Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

Pedal Vibration, Rough Idle when Cold

19K views 16 replies 13 participants last post by  Tivo532 
#1 · (Edited)
I have a 2004 Envoy XUV, 4wd, 6 cyl. with about 87K miles. When I start up in the morning cold, I have a strong vibration in drive when brakes are applied. I also feel a thump and shudder in the underbody at the moment the engine starts. I can even engage the parking brake, leave in drive and go to my front tires and feel them shake. The exhaust and cat are also vibrating abnormally. The funny thing is when the car idles hot and you drive it for a while the shake disappears and even stopped at light at full operating temp, she idles smooth as glass. I can however feel a gas pedal buzz or vibration upon accelerating. Recently on a trip I also detected a hum at highway speed especially when decelerating. I have changed plugs, CPAS, water pump, serpentine belt, flushed the transmission and changed oil, tran and air filters.
I know about the motor mount issue and thought about it but it does idles smooth when hot, no body vibration felt but still have the pedal buzz. Any advice or direction would be most appreciated. I need to get this addressed before another planned long trip.:thx:worried:
 
#5 ·
But It Idles smooth as silk when hot

The only time it vibrates violently is after a cold start like first thing in the morning. After starting in the morning I can put it in drive, apply my parking brake and go outside and you can see and fell my tires shake. ONLY in drive, not neutral or reverse. After the engine goes hot and I drive a while, the idle smooths out and idles fine in all transmission positions. If it were motor mounts wouldn't I feel vibration all day at every stop light in drive?
 
#6 ·
The only time it vibrates violently is after a cold start like first thing in the morning. After starting in the morning I can put it in drive, apply my parking brake and go outside and you can see and fell my tires shake. ONLY in drive, not neutral or reverse. After the engine goes hot and I drive a while, the idle smooths out and idles fine in all transmission positions. If it were motor mounts wouldn't I feel vibration all day at every stop light in drive?
i didnt feel mine ever when i drove. like you said as well, i felt it hard when i shifted into drive. all other gears were fine for some reason. and unlike you when i stopped at a stoplight it started again. maybe your mounts are not as bad as mine were and it does it until it gets warmed up. idk man. :confused:
 
#7 ·
Same Problem with the rough idle on a cold start

I'm having this exact issue. I just hit 95K and thought maybe it is the spark plugs or throttle body so I changed the plugs and cleaned the throttle body. No change. I have no idea what could be causing this. Please let me know if you find a fix.
 
#8 ·
Same here

I've noticed this recently and have no idea what causes it. I first thought about engine mounts, but it stops vibrating after it warms up a bit. Doesn't vibrate in Neutral or Park, but I really notice it when I come up to a red light or stop sign. Any ideas??
 
#9 ·
It sounds that there is something in master cylinder or brake booster. Have you check the physical connection of of your pad to see if there is somehow any play there. You should also check the brake fluid and make sure you are not low. Low fluid can not be the cause of vibration but it could reason to lower then your usual pad.
 
#11 ·
Same problem here. From what I've come across, I think the problem has been with the mounts. I'm just not sure if its the motor mount or the tranny mount. I need to look into it a little more.

Hopefully someone here has an exact answer before I go ahead and start changing everything.
 
#12 ·
same issue

145k - Same issue here, especially the part about going away after warm-up. I'm going to be getting it in the air in a week to see if i can find anything. ive noticed that when i shut either of my front doors, i hear this squeaking for a few seconds which i've isolated as my motor mounts. So I'm putting that together with the vibration and am definately leaning towards the motor mounts being the solution to this problem. I'll update on my findings.

-Devon
 
#13 ·
145k - Same issue here, especially the part about going away after warm-up. I'm going to be getting it in the air in a week to see if i can find anything. ive noticed that when i shut either of my front doors, i hear this squeaking for a few seconds which i've isolated as my motor mounts. So I'm putting that together with the vibration and am definately leaning towards the motor mounts being the solution to this problem. I'll update on my findings.

-Devon
Any findings on this? I'm having the same problem only vibrates while it's cold stops when it has warmed up. No SES light here. The motor mounts were replaced 5 years ago at 97k currently at 166k. Could it be the mounts again?
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top