cruise has always performed superbly until 5 days ago. and that hasn't changed when driving on level or uphill roads. but driving on something like a scant 5 degree decline will immediately cause the tach to oscilate about 200-300RPM(peak-to-peak)
the car has 115,000miles on it. Anyone have some insight?

 

tune up needed

 

give me a break

 

I'm guessing it's an automatic, and that to do this it is unlocking the torque converter? What speeds is this happening at?

 

check the following

IAC
MAF
TPS
VSS
BOO(most likely this is your problem)

 

yes, it's an auto and the speeds i'm driving at are 50-60MPH.

 

Whoooaaaa.......it's acronym hell! Um, help me here. it's IDLE AIR CONTROL VALVE? MASS AIR-FLOW SENSOR? THROTTLE POSITION SENSOR(I think this one i can eliminate. sensor failed years ogo resulting in the tranny never shifting above 1st gear.) VSS?

 

Vehical Speed Sensor(located in the trans) BOO is brake on off switch, you may also want to to check WSS(wheel speed sensor)

 

This happens to me too. More so on my old Maxima but I live in a very hilly area and there is one hill in particular that causes the RPM's to go up and down. I haven't noticed it on my new Maxima but my Mom does and it annoys the hell out of her! One of the reasons we got rid of the old Maxima was cause the mechanics couldn't figure out what was happening. I don't have it on cruise control though, this is just driving down the hill at 90 km/hr (55 mph?).

 

Okay, you're gonna be disgusted with me. i knew before starting my thread that i needed to to observe the swing amount on tach but was impatient so i guessed when posting, hoping to read feedback after work.
UPDATE: RPM fluctuation is really almost nil but you definately notice it's like letting off the gas for a fraction of a sec and repeating about once every 5sec

 

I would check the vacuum line from the cruise control actuator to the throttle cable for any cracks or holes, or loose connections. Secondly, I would also run a grounding wire from the actuator bracket to the right side of the engine bay at the point where the main wire from the negative battery terminal connects to the frame (it's located under the fuse box).

Vacuum leaks and bad grounds can cause what you described.

 

thanks, i'll check it out.

 

Mine does this too. It's basically trying to keep a constant speed when you are downhilling. There is nothing wrong with IACV and the likes, believe it or not, the engine was deadvancing/re-advancing due to light load......

The solution that I have is to have aftermarket shocks and set them to somewhat hard. When I set my AGX/Maxspeed to 2 for fronts and 4 rears, I could not feel the "rocking" part.

 

i never had a problem on mine, but i didn't get to use cruise control that much living in seattle, where the traffic really never ceases

 

Mine works great, I just hate when I press the resume button and I'm not in gear.... REDLINE here I come!

 

nismo- you want to see your car? my 97 5speed SE was just totalled last week and am looking for a replacement

 

How much you offering? I just put 1300 into a trans re-build and new brake lines all around - $ 400 plus all the mods... full system dvd player and screen, cd changer in the glove box...5 remotes... lol .....

 

haha, that might be a little to much for me- i am simple and like them stock although it would be nice...
i have no idea right now what i am looking for other than a maxima- i have to get a check from the insurance and they aren't being cooperative...insurance companies rock

 

Oh its also got y pipe exhaust drop ecu short shifter new clutch lol Good luck on you're search