99 Buick Park Avenue Ultra Vibration/02 Sensor Issues

Hello everyone, newbie here.

I am the happy owner of a 1999 Buick Park Avenue Ultra that my aunt (graciously) gave to me two years ago 😱 😀 😀 😀. I am absolutely in love with this car, especially since I am the only kid on my electrical engineering class that can claim to have a supercharged V6! I got it with 129000 on the clock and now have run an additional 150800 miles. The engine starts and runs just fine and the tranny shifts as smooth as ever. The only parts that we've had to replace were the trailing arms, a supercharger belt pulley, and the driver-side climate actuator, all due to old age.

However, she's developed some issues over the past several months. I've done research here and in Google Land and have made some estimations, but would like your opinion(s) before I commit to any service:

VIBRATIONS AT SPEED AND TURNS:
Symptoms: A distinct vibration/shudder can be felt in the steering wheel when the engine is in the 1100-1400 rpm range, whether accelerating or cruising in that range; sometimes it is significant enough to cause the dashboard to visibly vibrate. 1500 rpm and above it goes away, 1000 or lower and the only vibes are those from the road. She also vibrates while idling in Drive. A shuddering is felt in the steering wheel while turning left or right with some throttle, such as from a stop sign, with the dash always vibrating quite a bit. It's generally more severe turning left, but is present while turning right too.

Possible Causes: My primary guess for the turning vibes is that my CV's are bad, since that is what the service manual suggests. For the vibes at speed I suspect the engine mounts are going too, either causing or supplementing the CV shuddering. It could also be the wheel bearings, since my ABS/Trac lights have been on for a while. Any thoughts? Are the CV axles and engine mounts difficult to replace for DIYer's? Any recommended brands or brands to stay away from for these parts?

OXYGEN SENSOR
Symptoms: My Service Engine Soon light came on a few months ago, so I took the car to Autozone to be scanned. It returned P0442 and P0141. Also, I noticed that the engine can seem sluggish at times; after I replaced the plugs last summer I felt an increase in power but that seems to have faded now that the light is on.

Possible Causes: I know the P0442 is due to my shot gas cap. And I know the P0141 doesn't necessarily mean the sensor is toast, but some posts and sites I've seen have suggested that O2 sensors should be replaced as they age. The catalytic converter has a rattle in it (due to something broken off inside of it; I'm replacing it soon) so that may have been a cause too. I am still going to check for other causes, but is regular replacement of 02 sensors recommended or just a myth? I do know that AC Delcos are the best replacement.


Forgive me for the long post, but I figured I'd put this all on one post rather than clutter up the forum with separate posts. Looking forward to your feedback; Thanks!

Hi and welcome to...here! My guess for the moving vibrations would be CV axle, ( not difficult with the right tools) but I'd try putting the front wheels to the rear just to make sure it isn't a tire issue, and when you do, take a good look at the tires to be sure the alignment isn't out. The shaking at idle may be an out of tune loping, or possibly harmonic balancer. hard to troubleshoot from the 'net, but she definitely needs a good once over. Wheel speed sensors may be shot giving ABS code as well. You can get a lot of insight from here ---> http://www.regalgs.org/ <--- where there is a section for the P.A.'s.
Not gonna lie, the mount under the crank pulley is a PITA! you have to raise the car and lower the cradle. not fun!

Can't help much with your questions, though I'll watch this thread since I also have a 99 Ultra. You really put 150K on in 2 years? Or is that 15K?

... and I'm an EE too..

We have actually rotated the tires already, and now there is woba-woba-woba noise from the front left tire, so it may very well be a balance issue. That wheel also seems to have lost its counterweight, but I would have no idea where to get one, so I'll see about having the wheels balanced. And i know what mount you are taking about: we had to loosen it to change the S/C pulley, and that alone elicited plenty of cursing! We did snug it back, though there is the possibility that it went bad.

No, no typo, I went from 129k to 150k in two and a half years. I commute 7 miles to my college, and my parents take the car to go shopping because it gets "better" gas milage than our GMC Safari, LOL.

I replaced mine about a week ago after the same code... I sprayed the sensor with pb blaster on accident during my header install. Code went on, seemed to be running a little funky and after a scan, I discovered I was running a bit lean. New 02 sensor, trims back to normal. However, my sensor was the upstream sensor that the PCM uses for trims. If its the downstream sensor, im thinking that code wont affect performance. In fact, I had the downstream O2 code deleted and I only have the one upstream sensor as of now.

Kevandkaye- Any chance your ultra was at buick day on sunday? I see youve visited norwalk and I parked a few cars down from a nice looking white one like yours.

Sadly, I couldn't make it this year but was there the 4 previous years, and hope to bring the car next year even though She's too old to race and show now.

Tonight we pulled off the left front wheel to check the bearing and axle. We put the car in neutral and turned the axle by hand, and felt no binding or play what so ever. The axle and boots looked good too. The only thing to report was a rubbery "zzzzzzz" from the boots that was heard only at certain positions of rotation, but this is probably just the rubber stretching and contracting (forgive us if this is normal, we don't have much experience with front drivers).

I'm beginning to wonder if some of the vibes may be bad running. It may still be the rear mount that I haven't looked at, but tonight I noticed that she was surging when in OD on long inclines. If I shift to third, goes away. The only thing different I did was put 93 in instead of 87. Maybe a too-lean mixture resulting from the bad the O2 sensor? Could the blue NAPA spark plug wires cause this too?

Do you still have original vacuum lines? I had to change mine 5 years ago with a lot less miles than you have! They can be had at the dealer usually for less than $50 bucks for a set....

Hmmm, as far as I know, they are the originals; I don't think my aunt ever had them replaced. I'll put those on my parts list!

The test for wheel bearings is probably that there should be less than .05 in play in and out. Most people rely on the wobble amount to gauge when they are worn, but GM in a leSabre service manual stated the in/out movement amount.

Were the spark plugs replaced with proper GM plugs for the stumble under load in OD? Because it's a supercharged engine there may be other causes. However, the plugs or wires are first to check for a miss under load in high gear.

imidazol97 said:

The test for wheel bearings is probably that there should be less than .05 in play in and out. Most people rely on the wobble amount to gauge when they are worn, but GM in a leSabre service manual stated the in/out movement amount.

Were the spark plugs replaced with proper GM plugs for the stumble under load in OD? Because it's a supercharged engine there may be other causes. However, the plugs or wires are first to check for a miss under load in high gear.

Click to expand...

We wiggled the heck outta that bearing; virtually no play, which is good for its age, I guess.

What exactly are "proper GM plugs"? I replaced the old ones with Bosche Platinums, and the wires with $30 NAPA blue wires. The surging presented it self only once in a blue moon after that, and has been significant only tonight.

Bosch Platinum plugs do not work well with DIS ignition, they always seem to fail early. Use ACDelco, Autolite, or NGK. BTW, you should always run 92-93 octane fuel in the S/C engine. Click Here

I stand corrected, we did put Autolites in.

Well, the surging went away after some driving, so I'm not sure what that was about. She seems to like the premium a little better.

I'm having the cat and O2 sensors replaced next week, so that will take care of the SES light and rattle. I'm still open to any ideas about the vibrations; what you've provided so far is great!

So wheel bearings can cause vibrations also? I also have a vibration but only when going 55 or over not exact on the RPMs. I balanced the wheels twice at different reputable shops and the vibration is still there I have also replaced the tie rods with no luck. Sorry for thread jacking lol.

My pa has that same vibration in the left wheel. I noticed my rear Tranny mount is broken so maybe that's the issue

Where is that mount, anyway? On that side of the car there is a lot of equipment (washer fluid tank, coolant tank, air filter, strut mount) so its difficult to see down there.

Just a quick update: I had the cat. replaced a couple of weeks ago, and MAN does she sound good! For once I can actually hear the grunt of that beautiful V6 instead of a metallic rattle! Did notice a subtle whining noise too but that's either the tranny or the supercharger.

I'm going to order the front tranny mount and get started with that one, since my research indicates that this one is the easiest to change and it takes the most stress. Does anyone know how hard the rear tranny mount is to change?

I had a vibration at different rpms as well and found it was my harmonic balancer going out. I found a place in Northern California that rebuilds balancers. I sent it to them and when I got it back, no more vibration. www.damperdoctor.com

I'm betting it's your front brake rotors.

It was for me.