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Discussion Starter #1
I drove to NJ over the weekend and added another 450 miles to it :rolleyes:

1. I did a little bit spiritual driving and I found that 75mph is the resonance peak of my car. Before the trip, the tire pressure was adjusted to 28 and 38 (factory spec), respectively. 3 people were on the car during the driving so I suppose it nears full load.

Any similar experiences on the resonant frequency of the beetle? Should we stay away from it? (I guess driving faster is a theoretical option, but not a practical one...)

2. During the trip to NJ, when the car was resonant for some while, I got CEL for a total of three times, each time 2-3 seconds. The code is my old friend (I got them last time I did some spiritual driving :eek:)
16705 - Engine Speed Sensor (G28): Implausible Signal
P0321 - 35-10 - - - Intermittent
I guess it's due to the lose of sensor? Or it's just normal when the car is in resonance for a while?

3. As my car's mileage has been bad, I took the opportunity to try some gas additive. It turned out that, sadly, after I came back today, I feel the car has a strong smell of the gas additive... is there anything wrong, say leakage anywhere? (I opened the fan all the way) Really don't want to get poisoned by various kinds of funny liquids in the car...

Thanks!
 

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My 99 2.0 does Resident speak at about 118 miles per hour. That's when I roll up the windows,and get another 3 miles per hour out of it.
As far as fuel mileage goes, keep your money in your pocket. Save it for plugs,wires,coils,things like that.
Because it doesn't matter what you put in your tank,it's gonna get burned up quickly unless your car is running at peak efficiency.
Sent:)
 

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Discussion Starter #3
My 99 2.0 does Resident speak at about 118 miles per hour. That's when I roll up the windows,and get another 3 miles per hour out of it.
As far as fuel mileage goes, keep your money in your pocket. Save it for plugs,wires,coils,things like that.
Because it doesn't matter what you put in your tank,it's gonna get burned up quickly unless your car is running at peak efficiency.
Sent:)
Woo, your peak seems to occur at a speed I'm not able to try :D
 

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Discussion Starter #6
Describe what you mean "resonance peak"??

What leads you to believe this you have a "resonance peak" at a specific speed and what are the symptoms you have.
Both my friend and I tried to vary speed and we feel the car has the strongest vibration at 75mph, and the vibration decreases as the speed moves away (higher/lower) from 75mph. Should we plot level of vibration with respect to the driving speed, we will see a peak which I called as "resonance peak."

The symptoms includes but not limited to: the shaking feeling of the whole car, and observabe vibration of the steering wheel.

Thanks!
 

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Could be wheels/tires or likely front axle(s).

Tire balance is key, HOWEVER, contrary to what everyone thinks you cannot make an out of round tire/rim round again with balancing.

So even the Hunter Road Force balancing machines cannot solve all problems and you need a REALLY GOOD tire tech using the Hunter Road Force Balancer to point out bent rims, out of round tires and such.

Not sure what type of rims you have on your car, but aluminum rims bend VERY easy and bends usually show up on the inside portion of the rim first.

My suggestion is to start by jacking up the car so a tire is only about 1/8" off the pavement and spin the wheel/tire and look for low spots and movement between the bottom of the tire and the pavement. If you have a bent wheel, you WILL easily see it.

I can recommend only 1 shop with only 1 person they really trust with the Hunter Road Force Balancer located in Rockville, MD. Road Force Balancing is not cheap, around $40-$45 per wheel, so if the tire(s) are questionable, it may not be worth spending the money until you get new tires? The shop also provides Lifetime balancing for this price.

This tech showed my how the Hunter Road Force Balancer indicated that one tire/wheel I had for a car indicated fully balanced on the Hunter machine, however, if you knew how to watch the machine and feel for vibrations in the machine, this specific rim had a slight bend in it. As the tech mentioned, he wanted me to be aware of the issue, but was not sure it would be a problem on the car. I really appreciated him pointing this issue out to me. In the end, the specific bent rim was not noticeable on the car, however, I may still get a replacement rim or have it straightened sometime in the future.

The other option is to rotate the wheel/tires and see if the problem is reduced/eliminated or moved to the rear of the car.

Again, balancing is only a small part of this type of problem, you need to make sure the wheel(s) are true and not bent, the tires are not cupped or have low spots or twists, the wheels do not need concentric spacers and that the wheels/tires are road force balanced.

Axles are harder to track down, but you really have to get the wheel/tire problem out of the way before you move onto other areas of the car.
 

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Discussion Starter #10
Thanks, jfoj. I've looked at some videos from Hunter Wheel Balancer and now knows what's going on. I'll first jack up my car and see whether the tire and rims are bend. BTW, my rims are aluminum.
 

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Even the Hunter Machine is not foolproof and cannot make something unround roll round. Even Hunter skims over this IMPORTANT piece.

Aluminum wheels bend a lot easier than people think. The lighter in weight and the lower the tire profile, the easier it is to bend a wheel!

I can give you the tire place info in Rockville if you need it.

There is only 1 tire tech the shop manager will usually schedule you will if you specifically ask for Road Force balancing. I spent a bit of time working with the tech and he CLEARLY demonstrated to me how the Hunter Balancer would indicated a balanced wheel, but the wheel/tire assembly had a problem, caused vibrations into the machine while the wheel/tire was under the load roller and a way he could EASILY detect a problem the machine did not. The test was stupid simple and he even showed may and had me feel the vibration, showed me the Hunter Balancer indicated no weight was required, which was true as the wheel/tire was balanced, but the wheel/tire was not 100% round! He then stopped the wheel/tire from spinning and manually rotated the wheel/tire slowly by hand to show me where the slight bend was and how the tread would slightly roll to one side because of the bend in the wheel!! The eye and the hand are much better tools than most people give it credit for!! Case in point, you can feel the vibration in your car, usually through the steering wheel or many times while watching out the rear view mirror as it will usually shake/vibrate at the max vibration point.

So this is a fair warning to all the forum members that really think you can just drop your wheels/tires off for road force balancing and expect that everything is 100% and solved with just the Hunter Road Force Balancer, this is not the case. The tire tech is still actually MORE important than the balancing machine!!!

Was demonstrated this is the case, witnessed this and actually felt the vibration in the machine that had a fully balanced wheel/tire mounted.

Be forewarned. In this age too many people believe what a computer screen displays and do not use their own brain and eyes to cross check what the computer screen displays. This is our NEW generation!!!
 

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Discussion Starter #12
Thanks, would you please post (if you think it's okay) or privately let me know the tire place info in Rockville, and also the trustful manager?

I get you point that although Hunter Machine is designed to balance tires with minimum inputs from mechanics, however, they do not be in lieu of the knowledge that a mechanic needs to troubleshoot those problematic tires. No matter how great the algorithms/models are designed within the Hunter Machine to identify defects, there are always cases that those models cannot deal with. I believe, and hope... that a skillful mechanic would not fully rely on the Hunter Machines after getting some comebacks.
 

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Just keep in mind that tires that have been parked for long periods, tires that are deformed and bent wheels cannot be "balanced" by any means.

You have to start with something that rolls round and true, then worry about the balance.
 

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I looked, but I didn't see any prices. How much do they cost?

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I'm guessing 40-60 range?? These are big in the motorcycle/big truck market, I assume they are not in cars because the tire chains don't want to loose a source of income.
Personally, I'm for anything that will keep me out of those auto shops. For example, I just had car aligned (something I can't do at home) and they automatically did a 40pt inspection. They noted things that needed attention, one was air filter, I had just replaced 3 days prior :rolleyes:
As was said, if your tires are flat spotted, there isn't much you can do but, replace, although (has happened to me)if you go get your tires re-balanced and they are flat spotted, they'll throw a hundred weights on them and you'll assume they are balanced and still be chasing your tail searching for a vibration, when it was actually out-of round tires/rims to begin with. I like to limit my exposure to these incompetent shops
 

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Discussion Starter #18
I recently have my tires rotated. However, they did an X pattern rather than the || pattern required by the manual. Does it matter?

After rotation, the car shakes more. Is there a general knowledge that the rear tires tend to distort more than the front tires? Thanks.

(Depths of tires are now 5/32 *3 and 3/32 * 1. I think I'm going to buy 4 tires from CostCo before it begins to snow.)
 

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I recently have my tires rotated. However, they did an X pattern rather than the || pattern required by the manual. Does it matter?

After rotation, the car shakes more. Is there a general knowledge that the rear tires tend to distort more than the front tires? Thanks.

(Depths of tires are now 5/32 *3 and 3/32 * 1. I think I'm going to buy 4 tires from CostCo before it begins to snow.)
There is a lot to all of this.

You likely need to rule out tires and rims, the next likely culprit could be front CV joints/axles.

But since you indicate that the tries were rotated and now it is worse, likely you have tire issues.

Here is the deal, as tires age, they get hard and stiff. The rubber also gets tempered due to all the heat from the road and rolling resistance.

If the tires are 5+ years old, ditch them regardless of the tread.

I just put 4 new Michelin`s on my 2003, this was the 3rd set of tires. Plenty of tread, however, the car sat for a long time and the tires were square and hard. They got better after driving and warming them up a bit, but they had a pattern set due to them sitting a long time, plus the rubber was hard.

Again, the problem is you cannot make something not round, roll round, even with all the wheel weights in the world. Rims need to be round, tires need to be round, then you deal with the imbalance in weight of the tire carcase based upon how the tires structure is built.

Occasionally you can run into bad wheel bearings, worn struts or other suspension components, warped or bent hubs or disc brake calipers sicking causing funny vibrations or other unusually strange behaviors, but these are usually not as prevalent and out of round rims/tires.

Depends also on the rim style and weight, some are more prone to bending. Usually the lighter the rim, the easier it bends, even aluminum wheels. Usually wheels bend easier on the inside than the outside.

Given the tread depth you are talking about, I would not spend money on trying to balance the tires. If you have free lifetime balancing, great, but you will be better off with new tires and a tire tech that can check the wheels for bends.

My aunt has a 2002 Buick with 36k miles on it, garage kept. She was complaining about a vibration again at highway speeds, and when I found out she had original tires on the car (13 years old), I told here to get new tires, which she did and was pleased that the new tires were a much nicer ride and did not have the vibration at highway speeds.
 
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