Tac surges

[Dagan]

Hello i have a problem with my 1995 jeep 4.0 strgt6. The tac will raise and lower while i am driving say i am doing 50 mph the tach will jump up the motor will speed up but i gain no mph it stays at 50mph then the tac will drop back to normal. Sitting still in park the thing runs no misses the tac stays steady. It is just when i am going down the road it will do this. tac also stay constant with a load on it foot on the brake. Any ideas? I replaced the speed sensor on the trans no luck tac still surges ans motor still reves. Replaced the TPS Sensor no luck there either.

 

[Jason4x4]

Ok, so does your YJ have an automatic transmission?? I am going to assume for the moment that it does and I'm going to ask a stupid question - is it possible that it is switching gears...like in other words, maybe 50mph is right in between 4th/5th gear and the auto transmission is switching back and forth between the gears trying to stay happy? That's the only explanation I can think of.

 

[Dagan]

Ok, so does your YJ have an automatic transmission?? I am going to assume for the moment that it does and I'm going to ask a stupid question - is it possible that it is switching gears...like in other words, maybe 50mph is right in between 4th/5th gear and the auto transmission is switching back and forth between the gears trying to stay happy? That's the only explanation I can think of.

ya its an automatic hell it does it at 40 45 an on... its weird the tack will jump from say 1500 to 1550 three or four times and then it will surge to 3000 and hold like passing gear is kicking in but i gain no speed. Then it will drop back and start it all over again

 

[Dagan]

ya its an automatic hell it does it at 40 45 an on... its weird the tack will jump from say 1500 to 1550 three or four times and then it will surge to 3000 and hold like passing gear is kicking in but i gain no speed. Then it will drop back and start it all over again

Its a 1995 grand cherokee laredo 4.0 automatic 2 wheel drive sad to say