Last thing "broken"---Help me figure this out.

[PewterBird]

O finnally got my brakes fixed as well as some other things, and I have one last mechanical problem to figure out befor my car is completly mechanicly perfect.

I don't throw a code, and I it will only do this 5% of the time mostly on hot days, but not always.

I have a 99 3.8 auto. When I step on the gas from a stopped position it holds first gear really long, then it will shift slowly but rough with a thud. Second and so on are fine. It doesn't matter how slow or fast I take off, or if I use 1,2,3,D.

It will do this for the duration of the drive approximatley 15-20 minutes, then I will let the car sit and I don't see it again for at least a month.

What could it be, bad TC, Clutch?

Im not sure if it is related, but sometimes when I am cruising at around 45 it will start to bog down and surge, like it is deciding which gear to use, so I just speed it up to 50 and it is fine.

[tWiStEdBird]

Do you hit the rev limiter when it does this? And if so, does it stay up there?

[PewterBird]

No, I don't let it hit the limiter, as soon as it start to shift I let off the gas, so it won't rev up to high. But it probably would hit the limiter. Then after the huge jolt, every other gear is fine

[snatch]

The thud could be a tranny mount. Put your car up on ramps and push on the tail of the tranny, if its your tranny mount there will be alot of movement and you might be able to see the broken mount.
I couldnt see the tear on mine cause it was on the front facing the engine but when I took it off there was only like a 1/2" patch of rubber holding it on.
You can also put your hand right behind the console(actually butted up against the back), between it and the back seats, and when you take off you'll feel the tranny slap the bottom of the transmission tunnel.
Shane

[PewterBird]

Originally posted by snatch:
The thud could be a tranny mount. Put your car up on ramps and push on the tail of the tranny, if its your tranny mount there will be alot of movement and you might be able to see the broken mount.
I couldnt see the tear on mine cause it was on the front facing the engine but when I took it off there was only like a 1/2" patch of rubber holding it on.
You can also put your hand right behind the console(actually butted up against the back), between it and the back seats, and when you take off you'll feel the tranny slap the bottom of the transmission tunnel.
Shane

Thanks for the help, Most of the time a thud is the tranny mount, but unfortunaltly this one isn't that easy, I have had a tranny mount go out, and this is different.

It only happens like once a month for an hour or so. A broken tranny mount would be broken all the time.

And the thud is not the vertical type of thud of the tranny hit'n the floorboard, but more of a horizontal thud going fowards.

[95Batmobile]

Hey Jeff, my car used to do that surging crap too and I never figured out what it was because it was such a rare problem.

As far as your shifting problem, the only thing that I can think of is dropping down the pan on your tranny and taking it to a tranny shop to check the solenoids (however you spell that).

When I just rebuilt my tranny, my torque converter was DEAD, but I wasn't having any problems shifting. Check your tranny fluid... its supposed to last 20,000 miles and mine would burn the fluid in under 800 miles.

Oh, it could be a hard part messed up in the tranny as well. I had to replace some drum that, had it gone out, would have made me completely lose 2nd gear and Reverse. Maybe you've got a hard part dying? I don't know what else could be wrong.

[HBHRacing]

things thta can cause shifting problems.

Internal tranny issue.
Fluid too dirty or not enough fluid
faulty TPS
Cloged converter

[Turbo V6 Camaro]

Originally posted by HBHRacing:
things thta can cause shifting problems.

Internal tranny issue.
Fluid too dirty or not enough fluid
faulty TPS
Cloged converter

MAF have given auto owners of these car woes too

[HBHRacing]

yes, but it is rather rare. It's also difficult to test for so I consider it a last resort

[chas]

sounds like the standard 'tcc apply' apply problem. older version of the 4l60e (it was fixed mid 2000 apparently) develop wear in the tcc apply bore. so the tc doesnt lock up the way it should. its aggravated by hot conditions. sometimes the pcm notices this slipping problems and commands maximum line pressure from the transmission. this causes a harsh 1-2 shift. restarting the car will return the transmission line pressure to normal. the pcm doesnt throw a code unless it sees this during two consecutive trips.

[PewterBird]

Originally posted by chas:
sounds like the standard 'tcc apply' apply problem. older version of the 4l60e (it was fixed mid 2000 apparently) develop wear in the tcc apply bore. so the tc doesnt lock up the way it should. its aggravated by hot conditions. sometimes the pcm notices this slipping problems and commands maximum line pressure from the transmission. this causes a harsh 1-2 shift. restarting the car will return the transmission line pressure to normal. the pcm doesnt throw a code unless it sees this during two consecutive trips.

Sounds right on, how do I fix this....possible recall?

[chas]

there was a tsb for this problem but convincing the dealer that you have it is difficult. if you dont have a check engine light they wont perform the fix specified in the tsb. i tried to get mine fixed while under warranty and even though i had p1870 in the history of my pcm they still wouldnt fix it.

the right fix is a new valve body or a repair kit from sonnax.

for a short term workaround (about 20000 miles now) i installed a transmission cooler. since heat makes the problem worse and the slipping tcc will produce more heat this seems like a little protection until i decide to do something more drastic. havent seen the problem since i installed the cooler.