linuxrunner

i am getting this odd stong vibrarion at WOT when in 4th or 5th gear. Its hard to explaine but i have put almost 200k miles on this car so i know the diffrence between a normal buzz vibrarion when lugging and this.

Only at WOT as soon as i let off the gas it stops, only notice it a little in 4th and lots in 5th.

So since this issue is so hard to describe and search for i decided i would have to find it on my own...

Feel free to follow along as i attempt to track it down.

I will be troubleshooting and testing in sections. air/intake, electrical/spark, fuel, mechanical.

Teuf

Check your U joints..........U bolts, lug nuts, left blinker etc.....

linuxrunner

DAY ONE:

Today was air/intake, however i started with the catalytic converter because i have never touched it in almost 200k miles and i figured a plugged cat might be the cause.

had to cut off the cat because it was welded, it looked great. No clogs and all the honeycomb stuff was still there in great shape. Replaced with a piece of pipe until it can be welded back in.

Pulled intake hose, checked the rubber accordian part with flashlight no cracking and i didn't see any light leaking through. Checked and cleaned AFM (good), removed and cleaned TB, noticed that i put the TB gasket on backwards last time i had it off blocking off a vaccume port

Opened and cleaned IAC valve (was testing fine, but i figured why not) checked all other air intake hoses for leaks and tight clamps.

Blew out resonator, it was full of some yellow powder stuff.

Checked TPS (it's new OEM and still right on).

put it back together and fired it up... still same buzz/vibration. But CRAP it feels like it gained 50HP i can climb hills again.

linuxrunner

DAY 2

(i am already 3 days in while typing this, just trying to catch up)

Decided to move to machianical after the intake work because i didn't want to confuse any new engine behaviors i get from electrical/fuel with intake fixes.

Jacked up and made sure that all my tires spin freely and no seazed brakes.

Rear drivers side has a seriously warped drum or something because i can not even turn the wheel by hand (just one part of the rotation is stopping). Adjusted the shoes back until i can fix the drum and replace the pads. Wheel turns smoothly now.

E-brake still catches fine after 7 or 8 clicks.

while spinning the wheels i hear a squeaking sound from the drive shaft, turns out to be the rear U-Joint, (the only one i have not replaced recently) just had the shaft off about 2 months ago and it felt good, but now i can't move it at all.

Replaced with new greesable U-Joints (always keep a few on hand).

Check many other things for binding everything else looks good.

Possibly need to refill the silicone in the fan clutch notice that it seems to turn easy no matter the temp. No time to fix it today will test this more later.

Test drive and the buzz/vibration is still there, but it diffently has more power without the brake dragging and is quieter with the new U-Joint

linuxrunner

DAY 3

Moved on to fuel testing today.

Cranked a few times with wires removed and pulled the plugs to ensure each one at least had fuel on the plug.

Injectors were rebuilt about 20k miles ago so i am doubting it's a plugged injector, but you never know.

happened to have a new fuel pressure regulator i had never got a chance to put in, so i installed that. (don't really think my old one was bad, but i figured if i was already in there)

Tested fuel pressure (around 40psi ish kind of a crappy guage) and it looked to be in line with what i should be expecting.

Fuel pump is <2 yr old OEM seems to be building pressue fine.

This tells me that at idle and in nutral (under no load) the fuel system looks great, but how can i test it under load at WOT? my guess is that i would have to plumb in a fuel pressure guage to the cab and watch it while doing 60mph up a hill.

Drove it around and still same lugging vibration at WOT. Although i could swear it seems much better.

Teuf

Rear drive shaft out of phase? Pinion angles wrong?

ktmhans

Any thoughts on the clutch, it could be slipping in a tall gear, with higher rpms being put to it. Just a chance but on a bike you can. Only tell its dlipping in 4th,5th gear. All this new found power youll find out pretty soon .

linuxrunner

DAY 4 (and the solution!!!)

This Saturday i picked up some silicone to refill my fan clutch and pulled the clutch. While it was out i figured my next steps were going to be electrical so i pulled the alternator to have it tested... WOW i was litteraly unable to turn it by hand.

Purchased a new denso alternator and put everything back together.

The fan clutch was a good opertunity to drain the coolant and refill with toyota red instead of 90% water 10% whatever antifreeze i had around.

After opening up the fan clutch the silicone level seemed full. I don't know but i thought when cold it should be hard to turn by hand? Flled a tiny bit and put it back, still seems really easy to spin when cold.

took it out for a spin and what do you know vibration is GONE!!!

My best guess is the difficulty turning the alternator made the engine lug really bad at higher gears.

The crazy part is i didn't have any charging issues or noise coming from the alt, and i don't think my belt was slipping.

Kiroshu

^-- Good find. Glad you found your problem.