Help! Foot on brake, AT in Drive, drivetrain lurches.

[ZachAttack]

So, I've been having a problem that showed up in the last month or so.

At a stoplight, with my foot firmly on the brake, I can feel the drivetrain trying to engage, lurching.

This is NOT the air conditioning compressor cycling that I've heard some people talking about.

It happens about once a second, although sometimes faster. The engine lugs a little (RPMS go down) right as the lurch occurs. Lurch (one second) Lurch (one second) Lurch Lurch. The lasts about the same time as it would take you to say "lurch."

If I shift to neutral, it goes away.

I had the fiance sit in the car with her foot on the brake and the car in drive (and reverse...same symptom), and I looked underneath.

Both driveshafts turn a little, then back off, just as it happens.

I think this means that the torque converter (which allows disengagement while stopped, right?) is trying to reengage while I'm stopped. Not keeping the drivetrain disengaged.

Any ideas? Anything I can do?

(I've already added a quart of ATF, then re-leveled with the overfill plug once warm...just wanted to make sure it wasn't low fluid. Also, checked the transfer case oil. Still fairly fresh, and plenty full.)

Help!

(And thanks in advance.)

 

[ZachAttack]

Oh yeah. 2004 Sport Edition, V8.

 

[JB.]

Been waiting for an expert to show up but since that hasn't happened I'll give you a bump and my limited perspective.

Sounds to me like the torque converter clutch is briefly trying to lock. The only thing I would know to do would be a transmission flush but those can be a little risky on an older truck.

You could do some drains and fills yourself (at least 3), spaced a few days apart, to get mostly new fluid in there.

Hopefully you'll get some help. If not, maybe post the same question in the 4th gen section. If you do that, post a link to the other thread here.

 

[ZachAttack]

So, I finally took it into the Tx shop. "I have a transmission problem." So, the nice gentleman behind the counter said, "what are you driving?"

"2004 4Runner."

(laughing ensues)..."You don't have a transmission problem. Those don't break. Let's go look at it."

So, he came outside, agreed that to someone like me, it would feel like a torque converter thing.

Then, he said, "I bet you just replaced your spark plugs."

(OH CRAP.) "yes, I did."

"You have a good ole MISFIRE."

Then, the nice man told me his shop wasn't busy, and that for a small fee (not the $4k I was prepared to swallow to replace the tranny), he could tell me which cylinder it was. I thought about taking it home to replace them all again, and realized my time and materials would be about $100 anyway, so what the heck, I'll have him look.

In five minutes, he assured me that all my plugs were good, but that I must've cracked the coil pack boot. it was about 1 cm long, right where the coil pack spring and spark plug meet. The spark was jumping through the boot to the head. We called around for a new boot ("we don't sell them individually, but you can buy a whole coil pack for $130.") He then helped me find rockauto.com, where you can get them for $4, plus $2 for shipping.

So, he put some electrical tape on the boot "JUST TO GET YOU HOME, DON'T GO JOYRIDING OR ANYTHING".

Boot from rockauto is on its way, and now my $4k transmission problem has been fixed for $6.

Huge weight lifted off the shoulders.

But, I still feel like an idiot. Hope you can all learn from my stupidity.

 

[JB.]

Interesting info. Thanks for the follow up.

 

[ironhippy]

"2004 4Runner."

(laughing ensues)..."You don't have a transmission problem. Those don't break. Let's go look at it."

That's awesome, I hope you go back to him if you need anything else.

 

[ZachAttack]

That's awesome, I hope you go back to him if you need anything else.

Yeah, I left him a pretty stellar review on cartalk.com.

Incidentally, that's where I found him, and he lived up to everyone's high praise.