RPM Dropping to near 500 when stopping and shaking truck

[Tuesdak]

Mentioned to dealer that the engine surges for a second when I release the throttle. Literally like double tapping the throttle. They claimed it was normal due to rail pressure etc.

If I take off it oftentimes acts like the carb is set too lean: goes a sec, bogs, and then takes off. The randomly shifting the moment I get rolling after sitting at a full stop is just weird. Like it's not in 1st gear at a full stop and then shifts into 1st from whatever gear it's hung in.

This summer I was coming to a stop and the truck shook like the engine was about to stall. Even though it's an automatic I was attempting to slam the clutch to the floor. (Because it felt like I left it in gear forgetting to clutch it with my old NV5600 MT coming to a stop.) I watched the tach shoot back up to normal idle RPM from near 500. Passengers asked 'what was that'?

It's getting worse lately where every stop is having the RPM drop near 500 and recover, but, not shaking the truck.

I locked it into 1st gear due going through a big parking lot and noticed it nearly stalled out coming to a stop twice in a row. Noticed as it was shaking the truck at low RPM.

Idle is rock steady when stopped.

Fuel filters were replaced this fall and made no difference. Replaced at normal interval.

 

[Cummins12V98]

No help here but that is NOT normal. Hope you get it resolved.

 

[NIsaacs]

Converter slow to unlock?

 

[Hoefler]

When was the last fluid change on the transmission?? The Aisin requires fluid change every 30,000 miles and filter every 60,000 miles.

 

[AH64ID]

Do you have anything that monitors engine load?

Converter slow to unlock?

It shouldn’t even be locked in 1st.

 

[Tuesdak]

When was the last fluid change on the transmission?? The Aisin requires fluid change every 30,000 miles and filter every 60,000 miles.

Yes it had a fluid change at 30,000 miles.

Converter slow to unlock?

I can't wrap my head around this in 1st gear, but, it's acting like this.

Other than a fuel system problem where it can't bring the fuel back on in time to idle when slowing down I am out of ideas.

 

[Tuesdak]

Do you have anything that monitors engine load?

I don't. Suggestions?

Keep in mind I am just going to have the dealer handle it, but, getting the proper area to look at it is helpful to keep the wait times down. Last I checked it's 2 weeks to get it in to the transmission people.

 

[C M McCormick]

Try putting the truck in neutral before coming to a stop if you haven't tried that yet.

 

[AH64ID]

I don't. Suggestions?

Keep in mind I am just going to have the dealer handle it, but, getting the proper area to look at it is helpful to keep the wait times down. Last I checked it's 2 weeks to get it in to the transmission people.

A used CTS2 would be the best in terms of capability and cost.

 

[Timd32]

Did not notice anything posted in Alldata about this one. But I did notice they had a simple check sheet for shifting issus...... will paraphrase.

1. Check fluid....
2. Drive....
3. Perform quick learn....
4. Remove transmission and fix.....

That escalated quickly.......

Did find these cool Aisin pdf, they seemed pretty neat.

Figure they show the fluid flow in the different gears.

 

[Tuesdak]

The low RPM point when stopping before it 'recovers' after a complete stop. Does the same with the EB off: just a better video taken with it on. Stop from about 30 MPH shown in video.

https://youtube.com/shorts/13aCW7k6r3E

 

[2013megacab]

My truck stumbled on acceleration. The air filter was clogged. Another air flow problem was the cold air intake tube disintegrated and pieces of the plastic lining clogged the air filter.

Al

 

[SnoKing]

My truck stumbled on acceleration. The air filter was clogged. Another air flow problem was the cold air intake tube disintegrated and pieces of the plastic lining clogged the air filter.

Al

That issue was resolved by MY 2015. Dealer tech showed me how to open flap behind passenger highlight and reach in an feel the upgraded intake hose in the inter fender.

 

[slowmover]

The long rear-facing air intake is said to be of poor materials some MY. That — and air filter getting dirty — “might” be enough for a restriction at low rpm (until computer pulls it back up).

It’s a good design. I wouldn’t delete the hose so much as install one of better quality.

“Smoothed air” all the way to the face of the T/C is what’s at stake. A long air-intake runner, clean filter, and stock filter housing-to-T/C intake system is worth checking over. No restrictions and no leaks.

I think it’s more than this, but this would be an easy set of checks (where several problems conspire to make you go bald).

.

 

[Tuesdak]

I put a shop vac with the big hose to the fender intake after removing the air box flapper. No critter nests. No restriction in blow mode either. Air filter looks fine. Put the flapper back in. Still has problem.

I did notice severe rubbing on the boot off the turbo from the intake silencer. I recall one of the oil filter through the top fans mentioned catching this so I looked for it. Like a bad tire… when you see cord it’s time to replace.

https://www.turbodieselregister.com/threads/ram-active-air-sytem-operation-and-facts.264955/

Try putting the truck in neutral before coming to a stop if you haven't tried that yet.

Trying that out.

 

[slowmover]

I put a shop vac with the big hose to the fender intake after removing the air box flapper. No critter nests. No restriction in blow mode either. Air filter looks fine. Put the flapper back in. Still has problem.

I did notice severe rubbing on the boot off the turbo from the intake silencer. I recall one of the oil filter through the top fans mentioned catching this so I looked for it. Like a bad tire… when you see cord it’s time to replace.

https://www.turbodieselregister.com/threads/ram-active-air-sytem-operation-and-facts.264955/



Trying that out.

Ram Active Air

According to aftermarket supplier S&B (paraphrased):

Testing shows that when outside (ambient) air temperatures

1). Are greater than 91F
2). And the truck is at WOT

A). The Ram-Air Inlet is opened and remains so for 3-5/miles; or,

B). Closes earlier if
truck slows by 5-MPH.

C). Is not allowed to open in above when windshield wipers (rain sensors) have activated; (plus more trickery to avoid sleet or snow, etc).

The burden for engine air intake is almost wholly with the long rearward tube. Warmer air is best for full fuel burn (IAT just above 100F) thus also emissions and sound abatement. The long length is turbulence reduction.

Fenderwell liner removal for inspection.

.

 

[Tuesdak]

So it's turned cold and with a steep driveway I figured the Low Coolant was nuisance. Only added coolant one other time and it's soon due for a change by age. It's not that low as on level ground it's not triggering the warning.

What's concerning is "Where is it going?" in context of this and another possibly related problem.

Emission Test Time. Here we go again as I watch them clean the sensor to zero it after the Snap Test. It can't possibly be dirty enough to foul the test eye?! Supposedly I have a DPF on this model year: it don't act like it. It blew nearly a 10 out of 40 Opacity. My Stock 2003 Cummins was cleaner (7.4) and it didn't even have a cat from the factory!

Wiped the tailpipe with a white rag and sure enough it's sooty. Warranty time for sure.

 

[Lordsman]

Probably the EGR cooler is leaking if no other trace is found.

 

[AH64ID]

I think my 05 blew a 4.x with the wick turned up , course that tuner had a lot of time into the tune

Probably the EGR cooler is leaking if no other trace is found.

This still shouldn't pass thru the DPF thou.

 

[Tuesdak]

Here we go again with Dealers who can't do anything re DPF unless there is a code. I have gone to a couple dealers. I am in awe that the first dealer missed the rubbing and really didn't go over what they found so they could take a second look... Second dealer did replace the 52014734AC Duct-Charge Air Cooler. It was worn to the cords!

Another ECM Software update was done and No Change. TSB 18-061-20 TO P/N 32381832AI

They noted high idle time and recommended high idle be used. I mentioned they may have to replace the cruise buttons from me using 'high idle mode' when I do idle it.