RPM's jump at low speeds

TJ Tigers

TJ Tigers

Member
Joined
Nov 25, 2017
Messages
37
Location
Burnsville, MS, United States
Over the past week, I have been getting rpm increases at low steady speeds(10-15 mph). Like when easing through a neighborhood. It only happens when lightly on the throttle. I haven't noticed any other issues in shifting. I am obsessive about noises and changes in the way my Jeep runs. My buddy, who owns a small shop tells me all the time that I bought the wrong vehicle. I just want to make this Jeep last. My 6 y/o daughter already had plans for it one day. What could be the issues?

97 4.0
99,400 miles
4 inch lift w/33's
 
TJ Tigers said:
Over the past week, I have been getting rpm increases at low steady speeds(10-15 mph). Like when easing through a neighborhood. It only happens when lightly on the throttle. I haven't noticed any other issues in shifting. I am obsessive about noises and changes in the way my Jeep runs. My buddy, who owns a small shop tells me all the time that I bought the wrong vehicle. I just want to make this Jeep last. My 6 y/o daughter already had plans for it one day. What could be the issues?

97 4.0
99,400 miles
4 inch lift w/33's
Click to expand...
My Mustang would do that. Changed the TPS and no more problems.
 
  • Like
Reactions: TJ Tigers
This is a stab, so take it for what it’s worth and others more knowledgeable of the engine side will chime in.

Clean out the throttle body intake. It regulates the amount of air that enters under acceleration. It’s a common and easy problem to fix.

And you bought the right vehicle. Jeeps are either for you or not. If you try and it doesn’t work, give up there
 
  • Like
Reactions: TJ Tigers
Your buddy told you that you got the wrong vehicle because he knows you are obsessed with the vehicle noises. I do tell that to my step son every day on the last year he has own his TJ.
Truth it is that the Jeeps choose Us not Us to them.

Follow @JMT suggestions.
 
  • Like
Reactions: TJ Tigers
I tell him all the time that he's just jealous, his wife won't let him get a Jeep. I read the other day on here someone posted that the 4.0 is closer to a tractor engine than a Ferrari. I guess I need to let that sink in. Either way, I am happy to be obsessed with my Jeep. Thanks again guys.
 
TJ Tigers said:
Thanks for the quick responses. Cleaning the throttle body and IAC are both on my weekend to do list. I'll change the TPS while I'm in there. Thanks again.
Click to expand...
If you decide to replace the TPS, make sure you use a genuine Mopar part. Aftermarket sensors don't work well most of the time.
 
  • Like
Reactions: TJ Tigers
TJ Tigers said:
Over the past week, I have been getting rpm increases at low steady speeds(10-15 mph). Like when easing through a neighborhood. It only happens when lightly on the throttle. I haven't noticed any other issues in shifting. I am obsessive about noises and changes in the way my Jeep runs. My buddy, who owns a small shop tells me all the time that I bought the wrong vehicle. I just want to make this Jeep last. My 6 y/o daughter already had plans for it one day. What could be the issues?

97 4.0
99,400 miles
4 inch lift w/33's
Click to expand...
Vacuum leak. Check your vacuum lines.
 
TJ Tigers said:
Over the past week, I have been getting rpm increases at low steady speeds(10-15 mph). Like when easing through a neighborhood. It only happens when lightly on the throttle. I haven't noticed any other issues in shifting. I am obsessive about noises and changes in the way my Jeep runs. My buddy, who owns a small shop tells me all the time that I bought the wrong vehicle. I just want to make this Jeep last. My 6 y/o daughter already had plans for it one day. What could be the issues?

97 4.0
99,400 miles
4 inch lift w/33's
Click to expand...
RE: vacuum lines - see if you can reproduce the RPM problems with and without the HVAC / heater on..
 
I wanted to come back and update. I had a small leak at the exhaust manifold gasket, 2 months old, replaced with Fel-Pro gasket. Cleaned TB while I was in there. I checked everything for leaks and put it back together. Runs great and no more revving at low speeds. Hopefully this gasket lasts a long time because I don't want to change it out again any time soon. Thanks again guys.
 
  • Like
Reactions: Jerry Bransford
Top Bottom
Back