Vibration under heavy acceleration 65 - 80mph

[benczuk]

Went away at the weekend and found a heavy vibration though the steering wheel in 5th when on full acceleration (cruise control resume etc) between about 65 and 80mph. Not noticed it before though the car was loaded up with luggage and a bike rack on the back.

I currently have a DieselExpress boost box fitted (came with the car, thought I would try it out) which supposedly bumps the torque to 370 and 160bhp and searching here indicates that others who have remapped have seen roughly the same thing.

My question is does this sound like DMF failure or anything else I should be worried about?

[plod]

My initial reaction is to say DMF, but i'm sure someone more in the know will come along shortly

[rwb]

I thought the consensus was that these tuning boxes are a bad idea?
E.g.,
Diesel Tuning box (Van Aaken)
Diesel performance chip.....Anyone tried one?

[highlander]

Regardless of whether or not they're a good idea, we're told that they are going to be outlawed in the next revision of the MOT regulations (starting in January?)

Piggy-back ECU mods will be classed as MOT failures

ECU remaps cannot be easily detected and cannot be classed as MOT failures

ECU remaps are typically better-suited to the vehicle they are applied to, particularly if they are performed by a competent tuning house, customized to your specific car.

[Doggy]

Mine does something similar, if you accelerate hard in 4th or 5th below about 2200 RPM & has recently sowed signs of doing it in 3rd. This is with the 180 bhp / 400 Nm remap. It doesn''t do it at all with the standard ecu map.

I don't know what it is, but lots of things it's not, (mountings, driveshafts & the like). My suspicion is it's the rubber element in the DMF being compressed to the point where there's no 'give' in it anymore, hence it transmits all the vibration it would otherwise isolate you from. It's also likley the engine vibrates when generating considerably more torque than it was intended to, much like a small petrol engine straining at low revs.

The accelerator's not an on/off switch - I just feed it in gradually. With the remap it pulls hard all the way to the red line, so you can adapt your driving style to suit easiy enough.

[Welly]

I believe this vibration is linked to engine power, the engine mountings get squished so much that they begin to 'chatter' under the load and transmit this to the cabin. The standard mounts are barely fit for the standard car as they are......

My 'high powered' petrol engine does this a bit and research has pointed me in the direction of a revised/uprated rear lower engine mount (fit for a Focus RS nonetheless) and something I have now ready for fitting

[benczuk]

Thanks Guys,

Just unplugged the box and taken it for a run on standard power. Granted it was not loaded up but there was no signs of the vibration at any speed / revs / gear.

One thing I can tell you though is that the box makes a hell of a lot of difference to throttle response. You don't notice it that much when you first plug it in, but unplug it after using it for a few thousand miles and you really notice the difference. You can hear the turbo wind up and you just sit there thinking "ok so where is the kick in the pants?"

The accelerator's not an on/off switch

The cruise control pause button is pretty much an on/off switch hence why I noticed it!

[Bailes1992]

Steering vibration won't be the DMF.
If it's only under acceleration I'd be keen to say it is a driveshaft issue. Look for play in the driveshafts between the CV joints, split CV boots etc.

Things that can generally cause a steering vibration...
Buckled wheels,
Unbalenced tyre,
Flat spot on a tyre,
Buckled brake disc,
Worn Track Rods,
Worn Track rod ends,
Worn bushes,
Worn Ball joints,
Worn Top mounts
and as Suggested, the driveshafts.

Loose and worn engine mounts can cause vibration but very rare.

[john170277]

i hgave the same problem with mine put 2 new drive shafts on but made no difference my next job is new discs and pads and then maybe a new wheel bearing

[Doggy]

Just unplugged the box and taken it for a run on standard power. Granted it was not loaded up but there was no signs of the vibration at any speed / revs / gear.

One thing I can tell you though is that the box makes a hell of a lot of difference to throttle response. You don't notice it that much when you first plug it in, but unplug it after using it for a few thousand miles and you really notice the difference. You can hear the turbo wind up and you just sit there thinking "ok so where is the kick in the pants?"

Did you not try the remap ben? (it might be a bit more progressive).

The accelerator's not an on/off switch

The cruise control pause button is pretty much an on/off switch hence why I noticed it!

Yes, I tend to do most of my accelerating back up to cruising speed with the pedal as resume seems to give you about 3/4 full throttle. A bout of 5th gear wheelspin on an unfamiliar dual carriageway one stormy night convinced me this was a good idea.......

I believe this vibration is linked to engine power, the engine mountings get squished so much that they begin to 'chatter' under the load and transmit this to the cabin. The standard mounts are barely fit for the standard car as they are......

My 'high powered' petrol engine does this a bit and research has pointed me in the direction of a revised/uprated rear lower engine mount (fit for a Focus RS nonetheless) and something I have now ready for fitting

Now that's an interesting thought - during my recent search for vibrations, (which turned out to be dodgy injectors), I thoroughly checked all the mountings etc to see if any were responsible for transmitting vibration at idle and could not fault any of them. Clearly this doesn't prove one of the blighters isn't becoming 'solid' under maximum torque.

I'll have a think about how to prove that one. (I'm loathe to change the bottom mount if it isn't essential, in my experience, disturbing a driveshaft also gets you a hub bearing failure within 6 months).

[benczuk]

I'd be keen to say it is a driveshaft issue. Look for play in the driveshafts between the CV joints, split CV boots etc.

I did consider this, but I would have expected something out of balance to cause vibration all the time at a certain speed range, not just when under heavy acceleration.

Did you not try the remap ben? (it might be a bit more progressive).

Nah, I chickened out at the time. The stuff I had read indicated that you should have a hardware and software version match before flashing which the 180 file didn't. I was also dealing with a rather bodged BSI / ECU fix by the previous owner which eventually required me to fork out for a "new" ECU. Having just spent that money didn't want to brick it

[Doggy]

Shame.

(I was kinda wondering what a remap + tuning box might be like).

[Bailes1992]

I'd be keen to say it is a driveshaft issue. Look for play in the driveshafts between the CV joints, split CV boots etc.

I did consider this, but I would have expected something out of balance to cause vibration all the time at a certain speed range, not just when under heavy acceleration.

Did you not try the remap ben? (it might be a bit more progressive).

Nah, I chickened out at the time. The stuff I had read indicated that you should have a hardware and software version match before flashing which the 180 file didn't. I was also dealing with a rather bodged BSI / ECU fix by the previous owner which eventually required me to fork out for a "new" ECU. Having just spent that money didn't want to brick it

My 406 with a inner driveshaft issue used to shake when I let go of the accelerator or applied full throttle.
If you think the power the engine makes isn't 'smooth' it's a large jolt on every combustion cycle. This will cause any play in the drivshaft to show.

[Bigcol]

I had a 350bhp (stage 4 remap) Saab 9000 Aero a few years back, i had poly engine mounts fitted to cope with the extra oomph!!
I loved that car!!