[Kosfactor]

Originally Posted by pkulkarni.2106

Do diesel engines have IAC valve?
https://mechanics.stackexchange.com/...-control-valve

As far as I know in modern diesels , The 'throttling' is done using inert air to maintain compression ratio - also known as EGR , Safari uses an integrated EGR valve/cooler assembly (very expensive) to achieve this.

[a4anurag]

In my 2017 Creta 1.6L CRDi, there was a humming issue of the whole cabin between 1,600-1,900 RPM. Made city driving a pain but after a lot of reading on various Hyundai forums, it was pointed that the clutch was the one creating the issue. Hence I went ahead and changed the clutch set in my car, has been a smooth drive thereon.

[Reinhard]

Originally Posted by IP_Man

Car is very smooth at idling (850 RPM). Pickup is also very smooth and vibration free but when RPM needle crosses 1000 RPM, car starts vibrating and there is audible boom inside the cabin. As RPM middle crosses 1100RPM (and above), car again become vibration free. This happens in all gear positions and also during coasting.

During city stop and go traffic condition, RPM needle frequently crosses 1000 RPM so it becomes difficult to ignore offending vibrations.

So these vibrations/resonance - is also present if the car is revved in the specified RPM range in neutral when standing still? Happens only when in gear & in motion? Any difference when the clutch is engaged/dis-engaged?

1. If it happens even when the car is at a stand-still and in neutral, I guess the transmission & clutch will get eliminated from the list of suspects - to some extent.
2. In this case - I'd start looking from the air-intake plumbing, turbo charger & EGR valve. The RPM you mentioned is near the lower end where the turbo charger starts spooling up.
3. In fact - resonation based vibration/sounds are tricky to find because it can be anything anywhere in the car that resonates with that frequency and rattles/vibrates. If its not the intake plumbing / transmission components, then 2-3 guys together will need to thoroughly check the car. Including from under the car - to hold components one by one & to find which one is the root cause. The old school way if not done already. Do include the down-pipe, catalytic converter & nearby mounting points also. I have had similar resonation induced by the exhaust system in my old Omni in the past.
4. If this happens exclusively when in motion / in gear & behaviour changes with clutch modulation - the transmission & clutch need to be looked at.

[AirbusCapt]

Folks, does the vibration occur at idle with gear in neutral? Or is it present when the vehicle is accelerating in gear. Where can the vibration be felt? Is it on the pedals, the seat, the steering wheel, the door pads? Are there any loose objects in the cabin/boot? Sometimes a loosely placed jack or warning triangle can cause vibrations and due to the huge cabin, it's difficult to pinpoint.
The prominent area of vibrations in a Storme is the engine cover and the black plastic grill covering the wiper motors. Damping them will stop the rattling sounds. The other area to check and replace are the two rubber engine mounts.

[landcruiser123]

A friend of mine had a similar issue in his Scorpio between 900-1000 RPM. An FNG diagnosed it to a couple of lose body mounts which were torqued.

FNG knew it because it was apparently a common occurrence in Tata 407s.

[condor]

Originally Posted by IP_Man

offending vibrations that peaks in between the RPM band of 1000 to 1100. .

Can you share a recording of that sound ?

26Hz ? On the lower side of the audible range for humans. I could be wrong, but may be the metal sheets in the engine area.

Also, may be try adding some pieces of damping material on the metal sheets in the engine area.

[Ace F355]

I can totally relate to the owner's frustration. In my 2016 Ford Endeavour, I also have a similar observation, the slow seeping vibrations come between 1600-1900rpms only, and Ford A.S.S. is clueless about the cause. What makes matters worse in case is that Endeavour is so silent overall and these small vibrations feel too much for someone like me - especially when the typical speeds of 90-110 kph that I do on highways, the engine settles within this band only.

From my experience -

1. Check on engine and transmission mounts. Usually, when these go bad, vibrations seep in. Only catch is, those vibrations would be permanent in nature if the mounts are bust, while here we are talking rpm band specific. In my case, the engine mounts of the Ford pick up a lot of dirt/sand from the off-roading that I do and this results in added vibrations. I have made it a habit to get engine mounts cleaned by pressured air and water everytime I get my car washed post off-road. Makes a difference in my case.

2. My other suspect is the flywheel. Because it is a DMF (dual mass flywheel), it does a phenomenal job of cutting down on vibrations. However, it is possible that in my use case, the flywheel might have worn out a bit and that's causing vibrations in a fixed rpm band. Since my clutch is absolutely fine so far, I am going to look at it at during next clutch change which is still sometime away (53k on current clutch and I expect another 35-45k minimum). From my experience with Ford A.S.S. so far, I unfortunately don't trust Ford's diagnosis abilities to understand this right now - hence living with the current situation.

3. Do a general check on air intake and body panels to isolate the usual suspect of such issues.

Good luck in finding the problem, and please keep us posted on the possible solutions.

[amit_purohit20]

Let us breakdown this activity in two parts:-
1) What causes the vibration and
2) Which parts vibrate once they are excited.

As you said the vibration happens at 1000-1100 rpm that means the vibrating source is a problem or the subsequent parts which vibrate are the problem. These subsequent parts can reach resonance and can amplify the effect of vibration.

In Engine assuming that the Engine does not has a imbalance issues right from factory, the other factor which can imbalance your engine is Front Damper pulley. This pulley is mounted on the crankshaft opposite side of Flywheel which reduces the torsional vibrations.

Other parts which can be of imbalance itself is the crankshaft and flywheel itself. Many auto manufacturers pair these two parts, check for imbalance and then drill holes to reduce the imbalance.

Subsequent parts which can vibrate - well the entire car components! As you have said that the vibrations occur when the car is at stand still that means you can eliminate subsequent to engine - rotating parts like transmission wheels etc. You can also eliminate from the list the suspension parts as they are not in operation when the car is at standstill.

Those parts which are mounted in a cantilever fashion that means hold/mounted at only one point tend to vibrate (Higher amplitude) a lot. These parts if they are rubbing against other part can cause vibrations to seep into the entire body of the car. Example a loose dangling AC condensor pipe. A loosely mounted pipe on the firewall caused vibrations to seep into my gear lever! Check all the mountings on the firewall.
As you have already replaced Flywheel, Engine mounts etc. check all plumbing, exhaust pipes, torque all mounts, all shields and dangling covers.
While checking give priority to parts which are mounted on the car body than on the engine as these are the parts which amplify the vibration can transmit it to the body shell.

Off topic- In my Indica vista TDI, I still have a vibrating gear lever. The lever vibrates only in Top gear at low engine rpms (not engine lugging) and under load (5 occupants with ac). Its a case of torsional vibrations. I replaced the clutch and was able to reduce the vibrations but not eliminate it. Next in line culprits are the Crankshaft damper pulley and the transmission fifth gear assembly itself as I suspect play or faulty tolerances on the gear width. Now my car is 11 years old, I have lived with the problem till date so no point in replacing these many critical parts and land up with another issue due to faulty workmanship, so I prefer to stay with the problem.

[TorqMaster]

Also , try measuring this data at different places in the car. Steering is one. Measure it at one of the footwells, near the windshield and dashboard junction , below the front seat floorboard etc. this could also lead to the solution. Check if the steering column is firm or if it needs any bushing to be changed.
I suspect the new engine mounts to be bad ones. Maybe they changed the parts to bad quality ones?

[SS-Traveller]

Originally Posted by IP_Man

My friend is facing this problem from day one of the purchase.
...when RPM needle crosses 1000 RPM, car starts vibrating and there is audible boom inside the cabin. As RPM middle crosses 1100RPM (and above), car again become vibration free. This happens in all gear positions and also during coasting.

Body on ladder frame chassis, with low rpm harmonic vibrations - first thing to check and replace are the rubber mounts, and then tighten all the bolts connecting the body to the chassis.

Was this item checked by the workshop?

[IP_Man]

Lots of input

I will try to answer question asked.

IMP update: When fuel tank is full, vibration intensity reduces to the minimum. Could this is because of damping due to fuel weight? As fuel tank becomes empty vibration intensity increases. Or, is it something to do with fuel pressure?

Originally Posted by Jeroen

15- 30 Hz usually comes into play on suspension components. But they are designed to transfer much lower frequencies to the body/chassis. But then again a faulty suspension component could cause this as well. But tends to play up at a given speed, rather than a specific RPM in all gears.

Suspect of suspension is ruled out because at 1000 RPM, in first or second gear speed is very less.

Originally Posted by hserus

That rpm band is very specific - just past the idling speed. There's an idle air control valve that is a prime suspect in such cases. Or a fuel temperature sensor.

Was the vehicle scanned for errors at all?

Fortunately, no error indication. Service center also checked error code by connecting laptop, no error code.

Originally Posted by srini1785

Check the engine mount rubber pads and all place where the engine is connected to the body. You need to stop the engine vibrations from transmitting to the body.

Vibrations are there from day one of the purchase. Engine mount was prime suspect and Concord service center tried changing them.

Originally Posted by --gKrish--

Try removing the belts for engine auxiliaries like PS pump, AC Compressor etc. and check.

Also, it wasn't clear from the post whether the noise occurs when the vehicle is not in motion and the engine is revved to 1000-1100 rpm. Could be an out of balance shaft.

Vibration intensity increases as load on the engine increases. For e.g. if A/C is ON or if car is driven on incline, vibrations becomes stronger.

Vibrations are minimum when car engine is revved in neutral. Vibrations are also minimum if clutch is depressed, car is in gear and engine revved to cross said RPM band.

Originally Posted by alpha1

Anyone on this forum who has the exact same make/model/version of the vehicle: if they can verify that the same happens or doesn't happen in their vehicles.

Exactly! I request Safari Storme EX (updated) owners to report.

Originally Posted by hserus

Check the air intake as he says, and also the idle air control valve

AFAIK, air is not throttled in diesel engine.

Originally Posted by Kosfactor

The resonance starts around the time the engine is coming off idle and increasing revs. At this point the engine is asking for more air and fuel - its not getting enough of it perhaps.

This is good point.

Originally Posted by Turbanator

I don’t have an answer for this but why will someone get so many parts changed on his new car?

Perhaps, that’s the old TATA way of doing but in my opinion absolutely wrong way to diagnose or rectify a problem.

If the manufacturer is not sure of the parts it put in a new car, they should simply stop production until they are absolutely sure of the quality of what they are going to assemble.

Yes. Concord service center could not diagnose problem. They involved Tata Motor also but no solution to the problem. This method of diagnosis is like shooting in the dark.

Originally Posted by Reinhard

So these vibrations/resonance - is also present if the car is revved in the specified RPM range in neutral when standing still? Happens only when in gear & in motion? Any difference when the clutch is engaged/dis-engaged?

Vibrations are minimum when car engine is revved in neutral. Vibrations are also minimum if clutch is depressed, car is in gear and engine revved to cross said RPM band. Clutch engaged/disengaged makes no difference.

Originally Posted by landcruiser123

A friend of mine had a similar issue in his Scorpio between 900-1000 RPM. An FNG diagnosed it to a couple of lose body mounts which were torqued.

Engine mounts changed and torqued to correct specification made no difference to the vibrations.

Originally Posted by condor

Can you share a recording of that sound ?

26Hz ?

Such a low frequency vibration are felt rather than heard but there is audible boom inside the cabin. There is one more app in iPhone that can record sound db level. Pl. refer the screen shot when car is moving in that RPM band.

Originally Posted by Ace F355

2. My other suspect is the flywheel. Because it is a DMF (dual mass flywheel), it does a phenomenal job of cutting down on vibrations. However, it is possible that in my use case, the flywheel might have worn out a bit and that's causing vibrations in a fixed rpm band. Since my clutch is absolutely fine so far, I am going to look at it at during next clutch change which is still sometime away (53k on current clutch and I expect another 35-45k minimum). From my experience with Ford A.S.S. so far, I unfortunately don't trust Ford's diagnosis abilities to understand this right now - hence living with the current situation.

Engine mounts are good. Flywheel is not of DMF type. They changed flywheel also but all efforts in vain.

Originally Posted by amit_purohit20

In Engine assuming that the Engine does not has a imbalance issues right from factory, the other factor which can imbalance your engine is Front Damper pulley. This pulley is mounted on the crankshaft opposite side of Flywheel which reduces the torsional vibrations.

Other parts which can be of imbalance itself is the crankshaft and flywheel itself. Many auto manufacturers pair these two parts, check for imbalance and then drill holes to reduce the imbalance.

Unbalanced components inside the engine is my worst fear because car is new. My friend has filed complain in the consumer court.

Drilling holes in the flywheel to balance it or adding balancing weights to the appropriate position on the drive shaft is solution but expert level of Concord service center is too low to do this. TATA should have solved this problem but they don't have will to solve this problem. Surprisingly Varicor-400 engine (VX version) don't have this problem that means TATA is aware of this problem.

Originally Posted by SS-Traveller

Body on ladder frame chassis, with low rpm harmonic vibrations - first thing to check and replace are the rubber mounts, and then tighten all the bolts connecting the body to the chassis.

Was this item checked by the workshop?

They re-torque all the bolts in every service but no effect on the vibration.

[superguy282]

Originally Posted by IP_Man

Lots of input
I will try to answer question asked.
IMP update: When fuel tank is full, vibration intensity reduces to the minimum. Could this is because of damping due to fuel weight? As fuel tank becomes empty vibration intensity increases. Or, is it something to do with fuel pressure?

It could very well be the fuel pump. Especially as you have mentioned that the vibrations aren't much when the car is in neutral and they also tone down when the tank is full. Now the things that need to be checked are, if there are more vibrations at the back of the car? If yes, the fuel pump itself may be vibrating.

If no, then maybe it isn't providing enough fuel to the engine and is defective.

[Turbanator]

Originally Posted by IP_Man

When fuel tank is full, vibration intensity reduces to the minimum. Could this is because of damping due to fuel weight?

This method of diagnosis is like shooting in the dark.

Try with one or two sand bags in the trunk. Also, check if it stays or goes when there are passengers in the rear seat!

[SS-Traveller]

Originally Posted by IP_Man

They re-torque all the bolts in every service but no effect on the vibration.

No, did they change the rubber body mounts before re-torquing?

Also, leave the rear hatch open and test, whether vibration goes away or not.

[landcruiser123]

Originally Posted by IP_Man

Engine mounts changed and torqued to correct specification made no difference to the vibrations.

I meant Body mounts. These hold the body to the chassis in a body-on-frame SUVs.