which can only stop it from starting? Does anyone have any ideas on how to trouble shoot possible alarm issues?
Hell, does anyone have any ideas at all?????? Needless to say, after this ordeal, I would be MOST GRATEFUL for any assistance!!!
Summary: The car will stall. Usually, it will stall when you hit a bump or crack in the road. "Sharper" jolts TEND to cause it to stall more often than softer jolts. But, it won't do it when the car is cold, nor if it was cold and you just start it up and drive. You have to drive it for a while (10, 15 minutes) and THEN let it sit for 1/2 and hour or more. When you get back in, it will run perfectly fine for anywhere from a minute (hot days) to 10 minutes (colder fall days) before it first stalls.
Normally, the car will start right back up like nothing happened by either pushing the clutch in and hitting the starter (no need to turn the key off first), OR you can just push the clutch in, wait for the engine speed to drop below about 300 rpm (when the oil pressure light and check engine lights come one), then let the clutch out and it will start right up.
It will start stalling more and more frequent until it almost wont run (I'm been on the side of the road trying to get the engine restarted more times than I want to admit), then the stalling will get better and better until it goes away completely. During the hot days of summer, the time between first and last stall was about 10 minutes. Now that the high is only in the fifties, it can take up to 25 minutes or so before it clears out and runs right.
Other indicators: The vehicle security icon will USUALLY (but not always) come on right after a stall event. It will USUALLY stay on for a couple of seconds then go out. The car will turn over but NOT start so long as the vehicle security icon is lit. Occasionally, it doesn't come on at all (maybe it came on and went off so fast it didn't light up the icon?) and occasionally it will stay on for five seconds or so.
ODBII codes: My XCAL2 has NEVER found a single code related to this problem. At the dealer, there MATCO scanner also did NOT find any codes. BUT, the IDS system DID find two codes, P0689 and P0670. One code is because PCM thinks the ignition is on and PATS does not and the other one is just the reverse of that. More on ODBII codes later...
What has been done to date:
- Crank, Cam and MAF sensor replacement (cheap sensors and easy to replace)
- MAF connector replacement (explained below).
- Replaced both PCM#1 and PCM#2 replays.
- Replace the TPS sensor.
- VPWR at pins 35 and 36 on C175B datalogged .
- PATS module Pin Point Testing followed with no issues found.
- Pin Point Tests for P0689 and P0690 followed where possible (explained below).
- Datalogged alternator voltage on both DC AND AC scales.
- After all trouble shooting was completed, every Pin Point Tests last item was "if problem persists, replace PCM", so it was.
- Datalogged VREF voltage at MAF.
- Lots and LOTS of cussing.
Let's see if I can make sense out of this list. The problem started out at about 38,000 miles with a VERY occasional stall. Maybe once every couple of months, and it pretty much went away completely last winter. This spring, it came back and has been getting worse and worse.
So, my first attempt at "fixing" this problem was fairly well shotgun: what sensors did I think COULD possibly cause the problem, then replace them. Most of those sensors are pretty cheap and I don't mind having them around in case it turns out the original sensors where still good. I started with the crank sensor (the most obvious cause), then went to cam sensor (but I REALLY didn't think they would cause it as they are generally only used to sync the engine during startup).
During my trouble shooting, it SEEMED like the problem would go away for a few days to a week when I messed around with the MAF or CAI (JLT2). I tried returning the car to stock (that sucks by the way) and the problem DID go away for about a week. I decided I was ON TO THE PROBLEM(!!!), so I went ahead and replaced the MAF ($130, so I wasn't quite as fast to replace this sensor!). No dice. I actually replaced this one in the parking lot of the parts house so I wouldn't have to bring the core back. The car stalled on me not 150 feet from their drive way!
That led me to buy and replace the MAF sensor connector. And that REALLY hurt as I had been trying to keep all my wiring as intact as possible, but you have to cut and splice to replace the connector.
At this point, I decided I just had to get some professional help (of the automotive kind!!!) and the next time it started stalling on my, I headed straight for the nearest Ford dealer. I was able to talk their senior tech (their "electronics" guy) into plugging in the IDS system and going for a test drive with me (actually, it was the $100 they where going to charge me for test drive that convinced them, but still...).
This drive was a bust. One, half way through the ride, his laptop battery died and he didn't have the car charger with him. Two, the car never stalled once during the test drive, so he didn't get to see what was happening. I had explained in detail what was happening and what I had done so far and he did have another suggestion: swap the PCM relays with other relays in the BEC. It's free troubleshooting. It also didn't do shit to fix the problem. On the bright side, because his laptop died, I didn't get charged for the test drive either...
His other suggestion (based on seeing similar problems on a few older Mustangs) was to replace the TPS sensor. Again, no change at all.
My next visit was a few weeks later and to a different dealer. One of their senior techs had me bring the car in on a Saturday morning and he spent about three hours "off the clock" going over it with me. This one started out VERY promissing as he found two ODBII codes as soon as he hooked up the IDS: P0689 and P0670. Unfortunately, there are no Pin Point Tests for these codes for 2005 Mustangs. They ARE in the 2006/2007 service manuals, but there is a change in wiring between 2005 and 2006, so 80% of the actual PPTs where not able to be performed on my car.
He did go through the schematics and identify what the PPTs where TRYING to do on the 2006 and then came up with some tests that we could do on my car. This mainly resolved around verifying that we had constant power at pins 35 and 36 (VPWR from two different sources) during the stall events by data logging the voltages here. Needless to say, like everything else, these tests proved there was NO issues with power coming into the PCM during the stall.
His other suggestion as a possible cause was to data log the AC voltage at the battery. He had seen past cases where the alternator was dumping AC onto the battery (and then the PCM) because the rectifier was going back and the diodes where intermittently shorting out. Once more, data logging showed there wasn't an issue. I had a max of 110mV (0.110V) of AC AT THE WORSE CASE and normally had around 50mV of AC at the battery. This didn't change during the stalls.
My next attempt at getting help on this was a call to a Master Technician who is a service manager at a Ford dealership my mom works for. After discussing the issue in depth with him, he wanted to do some more testing on the PATS module, even though we both agreed that PATS can not kill the car when it is running (it is only a starter interrupter). The PPT on the PATS module all passed and I found myself once more staring at the "if all other tests fail, replace the PCM" line.
So, it was back to the dealer and they did replace the PCM. Under warranty actually as the PCM is part of the emission system... Of course, the very next day after the PCM was replaced, it stalled about 10 minutes after I left the restaurant where I had lunch...
Since then, the tech has talked to two different Ford engineers about the problem, but neither one has gotten back to him with a possible solution.
I talked to another tech at the same dealer and he suggested I test VREF (the reference voltage used by pretty much all the switches and many of the sensors) to see if it is being shorted out during the stall events. This was datalogged on the MAF and there was no real change during the stall event. Plus, every single place where VREF leaves the PCM, it is behind a pull up resistor. So even if a specific sensor gets shorted, it won't affect any of the other sensors or switches.
Other Thoughts: The PCM is not losing power during the stall event. I say this because the dash does not go through it's power up cycle with the idiot lights being turned on, etc. I even tested it by starting the car and then quickly turning the key to accessory and then back to run. The car did die, but the PCM was obviously reset as well. It's almost like the PCM is fooled into thinking the engine should be shut down.
Questions On Active Security: My car does have the factory installed active security system (aka: alarm system). I specifically get the factory system because I did NOT want some aftermarket alarm installer screwing around with my electrical system and causing issues down the road...
Does anyone know if the active alarm system CAN kill the engine while it is running versus the PATS which can only stop it from starting? Does anyone have any ideas on how to trouble shoot possible alarm issues?
Hell, does anyone have any ideas at all?????? Needless to say, after this ordeal, I would be MOST GRATEFUL for any assistance!!!
