Truck jerks/hesitates at around highway speeds.

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.

bluwarguy

Member
Joined
Oct 20, 2016
Posts
70
Reaction score
4
Ram Year
1997
Engine
5.9 Magnum V8
So today something new happened to me.
When I was on the highway, my truck started to jerk a tiny little bit in 4th gear. So i pulled over, turned off my engine, and started it again. This time, once I hit 40mph it did something really weird. It didn't want to accelerate, and it revved in two separate intervals. It's hard to describe. Turning overdrive off made it worse. At that point I let off the gas and just drove as slow as I could home. When I was slowing down to about 35mph, I noticed my rpm needle moving back and forth quite a bit within an area of 250 RPM. I have no clue what could cause this and I'm pretty nervous. Sparkplugs were just changed last weekend.

EDIT: I would like to point out that my front o2 sensor is temporarily not connected to the exhaust because I have a little more work to do on it. Would this be the cause of the problem? I know it's causing it to run lean.
 

dudeman2009

Senior Member
Joined
Feb 9, 2016
Posts
1,562
Reaction score
208
Location
Arizona
Ram Year
2001 1500 Sport with enough electrical modifications to make my brain hurt
Engine
Magnum 360
If the O2 sensor is unplugged it will run rich in open loop mode, if its hanging, it will read tons of oxygen in the atmosphere and run rich, not lean.

Generally an O2 sensor issue will just make it run crappy, not erratic, but it is possible.

TPS issues and IAC issues are known to cause these types of problems. Crank position sensor can also cause similar issues.

Are there any codes?
 

dapepper9

Senior Member
Joined
Feb 7, 2013
Posts
5,908
Reaction score
2,224
Location
Iowa/Nebraska Border
Ram Year
2001
Engine
5.9L V8
Sounds more like a severe trans slipping issue, especially if it was worse with od off where tq is much greater.
 
OP
OP
bluwarguy

bluwarguy

Member
Joined
Oct 20, 2016
Posts
70
Reaction score
4
Ram Year
1997
Engine
5.9 Magnum V8
Unplugged the o2 sensor to put it in open loop and while I didn't drive it that much to test it out, it still sort of did it.

I tried OD off again, and it didn't do it for a while but eventually it did it again but less severe.
 
OP
OP
bluwarguy

bluwarguy

Member
Joined
Oct 20, 2016
Posts
70
Reaction score
4
Ram Year
1997
Engine
5.9 Magnum V8
If the O2 sensor is unplugged it will run rich in open loop mode, if its hanging, it will read tons of oxygen in the atmosphere and run rich, not lean.

Generally an O2 sensor issue will just make it run crappy, not erratic, but it is possible.

TPS issues and IAC issues are known to cause these types of problems. Crank position sensor can also cause similar issues.

Are there any codes?

I think my o2 sensor is fouled, it's completely blackened. I can't remember them off the top of my head but there are 3 total and they're all related to the o2 sensors. One told me I was running lean, the other said something about the o2 heater circuit malfunctioning, and the other was telling me my after-cat o2 sensor wasn't working, but i already knew that one.

Another note I'd like to make, it happens the most when I'm going a steady speed. It will hesitate, then accelerate. Repeat. I think sometime after school today or maybe tomorrow I'll record video of it from inside the truck.
 

Yeret

The Village Drunk
Joined
Oct 2, 2014
Posts
938
Reaction score
178
Location
Under the hood fixing/breaking something.
Ram Year
1999
Engine
5.9 Magnum
Does it do the same thing while the engine is cold vs warm? As long as the engine is in open-loop mode (during warm-up or WOT), the computer ignores inputs from the O2 sensors so even if they're faulty, they shouldn't affect things if the engine is in open-loop.

You say that your O2 sensors are fouled. I'd plan on replacing them soon or they're just gonna keep lighting up your CEL (best case scenario) or totally ***** the engine's performance (worst case scenario).

Telltale sign of faulty O2 sensors is an engine that runs okay when cold but crappy when warm.
 
OP
OP
bluwarguy

bluwarguy

Member
Joined
Oct 20, 2016
Posts
70
Reaction score
4
Ram Year
1997
Engine
5.9 Magnum V8
Does it do the same thing while the engine is cold vs warm? As long as the engine is in open-loop mode (during warm-up or WOT), the computer ignores inputs from the O2 sensors so even if they're faulty, they shouldn't affect things if the engine is in open-loop.

You say that your O2 sensors are fouled. I'd plan on replacing them soon or they're just gonna keep lighting up your CEL (best case scenario) or totally ***** the engine's performance (worst case scenario).

Telltale sign of faulty O2 sensors is an engine that runs okay when cold but crappy when warm.

I usually wait for my engine to reach normal temperature before I drive it, but i'll test it out right after school and let you know how it goes.
 

dudeman2009

Senior Member
Joined
Feb 9, 2016
Posts
1,562
Reaction score
208
Location
Arizona
Ram Year
2001 1500 Sport with enough electrical modifications to make my brain hurt
Engine
Magnum 360
Since you unplugged your O2 i'm going to agree with Dapepper on this one. It sounds like the trans is slipping for some reason or another. Unlike standard gear trains, planetary gear trains do weird things when they malfunction. 'Surging' and hesitating are common problems when bands are starting to wear out or if there is a clog in the valve body.

Does putting it in neutral and flooring it for a couple seconds, then putting it back in drive change anything?
 
OP
OP
bluwarguy

bluwarguy

Member
Joined
Oct 20, 2016
Posts
70
Reaction score
4
Ram Year
1997
Engine
5.9 Magnum V8
Since you unplugged your O2 i'm going to agree with Dapepper on this one. It sounds like the trans is slipping for some reason or another. Unlike standard gear trains, planetary gear trains do weird things when they malfunction. 'Surging' and hesitating are common problems when bands are starting to wear out or if there is a clog in the valve body.

Does putting it in neutral and flooring it for a couple seconds, then putting it back in drive change anything?

would the bands or clog be easy to replace/fix?

i'll try that as well after school
 

dudeman2009

Senior Member
Joined
Feb 9, 2016
Posts
1,562
Reaction score
208
Location
Arizona
Ram Year
2001 1500 Sport with enough electrical modifications to make my brain hurt
Engine
Magnum 360
would the bands or clog be easy to replace/fix?

i'll try that as well after school

No, bands require a trans rebuild as they don't make snap bands for these transmissions, if the valve body is clogged, and a fluid and filter change doesn't fix it, then its a rebuild on that too.

Rebuilding the automatics is easier than the new venture manuals, as well as easier than chevys autos, but more complicated than fords autos. I'd call this generation of auto Dodge trans easy to rebuild. But i've rebuild just about every engine CAT makes, most Cummins, and the old Detroits. I'd guess that it's about twice as hard to rebuild an auto trans as it is a gas engine.
 
OP
OP
bluwarguy

bluwarguy

Member
Joined
Oct 20, 2016
Posts
70
Reaction score
4
Ram Year
1997
Engine
5.9 Magnum V8
Well guys, after I unplugged the front o2 sensor, the problem has completely stopped. It hasn't done it again since.
 

dapepper9

Senior Member
Joined
Feb 7, 2013
Posts
5,908
Reaction score
2,224
Location
Iowa/Nebraska Border
Ram Year
2001
Engine
5.9L V8
Replace the front 02. NTK or direct from Mopar

02s can cause weird issues in these trucks as this has clearly shown.
 

Staff online

Members online

Forum statistics

Threads
194,902
Posts
2,863,860
Members
155,252
Latest member
radikio
Top