[FabricGATOR]

p1684 is a TCM code and on your 2002, TCM is separate from ECU - it can be a clue that there is/was poor battery connection or dying battery. If you erase the code and it comes back, start looking for cause otherwise chalk it up to a 'fluke' since it's ~50 drive cycle 'memory' code.

So basically an interruption in power to Trans Control Module?
and wring out all the TCM wiring and sensors?
IPM check?

 

[atoman]

So basically an interruption in power to Trans Control Module?
and wring out all the TCM wiring and sensors?
IPM check?

Yes, TCM detected power anomaly (low voltage or unexpected power down during operation)
Not all wiring, only power and ground distribution
IPM is good plate to check for bad contact/corrosion/broken wires etc.

 

[FabricGATOR]

So todays antics included a full tank (14.5 gallons) of Sunoco reg e-10 followed by a spirited 93 miles south down the turnpike. I was late for an important meeting. The van performed flawless and with gusto.
Worked all day out of the van with the doors open and the courtesy dimmer off. 9 hours @ 83degF
Found Marathon fuel south for $0.14 less as I was departing so topped up 4.5 gals (20.67mpg by math)
On the way home, a more relaxed (3:30 weekend dinner rush traffic)(and a bunch of self important Tesla fux in the left AND middle lanes just tooling along like the pace setters) I digress
Elon should teach that car to yield to faster traffic as per Florida statute, I digress again...

So, I start to feel a little grumble in the pedal, then it is really starting to hesitate at the most inopportune times. 56 miles to home... no CEL just a little indigestion.

I discover for whatever reason it runs better the faster I trot. 78-85 is the sweet spot although at the top range of my comfort level. Coasting is Achilles heel but as long as the momentum keeps the rpm's up I can seem to get it to catch and then slowly accelerate back up to 75+. Now 32 miles to home, I am now North of little NY so traffic is more favorable...

I continue on and make it off my exit and then real trouble. Lucky me as I am coughing down the ramp, the empty traffic light gives me the green arrow and I am on the home stretch.... BUT I certainly can't (well, shouldn't) do 85 on a 35 and especially past the middle school.

2.3 miles to home. CEL illuminates

rattle and sputter but I am determined. Only 3/4 mile and one left turn then three blocks with one red octagon in my way.

it died 75 yards from my turn

BUT it started right back up after two key on 'pump primes' *chirp I cross two lanes and cut off across a solitary Honda Element

sorry %#@^ "serves you right for driving a toaster"

Neutral at the stop sign, keeps idle and I chug into driveway.
It was a long day, but I made it.

Key dance P1684 and P0171 (same though never cleared)
5 minute rest and then started right back up and idles smooth. I bet she'd make a run to the border for a Burrito Supreme.

 

[FabricGATOR]

Reflection, TPS maybe? to me it seems like a certain pedal position is sweeter than others and maybe it isn't calculating the injectors quite right. That may also account for break up at certain speeds (throttle positions) while the position (speed) less traveled seems to be better..

I am looking for power and ground discontinuities but just thinking out loud.

THANK you all so very much. Like atoman say's
"Fix it if you can"

 

[Road Ripper]

Hmm, in my Toyotas when the alternator brushes (Nippondenso alternators, same as Chrysler uses now) would be worn down and start to lose contact, the charge light would come on at lower engine speeds. Rev the engine and the charge light would go off when the engine was running faster. Maybe this is why the van ran great on the freeway at higher RPMs, and not so good when you had to slow down?

 

[Mopar-Mofun]

Hmm, in my Toyotas when the alternator brushes (Nippondenso alternators, same as Chrysler uses now) would be worn down and start to lose contact, the charge light would come on at lower engine speeds. Rev the engine and the charge light would go off when the engine was running faster. Maybe this is why the van ran great on the freeway at higher RPMs, and not so good when you had to slow down?

You are so right. I've experienced this onset problem too in the past.

Ours vans over 16+ years with the original alternator could behave just like that.

 

[atoman]

These alternators are externally regulated and are very easy to test (only 2 field coil contacts), if you can't / have no desire you can simply unbolt it and have it bench tested.

TPS can be tested with a multimeter too, but TPS can't overheat the coil pack.

Again, I don't like the lean code and coil pack overheating, it could be a strange coincidence but likely not.
What could it be?
fuel delivery (pump/regulator - pressure, filter or injectors - flow)
emissions controls (overcompensating for o2 sensor defect)

Lean running engine will have a different torque 'curve' - it will have easier time with higher rpms (until it burns the valves).

 

[FabricGATOR]

Again, thank you all for continuing to help me figure out this intermittent frustration and potentially stranding let alone perhaps dangerous situation. Everyone's input is helpful and considered.
"The van that the internet repaired as a community" We may even be able to solve world hunger...

These alternators are externally regulated and are very easy to test (only 2 field coil contacts), if you can't / have no desire you can simply unbolt it and have it bench tested.

I hadn't considered alternator, low voltage or AC ripple for this, I am interested in this as a possibility. Cheers

TPS can be tested with a multimeter too, but TPS can't overheat the coil pack.

After my hours long test drive and observations, I am thinking that my P0171 perhaps may be something else such as the TPS, [or a friend suggested (MAF) but I think that is a different technology to calculate and control injector squirt] contributing to this happening. While I did put a heat baffle as a test a few years ago, over my exhaust cross over pipe that then since become a permanent contraption, AND I do (did) believe that to have had cured the very similar intermittent 'poor running' what ever it was has returned.

Now that you mention it, when I rolled into the driveway the day before yesterday, I left the van running a little rough and I poured a room temperature 20 oz water bottle atop the ignition coil, hoping to notice the engine to start running better as the coil cooled. Alas, no change in idle performance noted. and I was too tired from the day to try to make it around the block.

My belief that my ignition coil was failing when too hot, a few years ago, may have just been my "Analysis Paralysis"

Again, I don't like the lean code and coil pack overheating, it could be a strange coincidence but likely not.
What could it be?

Please help me focus on Lean Code p0171 I am not certain about hot coil. I I now believe that I may have been kidding myself with that BS

fuel delivery (pump/regulator - pressure, filter or injectors - flow)

Now, years ago when this first started happening to me on my road rage spirited drive home while crossing state ( I am sometimes ashamed that I let inconsiderate and offensive drivers get me wrapped around MY axle) I am trying to remember the timeline, but I checked fuel pressure (and I don't remember if it was part of diagnosing this or if I found low pressure or IF the van just outright died on me another time) Perhaps I (and now that I think of it) I remember hooking up the FP test rig two times. I digress... I found a blown fuel pressure regulator in the tank pump assy. Replacement was required and the preferred wholesale parts house was two days for my preferred Denso/Walbro pump assy or they had a Delphi pump assy in stock that day.
The Delphi pump, I did note after R&R was audibly louder than the OEM pump.
Yes, I did also replace the fuel filter 'spider' assy.
Last week when I thought I had gotten a bad fill of fuel and that was what was making this fault start running rough and stalling, I remember thinking, that the pump did sound louder than I had been used to these past few years since replacement.

I intend on returning the AutoZone loan a tool inner tie rod tool kit and borrowing the fuel pressure test kit once again...

emissions controls (overcompensating for o2 sensor defect)

I did replace the upstream o2 sensor BUT I didn't follow the forums recommendation of using a Denso and NOT using a Bosch (or perhaps the other way around) I think I used Bosch, I'll have to research further... [YET ANOTHER time when I kick myself for not keeping a maintenance LOG BOOK in every vehicle glove box to refer to]
No code or reason for the replacement of the o2 sensor other than parts canon to get improved fuel efficiency. I understand (or believed something) I read about the fuel efficiency getting worse over time as the o2 upstream o2 sensor started to age?

Lean running engine will have a different torque 'curve' - it will have easier time with higher rpms (until it burns the valves).

Flying by the seat of my pants??? I have seldom been able to feel much. Though I do feel it when it starts to run rough and/or hesitation.

I should pull and read the plugs, at the very least the front easy ones, as asides from a 20 second idle restart test, it is as it was when I had my trip two days ago.


I know I use a lot of words. Thank you for those who take the time to read all my BS and to those who don't have the time or interest... I do understand.
I am just trying to provide thorough information and observation so YOU CAN HELP ME and also to let folks (both present and future) view my thought process and diagnosis steps. Not everyone has exposure to diagnostic thought logic.

Cheers

 

[FabricGATOR]

And after all that I forgot to ask. The P1684...
I know this is going to sound out there, but is there any reason why the TCM reporting 'interrupted power'... there is no reason that the TCM (transmission control module) should or could make the engine run rough, right?

I ask because either OMC or perhaps Yamaha outboard engines have a momentary if not imperceptible ignition disruption when you shift from forward to neutral or reverse to soften the 'hit' on the gear train. I didn't know if that technology may have made its way into our automotive drivetrain technology.

I want your help to define if both codes are possibly related or if I am seeing two different faults.
...just another thought bouncing around in my head like a pinball.
TY

 

[atoman]

Theoretically, if TCM loses power for just long enough, it could loose and re-engage TCC and you would feel that (but it would probably drop into "Limp" mode and need a restart)
Crappy power supply or ground can also undermine (throw off) sensor feedback and chances are if TCM power is interrupted, so is ECU and other modules.

 

[FabricGATOR]

Theoretically, if TCM loses power for just long enough, it could loose and re-engage TCC and you would feel that (but it would probably drop into "Limp" mode and need a restart)
Crappy power supply or ground can also undermine (throw off) sensor feedback and chances are if TCM power is interrupted, so is ECU and other modules.

So YES, the P1684 'clue' COULD be associated with the rough running, loss of power, stalling, bucking, etc...
AND when I coast to the side of the road, shut off the ignition and then immediately restart, it will run ok for a minute or even a mile or two because I reset the TCM by ignition cycle.

OK thanks for clearing that up. Well, in theory, it could be possible.
I am leaning towards the p0171 being reported a symptom of the underlying cause.

All this talk and feedback is great but it is going to be actual hands on searching, inspecting and testing that hopefully finds my cure.
The theoretical mental masturbation will open my eyes to possibilities I might miss if looking with blinders blocking my view.
Thank you.

 

[Mopar-Mofun]

Theoretically, if TCM loses power for just long enough, it could loose and re-engage TCC and you would feel that (but it would probably drop into "Limp" mode and need a restart)
Crappy power supply or ground can also undermine (throw off) sensor feedback and chances are if TCM power is interrupted, so is ECU and other modules.

My 2005 SXT would do something stupid like that. Those electrical gremlins for that 2005 year were really bad. Yes, when it lost power a trans jolt or two would happen, and at times the engine would cut out.

 

[atoman]

My 2005 SXT would do something stupid like that. Those electrical gremlins for that 2005 year were really bad. Yes, when it lost power a trans jolt or two would happen, and at times the engine would cut out.

IIRC, the PCM is supposed to keep working down to 8 or 9 volt (which makes sense because it has to start the engine with starter still engaged) but the solenoid pack is probably the first thing that "disengages" when voltage drops below 10v...

 

[FabricGATOR]

I haven't had any time to investigate or look into it further yet,
But I can say that she starts right up, runs smooth, gets me where I am going around town and back several local jobs without a *hiccup

What I am experiencing when it acts up is perceived as engine running and loss of power. If it felt anything transmission related I would report that. Someone mentioned TCC and that appears to operate normally. MYSELF, I don't detect anything that would make me believe (other than the P1687 code) that makes me think anything transmission.

If it were outright dead I could likely find it but when it is running like it is, I got nothing other than flipping the ipm over and pulling on wires till one falls out.

Now I could believe the wiper on the TPS could have some malfunction. Does anyone have guidance on testing that. Isn't it something like checking for smooth change in resistance over a range?
[acceptable range]
[pin to test if not obvious]

It may also be time to go back and inspect the condition of the injector wiring harness again. Perhaps I didn't do as good a job of insulating and repositioning away from the heat as I thought I did...

 

[atoman]

If it's treating you right, no rush.
You might want to take a peek at a spark plug or few next time you're 'in there" that's going to be your most reliable indicator if it's running lean or not.

 

[FabricGATOR]

It has been running fine these several days. CEL extinguished on its own.

Very busy these past few months and it is the squeaky wheels are the ones that get the grease.

If only it can stay together for another few months until I anticipate having more time for love and affection.

 

[atoman]

Could've been water logged gas.. if it keeps running fine no point in messing with it. (Maybe make a note of that questionable gas station and try to avoid it, at least when tanks are being filled or shortly after while tanker is still there)