RPM Surging
#1
RPM Surging
Normally when I see threads on DF about RPMs Surging at cruising speed, it's the 06+ Hemi guys with MDS kicking on and off, but as I don't have MDS (or a hemi) that's not my issue...
The symptoms: At cruising speeds, 65+ MPH, my engine RPM will surge +200 revs (most often from 2100 to 2300 rpm) for a second or two, then back to normal. It doesn't matter if the cruise control is on or not, and the PCM isn't throwing any codes. Once this started happening, my gas mileage went to sh*t, dropped by about 35%. I eliminated bad gas as a possibility, since I've drained the tank and it's still happening with fresh gas from a different station. The only thing I could think of is the torque converter locking and unlocking, but I'm hoping there might be a less expensive explanation...
The symptoms: At cruising speeds, 65+ MPH, my engine RPM will surge +200 revs (most often from 2100 to 2300 rpm) for a second or two, then back to normal. It doesn't matter if the cruise control is on or not, and the PCM isn't throwing any codes. Once this started happening, my gas mileage went to sh*t, dropped by about 35%. I eliminated bad gas as a possibility, since I've drained the tank and it's still happening with fresh gas from a different station. The only thing I could think of is the torque converter locking and unlocking, but I'm hoping there might be a less expensive explanation...
#2
didnt no a 4.7 could hit speeds of 65 mph. lol joke lil sis dont get uptight. thats a weird one i hear allot about serging on the mds hemi but never heard it on a 4.7. but i have a friend with a 3.7 ram and his did the same thing , it was a TQ lock up so the dealer said, but like i said i no nothing on smaller engins.
#3
Join Date: Jan 2009
Location: Minot AFB, ND in person, the 'burgh at heart
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you're a mod... your trucks are supposed to be perfect and without problems. what the heck...
i suppose its too small of a difference to be changing from 5th to 4th gear. is it only at that speed/rpms or others too? Whens the last time you ran some fuel injector cleaner through it? sounds like it could be dirty or clogged injectors making the ecu think its getting less fuel, so it just pumps more though occasionally, creating the surge and terrible mpgs. i'd go with the cheap fixes first, like fuel injector cleaner and then possibly seafoam it.
i suppose its too small of a difference to be changing from 5th to 4th gear. is it only at that speed/rpms or others too? Whens the last time you ran some fuel injector cleaner through it? sounds like it could be dirty or clogged injectors making the ecu think its getting less fuel, so it just pumps more though occasionally, creating the surge and terrible mpgs. i'd go with the cheap fixes first, like fuel injector cleaner and then possibly seafoam it.
#4
Normally when I see threads on DF about RPMs Surging at cruising speed, it's the 06+ Hemi guys with MDS kicking on and off, but as I don't have MDS (or a hemi) that's not my issue...
The symptoms: At cruising speeds, 65+ MPH, my engine RPM will surge +200 revs (most often from 2100 to 2300 rpm) for a second or two, then back to normal. It doesn't matter if the cruise control is on or not, and the PCM isn't throwing any codes. Once this started happening, my gas mileage went to sh*t, dropped by about 35%. I eliminated bad gas as a possibility, since I've drained the tank and it's still happening with fresh gas from a different station. The only thing I could think of is the torque converter locking and unlocking, but I'm hoping there might be a less expensive explanation...
The symptoms: At cruising speeds, 65+ MPH, my engine RPM will surge +200 revs (most often from 2100 to 2300 rpm) for a second or two, then back to normal. It doesn't matter if the cruise control is on or not, and the PCM isn't throwing any codes. Once this started happening, my gas mileage went to sh*t, dropped by about 35%. I eliminated bad gas as a possibility, since I've drained the tank and it's still happening with fresh gas from a different station. The only thing I could think of is the torque converter locking and unlocking, but I'm hoping there might be a less expensive explanation...
#5
you're a mod... your trucks are supposed to be perfect and without problems. what the heck...
i suppose its too small of a difference to be changing from 5th to 4th gear. is it only at that speed/rpms or others too? Whens the last time you ran some fuel injector cleaner through it? sounds like it could be dirty or clogged injectors making the ecu think its getting less fuel, so it just pumps more though occasionally, creating the surge and terrible mpgs. i'd go with the cheap fixes first, like fuel injector cleaner and then possibly seafoam it.
i suppose its too small of a difference to be changing from 5th to 4th gear. is it only at that speed/rpms or others too? Whens the last time you ran some fuel injector cleaner through it? sounds like it could be dirty or clogged injectors making the ecu think its getting less fuel, so it just pumps more though occasionally, creating the surge and terrible mpgs. i'd go with the cheap fixes first, like fuel injector cleaner and then possibly seafoam it.
#7
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#10
Ok - Ive been on this forum -- what -- almost 6 months now?...
Ok it sounds like one of 2 things to me.
One - it could be spark plugs going bad... My Colbalt Twin had this issue with her 05 Balt - and she got it fixed under warranty, so this is something that I know it could be that has NOT been said yet
and the other... is the wiring... Go check them... Bet ya if you go looking for these, ya will find what's wrong...
--Cow-Chick--
Ok it sounds like one of 2 things to me.
One - it could be spark plugs going bad... My Colbalt Twin had this issue with her 05 Balt - and she got it fixed under warranty, so this is something that I know it could be that has NOT been said yet
and the other... is the wiring... Go check them... Bet ya if you go looking for these, ya will find what's wrong...
--Cow-Chick--