transam_man

have a freshly rebuilt lt1 in 95 t/a replaced the torque converter after first start because vibration was really bad, after replacing vibration got a lot better but still likes to vibrate at highway speeds, and every now and then when I come to a stop the rpm fluctuates and car vibrates then it goes back to normal. Could it be the transmission? pretty lost and dont know where to go now

hrcslam

Can you list all your mods?

transam_man

just removed egr valve, air pump, and catalytic converter

Corvett z07

iTrader: (2)

I'm still pretty new to the F-Body world, but I've had a 95 Camaro (why does it say that Camaro is spelled wrong?) with a horrible vibration issue. It seems to haunt the 93-97 Camaros/T/A more than the 98-02, no idea why but regardless I started blaming so much stuff on the vibration (driveshaft, misfire, transmission, miscellaneous suspension, and steering.) The worst thing you can do is start throwing money on your car hoping it will fix it, this comes from experience, but the best thing you can do is try independent tests on certain parts that may be causing the vibration and checking out individual parts and seeing if they are bad. I don't want to say this but it could be a whole pile of things that could be causing your vibration, but don't get your hopes down, it just takes a little time to pinpoint down to what is causing the vibration and when you fix it, it feels awesome. On another note, how bad is the shaking, is your steering wheel vibrating back and forth at all at highway speeds, and does it seem to get a lot worse when you brake while it's shaking?

SS RRR

iTrader: (2)

Do searches here and camaroz28.com. You need to figure out whether the vibration is coming from from the engine, chassis or both.

hrcslam

Did you tune it for the removed emissions? You may also have a vacuum leak.

What really needs to happen here is a data log. Do have a way to data log?

cardo0

U can try repositioning the TC. Drop the trans inspection cover and remove the 3 TC bolts to the flywheel and rotate the TC 120 degrees. U can do this one more time but be sure to mark the TC and flywheel the first time so u dont put it back to the first position.

U can also have the driveshaft balanced too - not much money at all.

thumpr

Having same troubles with my 94 Z28. Vibrates but goes away when tap brake and comes back soon as I get back into gas.

transam_man

havent got it tuned yet still looking for someone close by who can do it. And I dont have a way to get a data log

transam_man

ill probably try that when i get the time.

BALLSS

was your "freshly rebuilt" motor internally or externally (stock) balanced?

Corvett z07

iTrader: (2)

To OP, +1 to hrcslam's thought on getting it tuned for the ripped off emissions. Your computer may be trying to compensate for it and it could be causing the slight shudder when you slow down but I've heard that the air pump starts running when you slow down and causes a slight drop in voltage for a second which is normal, food for thought, you could try unplugging the air pump fuse and see if that helps, correct me if I'm wrong though.

To thumpr does it only vibrate when you press on the gas and only in a certain gear?

transam_man

externally, and im taking it by a mechanic shop monday, the guy said he has some experience with lt1's and issues like im having

Corvett z07

iTrader: (2)

Anticipating your mechanic's thoughts. Maybe it's the same as my problem was.

BALLSS

my thought direction was if your "freshly" built motor was "internal" balance and you kept a "external" balance flexplate...it would vibrate (read shake like a dog shitting razor blades)

beyond that, Hope your mechanic finds the issue......and it is not a 2 piece crank. Since you report it got "better" after TC swap but still does it...it may very well be TC and or tranny related

good luck

transam_man

took it bye my mechanic today and he finally got the scanner to read some codes, it coded for o2 sensors, egr valve, and air pump, but sense the o2 sensors are only before the catalytic converter on my model would removing the cat throw a sign still?

ThoR294

iTrader: (6)

What is the o2 code? Like b1s1 OE b2s1?

hrcslam

Check your driveshaft yoke bolts and your universal joints. Sounds like too much play in the D/S. My Suburban did this once and my yoke bolts that hold the universal joint to the yoke came loose. Almost lost the D/S.

Removing the cat would not throw the O2's off as you only have pre-cat O2 sensors.

Get a data log done on it so we can look that over. $55 for the cable (16 pin ALDL cable) and Scan9495 for free..... (get Tuner Pro RT for free and $20 for WinFlash from TunerCats and you can tune too!)

The removal of the EGR and Cat should effect the engine minimally if at all. But, if other things were wrong before you did all that it could have made that other situation worse; possibly. But, the only way to know for sure is a data log and some other tests.

It wouldn't hurt at this time to check all your spark plugs (take a picture of the firing tip and post it here), compression check, check all wires, leak down check, spark check, and fuel pressure check.

Since this has been going since rebuild, who did the rebuild? Did they use the proper fly wheel or crank? If you replaced pistons and rods, did your machinist balance the rotating assembly?