Has your 5.7L Hemi ever acted like this?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Curt Gobbell

Senior Member
Joined
Sep 14, 2020
Posts
216
Reaction score
211
Location
Memphis TN Area
Ram Year
2014
Engine
HEMI 5.7L
Vehicle: 2014 1500 with 150k miles (5.7L HEMI)

Issue: at cruise (7th or 8th gear, 70mph on the highway) my engine has started a "tachometer hiccup" about every 4 seconds (very constant cadence) where the engine will increase RPMs by ~100 for a split-second then return to normal. I've capture about 10 seconds of it via TORQUE below.

Anybody experience this?



1627999431143.png
 

Fast69Mopar

Senior Member
Joined
May 10, 2019
Posts
1,997
Reaction score
1,706
Location
Texas
Ram Year
2004
Engine
5.7 HEMI
Vehicle: 2014 1500 with 150k miles (5.7L HEMI)

Issue: at cruise (7th or 8th gear, 70mph on the highway) my engine has started a "tachometer hiccup" about every 4 seconds (very constant cadence) where the engine will increase RPMs by ~100 for a split-second then return to normal. I've capture about 10 seconds of it via TORQUE below.

Anybody experience this?



View attachment 466460
Without being in the truck and performing a test drive myself it looks like the converter clutch is unlocking/disengaging and then engaging again or the truck is shifting from 8-7-8 repeatedly.
 
OP
OP
Curt Gobbell

Curt Gobbell

Senior Member
Joined
Sep 14, 2020
Posts
216
Reaction score
211
Location
Memphis TN Area
Ram Year
2014
Engine
HEMI 5.7L
Fast69...you may be on to something, as I have also noticed a shudder between 2-3 and 3-4 shifts. Kinda sounds like the TC is failing
 

caulk04

Senior Member
Joined
Mar 24, 2013
Posts
871
Reaction score
1,501
Ram Year
2018
Engine
5.7 Hemi
I noticed it once, roughly 900 miles into a 1000+ mile day on the road. Shifted into 7th for a mile or so then let it go back to auto. Haven't noticed it once since, I've logged at least 2000 miles since.

That's not enough rpm delta to be shifting 8-7-8, it's converter slip. Can't advise, sorry.
 

pacofortacos

Senior Member
Joined
Apr 18, 2017
Posts
3,564
Reaction score
4,341
Ram Year
2016
Engine
5.7
I had something similar on my old 5.9 Dakota, just unplugging the pcm and plugging it back in 2-3 times fixed the issue (battery disconnected of course). For me it was just a poor connection issue that just happened to rear it's ugly head after many years.

At least it was cheap and quick for a fix.
 

savage_46

Senior Member
Joined
Mar 7, 2016
Posts
553
Reaction score
348
Location
Alaska
Ram Year
2016
Engine
6.4 swapped
Start with the simple stuff. Clean the throttle body & do a relearn. Ride the brake pedal just enough to trigger the brake lights. If it goes away, then it's torque converter clutch related (TC, wiring, module). I recently had my 1st rpm surge caused by a bad throttle body. Replacing it fixed it in that case.
 

caulk04

Senior Member
Joined
Mar 24, 2013
Posts
871
Reaction score
1,501
Ram Year
2018
Engine
5.7 Hemi
Just being on the brakes is no longer a surefire way to unlock the converter. It used to.

I've found with my truck that the converter rarely unlocks, seems only to do it when slowing down say for a turn then as soon as I'm back on the throttle it locks back up.
 
OP
OP
Curt Gobbell

Curt Gobbell

Senior Member
Joined
Sep 14, 2020
Posts
216
Reaction score
211
Location
Memphis TN Area
Ram Year
2014
Engine
HEMI 5.7L
Update....

Lately I've noticed that the transmission (8HP70) takes about 15 minutes to driving to get to its normal 190F temperature, but once it gets there, the RPM surging is either gone or unnoticeable.
 

Glenn Williams

Junior Member
Joined
Aug 22, 2019
Posts
17
Reaction score
8
Location
Norfolk ON.
Ram Year
2014
Engine
5.7
Start with the simple stuff. Clean the throttle body & do a relearn. Ride the brake pedal just enough to trigger the brake lights. If it goes away, then it's torque converter clutch related (TC, wiring, module). I recently had my 1st rpm surge caused by a bad throttle body. Replacing it fixed it in that case.

@savage_46 How do you do a relearn?
 

Rlaf75

Senior Member
Joined
Nov 13, 2015
Posts
1,488
Reaction score
1,504
Location
East Hartford CT
Ram Year
2011
Engine
Hemi 5.7
Does the engine rev or is it just the tachometer that "glitches"?
 
OP
OP
Curt Gobbell

Curt Gobbell

Senior Member
Joined
Sep 14, 2020
Posts
216
Reaction score
211
Location
Memphis TN Area
Ram Year
2014
Engine
HEMI 5.7L
Does the engine rev or is it just the tachometer that "glitches"?
Rlaf75, the engine will raise RPMs by about 100.

However, this week I've noticed that as the transmission reaches the 190F operating temperature, RPM dissappears.
 
Top