2016 Explorer Grind from 1st to 2nd

[maciek1312]

2016 Explorer XLT, 3.5 L (Duratec) AWD
What's the issue?:
After sitting in park, when I shift into D (or after reversing from a parking spot and then shifting into D) and I go to drive away, the first gear shift from 1st to 2nd, I always encounter an audible, but brief grind. I can even feel the shudder in the gas pedal (it vibrates just slightly). For the rest of the duration of my drive, I don't encounter this issue again, even after sitting at a red light or pulling over for a moment. I only hear/feel the grind when the car has been parked. This grind happens every day and every time I pull away from a parked position.

Within months of purchasing back in 2016, I took it in to have this same issue checked out. (I purchased used with 10k). They replaced the PTU and the Tech's notes read:
"Verified CC and ran OASIS no info found noise coming from PTU assembly remove fill plug to inspect fluid. Fluid is contaminated and full of metal AUTH to replace with exchange unit due to lack of repair parts or procedures remove PTU install exchange unit verify proper fluid level fill trans to spec at operating temp and test drove to verify repairs"
I didn't hear the grind again for maybe a couple weeks. Since then, I hate to admit, I just kept driving and dealing with it. However, with warranty drawing to a close, I wanted to get it checked out one more time, SO, I am actually taking it in tomorrow and I hope to: 1) Update with results and 2) see if anyone else had a similar issue.
THANKS!

 

[peterk9]

Welcome to the Forum.
What you could be feeling is the ABS Self Check. ABS Self Check?
For some reason it is more noticeable in some vehicles than others. The self check occurs every time you start up the vehicle and begin to drive.

Peter

 

[maciek1312]

Welcome to the Forum.
What you could be feeling is the ABS Self Check. ABS Self Check?
For some reason it is more noticeable in some vehicles than others. The self check occurs every time you start up the vehicle and begin to drive.

Peter

Thanks a lot Peter, that's a really interesting possibility, especially based on the link you gave above. I'll bring it up with the dealership and see if they can also check on that!

 

[KayGee]

Has the ABS self check/test at speed been confirmed in the workshop manual for 2016 explorer? I see mentions of it in older explorer owners manuals (2011), but nothing in 2016+ owners manuals.

I have never experienced anything like that in any vehicle I have driven and I tend to drive without radio or other noise 75% of the time.

Based on OP stating tech found noise coming from PTU and replaced the PTU, something seems odd. If grind stopped after PTU replacement and then came back, maybe PTU is bad again (if that was really the cause of the noise to begin with). I would take it back to same dealer and tell them it is doing same thing as before and see what they do this time.

 

[maciek1312]

Two updates:
First, the car came back from the dealership. Here is the report from the tech:
"Client states that there is a grinding noise when shifting from 1st to 2nd, happens after sifting [SIC] from park to drive or reverse to drive please C/A
D8 Pressure port fitting seal leaking
4411 6636 Road Test to duplicate concern. Whine noise while driving & during upshifts at times. Test & monitor EEC system. No trouble codes stored. Fluid level is low. Leak near top of trans. Clean residle [SIC] fluid, add trans dye & road test. Remove battery box and air filter for access. Perform dye test using black light. Leak at pressure port fitting. Remove fitting and reseal. Reassemble, set fluid level to specs. Reprogram PCM to the latest calibration. Clear keep alive memory, set to specs & road test to relearn adaptive shift strategy & to verify proper operation."
Second, the slight "grind" is still present from 1st to 2nd (but it is much more subtle than before), but I had a car mechanic that is a friend take it out to see what he thinks, and he says it's less of a grind and more of a "knock". He thought it might be a valve opening after start-up. But it could still be the ABS self-check. He thought it was bad engineering to do an ABS self-check once you're on the road and that the ABS self-check should conduct automatically when the car starts up instead (he works on European cars, so whatever).
Anyway, I'm less worried about the brief knock, but I'm glad I took the car in still.

 

[613GT500]

The ABS self check consistently comes on around 5mph in my experience.