Engine Vibration [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: Engine Vibration


mbeadle
07-15-2010, 08:19 PM
Hey everyone,

I have a 2002 Trailblazer LT 2WD. I am noticing a vibration in the engine when I am in Park or in Drive. The vibration gets worse when I first accelerate and then smooths out until I bring it to a stop and then the vibration appears again. I notice that when I let it idle for a bit and then lightly touch the gas it acts like it wants to stall. Also when I turn off the Key the truck shakes, like my diesel does when I shut it down. I took a look at the motor mounts and cannot see any tears but have not checked the transmission mount. I have just seen that there may be a problem with the fuel pressure regulator or the vacumn to it. Where is the regulator located? And does anyone have any info on finding the vibration. Thanks

RayVoy
07-15-2010, 08:33 PM
Generally, when a gas engine continues to run after it is shut off, it is full of carbon.

You need to remove the carbon.
A number of highway speed miles, maybe 100 will usually do it,
or, a Seafoam cleaning.

mbeadle
07-15-2010, 08:39 PM
Hi Ray,

I doesn't run after shutting it down but rather it really shakes. I compared it a diesel engine when it shuts down you notice that shake from diesel engines which is what my blazer is doing. Could it still be carbon. It wouldn't surprise me since we do short distance driving in Hawaii.????

WOOLUF1952
07-15-2010, 08:46 PM
There is a small vacuum line at the front of the air intake resonator on the drivers side. It is pretty much in-line withe the 4200 Vortec molded in the resonator. Follow that down to the fuel pressure regulator.

Seafoam, FTW :m2:

RayVoy
07-15-2010, 08:50 PM
Could it still be carbon ?

Well, it could be carbon, it could be a number of things.

I might be a bad plug, a leaky injector, a vacuum leak, a valve not seating, etc.

I would clean the throttle body 1st, then try some carbon cleaner, like Seafoam, and then see how it works (get the easy things out of the way).
There are "how-to"s for both of these on the site, the search will find them for you.

Do you know how many miles might be on the plugs?

Has the Check Engine Light ever come on?

mbeadle
07-15-2010, 08:52 PM
Ok I saw that yesterday. I actually pulled it off at the resonator side and did not feel a vacumn and did not change the idle at all. Any thoughts??

mbeadle
07-15-2010, 08:53 PM
Ray,

About 47,000 on the truck and original plugs. Never had a light come on in this truck and for sure not for this problem.

RayVoy
07-15-2010, 09:13 PM
Ok, that should eliminate plugs and coils

The list gets smaller :thumbsup:

Hey Super, I see your reading the thread, got any ideas?

mbeadle
07-15-2010, 09:22 PM
not sure is this is seperate or related but this thing gets terrible gas mileage. about 10-12 but has been like that since we bought it new.

mbeadle
07-15-2010, 09:33 PM
ok just went to the TB and checked the vacumn line to the fuel regulator and I didn't feel any suction on either end of the line. Also noticed that there is more vibration on the manifold cover ( I think that is what it is) or where the coils are mounted than anywhere else on the engine.

Super 88
07-15-2010, 10:18 PM
Hey Super, I see your reading the thread, got any ideas?

First thing - I'd do a compression check. A very low or dead cylinder could cause this (vibration and bad mpg). I realize it's low mileage at 47,000 miles - but stranger things have happened.

The other thing is I'd take the fan belt off and check all the pulleys for play or roughness - especially the water pump.

WOOLUF1952
07-16-2010, 01:23 AM
ok just went to the TB and checked the vacumn line to the fuel regulator and I didn't feel any suction on either end of the line. Also noticed that there is more vibration on the manifold cover ( I think that is what it is) or where the coils are mounted than anywhere else on the engine.

There should be vacuum, however the line is so small, you may need a vacuum gauge to test it.

As I understand it, when the throttle is opened, the vacuum goes down and allows higher fuel pressure.

If you have no vacuum, you have full pressure all the time.

That might be why your mileage is so low.

Having a 2.5 ton vehicle and driving mostly in stop and go traffic doesn't help any. :m2:

skoehlke
07-16-2010, 08:04 AM
I am having a similar vibration issue with my 02 TB. It vibrates in Drive. It does not vibrate in neutral or reverse. The vibration is still present when you move the vehicle into Park from any other gear, but it is not real bad. I am also leaning towards motor mounts, but I have to rule out front end damage first. My daughter had a small fender bender awhile back, that I feel is contributing to my issue.

I believe your two issues are not related at all. I think you have a fuel issue causing the run on, and your motor mounts are bad. Do a search on the forum for motor mounts and find the recent posting my Roadie. He had the same vibration you are experiencing and new motor mounts solved his problem. He also had no visible signs of damage, but the comparison from old to new really told the story.

Here is a link to Roadie's post.

http://forums.trailvoy.com/showthread.php?t=73532&highlight=motor+mounts



just my opinion. I am not nearly as knowledgeable as others on this forum.

mbeadle
07-16-2010, 10:42 PM
Just to clarify, The truck when turning the ignition off is not running on. It shakes (in reference to a diesel engine when it turns off. Diesels shake when you shut them down and this is what the TB is doing.) Have picked up some things and will try to knock out some small things and get back to you all. Thanks for all the great tips. Hope I can find it. Keep em coming if you can think of anything else.

Thanks

mbeadle
07-22-2010, 08:36 PM
Ok did the compression test and all cylinders running between 185 and 190. compression built quick and stopped at 4 strokes and is in range with specs. Replaced the plugs while I was at it since I had some. Old plug were red on the ceramic tip and gap was a little tight. Put it all back together and vibration still there. Now on to cleaning the throttlebody and if that doesn't work will take another look at the motor mounts and trans mount. Any other suggestions please let me know. Thanks

WOOLUF1952
07-23-2010, 12:15 AM
Do you need to add anti-freeze often?

The only reason I can think of for red on the plug tip is rust. Maybe a bad head gasket?

Someone else, please jump in here if I'm way off.

mbeadle
08-03-2010, 09:16 PM
@ wooluf..Checked on the color of the spark plug and what I found was that it was normal and the red coloring was additives in the unleaded fuel. Having said that I did find a TSB for this problem but have to pay to read it. Anyone able to get TSB #061903 for a 2002 Trailblazer. Have plans tomorrow to clean out the throttle body and see if that works. However this TSB comes under the powertrain section so am wondering what it could be. I am noticing that there is vibration no matter what gear I am in and this just started about a week now. I also notice that not much vibration when parked on a level surface but more when I am parked uphill or down hill either in drive, park, neutral or reverse. Any thoughts???

mypetropig
08-03-2010, 10:45 PM
There should be vacuum, however the line is so small, you may need a vacuum gauge to test it.

As I understand it, when the throttle is opened, the vacuum goes down and allows higher fuel pressure.

If you have no vacuum, you have full pressure all the time.

That might be why your mileage is so low.

Having a 2.5 ton vehicle and driving mostly in stop and go traffic doesn't help any. :m2:
:hijacked

If you do not have a vaccum gauge, is there a way or maybe a trick to test the fuel pressure regulator?

mbeadle
08-04-2010, 09:33 PM
Throttle body was cleaned today. Looked pretty gummy in fact have before and after pictures to show. Put it all back together and vibration still there. Loud rattle by the Battery cover so took that and the cover off and found a missing bolt on the support rod over the battery. Dealer didn't put it back in when I had the battery replaced under warranty many years ago. Put a bolt back in and rattle when away. Took the TB for a spin for a while and seems to have some pep back to it and not as bad of a vibration but still there mainly in Drive. Turned off the A/C and the vibration is pretty much gone. Dumped some fuel system cleaner with a full tank of gas to see if that will help. Any other thoughts?? Thinking maybe the Fuel regulator, injectors or maybe back to the motor or tranny mounts. ???????

petevw
08-04-2010, 10:00 PM
Throttle body was cleaned today. Looked pretty gummy in fact have before and after pictures to show......Took the TB for a spin for a while and seems to have some pep back to it and not as bad of a vibration but still there mainly in Drive. Turned off the A/C and the vibration is pretty much gone......

You DID disconnect the battery for at least 40-45 min. while cleaning the throttle body, right?:undecided

BTW, GREAT job cleaning it....that sucker looks new!:yes:

mbeadle
08-07-2010, 03:24 AM
@ petevw... sorry I didn't get back to you sooner. My 3 kids are keeping me quite busy, which is why it is taking me a while to track this problem down. But yes I did forget to mention that I did disconnect the battery while I did this and it took me about 30 min or so to clean it. I am thinking of replacing the fuel regulator. I started it today and noticed a strong fuel smell at start up which I am thinking that this thing is getting too much fuel. I filled the truck on Wed and today have already burned a 1/4 tank of fuel. I am thinking it is allowing too much fuel during driving speeds and not enough fuel at idling speeds. Any thoughts....anyone?? :confused:

trailhound05
08-07-2010, 04:30 AM
Do you notice your exhaust looking dark while driving? I had the regulator go out on a pick-up I owned, and the exhaust was very noticeable even in warm weather.

Throttle body looks great. I want to check mine since I have no idea when it would have been done last. Having over 100,000 miles makes me think it might need it. I haven't had any issues though. Problem I am having is finding time.

mbeadle
08-08-2010, 03:04 AM
Haven't noticed any dark exhaust coming out but it has a strong fuel smell at the tail pipe and has some black residue in the pipe. I think I am going to take a trip to the dealer Monday and see if they have a regulator in stock. Scared to see the price.

trailhound05
08-08-2010, 03:11 AM
Sounds like a good idea. When I fixed mine I think it was something like $250 but this was a few years ago, and on a 91 Ford Ranger. Made a huge difference though in both fuel economy and how the engine ran.

xj2202009
08-08-2010, 03:52 AM
one of the first threads I read here was of a diary from a Canadian fellow and he talked about similar problem, if I remember correctly it was something having to do with rust in the disk brakes, pads are something like that.. have you considered o2 sensors?

mypetropig
08-08-2010, 10:17 AM
rockauto.com has the regulator for 58.79, search the site and find a 5% discount code. Even with shipping you will come out way cheaper than the dealer. I am also thinking about replacing mine as my fuel mileage has tanked, I havent noticed any black smoke though. Let us know what you find.

mbeadle
08-08-2010, 09:12 PM
Thanks for the link to Rockauto.com will be sure to check it out. Mileage has really tanked in the past few months for us too. Might as well put a big block in it and have fun. LOL But since it's the wife's car will just fix it. :)

XJ - Not really sure why dust or dirt in the brake pads or calipers would do unless that vibration is felt on braking. Think were looking at a fuel problem with the bad mileage and stong fuel smell but then again I have been wrong before.

Thanks to all for the tips and keep em coming and will update as I fix it one step at a time.

brycemartin
09-10-2010, 01:05 PM
I have a 2003 Envoy XL with the 4.2 I6 and had a similar issue with vibration. It was getting so bad that all but one of the clips on the front grill were broken. I noticed that when I watched the idle tensioner pulley at idle it was bouncing around quite a bit. The cause of this bouncing was the idle pulley (not the one on the tensioner) bearing was going out. I decided since I had the belt off I would replace both the tensioner and the idle pulley. After replacing that 98% of the vibration ceased. I still have the original power steering pump installed so I think that the rest of the vibration would be fixed after replacing the power steering pump.

By the way, I have cleaned the throttle body which did help a little for vibration and driveability. I have also run seafoam (injected into manifold) to clean the intake manifold/valves/combustion chamber. I have also cleaned the injectors using a "professional" cleaner injected directly into the fuel rail. I believe there is a post here in these forums showing how to do this injector cleaning.

Good luck.

mbeadle
10-04-2010, 11:20 PM
Ok everyone, still battling this problem only a new twist today. Finally got around to changing the fuel regulator today. Followed the steps to the letter and yes I disconnected the negative cable after releasing the pressure in the lines. Replaced with the new regulator and put everything back together and started it up and the thing runs rougher than ever and now the engine light is flashing. Is this a computer memory issue? Any ideas? Bought a scan tool but the *&%$ will not connect to the car or even my truck. Trying to avoid the dealer but getting close to making an appointment. HELP????

WOOLUF1952
10-05-2010, 01:38 AM
Ok everyone, still battling this problem only a new twist today. Finally got around to changing the fuel regulator today. Followed the steps to the letter and yes I disconnected the negative cable after releasing the pressure in the lines. Replaced with the new regulator and put everything back together and started it up and the thing runs rougher than ever and now the engine light is flashing. Is this a computer memory issue? Any ideas? Bought a scan tool but the *&%$ will not connect to the car or even my truck. Trying to avoid the dealer but getting close to making an appointment. HELP????


I don't know about the car, but check fuse #13 in the under the hood fuse box.

That is the fuse that powers the OBD connector under the dash.

mbeadle
10-05-2010, 02:00 AM
Perfect that fuse was blown and the scanner connected giving me a P0300 code. Random Misfire detected. Where should I go from here??

WOOLUF1952
10-05-2010, 02:10 AM
When you replaced the FP Regulator, did you disconnect the battery? That could explain the rough idle, but not the P0300.

You may just need to clean the throttle body. (Sorry if I missed it)

mbeadle
10-05-2010, 02:37 AM
yes disconnected negative cable after I relieved the pressure in the lines. Battery was disconnected about 20 min. Throttle body was cleaned about a month ago.

brycemartin
10-05-2010, 02:58 PM
mbeadle

I went through exactly the same symptoms that you are battling. I have another thread that I am going to update on here reagarding this. Here is what happened to me.

My mileage was dropping and the engine was running very rough. Found out that two of my coil packs were bad, cylinders 3 & 4. I used this tool to check the spark on each cylinder. You can find them at any parts store if you don't have a Harbor Freight nearby.http://www.harborfreight.com/inline-ignition-spark-checker-4424.html

I replaced the coil packs on cylinders 3 & 4 and the engine ran nice and smooth, but I no longer had any power especially at high RPMs.

Since the engine was misfiring not all of the fuel was being burned, therefore, it was causing raw fuel to be dumped into the catalytic converter. Well, to make a long story short I had to also replace the catalytic converter since it had become clogged due to the rich exhaust.

I also replaced my fuel pump & regulator since they were original and had 175,000 miles. Hope this helps.

WOOLUF1952
10-05-2010, 03:00 PM
A random miss can be hard to find.

Try running a bottle of injector cleaner and/or Seafoam the engine. Might be dirty injectors.

If you still have the P0300 and rough idle, try disconnecting the coils, one at a time, while the engine is running.

The one/ones that don't cause a big change in the idle, is the cylinder to look at.

Could be plug, coil, or injector.

mbeadle
10-05-2010, 03:11 PM
@wooluf - The funny thing is that the car was idiling fine before I disconnected the battery and replaced the regulator. I will check out the coils when I get home but wondering if the computer has to relearn?

WOOLUF1952
10-05-2010, 03:25 PM
Disconnecting the battery while cleaning the t-body, should have reset the PCM, and as long as everything was reassembled correctly, the engine should run to factory specs.

If it is PCM related, 3 or 4 heat/cool drive cycles should be enough for a relearn.

brycemartin
10-05-2010, 04:01 PM
I will repeat, CHECK YOUR IGNITION COILS!!!!

If you have poor mileage and a rough idle it either means you have an ignition or fuel problem. It is easier to check for an ignition problem since you can test each coil pack with a spark tester. If you eliminate the ignition as a possibility then it is probably a fuel problem such as clogged injectors or weak fuel pressure (bad pump).

brycemartin
10-05-2010, 04:07 PM
Oh, I also wanted to help with what the P0300 code, "Random Misfire" means.

This code does not really mean that there is a "Random Misfire" in the engine. It means that the computer knows there is a misfire, but it can't determine the specific cylinder that the misfire is in. When I was diagnosing my rough idle problem I first had a P0303 code, "Misfire in Cyl 3". This was confirmed when I tested that coil pack which was bad. Then, after driving the vehicle for a few days the rough idle came back with a P0300 code "Random Misfire". After testing all of the coils with the cheap spark tester I found out that the cylinder 4 coil pack was dead. I then replaced that coil pack and it has been purring like a kitten ever since.

So, to summarize, the Random Misfire code, P0300, probably means you have a dead (or about to die) coil pack. The engine computer just can't determine the specific cylinder.

mbeadle
10-05-2010, 06:19 PM
Just did the relearn process and that didn't work but did pull a p0305 code. so started it back up and pulled the plug on each coil and confirmed that number 5 is not firing. Off to Checkers to pick up the coil and see what happens. Probably been my problem all along!!!

bigcel4477
10-21-2010, 05:13 AM
Hello there. This is my first time posting. I had similar issues with the vibration and weird sounds. After changing spark plugs, pulling off and cleaning throttle body, it still persisted. A week ago, I was advised by my neighbor, who happens to be mechanic, that my water pump was shot (coolant leaked on engine and belt and wherever it wanted to). After he repalced the water pump and new belt, it runs absolutely perfect. Not sure what year your TB is, but mine is a 2004 LS and 100 miles away from the 100,00o mile mark. Hope that helps:)

mbeadle
10-31-2010, 05:59 PM
Ok still have the vibration. VERY FRUSTRATED!! Have been thinking and reading and wondering if my engine isn's carboned up?? Would make sense since we drive in stop and go and low speeds. So does anyone know a proven method to clean out the carbon in the engine? Have seen pouring small amount of water and oil into the Throttle body. What works best?

the roadie
10-31-2010, 06:07 PM
Seafoam.

And I still suspect the engine mounts. A member recently posted a clever diagnostic, since the passenger side motor mount by the exhaust manifold is the usual one to collapse - pry up on the motor mount bracket with a pry bar - see if the vibration changes behavior.

Or sometimes it's a bad or clogged oil screens on the cam position actuator solenoid (CPAS).

mbeadle
10-31-2010, 06:26 PM
@ roadie: Saw that post using the Prybar and will give that a try. My only problem with it being the motor mount is that I am only getting 10 mpg at last check about a couple weeks ago. That is why I am suspecting either carbon or injectors. Have heard that the injectors can crack and spill into the engine. Any thoughts?

mbeadle
02-18-2011, 07:43 PM
@ Roadie....You were right. It's been a while but finally got back to finding the vibration. Actually took to the dealer and left the car for 3 days and they insisted the mounts were fine even when I told them they may be collapsed. But they still insisted. They wanted to think about it, so I gave them a week before going back and told them when I am sitting downward on a hill the vibration was gone. They said they are going to change motor mounts and trans mount but would get back to me to see what they could do to help me out price wise. But they never did. Ordered from gmpartsdirect.com and replaced them myself and the vibration is GONE. Purrs like a kitten now.

One recommendation when replacing the mounts....Disconnect the radiator and hoses before lifting the engine. The engine will need to go up as high as it can and if hoses are connected this will crack your radiator....How do I know?? Well I didn't disconnect anything and you guessed it the car has a new radiator and it is not a fun job to replace it.

I attached pictures of the new vs. old mounts. Passenger side was badly collapsed. Hope this helps everyone.

Thanks to everyone for all your advice

the roadie
02-18-2011, 08:38 PM
Thanks for the report, and sorry about the radiator. But imagine what the dealer would have soaked you for the motor mounts! :eek:

slmdls1
02-24-2011, 02:06 PM
makes me wonder if mine are collapsed. i cant really tell without getting them off i guess, but visually they look fine with no rips/tears. a few small cracks though.

mbeadle
02-24-2011, 06:31 PM
They probably are. There is really no way to tell until you place the new mounts side by side the old ones. I suggest ordering from www.gmdiscountparts.com. Depending on your location you will spend about 60 per mount and then adding shipping. Just remember when and if you change them to disconnect the radiator and the fan from the engine. You'll need a fan clutch tool to remove the clutch from the engine. I learned the hard and expensive way that these items need to come off before lifting the engine. Good luck!!

slmdls1
02-24-2011, 09:49 PM
well, i found where my vibration was coming from. Bad tensioner pulley.

slmdls1
02-28-2011, 09:52 AM
check that, wasn't the tensioner...but it was bad and was replaced. did pick up part of my lost mpg though.

92s10blzr
12-06-2011, 08:43 PM
hi guys,

hate to bring up an old thread but i need some help. i've been experiencing the same symtoms as mbeadle, with the engine vibration. I've checked the plugs (good), checked spark (good), removed/clean TB, replaced both engine mounts and transmission mounts, double checked that all nuts and bolts are tight, but doesnt seem to stop vibrating. I thought I had it when doing the transmission mount because when i lifted the tranny to remove bridge, i decided to start up the car and there wasnt any vibration. keep in mind that the car was lifted by all four tires. also when i put the tranny mount side by side with the new one, the new one had about an inch more high than the original one. after putting it on, i started the car again and it was vibration free, but once i dropped it, the vibration came back. from there i decided to take it to a shop that i know is honest, and i explained to the mechanic what its doing and what i've done, so he took a look and after checking the play on all the pully's, the tensioner and even the fan clutch, which he said was all good, he then told me that since i've already replaced all the mounts and checked everything else that i could alond with his visual inspection, the only 2 things left that can cause vibration to the engine would be either the torque convertor and the harmonic balancer, and that when we noticed that the center bolt on the crank pully was not rotating in a straight circle, it had more of a oval rotation to it. he said that the HB could be going bad and that the half moon pin that goes in the shaft could be damaged. could this be true? what else besides those 2 things can I check for. the vibration is really driving me nuts. BTW, the engine runs fine, it takes off better than before, after cleaning out the TB, but when sitting in idle it just vibrates like a big rig. thanks for the help in advance.

:hopeless

busterbrown
12-07-2011, 12:05 AM
hi guys,

hate to bring up an old thread but i need some help. i've been experiencing the same symtoms as mbeadle, with the engine vibration. I've checked the plugs (good), checked spark (good), removed/clean TB, replaced both engine mounts and transmission mounts, double checked that all nuts and bolts are tight, but doesnt seem to stop vibrating. I thought I had it when doing the transmission mount because when i lifted the tranny to remove bridge, i decided to start up the car and there wasnt any vibration. keep in mind that the car was lifted by all four tires. also when i put the tranny mount side by side with the new one, the new one had about an inch more high than the original one. after putting it on, i started the car again and it was vibration free, but once i dropped it, the vibration came back. from there i decided to take it to a shop that i know is honest, and i explained to the mechanic what its doing and what i've done, so he took a look and after checking the play on all the pully's, the tensioner and even the fan clutch, which he said was all good, he then told me that since i've already replaced all the mounts and checked everything else that i could alond with his visual inspection, the only 2 things left that can cause vibration to the engine would be either the torque convertor and the harmonic balancer, and that when we noticed that the center bolt on the crank pully was not rotating in a straight circle, it had more of a oval rotation to it. he said that the HB could be going bad and that the half moon pin that goes in the shaft could be damaged. could this be true? what else besides those 2 things can I check for. the vibration is really driving me nuts. BTW, the engine runs fine, it takes off better than before, after cleaning out the TB, but when sitting in idle it just vibrates like a big rig. thanks for the help in advance.

:hopeless

I've read from other trailvoy members that motor mounts need to be GM OEM. Aftermarkets tend to have issues resolving engine vibrations. Head on over to www.gmtnation.com where more of the Trailvoy's guru's can may be of help. There has recently been a grand scale movement of memberships over to this new site due to poor web management (and vision) by the owners of this site. Good luck.

brycemartin
12-07-2011, 09:41 PM
I also have a 2003 Envoy with the I6 engine and had a problem with vibration. I am assuming that you have over 100,000 miles on the vehicle, so if that is the case I would suggest that you replace the Cam Position Actuator Solenoid.

After replacing the valve the engine ran much smoother and the gas mileage increased from about 18 mpg to 20-21 mpg on the highway. Also get much better acceleration after replacing the valve.

When getting a new valve, go to the dealer and get the GM part. They should have it in stock and it should be around $60. DO NOT buy the Dorman brand aftermarket part, it will not work. I went through three of them from RockAuto before I bought the GM part from the dealer. Was only $20 more and it actually worked. :)

Oh, and if you want this part to last make sure you use the specified weight oil, which I believe is 5W30. It regulates the oil flow in the head to actuate the valve timing and using a heavier or lighter weight oil will shorten the life of this part.

Here is a link to a thread that describes what it is and how to replace it.

http://forums.trailvoy.com/showthread.php?t=62398&highlight=Cam+Position+Actuator+Solenoid

Don't worry about the cleaning of the part because when this part goes bad it is because oil has leaked past the internal seals into the electronic part of the actuator. All of the cleaning in the world will not make the actuator work any better than it did before taking it out. It will just make it a shiny broken actuator.

Hope this helps.

92s10blzr
12-08-2011, 12:58 PM
Bryce, you're right I just hit the 100k mark a few weeks ago. let me give out the full history on when this started. It started about 3 months ago. It would vibrate when I first turn it on in the mornings but after a few minutes it would go away, so mainly it would vibrate if the car was parked for more than a couple of hours. I never noticed it getting worse, until just recently. But there's more, over the holiday weekend, the family decided to go to vegas and as most would know, the drive back from vegas during a holiday weekend is basically murder....so me being the wiseguy that i am, decided to take the envoy on an off road ride to bypass traffic, (dirt/rock road) for about 15miles. anywho, she handled it well and we got home safely, but very dirty. 3 days later, and still having that same 3 month old vibration when its cold, the battery decided to died. I replaced the battery, and when i cranked the car, it started shaking bad and occasionally it would stall. after scratching my head, i decided to do a search on this site and found a lot of great info on the shaking issue. Turned out that cleaning the TB worked to eliminate the shaking, but thats when the vibration got worse. The first night after cleaning the TB, it ran like a champ, then suddenly it start vibrating when i was idling on drive. So thats when i started chanding the mounts. When I go the shaking after changing the battery, my first thought was the cam actuator sensor like you mentioned but I had changed it at the 50-60k mark because i was getting the chk eng light and it was pointing to that sensor, which i had no choice but to buy it at the dealer($110) because the local autoparts stores didnt know i what i was talking about when i would ask for it. anywho, when i got that code for the sensor, the car was shaking realy bad at the time and would stall, it almost felt likt it was the fuel pump that went bad but it was that sensor. this time around, its not shaking, but vibrating, and i'm not getting any codes, no chk eng light. so that is why im hesitant to go buy the sensor again. for oil i'm using mobil 1 10w30, which is what i've been using for the past 2 yrs i believe. i have read a few post about people having issues after switching to mobil 1 oil, does anyone know if that is whats causing the issue?

thanks

brycemartin
12-08-2011, 01:29 PM
Bryce, you're right I just hit the 100k mark a few weeks ago. let me give out the full history on when this started. It started about 3 months ago. It would vibrate when I first turn it on in the mornings but after a few minutes it would go away, so mainly it would vibrate if the car was parked for more than a couple of hours. I never noticed it getting worse, until just recently. But there's more, over the holiday weekend, the family decided to go to vegas and as most would know, the drive back from vegas during a holiday weekend is basically murder....so me being the wiseguy that i am, decided to take the envoy on an off road ride to bypass traffic, (dirt/rock road) for about 15miles. anywho, she handled it well and we got home safely, but very dirty. 3 days later, and still having that same 3 month old vibration when its cold, the battery decided to died. I replaced the battery, and when i cranked the car, it started shaking bad and occasionally it would stall. after scratching my head, i decided to do a search on this site and found a lot of great info on the shaking issue. Turned out that cleaning the TB worked to eliminate the shaking, but thats when the vibration got worse. The first night after cleaning the TB, it ran like a champ, then suddenly it start vibrating when i was idling on drive. So thats when i started chanding the mounts. When I go the shaking after changing the battery, my first thought was the cam actuator sensor like you mentioned but I had changed it at the 50-60k mark because i was getting the chk eng light and it was pointing to that sensor, which i had no choice but to buy it at the dealer($110) because the local autoparts stores didnt know i what i was talking about when i would ask for it. anywho, when i got that code for the sensor, the car was shaking realy bad at the time and would stall, it almost felt likt it was the fuel pump that went bad but it was that sensor. this time around, its not shaking, but vibrating, and i'm not getting any codes, no chk eng light. so that is why im hesitant to go buy the sensor again. for oil i'm using mobil 1 10w30, which is what i've been using for the past 2 yrs i believe. i have read a few post about people having issues after switching to mobil 1 oil, does anyone know if that is whats causing the issue?

thanks

This may not be related to your vibration problem, but have you checked/replaced your alternator? That probably explains your dead battery. The original alternator died on my Envoy about the same mileage as you have described. When cold the alternator would output just fine, but once the engine was hot the alternator would quite working. Basically the diodes or regulator was going out. I had it bench tested at the parts store and they said it was fine becuase the alternator was cold and didn't show the symptoms. It didn't make any weird noise so the brushes and bearings were probably still good.

Also, start the engine and watch the belt tensioner. I just remembered that I had a vibration issue a while back and I noticed that the belt tensioner was randomly bouncing. I replaced the tensioner and it stopped bouncing and the vibration went away.

Another thing that I can think of that might be contributing to the vibration could be the transmission. When is the last time that you changed the fluid\filter in the tranny?

92s10blzr
12-08-2011, 02:30 PM
Alternator was fine, and tensioner was checked out a mechanic that i usually go too when im stumpped and he said it was good as well, he did tell me that the last 2 items to check out would be the torque convertor, (tran oil changed about 8months ago) or the harmonic balancer, <-- this because we both noticed that the center bolt was rotating in a oval position rather than a close to perfect circle while the engine was running. he didnt mention anything on the CPAS, either he's not aware of it or simply because the engine was not shaking as if it was having performance issues, I will remove the CPAS and inspect for damage and clean it out since that wont cost me a thing. the take off from a stop is beautiful, i dont feel any hesitation when I take off whether it be a normal take off or when i punch it. the only thing i feel and hear is the vibration of the front end when idling, and taking off but not while driving. im hesitant to replace the harmonic balancer because if the HB was really faulty, it would either be slowly slipping out of the pully and would cause the belt to slip off.....

92s10blzr
12-08-2011, 05:08 PM
umm do you mean the carbon build up that was on the Throttle Body? the TB is clean now, if thats what you mean....

92s10blzr
12-17-2011, 02:03 PM
well,I will admit, i am a big supporter of aftermarket parts, simply because i refuse to pay over bloated dealer prices. That being said. I simply didnt believe that aftermarket motor mounts was the issue to my vibration so i was ready to shell out 350 bucks to replace the harmonic balancer as suggested my a mechanic that i usually go too when im in a bind. but earlier this week something kept reminding of the aftermarket mounts complaint, but i didn't want to buy the same part twice then wait for UPS to deliver it. Then i ran into this site called www.gmpartsgiant.com that offers the pricing as gmpartsdirect, but this one was local to me so i would receive them faster, but i decided to call their 800 # and it ended up being a local Chevy dealer parts counter, and the worker told my, price out the pricing from the site and they'll honor the price if i walk into the parts counter to buy them so i got them. Just put them on and i'll be damn, the vibration is long gone :thumbsup: . TIP: had to loosen the bracket on the engine side for the new ones to go in. My thought to all this madness is, why after a 3 years of complaints because the aftermarket mounts (DEA) was not properly built, why haven't they redesign them to make them work? who knows. But i'm glad i got the mounts again and not pull the HB/pully cause that wouldve pissed me off bad cuz it would still be vibrating.

Sorry for not believing you guys, :hail: this forum and all the users in it rock :woot: :thx