Bucking/surging at around 40 MPH
06-16-12, 09:11 PM
#1
Bucking/surging at around 40 MPH
I need help.
Patient is a 1992 Lexus SC400
It has 149xxx miles with no modifications
The issue: At around 40 MPH, there is a surge, or thump that sounds out right under the center console.
If you catch it just right, it bucks and surges like a rodeo, but only within 37-43 MPH or so
I was thinking it was tranny mounts, torque converter, or driveshaft issues.
Would anybody out there have any idea what this is?
Enlighten me.
Thanks in advance
Patient is a 1992 Lexus SC400
It has 149xxx miles with no modifications
The issue: At around 40 MPH, there is a surge, or thump that sounds out right under the center console.
If you catch it just right, it bucks and surges like a rodeo, but only within 37-43 MPH or so
I was thinking it was tranny mounts, torque converter, or driveshaft issues.
Would anybody out there have any idea what this is?
Enlighten me.
Thanks in advance
06-16-12, 09:29 PM
#2
1JZ Single SC400
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My 1995 does the exact same thing. I am narrowed it down to the possibly the MAF. Try disconnecting yours and then crank it up and drive it. See if it goes away. Then plug it back in, and see if it the symptoms come back. This will also put the computer in the limp mode which is very rich and will eat the gas. If someone else has the possible solution, please chime in.
06-18-12, 03:03 PM
#3
I'll try unplugging the MAF, but I'm pretty sure it has nothing to do with it.
It is a noise you would hear like something is loose, it sounds like a "dug dug dug" and only at high 30s to low 40s (MPH)
I don't think it's electrical, it sounds mechanical.
Thanks
It is a noise you would hear like something is loose, it sounds like a "dug dug dug" and only at high 30s to low 40s (MPH)
I don't think it's electrical, it sounds mechanical.
Thanks
06-18-12, 10:58 PM
#5
My 92 SC4 used to clunk a lot when it downshifted and I swore it was coming from the driveshaft since I felt it in the console. Turned out both axle shafts were wore the f... out. That's something else you can rule out.
Since being replaced with lower mileage used ones, the clunking is gone.
Since being replaced with lower mileage used ones, the clunking is gone.
06-19-12, 04:18 PM
#6
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this sounds like another CL member did you change/check your tranny fluid? if it vibrates then you have a tranny mount problem, but check the tranny mounts i'm thinking you need a tranny fluid/filter change. if not it does seem like mounts....or gtsfire could be write as well!!!
Last edited by rogers2014; 06-19-12 at 04:20 PM. Reason: needed to reassure my answer
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06-26-12, 08:26 AM
#10
What I'm hearing is a thump, like a stick hitting the bottom of the car, and it jerks like crazy, but only around 40 MPH.
Ideas I have gotten:
Drive shaft (u joints, bushings, exc)
Tranny mounts
Torque converter
Drive shaft bearing, and
Axle shafts.
Tranny mounts seem to be the only likely solution.
If it was the torque converter, wouldn't it make the tranny slip, becouse the tranny is bulletproof!!!
Ideas I have gotten:
Drive shaft (u joints, bushings, exc)
Tranny mounts
Torque converter
Drive shaft bearing, and
Axle shafts.
Tranny mounts seem to be the only likely solution.
If it was the torque converter, wouldn't it make the tranny slip, becouse the tranny is bulletproof!!!
06-26-12, 10:31 AM
#11
Lead Lap
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I kinda have the same problem!
Right at 40 to 50mph. If i am accelerating at a steady pace with cruise control or my foot on the pedal it accelerates, dies, acceleratrs, and dies. Just keeps bucking. It happens when i try to stay at a constant speed. But if i speed up then it drives normally. I also have a rough up shift from 1st to 2nd. Good smooth downshift from 2nd to 1st though.
Right at 40 to 50mph. If i am accelerating at a steady pace with cruise control or my foot on the pedal it accelerates, dies, acceleratrs, and dies. Just keeps bucking. It happens when i try to stay at a constant speed. But if i speed up then it drives normally. I also have a rough up shift from 1st to 2nd. Good smooth downshift from 2nd to 1st though.
Last edited by durps; 06-26-12 at 10:35 AM.
