Car in question 6n2 1.4 8v MPI 70k.

Looking for some ideas as to what this could be....!

When accelerating relatively fast, and usually when i reach about 3000rpm there is a shuddering/vibration coming through the whole car, not just steering wheel or wheels or similar.

Everything is tight under the car, had it up on the ramp and wheels have all been checked for balancing issues....not problems found. Car has oil, is due a service but has had no issues.

The problem initially started on a journey about 20 mins in....and it just suddenly sounded like it was running on 3 cylinders....and when the car is idling its fine, no shudder. What i suppose i'm trying to say is that it didnt come on gradually, it just started mid journey.

Bent driveshaft has been suggested but we reckon it isnt this as nothing has happened to cause it to be bent and it also doesnt tie in with the shudder just happening out of the blue.

Have still to try cleaning the Throttle Body too as its been suggested.

Help?!!!

So it's happening when accelerating under load... sounds to me like an ignition component breaking down.

This would give you a misfire or a shudder as you described it. Have you tried replacing your plugs/leads/coilpack?

Would those things tie in with what you're saying?

got the mechanic sitting next to me that checked it today and he says its not a misfire, no lack of power.

more of a mechnical judder rather than an electrical misfire.

Honestly the strangest vibrating/thumping/shudder/knocking noise weve all heard!

I am very much hoping its not gearbox related...

What condition are the engine mounts in? could it be the exhaust touching something and resonating when you get to a certain speed/rpm?

exhaust all good...too big a vibration/shudder to be that.

Engine mounts is more likely to be when I take my foot off the accelerator...very much doubt it as its not that kinda noise!

Any thoughts on if it could be gearbox related??

gearbox faults are usually more of a whine than a shudder though and wouldn't really cause a massive vibration.

Nothing's wobbling or feels loose? and it's quite a heavy vibration you say? I had that when i had an engine mount fail.

would that not be more of a thud though when changing gear or changing down gears?? just doesnt seem to tie in, but i guess thats easy enough to have a look at and diagnose

Have a look at the engine mounts, also, when the car's not moving and you rev it, do you get the same shudder/vibration?

thought of that earlier on but haven't actually tried it yet....if it did what would that suggest??

Well it'd rule out the gearbox for a start if your clutch was pressed in :)

Also, I still think it's a misfire, lol. Has it ever had the plugs and leads changed?

nope its going in for a full service next week and its due a plugs and leads change....we're pretty sure its not a misfire haha....poor guy next to me is crippled over saying "its not a misfiiiiiiire!!" lol!!

just gonna nip outside and see what it does in neutral

if it's a misfire will the "mechanic" do a forfeit? lol :)

Actually if he's that sure it's not a misfire, tell him to hold the leads in his hands whilst you rev the car... then we'll see how confident he is in his diagnosis :) if he's right, he'll be fine... if he's wrong he'll get a nice little electric shock! lol.

Doesnt happen when just sitting in the drive in neutral!

when i put the clutch in it definitely gets better, we're not sure if it definitely disappears completely or it just gets a LOT better...

he says..... if it was a misfire he wouldnt get an electric shock as it wouldnt be firing! lol

we're pretty damn certain its not a misfire.....! runs like normal when idling over no hunting or anything like that

could be a worn clutch plate, what does your mechanic friend think to that diagnosis? does he concur?

he does indeed.....

Hopefully another mystery solved :)

Ah well, glad to of been some help

I have stopped using clubpolo as i never found anyone to be helpful!

Boycotted thats for sure.

Well I'm glad to know theres one helpful person on here, so thanks for your help :)

Hopefully you'll get the new clutch put in and it'll be alright. 70k for a clutch is about right with a woman driving it I suppose :p

Haha :p thanks again

A couple of other suggestions to try, admittedly not common faults, but worth checking: 1) Is the end float on the crankshaft excessive? 2) If you take out the clutch and don't really find a problem with it, it could pay to check the flywheel run-out (and even that the flywheel is tight!)

Regards.

slight thread hijack (hope you don't mind dubbin*) but mine sometimes does the same shuddering/vibration with the brake pedal under heavy braking :/

Edited 20 December, 201015 yr by Joe_90

That's probably a warped disk Joe...

hey dudes

thanks for the replies...

today's update took it back down to the garage and had a look at other things people suggested - engine mounts, exhaust, cv joint gearbox/diff and all seemed to be good.

Jacked the car up on one side, put it in gear and put the foot on the accelerator to see what was happening and it was really bad...car shuddering quite a lot! Jacked it up on the other and it wasnt happening....or wasnt happening anywhere near as bad!!

So the driveshaft nuts were all tight but noticed that the end that sits tight to the gearbox wasnt running true the whole way round i.e bigger gap from the end of the shaft to the gearbox at some parts compared to others....we're talking mm's here though. (not had any problems with this driveshaft after it being fitted in july) So he took the driveshaft off and put it back on to see if everything was straight - no bent bolts and to make sure it hadnt for some reason moved :uhm:

but no noise still continued....!! Think a new driveshaft must be on the cards though to sort out the mm difference round the end.....but does this help diagnose with whats happening??

That's probably a warped disk Joe...

thanks, thought it might be that. Odd that its not happened for a while though considering that cause.