wierd like jerking problem

[Trigga-T]

when i drive and stay at the same speed the car like jerks like it aint gettin gas or somethin i have no idea wut it is some people told me maybe dirty fuel injectors but im not sure its a wierd thing to explain if anyone has any ideas let me know please

[CUSTOMGAGT2000SEDAN]

my 1997 se v6 with nearly 250,000 klms on it does it between 80-85 and if i remember 105-110. i describe it as yes jerking and a hestitation . as if it is struggling to get gas. i kind of wounder my self . i think it has been touched on though. my 2000 does it but barely notice it and it maybe at the dsame 80-85 klms speed ???? like a little hipcup.

[cardude007617]

here ya go:
Tranny surging in 3rd gear

[Graxall]

What speeds does it occur at? If its low speeds, is ther a delay when u try to take off? Or a delay with giving it gas at all, or if ur doing like 40 and try to gun it, when itshifts does it get really sluggish??

These are signs of a few things
a. Bad cat(covered under warranty until 80k mi, no matter what or where u are)
b. intake is clogged/dirty and needs to be cleaned.
c. o2 sensors
d. fuel pump or injectors...

[cardude007617]

whoa wait hold up. explain the if you're going 40 sluggish thing......... and what would cause that?

[Graxall]

Originally Posted by cardude007617

whoa wait hold up. explain the if you're going 40 sluggish thing......... and what would cause that?

Like ur cruising @ ~40 so your in between 2nd and 3rd gear(i beleive), and say u try to get on it a bit, and as soon as you shift you go low rpm but have no power basically......

that would usually be your cat or something in your air flow system being clogged up...

[Trigga-T]

Originally Posted by Graxall

What speeds does it occur at? If its low speeds, is ther a delay when u try to take off? Or a delay with giving it gas at all, or if ur doing like 40 and try to gun it, when itshifts does it get really sluggish??

These are signs of a few things
a. Bad cat(covered under warranty until 80k mi, no matter what or where u are)
b. intake is clogged/dirty and needs to be cleaned.
c. o2 sensors
d. fuel pump or injectors...

it does everything u said. it pisses me off and i hate it. ill just take it somewhere and tell them to figure it out

[CUSTOMGAGT2000SEDAN]

i know on my 97 se v6 as you gradually increase the spped along the hwy as soon as you hit 80 to 85 it shakes / jerks quite alot then gone til you hit i think 105 to 110 any other speeds higher lower or in between no problems.

[timka86]

Originally Posted by CUSTOMGAGT2000SEDAN

i know on my 97 se v6 as you gradually increase the spped along the hwy as soon as you hit 80 to 85 it shakes / jerks quite alot then gone til you hit i think 105 to 110 any other speeds higher lower or in between no problems.

that's poor tire balancing. get em balanced.

[timka86]

Originally Posted by Graxall

Like ur cruising @ ~40 so your in between 2nd and 3rd gear(i beleive), and say u try to get on it a bit, and as soon as you shift you go low rpm but have no power basically......

that would usually be your cat or something in your air flow system being clogged up...

that's actually right betweent the 3 and 4 shift not 2 and 3.

I'm not sure on this, but i Think it's the axles (half-shafts) causing this. Mine are going really bad, sometimes when I accelerate, not hard, just making a 20-30 mph turn and accelerating out of it to 40 i can a pretty violant vibration under the hood. at which point I immediately let off the gas and it goes away. I've had this on a previous car, and was told it's axles going bad and getting stuck. problem being if they're getting stuck they can snap any day/hour/minute. so get them changed. one way to check is if you grab the knuckle (sometimes called tulip) and they wobble a lot. also if you have quite a bit of miles on them and you have grease splattered all over the inside of you wheels, that means the boots on the exle broke and it's got no grease in it cuz it's on your wheel and that's pretty much the end to your axles.

when you're accelerating there's a lot of force on them and they're almost forced to turn correctly, but not always, when they're really bad, nothing helps, just changing them. but when you're coasting, where the trans is engaged one sec and not the next they tend to wobble cuz they're either playing catch up with the trans or wheels.

that seems like it may be a little confusing....

[redhotalero]

By a jerk do you mean you keep on going, but can feel a jerk/shudder as if the car was going over a road fracture but isn't? Mine was doing that - went away after a MAF/TB cleaning and changing of the O2 sensor pre-cat... Mine only did it at high speeds though, like above 70mph

[Trigga-T]

the car still goes but it jerks as ur goin around 35-40 and sometimes about 60-70

[CUSTOMGAGT2000SEDAN]

Yes That's What Mine Is Like A Jerk Or Shudder. As Soon As You Back Of Gentlely From Accelarating It Goes Away But Happens In The Speed Ranges I Mentioned. Not Tires As One Member Mentioned Not That Type Of Vibration. So You Mention O2 Change Or Maf Or Tb Cleaning

[PLUM_72]

Originally Posted by cardude007617

whoa wait hold up. explain the if you're going 40 sluggish thing......... and what would cause that?

I have searched and read a bunch of posts on this...I cannot believe no one has figured this issue out! It seems like this happens alot! there doesn't seem to be a specific fix. There is a lot of guessing, without firm resolution

I have his issue and have tuned up, cleaned MAF's and TB's, IAC, comp updates, swapped parts, etc all without fixing the problem. This over 40MPH surge or jerky rpm fluctuation at steady speeds thing is driving me nuts! It seemed to go away or be greatly reduced in the summer and reappear or has gotten worse when it got cold out, regardless of engine temperature.

Before I go to the trans shop and have them guess while I pay, I'd like to know what is the fix before hand...

HELP!

[CUSTOMGAGT2000SEDAN]

My Simptums Do Not Seem To Be Effected By Temputure Or Seasons. But We Seem To Have Same Problem But At Different Speeds.

[andrewe77]

It's your transmission starting to slip.

[PLUM_72]

Originally Posted by andrewe77

It's your transmission starting to slip.

Okay...What leads you to your diagnosis? Are you skilled in transmission repair? Or is this another off the wall guess based on the typical hear-say obtained from reading too many posts in the various forums?

Im no trans expert, but if it were starting to slip, would it not do it ALL the time? This problem only occurs under the right set of circumstances; 4th gear, a steady 40-50MPH, and the engine takes on an additional slight load such as going up a slight incline does the problem show up. If I reduce or add throttle, the car responds and the RPM fluctuation is gone.

My ride is long past the warranty stage...if I am going to foot the bill for a trans replacement, I gotta be damn sure the issue requires a trans replacement and that it's not some goofy $50 sensor going whack.

Based on some of the posts on this topic, even the pros who fix cars for a living have unsuccessfully diagnosed the problem, the problem may have been made better but only to return a short while later.

I need a sure diagnosis or at least a number of people confiming a particular fix especially if we are talking tranny replacement or rebuild...read expensive $$$

[Ajaxus]

i have to say it..every time i sign on to the forums and see this thread title i lose all self control

[andrewe77]

Originally Posted by PLUM_72

Okay...What leads you to your diagnosis?$$$

Here you go.

About a month ago I took my car in to a transmission shop to investigate whether or not to get the fluid and filter changed or a total flush. I have 120,000 miles on the car and it has had this exact jumping RPM problem on slight grade as well as the sloppy 1-2 shift since around 60,000 miles.
I learned that this transmission has an adaptive pressure system where the PCM can adjust the line pressures as needed to get an acceptable shift delay. This allows the PCM to compensate for wear over the life of the transmission. The tech noticed some very high adaptive pressure settings in the PCM on my car and reset everything back to zero.
For over a week after this, the car shifted like **** and I noticed that the part throttle slight RPM jumping became SEVERE jumping because the pressures were so low that the clutches weren't being held. AND this severe jumping occurs at 40-60 MPH under load like up a hill. The PCM has re-learned the pressures but it has maxed out and can't get them high enough to eliminate the slight RPM jumps as noted before.

One thing you could try is a modified PCM upgrade that is programmed to increase the line pressures. It may get you a few more years on the transmission.

All in all your transmission, like mine, has degraded enough that the PCM can't completely compensate for the wear. However, it seems like the problem only gradually gets worse and if you can live with it as a minor annoyance, the transmission should last the life of the car.

[Malibucdl]

Originally Posted by andrewe77

Here you go.

About a month ago I took my car in to a transmission shop to investigate whether or not to get the fluid and filter changed or a total flush. I have 120,000 miles on the car and it has had this exact jumping RPM problem on slight grade as well as the sloppy 1-2 shift since around 60,000 miles.
I learned that this transmission has an adaptive pressure system where the PCM can adjust the line pressures as needed to get an acceptable shift delay. This allows the PCM to compensate for wear over the life of the transmission. The tech noticed some very high adaptive pressure settings in the PCM on my car and reset everything back to zero.
For over a week after this, the car shifted like **** and I noticed that the part throttle slight RPM jumping became SEVERE jumping because the pressures were so low that the clutches weren't being held. AND this severe jumping occurs at 40-60 MPH under load like up a hill. The PCM has re-learned the pressures but it has maxed out and can't get them high enough to eliminate the slight RPM jumps as noted before.

One thing you could try is a modified PCM upgrade that is programmed to increase the line pressures. It may get you a few more years on the transmission.

All in all your transmission, like mine, has degraded enough that the PCM can't completely compensate for the wear. However, it seems like the problem only gradually gets worse and if you can live with it as a minor annoyance, the transmission should last the life of the car.

In the thread by videoman that was referenced above, he mentions the fix that was done to his transmission was to replace the drive bearing gasket, this may be the fix we are looking for. If this problem was just in the transmission and was not affecting my fuel mileage, I would just live with it, but my mileage has dropped to the low 20s so I need to get it fixed.

Chris