A/T doesn't like 4th gear at low speed/RPM
 

An odd issue came up with my '98 max last night ....

When cruising at low speeds around 40 mph and 1500 rpm....the car was ...sort of bucking....as if going in and out of gear.

However the issue immediately goes away when I give a little more gas and raise the rpm to over 2k rpm or higher...or turn off OverDrive and go into third gear....


Issue seem to come up after about 5-10 minutes of driving after everytime I stopped and parked the car somewhere.

I checked my fluid level this morning (transmission) and it seems fine, however I did see really small/fine bubbles on the dipstick...the kind I heard of when you have too much fluid in the transmission...don't know if this is the case or not.

I did replace the fluid about 5-7k miles ago, and earlier this year, on two separate incidents, I got a CEL code for Torque Converter Clutch solenoid, however in both cases the code went away on their own after a few days. I don't know if this is related

At the moment, I have no codes, (or lights really) but I have to borrow and reader and try to pull the codes anyways, if any exist in the system.

My Car specs: Stock to the bone 1998 SE, with 210K miles.

Only else comes to mind, is could this be a possible fuel issue instead of the transmission, since it only occurs at low RPMs after a few minutes of driving?

Also, I have not driven the car today to see if this issue has returned.


Any and all of your wise feedback is greatly appreciated.

I would assume that code you got was related. At around 35 mph with a low throttle angle, the TC wants to lockup in 4th gear. If the solenoid that locks it up is malfunctioning, it could be popping in and out of lockup, making the car "buck" like you said. And accelerating (providing a larger throttle angle) would prevent it from trying to lock up, so you wouldn't notice the issue.

Just an educated guess, though.

Well, its pretty educated, helps me know more about the TC lock up ...

I haven't pulled codes yet, but then again, no O/D flashing light or CEL but I'll get a reader soon.

I drove around today to LA and did a fair amount of street vs highway driving, and the problem is PRETTY consistent at the 35-40mph mark only....


Although, quite a few times while idling at a signal light the transmission "bucked" a little, again, could be the lock up acting up ...


Hopefully pmohr will have time to come across this thread and comment

I got the same problem on my 98. My solution: Upgrade to LSD. lol

I've had what sounds like the same problem off and on for the last 4 years on my 96. At light throttle, the idle will often bounce between about 2700 and 3500, which I assume means it's going in and out of OD. Also, if I'm going downhill at freeway speeds and take my foot off the throttle (or give it light throttle), the RPMs drop to idle, and it kicks back in if I give it gas. I changed the throttle position sensor (it tested bad), but that didn't help.

A couple of times it's been running right, then I hit a bump and that seems to trigger the problem. So I've always hoped it's a sensor issue of some kind, but I've pretty much run out of ideas. My solution has been to turn OD off, but I'd sure like to fix it. Although if it means replacing the tranny, I'll probably keep driving without OD...

@Dbear
Sounds like your issue is either a little different, or far worse than mine ....but interesting to hear that you've had it for a long time ......


I really like the max as the most reliable daily driver ever, and I still want to drive it full time for at least another year....so I'm hoping this issue is somewhat minor and its a part I can replace, instead of the whole transmission.


No codes so far (which makes it harder to find) but I'm working and researching whenever I can.

I had this problem where the RPMs dropped to idle after you let off the gas as well. I dont know how it happened but it went away by itself after about 6 or 7 months. Currently, I experience what the OP experiences.

It's a strange problem. If it really was the tranny going, I'd think it would have gone by now. I've posted a couple of times over the years, and not gotten anything useful. It does seem to come and go if I turn OD back on. And, of course, I have no codes. If I get motivated, I might try tracing wires past the infamous harness bend, and see if I can find a break in continuity.

Theres a lot of people who are experiencing these weird issues with lockup.
I am another one who cant seem to figure out the problem.

Basically the same as the OP the tranny slips in and out of overdrive and you can feel it do it a lite bucking if you will.
To me its just really annoying and if im going 50 mph it locks up just fine and stays that way.

Do these transmissions have something called a Speed Sensor or something equivalent bolted to it so it knows when to shift ? or mabey our TCC solenoids are flaking out on us.

This transmission is computer controlled, there is definitely a speed sensor input to the computer.

Keep in mind that, when in top gear with the TCC locked, this transmission holds the TCC lockup when you let off the throttle, and only unlocks it when you press the brake pedal or slow down below 34mph or so, or open the throttle wide like EnervinE wrote.

If it acts up between 35 and 40mph, but is fine above that, and you're sure it isn't the engine misfiring, then perhaps you can very lightly push the brake pedal while you're driving 35-40mph. That should prevent TCC lockup. If it still acts up then TCC lockup is not the problem.

Of course that could mask an engine problem too, because if you have an engine problem that only occurs under 1,500rpm then keeping the TCC unlocked will have it running at a higher rpm and thus outside the problem range.

With the OD switch on, transmission warm, and gentle driving, this transmission will also lock up the TCC around 28mph in 3rd gear. Does it hold that lockup properly?

I think it is important to determine whether you are experiencing an engine problem or transmission problem.

My old 95 max started doing this right before I got rid of it. Interested to see what was actually wrong.

Yes, I am noticing now TCC lock up problems in third right around 28mph too....but you're also right, to find out if its an engine problem or not. However, many people seem to have a similar issue, so could be transmission related

Im am just guessing here, I have a 94 max. The solution for me was to keep the OD off while cruising through the city at speeds of 35 to 45 mph. The torque converter lock up on 3rd generation transmissions, was at 45mph. If the OD is in the on postion while doing 45mph, the transmission would hunt/search between gears at that speed, unless you give it a little gas and let the TQ converter go into lockup at speeds of 50mph and above. Believe me, the searching between gears back and fourth was very annoying to me, thats why I only use the OD on when I am going on the interstate, or speeds above 45mph. Hope this helps

but obviously you'll sucrifice your MPG:D

That's what I have been doing for the time being, just driving in the city without OD, and with OD on the highway ( I do a lot of both on a daily basis)

At the moment, I'm going to take it to a transmission shop that is well reputed and referred by a good friend of mine. I already spoke to the head tech who said its most likely a TC/Solenoid pack issue and that he'll diagnose it for free later today.


He also stated that if its either issue, that its best to replace out both components, as they go hand in hand. I'll update as soon as I know, thanks for all the feedback, certainly helped.

Haha, nice word play

"sucrifice"

@maxinout93--

I don't think this is the same thing. I noticed the "hunting" when I first got the car too, but this is more pronounced, and more annoying. It happens to me at freeway speeds, well beyond the normal hunt range.

Its worth fixing man....the engine on these bad boys last forever. I replaced my tranny for 1200 bucks. Included tranny, new clutch, and labor. I look at it as: unless u gettin somethin else thats better then u might as well as dish out the cash to keep the car running.

Its cool that these cars can have issues and still run. SOme lesser cars would have croaked lol

:king2:

When I replaced my knock sensor the problem went away. Maybe?:confused:

So much is tied into that Knock Sensor that before u start to diagnose engine/tranny/EGR/MAF, first make sure the KS is working properly. Ppl underestimate how important that sensor is to the overall health of the car. Plus its so easy to replace that its really stupid not to replace it.

FWIW, I did replace my KS a couple of years ago. Didn't have any noticeable effect on the problem (although the response was a lot better).

A couple of years ago could mean that it has gone bad again, check the codes.

I scanned for codes a couple of months ago. Nothing there.

M00njal--

What did your mechanic say?

A bad knock sensor does not make the VQ30 engine run poorly, or buck, or any such thing. In my experience, all a faulty knock sensor does in the VQ30 is prevent aggressive timing advance, and thus you don't get maximum power, but it isn't a huge difference for regular driving. You may also lose 1mpg with a faulty knock sensor, again because the ECU is not using as much timing advance as it could.

Let us know how the TCC solenoid diagnosis turns out.

I'd scan for a knock sensor code, it caused bucking on my 5-speed, don't know about autos though.

My wifes car had a slenoid replaced to eliminate it from revvving to high on the highway. made a world of difference and thank god we didn't let the tranny shop have thir way with it

wait the t/c can lock up at 30mph?

m00njal i had the same problem on my 3rd gen. it's possible your tps is bad.
because at light throttle the volts would bouce around a little bit...basically enough to make the tcu think your messing around with the gas.

what did the shop diagnose and what was the result??