rumbling sound on acceleration

[Nice But]

Just been to collect my new wheels and didn't have the iPod in the car so no sounds just the engine........ Mmmmmm lovely, but the one thing I noticed at 50 in 5th (auto) when I step on the gas - not stomp - i noticed what I can only be describe as a rumble, can't feel anything just hear, seems to be coming from behind me, so I'm guessing it's not the box.......

Something to do with AYC or transfer box? Dunno, so this is why I am asking the combined knowledge of our superb Club. No lights anywhere on the dash, kickdown is all ok........just a rumble. I had a look at the AYC res the other day and it was slightly less than half way. :inquisiti :inquisiti

Thanks in advance all.

[Robotnik123]

It could have been the AYC - did you see the AYC lights activate? The AYC can come on even when going straight if your tyres are mismatched. If not, probably transfer box.


Just been to collect my new wheels and didn't have the iPod in the car so no sounds just the engine........ Mmmmmm lovely, but the one thing I noticed at 50 in 5th (auto) when I step on the gas - not stomp - i noticed what I can only be describe as a rumble, can't feel anything just hear, seems to be coming from behind me, so I'm guessing it's not the box.......

Something to do with AYC or transfer box? Dunno, so this is why I am asking the combined knowledge of our superb Club. No lights anywhere on the dash, kickdown is all ok........just a rumble. I had a look at the AYC res the other day and it was slightly less than half way. :inquisiti :inquisiti

Thanks in advance all.

[Nick Mann]

Not something I can imagine in mine. The only rumble I get from behind is the exhaust, or disgruntled passengers! /pan

The AYC is the obvious choice. Possibly the propshaft or a bearing? The transfer box is just in front and to the left of your left foot, so that seems like the wrong area.

[Nice But]

Defo no AYC lights...... all new tyres all round, strange it doesn't do it when pulling away normally though....... just on acceleration from 50-55 ish up to 80ish then I can't hear it anyway....

[Beastlee]

I get exactly the same thing and 3000miles later nothing seems any worse. I'm guessing based on my experiments with the right foot that it's a resonance in the exhaust. Releasing or pressing the accelerator seems to stop it happenning but just maintaining constant speed keeps it rumbling along.
Please don't tell me it's something expensive!

[psbarham]

check the propshaft centre bearing, it tends to get messy if that fails

[Beastlee]

is it expensive to replace?

[Nice But]

I get exactly the same thing and 3000miles later nothing seems any worse. I'm guessing based on my experiments with the right foot that it's a resonance in the exhaust. Releasing or pressing the accelerator seems to stop it happenning but just maintaining constant speed keeps it rumbling along.


So that must be a feature........ I think your right, as I experience no vibration or anything feeling untoward, is your at about 50 through to 60 then starts to dissapear?...... the guys at the tyre place did say " jeez if any of those heat sheilds come loose you'll have vibe city" I think the exhaust is a good place to start. I'm getting a custom one made in a couple of weeks so that can remove that variable.


check the propshaft centre bearing, it tends to get messy if that fails

I had one go on a transit at 70....... yep it was interesting, and bloody noisy. I don't think it's that as I'm getting no vibes or anything, but will have a look before I go off down to Devon on sat.

Thanks all for the suggestions guys.

[Beastlee]

Yep about 50-60 so I just travel about 70 instead....unless it's the Autobahn then its 100+ and definitely no vibrations all the way to about 135.

[Nice But]

That's it then it must be a feature installed by Mitsi.......happy now/thankyou this is my 1st 4wd car, so any curious noises make me wonder...... I get the occassional pump sounds from the AYC which keeps me happy as I know it's working.

Now all I need to do is get rid of the horrible brake vibration and put my new Enkies on /rally

Thanks again Beastlee it has put my mind at rest......:pimp2:

[Beastlee]

I don't get the AYC pump noises but do suffer with wobbly brakes despite them being new all round when I bought the car in September.

I hope I'm right about the rumble but I've not worried about it much anyway.

[Nick Mann]

It's easy to add wobble to brakes on a heavy, automatic, powerful car. The "distortion" is almost always due to coming to a stop and keeping your foot on the brake. The hot pad stays in contact with the disc, which either leaves pad on the disc, or worse, heat treats the steel in that one area.

The golden rule is take your foot off the brake when you stop - and use the handbrake. If you have been caning it, then try and drive slowly for a few minutes to let everything cool down whilst the wheels are still rotating.

[Nice But]

Your right, I do do that..../pan another thing for my feeble aging brain to remember, I can see the dash being covered in post it's....... trying to remember to let the engine spin over when i get on the drive for 30 seconds is the other one......... and I can't fit a turbo timer with a Toad...... unless I rewire it all...... not going there :inquisiti


Beastlee your describing exactly the sound I get, so as far as I'm concerned it's normal.

[Beastlee]

Nick, I nearly always use the handbrake, Heidi telle me off for letting it on and off to crawl at the lights instead of stop starting on the footbrake. I know it's naughty but it saves the footbrake!

[Turbo_Steve]

Or just put in in P when you come to a 'long' stop, and let off the brake?

[Turbo_Steve]

Exact same noise here, and seems to come from the back of the car. I've just been assuming it was something associated with AYC and that "They all do that sir" or that my next AYC fluid change was going to end in tears. It's a very specific speed & power level that seems to set it off, so I think it's just one of those things.

[Nice But]

Steve...it does seem that way, a Mitsi 'Feature' now thats 3 of us so I'm not worried about it.......

I'm having a new custom exhaust fitted on the 29th so will see if it does it after that..... I'll drop a post on here.

[Nick Mann]

I'm having a new custom exhaust fitted on the 29th so will see if it does it after that.....
Or see if you can still hear it, anyway! /pan


Or just put in in P when you come to a 'long' stop, and let off the brake?
Yes, but many people also say that the shunt you get in and out of Drive is bad for the TC, which is a whole lot more expensive than the brakes? Maybe a good solution for certain occaisons, especially track days, but on the whole the handbrake is probably the better option.

[Beastlee]

Nick, I agree with your comments there. I hate mine and the way it clunks back into gear. In Germany yuo have to be fast off the line too or the Germans complain at you taking too long (less than a second after green) so the time taken to shift backt to first is wasted.
Incidentally the lights here change more often as you don't have a pedestrian stage in the sequence so waits times don't normally justify the change to park.

[Turbo_Steve]

Fair enough...have to confess I don't drive ours during the day much, so traffic isn't really a problem.

If you KEEP warping the brakes, I can only think of two suggestions:
1) The VR4 doesn't have cooling ducts from the front of the car. This strikes me as a massive oversight.
2) Ceramic disks & carbon pads! :D :D :D Ouch..ouch...wallet cramp ouch.

[Ryan]

Or just put in in P when you come to a 'long' stop, and let off the brake?

I wouldn't recommend doing that on any sort of incline.

[Turbo_Steve]

Why? You're not using it to stop the car, just to hold it?

[Nick Mann]

Putting the car in P sticks a big tooth into a notched ring in the gearbox. Don't select P whilst moving!! /pan /duh

But it should hold the car better than the handbrake in a VR4, although the car may roll slightly one way or the other as the toothfinds the end of the notch.

[Beastlee]

I had mine up on a ramp today to do the oil change and, as it was the first time since I bought it, I did a full check of the rest of it whilst up there. The only thing of note on the propshaft was that the rubber ring at the midpoint was a little perished. There was no obvious play in anything either so I'm still happy.
The bald inner edge of the driver's front tyre was more worrying though, don't want a new set of tyres yet they still have 4mm+ on the rest!