How many owners have noticed engine vibration (around 2500 rpms)?

[89Vette]

The most common cause I can think of for this is an out-of-balanced motor, bad motor mount, and/or failing harmonic balancer.

How many of you have noticed your VX having an engine vibration that's most prominent about 2500rpms? (Hint: If it's really the motor, you'd be able to feel the same symptom when stopped and in PARK!)

Thanks!
Gregg

P.S. Bonus points go to anyone who's seen/solved the problem. (There's a VX I'd like to buy, but with a vibration and the 3.5L black-cloud, I'm hesitant. OTOH, engine vibrations aren't always the short-block.)

Is there a TSB for this?

[RamAirZ]

I have the same thing, I feel it even more now that I fixed my tranny mount (I had NO bolts holding the mount to the tranny lol). I'm not toooo worried about it as it has oil, runs smooth, just has a bit of a vibration, which could just be engine design for some cars (some engines just vibrate, even in perfect running condition). I looked at it this way, no check engine lights, no other symptoms, I'm ok with it lol. I've driven a small block 350 with solid valvetrain and solid motor mounts with a 4K stall converter as an everyday driver before, so this is plush for me lol.

[VX crazy]

i have so much vibration that I cant stop driving it around......especially since Moab.....vibration AND grinding!

[RamAirZ]

lol, saves money on toys huh

[89Vette]

Is the crank pulley integrated with the balancer? Have these been known to fail? How about motor mount failures?

Are these internal/externally balanced motors?

[RamAirZ]

I remember someone talking about the 3.2's having balancer issues (balancer coming apart) awhile back. I'll ask Jerry for ya. I'm pretty sure the puller and balancer are one

[Triathlete]

Seems to me that if there was a balance issue that it would be worse as the RPMs increased and not specific to just the 2500 RPM area.
Is the engine running smooth otherwise?

[RamAirZ]

I'm thinking it's more engine design, certain "frequencies" make it worse. Mine does it but runs smooth as heck

[89Vette]

I remember someone talking about the 3.2's having balancer issues (balancer coming apart) awhile back. I'll ask Jerry for ya. I'm pretty sure the puller and balancer are one.

Thanks! (BTW: Who's Jerry?) FWIW, I've also heard of balancer issues in whole companies. Pioneer balancers have a bad rap after lots of failures from 2003-2008. Some even say it's still going on. (Don't know what "brand" Isuzu uses.)

Edit: If Jerry's a tech, could you (or I) ask him how to determine if the balancer (or mounts) are failing?


Seems to me that if there was a balance issue that it would be worse as the RPMs increased and not specific to just the 2500 RPM area.

Is the engine running smooth otherwise?

The engine runs VERY smooth below 2k rpms. There is no miss. Vibration does continue to exist above 2500 rpms but it seems slightly less pronounced. When I let off the gas, there is a slight stumble/vibration as it passes below 2k rpms. It almost feels like a miss. OTOH, maybe it could be the balancer "settling" back into a slower rythm. (Or if caused by a mount, maybe it's torque rebound contact/vibration.)

This could be described as harmonic vibration. The level is similar to a lawn motor above 2200 rpms. But I expect an automobile motor to feel smooth until redline.

[RamAirZ]

Jerry is like the GOD of the Isuzu world (he hangs out on the Planet alot as well as 4x4wire and a few other forums I think), he's been an Isuzu Master Tech for, well i think forever lol.I'll let you know what he says, I sent him a PM.

[89Vette]

Jerry is like the GOD of the Isuzu world (he hangs out on the Planet alot as well as 4x4wire and a few other forums I think), he's been an Isuzu Master Tech for, well i think forever lol.I'll let you know what he says, I sent him a PM.

:thumbup:

[MSHardeman]

Glad to hear that it's not just me. I tend to get a harmonic/vibration right around the 2500 rpm range that isn't really there before or after that. I just changed my timing belt, water pump and spark plugs so I know everything is good there but the vibration was there before and after all that. Hmmmm....:_confused

[RamAirZ]

Here is a response from Jerry:

THEY ARE ALL INTERNAL BALANCED , THOSE BALANCERS /DAMPNERS DONT GIVE THAT MUCH TROUBLE UNLESS THEY HAVE BEEN PULLED ON BY THE WRONG PULLER, YOU NEVER WANT TO PULL ON THE EDGES ,

IF THE VIB,S YOU ARE TALKING ABOUT ARE THE KIND YOU CAN FEEL IN THE STEERING WHEEL OR BODY , YOU HAVE MISLOCATED ENG MOUNTS , VERY COMMON, ON THESE OR THE MT,S HAVE COLLASPED , I HAD THE SAME THING ON MINE


Then I asked him what he meant by mislocated mounts:

THE FRT MOUNT S SOME TIME CAN GET TO SAGGING OR TWISTED , AND THEYA ER HARD TO SEE , BUT TAKE A LOOK AT THE FRT MOUNTS WHERE THE TOP PLATE IS BENT OVER THE MOUNT ITSELF , IT SHOULD HAVE A GAP THERE THAT YOU CAN STICK THE ND OF YOUR FINER IN BETWEEN THE TOP PLATE AND THE MOUNT ITSELF, I BET IT IS SAGGED AND TOUCHIONG USUALLY IT IS THE PASS SIDE BUT THE DRV SIDE CAN DO THE SAME, THE REAR TRANS MOUNT SHOULD BE THE SAME WAY TAKE A LOOK AT THE MOUNT AND THERE SHOUDL BE AT LEAST A 3/4 IN GAP BETWEEN THE UPPER AND LOWER PART , IN THE MIDDLE OF THE MOUNT , THIS ONE CAN BE FIXED , BY JACKING UP THE BACK END OF THE TRANS AS HIGH AS YOU CAN GET IT AND PUTTING A PIECE OF FLATTEN 3/4 IN HTR HOSE IN THE MIDDLE AND THEN LET IT BACK DOWN, THE FRT CAN BE DONE THE SAME WAY BASICALLY BUT IT IS HARDER TO DO , NOT VERY MUCH ROOM TO WORK WITH

(he's not the best typer lol)

[SlowPro48]

But I expect an automobile motor to feel smooth until redline.

Then don't buy a vehicle that has a 75 degree V6 with no balance shaft! The 6VE1 is always going to feel a little uncivilized...

[RamAirZ]

Like I said, for me it's plush lol. I've driven things that shook the crap out of you at idle, mostly due to camshafts and solid mounts, that and I had a Harley for awhile lol

[Triathlete]

I had the pleasure of meeting Jerry last year in Moab. The guy will totally boggle your mind with the info he has in his head. I think the guy has every bit of Zu info memorized...truley amazing!!!!

[RamAirZ]

Ya he's an awesome guy! His trooper is one hell of a sleeper too lol

[SuperBoomTurbo]

i have so much vibration that I cant stop driving it around......especially since Moab.....vibration AND grinding!

You must be a nurse, right? :p

[SuperBoomTurbo]

For the actual post: especially in the body on frame cars of japanese origin, the motor mount Spacers were made of soft squishy rubber that all came from the same supplier. These are not like the indestructible urethane aftermarket type. After lots of hard revving or even just years of weather exposure (high heat, road salt, etc) they break down like wiper blades.

With that in mind, its easy to test. With the engine off, go push on it side to side and see how much wiggle you get. With the engine on, leave it in park (of course) and blip the throttle body through short rev ranges. Bet it moves a lot if your mounts are trashed! As the rpm's climb, the engine movement settles down as all the torque presses the engine down on the mounts.

I drove a '90 240sx for years with this same issue and didn't notice a problem mechanically til I swapped the transmission. It'd shake and shimmy at stoplights like it had a blown hemi under the hood, resulting in the occasional 'seat wood'. (TMI!!) though the lady passenger of the time didn't seem to mind.

Now if your motor vibrates when doing highway speed like something is about to explode under there (ie under load), that sounds quite a bit more complicated, and in which case, you will soon see money flowing down the street behind you in the form of engine internals becoming externals...

[RamAirZ]

Putting it in drive with your foot on the brake and giving it a little rev with someone watching will REALLY show you, when my Mustang's mounts went bad, the motor looked like it wanted to crawl out of the engine bay.

[89Vette]

Then don't buy a vehicle that has a 75 degree V6 with no balance shaft! The 6VE1 is always going to feel a little uncivilized...

Are you sh'ing me? Motors (cranks) don't have a balance shaft. They have counterweights on the crankshaft.

Should I check my muffler bearings too?

[SuperBoomTurbo]

...when my Mustang's mounts went bad, the motor looked like it wanted to crawl out of the engine bay.

Off topic, but do you remember that pennzoil commerical a few years back where the chevy 'burb did a wheelstand before launching the motor like a cannonball? I was working with a 60 year old mopar man who shart himself after watching it via youtube.

T/j over

[RamAirZ]

Are you sh'ing me? Motors (cranks) don't have a balance shaft. They have counterweights on the crankshaft.

Should I check my muffler bearings too?

Balance shafts go in the top of the engine, usually in the lifter/intake valley, here is a 4.3 V6 balance shaft:

http://i94.photobucket.com/albums/l117/minitrucker83/P2912090005.jpg

Not all motors have/need them but they are used in some.

And yes I've seen that commercial, it's pretty funny lol

[SuperBoomTurbo]

This isn't it, but still damn funny. Trying to lighten the mood, y'all!

http://www.youtube.com/watch?v=J3FIZR8Sp6w

[89Vette]

Balance shafts go in the top of the engine, usually in the lifter/intake valley, here is a 4.3 V6 balance shaft...Not all motors have/need them but they are used in some.

Well, that's a new one on me!

What does a balance shaft "balance". I saw an exploded view of the 3.5L and the crank appears to have the tradional counterweight lobes. Why wouldn't that balance the rotating assembly?

Why build an engine with "extra" vibration if it could have been avoided with this part? :confused:

[RamAirZ]

Well alot of it has to do with packaging, parts interchangeability, a certain goal they are trying to reach etc., and like with 4 cylinders, sometime it's just something you have to do. The 4.3's didn't start off with a balance shaft but they ended up going to one to try and smooth out vibrations. All crankshafts have counterweights but sometimes the design of the engine and the firing sequence can produce unwanted vibrations. Take the 4.3 for example, it's basically a 350 chevy with 2 cylinders chopped off. But due to the firing sequence, it's a shaker! In a V8 it works fine but in the V6 it makes it lopey. Here's a good read:

http://en.wikipedia.org/wiki/Balance_shaft

[89Vette]

Here's a good read:

http://en.wikipedia.org/wiki/Balance_shaft

Thanks. I note this paragraph at the end of the link....

"Another balance shaft design is found in many V6 engines. While an inherently balanced V6 engine would have either 60 or 120 degrees angle between the two banks of cylinders, many current V6 engines are derived from older V8 engines, which have a 90 degree angle between the two banks of cylinders. While this provides for an evenly spaced firing order in an 8 cylinder engine, in a six cylinder engine this results in a loping rhythm, where during each rotation of the crankshaft three cylinders fire at 90 degree intervals, followed by a gap of 90 degrees with no power pulse. This can be eliminated by using a more complex, and expensive, crankshaft which alters the relationship between the cylinders in the two banks to give an effective 60 degree difference, but recently many manufacturers have found it more economical to adapt the balance shaft concept, using a single shaft with counterweights spaced so as to provide a vibration which cancels out the shake inherent in the 90 degree V6."

The last couple of sentences seem to explain why some engines have a balance shaft and why the VX does not. I just noticed this evening that the 3.5L crankshaft sells for over $1000!

Since I doubt this is an availability thing (because the 3.5L was in other vehicles), I would appear a more expensive crank -- referred to in Wikipedia -- has been utilized in the VX. IOW, it doesn't have a balance shaft because it doesn't need one.

[RamAirZ]

Well NEED is a term used loosely by auto manufacturers lol. I don't think the engine needs one per se but like I stated earlier, I've driven alot rougher engines (due to my own choices). I'm not sure if the 3.5 actually uses the style of crankshaft they mention, it could just be expensive because it's not a "common" engine and specific to only one engine, which makes the market for it low, thus costing more.

[deermagnet]

I have an Isuzu tech training course for these engines and this is what it says-
Problem- Engine has a vibration at above idle.
Possible cause- Outer ring on the harmonic damper has moved.
Diagnosis- Look for abnormal harmonic damper oscillations. During a visual inspection, check to see if the inner damper spring is also damaged.

I checked the parts catalog and repair manual and can't find any info on the damper/balancer. :_confused

I don't believe it's normal for this engine to vibrate at all. In over ten years on the Vehicross forums this is the first time I've heard about any engine vibration. Mine is so smooth with 218,000 miles and at 80 mph my whole vehicle doesn't have even the slightest vibration.

Engine vibration on this 3.5L should be something that can be corrected, IF the problem can be found.

Mark Griffin

[RamAirZ]

Well also a vibration to one person might not be one at all to another. So it's hard to say. But it's very easy for any engine to vibrate when mounts go bad, which they can/will do over time. Like you said, should be able to be corrected. I'm thinking mounts or balancer, I know the earlier 3.2 had balancer issues.

[89Vette]

Well also a vibration to one person might not be one at all to another. So it's hard to say. But it's very easy for any engine to vibrate when mounts go bad, which they can/will do over time. Like you said, should be able to be corrected. I'm thinking mounts or balancer, I know the earlier 3.2 had balancer issues.

I agree this is a DIFFICULT topic to talk about/solve -- as one man's vibration might be another's soothing back rub! LOL

The vibration I'm talking about is definitely more than you could sell a new car with (and enough so that I can comfortably classify it as an "issue"). It's also enough that it would drive me toward a solution (or sale if never corrected). It's one that creates cabin resonance at hwy speed where passengers are annoyed (mainly in the back seat). But, it's definitely coming from the motor (since it is present when parked).

After reading Jerry's response, I tend to think this is a motor mount issue. Plus, the current owner had the belt removed, checked for balancer play, and if the vibration still existed w/o the belt. It does and there's no play.

That pretty much means it's the mounts (or the motor). When/if I can confirm the mounts, I'd like to purchase the VX in question.

The downside is the same shop said they did not see a problem with the mounts either. But that's probably harder for the average mom/pop wrench-turning shop to determine. It's one of those areas where a (dealership that's seen more specimens) might better diagnose. OTOH, lots of dealers have seen very few of these!

[89Vette]

The vibration I'm talking about is definitely more than you could sell a new car with (and enough so that I can comfortably classify it as an "issue"). It's also enough that it would drive me toward a solution (or sale if never corrected). It's one that creates cabin resonance at hwy speed where passengers are annoyed (mainly in the back seat). But, it's definitely coming from the motor (since it is present when parked).

After reading Jerry's response, I tend to think this is a motor mount issue. Plus, the current owner had the belt removed, checked for balancer play, and if the vibration still existed w/o the belt. It does and there's no play.

That pretty much means it's the mounts (or the motor). When/if I can confirm the mounts, I'd like to purchase the VX in question.

The downside is the same shop said they did not see a problem with the mounts either. But that's probably harder for the average mom/pop wrench-turning shop to determine. It's one of those areas where a (dealership that's seen more specimens) might better diagnose. OTOH, lots of dealers have seen very few of these!

Maybe this 6VE1 really isn't very smooth. I saw another 3.5L motor today. I went back/forth between both motors. They had (close) to the same vibration/harmonics around 2500rpms. Both smoothed out between 3500-4000rpms though one motor was noticeably smoother than the other. (Not a lot, just noticeable.)

Maybe this really is a combination of the motor's "character" -- plus a bit of mount vibration. It might also be that one needs plugs and/or injector cleaning to recover maximum smoothness.

Has anyone ever looked into installing new mounts and/or trying the heater hose trick relayed by Jerry?

[technocoy]

I think this is a car that you can find any number of things that shoulda woulda coulda.

Like I've said before it was never a secret that this car was a short run and essentially a prototype that was pushed to a short labored manufacturing run.

I previously owned a Trooper and an original model Amigo, every single Isuzu I have ever owned or ridden in had a certain "truth" about it for lack of a better term. They are robust and well built but there isn't much of an attempt made to mask every vibration, noise and such and there is always a certain lack of detail when it came to nonessential things such as window tracks.

I obviously can't drive the particular vehicle you are interviewing, but even if it did have an issue that can be remedied I can tell you at some point there will be another one. There is a passion for this vehicle that has to be had. I went into it knowing about the engine issues, the window issues, etc, but I also knew I had never seen anything I had wanted so badly and that it used a standard Isuzu powerplant for the most part. I resolved myself to the fact I was going to own this car forever and that if the engine goes that I would, in fact, replace it. Yes, I take it in and try to find resolve to some issues, but for others, it runs like a beast and I love driving it. It's loud, it's rough, but that's what I bought.

I just think that if you are already finding issues every which way you should either not settle with this particular VX if it's really an abnormal vibration, or it's possible that you may just not want to get a VX. There are features and characteristics that have been mulled over and over and over again on these forums.

Like you said, one man's vibration is another man's backrub, but I really honestly think that these "issues" (all relative right?) are standard on this model.

You are right, you couldn't sell the roughness of this engine today. Of course, you probably couldn't work on an engine in most of the cars today in your average garage either. But this car isn't being sold today, it was being sold 11 years ago and it was never a Honda Civic or Ford Ranger. There are less than 10,000 of these unicorns. They were hand assembled and it is essentially a short run prototype.

You may prove me wrong, but you aren't going to find a perfect VX. They are only perfect to the people who love them above and beyond all the little bits and annoyances.

Just my two cents, again, hahaha. I really do hope you get in one, it's exciting to still have the VehiCross getting people riled up, but it isn't for everyone. I can tell you now, if you do decide to stick with one, I have NEVER encountered a better support group and honest group of mutual fanatics as those here on this site.

Cheers.

[Ldub]

I think this is a car that you can find any number of things that shoulda woulda coulda.

Like I've said before it was never a secret that this car was a short run and essentially a prototype that was pushed to a short labored manufacturing run.

I previously owned a Trooper and an original model Amigo, every single Isuzu I have ever owned or ridden in had a certain "truth" about it for lack of a better term. They are robust and well built but there isn't much of an attempt made to mask every vibration, noise and such and there is always a certain lack of detail when it came to nonessential things such as window tracks.

I obviously can't drive the particular vehicle you are interviewing, but even if it did have an issue that can be remedied I can tell you at some point there will be another one. There is a passion for this vehicle that has to be had. I went into it knowing about the engine issues, the window issues, etc, but I also knew I had never seen anything I had wanted so badly and that it used a standard Isuzu powerplant for the most part. I resolved myself to the fact I was going to own this car forever and that if the engine goes that I would, in fact, replace it. Yes, I take it in and try to find resolve to some issues, but for others, it runs like a beast and I love driving it. It's loud, it's rough, but that's what I bought.

I just think that if you are already finding issues every which way you should either not settle with this particular VX if it's really an abnormal vibration, or it's possible that you may just not want to get a VX. There are features and characteristics that have been mulled over and over and over again on these forums.

Like you said, one man's vibration is another man's backrub, but I really honestly think that these "issues" (all relative right?) are standard on this model.

You are right, you couldn't sell the roughness of this engine today. Of course, you probably couldn't work on an engine in most of the cars today in your average garage either. But this car isn't being sold today, it was being sold 11 years ago and it was never a Honda Civic or Ford Ranger. There are less than 10,000 of these unicorns. They were hand assembled and it is essentially a short run prototype.

You may prove me wrong, but you aren't going to find a perfect VX. They are only perfect to the people who love them above and beyond all the little bits and annoyances.

Just my two cents, again, hahaha. I really do hope you get in one, it's exciting to still have the VehiCross getting people riled up, but it isn't for everyone. I can tell you know, if you do decide to stick with one, I have NEVER encountered a better support group and honest group of mutual fanatics as those here on this site.

Cheers.

Well said...:thumbup:

[navistar]

Any problems I've ever had with my VX has been more than made up for by the stares I get every time I drive it. Oh, and the great gas mileage. :winko:

[SlowPro48]

I don't believe it's normal for this engine to vibrate at all. In over ten years on the Vehicross forums this is the first time I've heard about any engine vibration. Mine is so smooth with 218,000 miles and at 80 mph my whole vehicle doesn't have even the slightest vibration.

Engine vibration on this 3.5L should be something that can be corrected, IF the problem can be found.

Mark Griffin

Haha! Mark your VX has been rockin' along for 218K and you didn't even know it! The vibration I was talking about that is inherent in our 3.5 is not something you'll feel when you're going down the road. Put it in Park and play with the loud pedal a bit and you will feel it between 2400 and 2800 though. Also at around 1300-1400 but it's really hard to hold it steady at those low rpms. It's not bad at all and you may not even notice it if you're used to riding a Jackhammer Davidson like RamAirZ is - but go from something that has a straight six to the VX and you will feel it!

89Vette I am fully aware that the crankshaft is weighted but those weights are not for your comfort, they are there to offset the mass of the pistons and rods and thus keep the crankshaft from self destructing - as is the harmonic damper at the end of the crankshaft. Even though the rotating parts within the engine are balanced, the engine itself - as a unit - can and will vibrate however - and some configurations are worse than others. The L6 and V12 are naturally smooth whereas the V6 is not - a result of having three cylinders per side. The only way to cancel the rocking couple of our V6 is with a counter-rotating balance shaft like what is seen in the picture of the GM 4.3. That balance shaft isn't "needed" to prevent the engine from self destructing - it's there for human comfort - to keep the engine from rocking along its length which is felt as vibration. But that adds extra weight/complexity/rotating mass. The designers of the GM 4.3 thought it was worth the extra weight, etc to include a balance shaft and they were probably right since it's a 90 degree engine. A lot of sixty degree V-6s don't have one since the more shallow V means less vibration. They make do with some squishy motor mounts that turn the rocking motion into heat (and break down eventually because of it) and call it good. I guess the Isuzu engineers thought our 75 degree V6 was close enough to 60 to go "au natural" as well and for most people it is.

Bottom line is if you're looking for something that's silky smooth when revved in the driveway - from idle to redline - don't go for a V6 with no balance shaft - you need a BMW L6 or better yet a Jag V12. This "cabin resonance" at highway speeds you speak of is NOT caused by the normal amount of engine vibration of the VX though. The normal VX engine vibration isn't noticeable when driving.

Did the vehicle in question have a roof rack?

[89Vette]

Haha! Mark your VX has been rockin' along for 218K and you didn't even know it! The vibration I was talking about that is inherent in our 3.5 is not something you'll feel when you're going down the road. Put it in Park and play with the loud pedal a bit and you will feel it between 2400 and 2800 though. Also at around 1300-1400 but it's really hard to hold it steady at those low rpms. It's not bad at all and you may not even notice it if you're used to riding a Jackhammer Davidson like RamAirZ is - but go from something that has a straight six to the VX and you will feel it!

89Vette I am fully aware that the crankshaft is weighted but those weights are not for your comfort, they are there to offset the mass of the pistons and rods and thus keep the crankshaft from self destructing - as is the harmonic damper at the end of the crankshaft. Even though the rotating parts within the engine are balanced, the engine itself - as a unit - can and will vibrate however - and some configurations are worse than others. The L6 and V12 are naturally smooth whereas the V6 is not - a result of having three cylinders per side. The only way to cancel the rocking couple of our V6 is with a counter-rotating balance shaft like what is seen in the picture of the GM 4.3. That balance shaft isn't "needed" to prevent the engine from self destructing - it's there for human comfort - to keep the engine from rocking along its length which is felt as vibration. But that adds extra weight/complexity/rotating mass. The designers of the GM 4.3 thought it was worth the extra weight, etc to include a balance shaft and they were probably right since it's a 90 degree engine. A lot of sixty degree V-6s don't have one since the more shallow V means less vibration. They make do with some squishy motor mounts that turn the rocking motion into heat (and break down eventually because of it) and call it good. I guess the Isuzu engineers thought our 75 degree V6 was close enough to 60 to go "au natural" as well and for most people it is.

Bottom line is if you're looking for something that's silky smooth when revved in the driveway - from idle to redline - don't go for a V6 with no balance shaft - you need a BMW L6 or better yet a Jag V12. This "cabin resonance" at highway speeds you speak of is NOT caused by the normal amount of engine vibration of the VX though. The normal VX engine vibration isn't noticeable when driving.

Did the vehicle in question have a roof rack?

Thanks for the reply! This is the kind of feedback I was looking for. It's thought-filled, detailed, and makes a genuine attempt to explain the dynamics of what's happening.

[No offense, but blind acceptance of a vehicle as a halo project is short-sided. The motor's character was my question -- which was used in other non-concept projects. As such, it shouldn't be doled off as half-hearted by Isuzu.]

I agree the motor seems to have some inherent vibration. Surprisingly, the only other motors I've noticed this on (in my 37yrs of driving) is a 2-cylinder motorcycle. OTOH, this is the first V6 I've driven with the intent of ownership. (My father has a V6 Buick which is also smooth -- but that's in the cabin. Maybe it has a balance shaft too?)

To determine whats "normal", I placed my hand directly ON the 3.5L motor. I repeated this for another 3.5L motor from 2001. With the isolation of the mounts removed from my perception, I could feel the similarity in cylinder pulses, variances at rpm, and stubbling during decel. With everything I felt, the character was the same. The only difference was that the strength of vibrations were approximately double in the newer 76k mile engine. (The other had 120k on the clock.)

Though it's possible that the lower mileage vehicle also transmits more vibration thru the mounts (to the vehicle), it seems more like the character of the motor itself.

Obviously, part/weight tolerances from the factory could make a difference, or these a specific action that could smooth the vehicle. Since air, fuel, and compression (plus timing) all play a part in the strength of an indidual cylinder pulse, this particular motor might see improvement thru: 1) spark plug inspection/replacement, 2) injector service/replacement, 3) coil replacement?, or 4) cylinder compression check. But I haven't gone so far as to do those myself. But, the owner was KIND enough to send it to a mechanic for the "once over". I have no idea if any of these individual points were examined.

That said, the mechanic gave his thumbs up. Though he also drove it, felt the vibration, and acknowledged it, his final judgement was to categorize it as a typical 9-yr-old vehicle. My problem with that assessment is the vibration CAN be felt and acknowledged, but an explanation could only be found thru my efforts here. (Thanks btw for that!)

I can feel the vibration on the hwy around those rpms. Because it can also be heard, one logical conclusion is the vibration is being transmitted to the frame via hardened/touching motor mounts. Just as an exhaust pipe can create exponential noise when touching a car's frame/body, so could an engine.

So, it would seem like the mounts might be the culprit. OTOH, because it's vibration does feel somewhat stronger than another 6VE1 specimen, maybe there's a tune-up issue that could affect improvement.

The issue is not resolved IMO, though I've gotten alot closer to determining the issue. Because there are SO many other GOOD things about the unit in question, I'm not so eager to assume it's just the nature of the beast or that a VX just isn't the vehicle for me. That approach just doesn't provide enough investigation/thought IMO. If you can't tell, I'm more eager to make this work than to give up!

Happy Memorial Day to Everyone!!!

gp

[89Vette]

Any problems I've ever had with my VX has been more than made up for by the stares I get every time I drive it. Oh, and the great gas mileage. :winko:

This is my "Man of the Hour". Navi is the one who personally visited and introduced me to the VX concept. Before he was nice enough to visit, I was only able to view/judge from afar. If was his congeniality that helped me move from intrigue to infatuation. At this point, I'm hoping to continue until I hit satisfaction!

I can't get no..., I can't get no...., satisfaction. Cause I've tried...and I've tried...and I've tried.

R. Stones
:dance:

[SuperBoomTurbo]

Any problems I've ever had with my VX has been more than made up for by the stares I get every time I drive it. Oh, and the great gas mileage. :winko:

Oh, I don't know. Eighteen highway is pretty thrifty compared to a bench stock 454, which gets 12 highway, 14 if you baby it!

I tell everyone that you have to remember, when the vx came out, gas was 1.12 a gallon. Who cared about mileage?! Its getting better than 1 hp per cubic inch of displacement, which is the bare minimum of acceptable performance in my mind (an I mean Bare! If honda and ferrari can get 100+ hp per liter and make it last, why can't someone else?) on a vehicle that's pushing 4000 pounds of steel and rubber. :yeso:

In that view, 18 doesn't seem so bad!

[RamAirZ]

I avg. about 17 with my lift and tires and what not, I'm pretty happy with that