RPM problem?

TaurineMike · 10-20-2011, 11:40 AM

Hey guys for the last year or so I've had a weird issue with my car. Each time I climb a hill or give it more gas slowly, the RPM's fluctuate up than back down where they should be. Any ideas? I just replaced the spark plugs and wires about 6months or so ago due to bad wires. Not sure what the problem is but its really annoying. Seems like the computer is trying to compensate for something but than stops. Help me out!

guiguilandry · 10-20-2011, 11:51 AM

IT'S CALLED DOWNSHIFTING...

J/K do you feel the tranny slipping or feel the car is bogging ???

TaurineMike · 10-20-2011, 11:55 AM

No sir, its not the tranny. No bogging, just simple rpm and acceleration that fluctuates up than back down where it should be when climbing a hill mainly.

Shiwnath · 10-20-2011, 12:26 PM

Seriously though...isnt that just downshifting....When you press on the acceleration pedal, the throttle opens and if you're in a higher gear it'll downshift so you can have more power to the wheels. This especially happens when going up a steep hill because of the extra amount of energy required to get your car up a hill. Its just your engine having to work at a higher speed to keep your car going at a constant speed.

03glgold · 10-20-2011, 12:28 PM

Quote:

Originally Posted by Shiwnath

Seriously though...isnt that just downshifting....When you press on the acceleration pedal, the throttle opens and if you're in a higher gear it'll downshift so you can have more power to the wheels. This especially happens when going up a steep hill because of the extra amount of energy required to get your car up a hill. Its just your engine having to work at a higher speed to keep your car going at a constant speed.

I think it may be going to the point just before downshifting...If you pay attention with cruise on when you are going up a hill it will fluctuate up a little before downshifting, however some hills that fluctuation is all that it needs to get back to speed. My car does that all the time.

sleepyalero · 10-20-2011, 12:40 PM

Quote:

Originally Posted by TaurineMike

Hey guys for the last year or so I've had a weird issue with my car. Each time I climb a hill or give it more gas slowly, the RPM's fluctuate up than back down where they should be. Any ideas? I just replaced the spark plugs and wires about 6months or so ago due to bad wires. Not sure what the problem is but its really annoying. Seems like the computer is trying to compensate for something but than stops. Help me out!

i think ive had the same problem, it comes and goes, and have never figured it out, i think it could be something to do with the transmission.

does it do it over and over? or just once? cause mine would fluctuate from say at 40 mph at 1100 rpms it would go to about 1400 then 1100 and go back and forth.

[ion] C2 · 10-20-2011, 12:42 PM

take a video FFS

Shiwnath · 10-20-2011, 12:45 PM

Quote:

Originally Posted by 03glgold

I think it may be going to the point just before downshifting...If you pay attention with cruise on when you are going up a hill it will fluctuate up a little before downshifting, however some hills that fluctuation is all that it needs to get back to speed. My car does that all the time.

Yup, that is expected anytime you go up a hill. Engine speed has to increase to accomodate for the energy required to make it up the hill. If the current gear thats you're in while going up a hill cant make enough power it'll just downshift.

guiguilandry · 10-20-2011, 12:46 PM

I say lockup solenoid disengaging/sticking... and at certain point it's normal (but in the case of sleepyalero I'm sure that was the problem)

TaurineMike · 10-20-2011, 01:06 PM

Quote:

Originally Posted by sleepyalero

i think ive had the same problem, it comes and goes, and have never figured it out, i think it could be something to do with the transmission.

does it do it over and over? or just once? cause mine would fluctuate from say at 40 mph at 1100 rpms it would go to about 1400 then 1100 and go back and forth.

It does it over and over, which is why i don't think its "downshifting."
Edit: Will try to post video later.

sleepyalero · 10-20-2011, 02:09 PM

Quote:

Originally Posted by guiguilandry

I say lockup solenoid disengaging/sticking... and at certain point it's normal (but in the case of sleepyalero I'm sure that was the problem)

it could be that, but ive asked on here before and never got a solution and the dealership couldnt give me one either, kinda a weird problem since no one really knows the answer to it lol.

Quote:

Originally Posted by TaurineMike

It does it over and over, which is why i don't think its "downshifting."
Edit: Will try to post video later.

that would be awesome, i would do mine to but it hasnt done that problem in awhile, it used to be really bad, now it just comes and goes when it wants to.

Thewolf · 10-20-2011, 03:36 PM

Is there any CEL? If there is it could be the Camshaft Position Sensor (CPS).

sleepyalero · 10-20-2011, 04:46 PM

mine never had a light when the problem occurs.

mmorello82 · 10-20-2011, 11:08 PM

My car did the exact same thing!! Small world! About a week or so after mine started doing it, it started shifting REALLY hard. Took it to the dealership and it turned out being the "pressure control solinoid". There is a o-ring around it and it goes back and leaks off pressure. When it does, your rpm's will "surge" because the torque converter is locking and unlocking. You can replace it, but it is located in the clutch packs, have to tear the whole thing apart. I just bought a reman, and no trouble since. This is what the GM dealership told me and I trust them, like I said no problems since. If you want, I can put up a exploded view showing where it is.

AleroB888 · 10-20-2011, 11:40 PM

Quote:

Originally Posted by mmorello82

My car did the exact same thing!! Small world! About a week or so after mine started doing it, it started shifting REALLY hard. Took it to the dealership and it turned out being the "pressure control solinoid". There is a o-ring around it and it goes back and leaks off pressure. When it does, your rpm's will "surge" because the torque converter is locking and unlocking. You can replace it, but it is located in the clutch packs, have to tear the whole thing apart. I just bought a reman, and no trouble since. This is what the GM dealership told me and I trust them, like I said no problems since. If you want, I can put up a exploded view showing where it is.

What did they charge for a reman trans, I'm looking for options now.

I could use a pinout diagram for the electrical socket, too.

Oh, and sometimes I've seen MAFs cause that idle surge up and down under load, if you have a CAI, but could be a few other things.

TaurineMike · 10-20-2011, 11:57 PM

Well I guess it could be the problem mmorello. But I also have a CIA too. We are talking about the 3.4 right mmorello?

sleepyalero · 10-21-2011, 02:18 AM

idk, all i know is i just want to replace the tranny with one that has more reliable parts. cause i think my trans pump/torque converter is goin out.

mmorello82 · 10-21-2011, 09:01 AM

Yep, we are talking about a 3.4L engine. The tranny cost 1,200 at autozone and it was about 800 in lobor to put it in. I did not pay for any of that though, it was under warranty (thanks JD buyrider). Part of the reason we went with a reman, is the remans they fixed the design flaw with the pressure control Sol. So a reman is going to be WAY more reliable. Again, this is what the GM dealer told me before I took it to JD buyrider and told them to fix it. This was with a 4T45E transmission in my 02 GLS 3.4. I hope this helps! Alero B888, I am going to e-mail you the exploded view as I can't do a .pdf on here.

mmorello82 · 10-21-2011, 09:04 AM

Alero B888, what's you e-mail address? I'll send what I have to you!

cavaliers60 · 10-21-2011, 09:09 AM

I don't think it's shifting... I know what you are talking about... My car has done it for the past 4-6 years. It will do it on the highway too if you are on cruise and accelerate. I can get a video of it up a little later today. I don't think it's anything serious... My car has done it for years, and no problems to report.

Edit: Mine does it somewhere around 2000-3000 RPM. fluctuates up and down several times until I either give it more gas or it makes it up the hill.