random stalling issue

[BenBB]

Wish I had an easy answer @Gryphon313 and @red_mr2, here's hoping you find it. Both cases are so similar, if it was mine I would be suspecting the same exact things; fuel or ignition. Playing "Sling Blade" advocate for a moment (I'll forego asking if it's got gas in it heh), did either of you try a fresh, new battery? These things are rolling computers more and more every day, some systems, or weak connections somewhere, can and will cause problems.

Along the same lines, can you start tracing wires from the battery on? There are several known failure points like @Blacktor mentioned, the trans harness just aft of the motor (symptoms are usually shifting related it seems since it leads to the trans), but also the main harness that drops below the frame rail inboard of the LH front wheel (which incidentally leads to the fuel pump and FPDM, several old threads here on relocating it along the top of the frame rail out of harm's way), and I've noticed one spot on the harness at the front of the LH front wheel that rubs the fender liner (I zip tied a layer of HDPE sheet there to protect mine, it looked like it was on the verge of cutting into wires, not sure if it goes to ABS or what). All it takes is one or two cut wires or connector pins not making contact to be a huge problem. Good luck!!

 

[Gryphon313]

@BenBB Thanks.

My battery has a 4/22 build sticker on it. I put a multimeter on it today and it is good. At face value… there is nothing obviously wrong with this truck. I have spent a great deal of time laying under the truck shaking all the harnesses with no recreation of the stall. I’ve loaded up every PID I could think of to watch on ForScan and have not seen anything obviously wrong.

My good pal (custom engine swap wizard) thinks the idle is just too low. If I left foot brake in traffic and keep the rpm’s up it will not stall. 600 rpm is the expected idle rpm. Any load on it at operating temp (brakes, steering, etc) and it ends up in the high 500’s. Let it idle in park long enough and idle will drop below 600 rpm. Never happens below operating temp.

**Forgot the best part. While checking things out, I discovered that my passenger floorboard was soaked. Looks like the woefully inadequate a/c drain strikes again!

 

[BenBB]

@BenBB Thanks.

My battery has a 4/22 build sticker on it. I put a multimeter on it today and it is good. At face value… there is nothing obviously wrong with this truck. I have spent a great deal of time laying under the truck shaking all the harnesses with no recreation of the stall. I’ve loaded up every PID I could think of to watch on ForScan and have not seen anything obviously wrong.

My good pal (custom engine swap wizard) thinks the idle is just too low. If I left foot brake in traffic and keep the rpm’s up it will not stall. 600 rpm is the expected idle rpm. Any load on it at operating temp (brakes, steering, etc) and it ends up in the high 500’s. Let it idle in park long enough and idle will drop below 600 rpm. Never happens below operating temp.

**Forgot the best part. While checking things out, I discovered that my passenger floorboard was soaked. Looks like the woefully inadequate a/c drain strikes again!

Ok stupid question, is there an IAC? I vaguely remember having a Chevy once that I had to replace the Idle Air Controller chingus. Does your guy think it could be injectors or anything?

Ugh that damn condensate drain, I just saw a thread here the other day that Gen2 had a TSB to add a rubber elbow to the outlet…

 

[Gryphon313]

Ok stupid question, is there an IAC? I vaguely remember having a Chevy once that I had to replace the Idle Air Controller chingus. Does your guy think it could be injectors or anything?

Ugh that damn condensate drain, I just saw a thread here the other day that Gen2 had a TSB to add a rubber elbow to the outlet…

I am fairly confident that IAC is part of the electronic throttle body and controlled by the PCM.

I’ll tackle the drain this weekend. Need to make sure it is not clogged with gunk before I stick an elbow on it.

 

[Gryphon313]

I remembered late last night that I have an unlocked Bully Dog tuner in my tool chest “junk” drawer. Had it for a Nissan Xterra to, coincidentally, increase the idle RPM. Their website says that my Raptor is supported. I’ll update it tonight after work and see if I can get it to work on my truck. I’ll report back here once I know what’s what.

 

[FordTechOne]

@BenBB Thanks.

My battery has a 4/22 build sticker on it. I put a multimeter on it today and it is good. At face value… there is nothing obviously wrong with this truck. I have spent a great deal of time laying under the truck shaking all the harnesses with no recreation of the stall. I’ve loaded up every PID I could think of to watch on ForScan and have not seen anything obviously wrong.

My good pal (custom engine swap wizard) thinks the idle is just too low. If I left foot brake in traffic and keep the rpm’s up it will not stall. 600 rpm is the expected idle rpm. Any load on it at operating temp (brakes, steering, etc) and it ends up in the high 500’s. Let it idle in park long enough and idle will drop below 600 rpm. Never happens below operating temp.

**Forgot the best part. While checking things out, I discovered that my passenger floorboard was soaked. Looks like the woefully inadequate a/c drain strikes again!

If the idle were too low then every truck produced would have the same issue, which of course they don’t. Have you removed the drive belt to check for any binding pulleys/components?

 

[Gryphon313]

If the idle were too low then every truck produced would have the same issue, which of course they don’t. Have you removed the drive belt to check for any binding pulleys/components?

Not yet, but I’ll look at it this weekend. Everything I have done so far, except changing the plugs and coils, has been in between getting home from work and dinner. I have not really had enough time to dedicate to figuring this out.

Whatever it is, it only happens at operating temps when at idle in P,R,N,or D. Braking and steering at slow speeds will draw the idle way down as well. When it cuts out, it always starts right back up like nothing happened.

 

[red_mr2]

If the idle were too low then every truck produced would have the same issue, which of course they don’t. Have you removed the drive belt to check for any binding pulleys/components?

do you think a bad ac compressor would be causing the random stall even when the AC is not running?

 

[Gryphon313]

I have been reading everything I can today about what goes on during idle. @FordTechOne is absolutely correct regarding the oem expected idle. Something is causing the idle to drop. I am now focusing my attention on the crankshaft position sensor. Looking for a way to test it without pulling the intake manifold. I can’t find a PID specific to it in ForScan tho.

**edit** I have seen that these sensors are prone to corrosion due to their location. My truck spent its first 90k miles in Canada, so corrosion could be a thing.

 

[FordTechOne]

do you think a bad ac compressor would be causing the random stall even when the AC is not running?

It’s possible if the clutch is bad and is causing excessive drag as it turns.