Advice: Harsh shift from P to D

I've recently acquired a 2000 tundra v8 4wd. Something isn't quite right because when I shift from park into drive but NOT reverse. It's like the engine is idling too high in park and doesn't idle down before going into forward gear catching and making the vehicle lurch forward extremely harsh. Sometimes even squeaking the tires. I really hope it's not something in the transmission but I don't know. I've already tried swapping the throttle body assembly with a different one. Idk where to go next. Has anyone experienced the same or have any advice? I've tried searching the site first too. Thanks in advance!
eta ~210,000 miles

 

Read the first two posts in this thread: https://www.tundras.com/threads/so-you-wanna-buy-just-bought-a-1st-gen-tundra-eh.115928/

Like, read that shit as soon as possible.

Next, pop back in here and let us know:

Is it 4WD or 2WD, that's kinda important?

Did you check the transmission fluid level properly, noting there's a notch for COOL and HOT?

How many miles on the truck?

 

Idle down from what? Are the rear brakes working?

 

~210,000

 

yes

 

The parking / emergency brake grabs after 4-5 clicks?

 

i do know that the parking brake pedal goes all the way that it possibly can. i'll hafta confirm if it actually engages and get back to you

 

Neutral Safety Switch?
I'm getting mine replaced soon, it doesn't lurch like what you're saying, but there is a noticeable "clunk" when going in/out of D on occasion.

The dash lights that illuminate PRNDL may be out if that's the case. My D isn't illuminated but the others are.
My understanding is weak, but I'm told the NSS helps verify the transmission is in the gear it thinks it should be in. A bad NSS can create awkward or partial shifts

 

P-brake function is pretty crucial to rear brake functionality, which is vital to keeping a non-mushy brake pedal. If p-brake pedal goes to the floor, you've got issues with that, I highly doubt your brakes are working as expected.

That said, being in NH, it wouldn't surprise me as a New Englander dealing w/salted roads, if the p-brake assemblage is totally frozen and in need of replacement. If the rear wheels spin freely, with no resistance, your rear brakes are likely one piece of the puzzle. They should barely spin w/resistance.

But that surge shifting into D isn't normal, and if the brakes aren't catching, I can see why that would be one suspect. I don't think that's the heart of the issue.

Sorry to keep going back to the transmission, but when you checked the transmission, where was it in the notch for hot or cool, like you checked it hot and it's in dead center of the hot notch?

And what RPM is the truck idling at?

 

In park it idles at like 1000-1200, which to me seems high? But only because of what happens shifting into drive. Lower idle in other gears

 

What if you let your truck warm up first so the rpms drop in idle before shifting out of park? Does the idle in park never come down even after waiting 5-10 minutes?

 

Does it shift normal otherwise when driving? Any other symptoms that would make you think the transmission was acting up?

 

Correct, doesn't change after warm

 

Normal otherwise yeah. My only 2 trains of thought are idle or transmission related. So I'm out of ideas after trying throttle body and I'm not equipped for transmission work.

 

There’s got be a circuit in there that would bring down the rpms much like shifting into drive from park. I don’t know enough about it but I’m willing to bet that’s the culprit.

 

Vacuum leak

 

Definitely agree this is likely what it is. Matches up with symptom and RPM nicely.

 

If fluid levels are OK, I believe it’s not the transmission. Are there any codes set for anything? Solenoids etc? Check engine light on at all? (Assume you know the bulb is good, eh?)

 

If those rear brakes aren't engaging, then your essentially line locking the fronts, then neutral dropping the trans at 1200 rpm into gear, giving that surge or chirping of the tires. What happens if you put the truck in neutral, then let off the brakes and select drive without your foot on the brake?

 

But why wouldn’t it happen in reverse also?

 

All part of the mystery I guess.

 

Only from park to drive though?

 

I would do a drain & fill on the transmission. It's simple and easy- and you can get an idea of your transmission's condition by the fluid. Just pull the plug on the trans pan, and about 3.5-4qts of fluid will come out. Put the plug back in, and fill 3.5-4qts through the dipstick tube.

Also- you mentioned you replaced the throttle body. When you did, was the battery unplugged to allow the ECU to reset? Also, are you sure you have the throttle cable properly adjusted? One time I over-adjusted my throttle cable and it pulled the idle up.

It's weird that it's harsh only from park to drive. I had some issues with the solenoids in my transmission, which caused a very harsh shift on some shifts, but not all shifts, so maybe it's something like that? If it was a solenoid you'd have a check engine light though.

 

For code history:
P0125 Insufficient Time Or Temp in Closed Loop, P0330 Knock Sensor 2 Circuit Fault, P1126 Magnetic Clutch Circuit Fault, P1129
Electronic Throttle Control System Fault. Cleared Codes and Code P1129 Returned
which is why i started with throttle body components, but havent checked codes since that's been swapped

 

Oh wow. Yeah, I would sort through and correct all of the code triggering conditions before addressing what may get solved in that process.

 

Hmm. I feel like this is definitely a throttle body related issue.

The throttle bodies on our trucks have this weird system where they are "drive by wire" for the first 2/3 of the accelerator pedal's travel. Even though there is a cable going to the throttle body, there is no physical connection between the pedal and the throttle valve until you reach that 2/3rds of the travel. Then it mechanically kicks in. I'm not sure why toyota did this- but I'm guessing for idle control via the throttle body, and cruise control.

With the truck off, using your hand, you can slowly push the accelerator pedal, and about 2/3rds of the way down, it'll get a bit harder to push. You can feel it. That's the mechanical part kicking in. Same thing with the drum that the throttle cable wraps around, you can turn that with your hands but it gets much more difficult when it mechanically engages.

Now, with the engine running, use your hands to work the throttle body. Does it respond to inputs before that mechanical override engages? if not, then something is wonky.


A long time ago I had an issue where I'd get no throttle response until that mechanical override engaged. The truck had code P0120- "Accelerator Pedal Position Sensor" fault. I actually don't know how the truck got fixed, the shop I took it to tried to scam me into buying a whole new throttle body. I told them to put it back together, and when I got it back it ran perfectly.

 

P1126 Magnetic Clutch Circuit Fault

That’s an eye opener along with 1129.