"48RE Partial Engine Stall & RPM Increase" - Torque Converter?

[10-9jc]

After lots of searching for my transmission "problem" on all the diesel forums - the title is from an article in "Search Auto Parts",
which describes it accurately.

Truck = 2005, 48RE - completely stock 4x2, owned since new with 75K on the clock.
Never a transmission problem prior to this.

Maybe this will help others - article quoted - my comments are in parentheses ():

Complaint:
2003 and up Dodge vehicles equipped with the diesel engine and the 48RE transmission may have a complaint of a partial engine stall at a stop followed by a sudden engine rpm increase. This sudden engine rpm increase may be difficult to overcome with the vehicles brakes.
(Yeah - first time it happens it *SURE* gets your attention! Req's *heavy* brake application, or you'll be running into whatever is in front of you!)

Once the vehicle takes off it may be also noted that the upshifts are firmer than normal as the Torque Converter Clutch is On. Note - this complaint does not include a complaint of stalling in both Drive and Reverse, as this is typically caused by a defective torque converter, a restricted cooler and/or a stuck TCC Switch Valve.

(Didn't notice the above. Release brake - with *no* accelerator input- rpms will increase to about 1,000, drop back to idle rpm - then drives and shifts as normal).

Cause:
The cause may be that the Torque Converter Clutch solenoid, is partially restricted, causing the Lock-up valve and Lock-up switch valve to stroke applying the TC Clutch. The 48RE/47RE has 1st gear TCC capability, and when the solenoid is mechanically restricted it will cause the TCC to apply in first gear. The ECM on these Diesel applications can bring engine rpm up when the TCC is applied, to keep the engine from stalling.

(article suggests if the vehicle is hard to stop - put it in neutral at a stop. Yeah - plan ahead for red lights.
No bueno to put it in neutral under the increased rpm load. Better to shut it off in Drive, then restart in neutral)

Correction:
To correct this condition, replace the Lock-up and Overdrive solenoid assembly. (END)

Should add - for me it was intermittent - didn't happen at every stop, but did occur on startup from sitting overnight - in both drive and reverse.
When this first happened - besides some choice expletives, figured it was time to visit Mike at Inglewood Trans.
Of course, when Mike drove it - never happened. Said everything was normal - and NOT a torque converter problem.
And - I had not yet found the above article.

So off it went to a Dodge dealer. They tried replacing the Throttle Positon Sensor - ho help. Remove new part, pd for about an hour labor. They didn't drop the pan - but after driving it - said probably some kind of Torque Converter issue.
(Brilliant)

Then I found the article on the solenoids. Had local transmission shop drop pan (it was clean), then replace the solenoids ("48RE Internal Wire Harness Group" - OD & TCC Lock-up solenoids, as well as a BW Pressure Governor & transducer while they were at it).

No luck.

Sooo - if you made it this far, LOL! - any ideas before I have the trans rebuilt? Cerb?

BTW - Sure seems like some guy's GF, wife, or? could be in a REAL jam when the "first time" RPM increase caught her unaware when she wasn't expecting it - with potentially drastic results!
Kinda like the Toyota throttle sticking "events" and resulting litigation.


~

 

[JJPage]

You could have a faulty control wire harness, driver's side of trans, round 7 pin plug. If for some reason a partial/intermittent ground running across pins 6 or 7 could cause tc lockup. Or if there is trans fluid present inside that same plug, you will have continuity flowing through the fluid and across the pins causing issues.

Those are two places I would investigate, I had the 2nd issue on my truck with fluid inside the plug. My fluid was coming from the front band adjuster, however it could also originate from inside the trans...Repairing my leak in the front band adjuster stud, and using dielectric grease in the two plug ends corrected my problems.

Let us know what you find. Jess

 

[10-9jc]

Jess -

Thanks for the reply. Will check it out.

JC

 

[10-9jc]

dbl post (as above) - deleted.
Added a link to the article I posted - see next.....

 

[10-9jc]

http://www.searchautoparts.com/motorage/powertrain-pro/dodge-48re-partial-engine-stall-sudden-engine-rpm-increase

 

[cerberusiam]

Those trouble shooting summations are right out of the FSM and are more often than not wrong, they are just one possible problem.

Changing the solenoids out will resolve that and if it doesn't, not the problem.

Same with the electrical problems. The most common symptoms are a flickering trans temp light and constant 3rd gear starts from burning out the transducer. A short across pin 6 and 7 will do nothing because they are ground wires, a short to ground on them will almost always trigger codes as that circuit is monitored for resistance and a good enough short to activate the solenoids usually triggers limp mode. Not always as there is always the exception.

A transmission that will exhibit rom rise and pull thru the brake sin both forward and reverse is almost always a stator clutch problem, and, they will intermittently hang then the symptoms disappear, usually when you take it to a shop.

Verify the cooler is flowig a good stream of fluid first, if so maybe just need a new TC. A rebuild is not always needed uless you want to be positive about reliability. I have swapped bad TC's out of several units and they are still running fine to date.

 

[10-9jc]

Thanks Cerb -
The only reason the article had any impact - if that's the right word - was that it described the problem accurately.
And, of course, it said replacing solenoids *may* solve the problem.

Everybody hears "new" noises their truck makes - no matter how quiet . Hmmm - It's new, wasn't there before.
When the fluid was changed at a local diesel shop last year (5K miles ago) - I noticed a slight "hum" that I hadn't heard before - the same day. (They dropped the pan to change fluid & filter - or so the invoice said).
It got progressively louder - asked the wife how she would describe it - she came up with a "buzz" sound - usually heard at a stop.

Fluid looked clean - no burnt smell, and truck hasn't towed anything during that time period.
And - yeah, each time I took it over to Mike (Inglewood Trans) it didn't do it's thing when he drove it.
But now - the TC stays locked at a stop just about every time. Shifting the trans to neutral just before a complete stop at a signal saves the required "power braking" waiting for the light to change, and it will sometimes make a metallic noise when shifted back to drive.

Think I've reached the conclusion the TC is history - was just kind of surprised at that due to the low miles, stock power, not much towing - and no abuse. Guess "Murphy" got me.

Suggestions for a "mild" rebuild - for the same stock configuration?

~

 

[cerberusiam]

If it is doing it in reverse and forward all the time, TC is the culprit. A good stock rebuild with Raybestos clutches, shift kit, the needed small parts, and a loe stall billet cover TC will make you wonder why you waited so long to do it.

There is no time factor when these TC's will fail, some last longer than others. Jyst th etypical cheap OE stuff with a finite life span.