Mcfly Posted June 21, 2010 Report Share Posted June 21, 2010 Hi folks, apologies already, this could be a long one! Before getting my remap on saturday, I already knew my car needed a guibo/doughnut due to the good old lift off clunk, but that was the only evidence it needed replaced. Since the remap, my car has started to make a vibration similar to the rumble strip on the motorway, but only under very hard acceleration and normally only evident when in a high gear at low revs (about 1500 - 2000rpm). Accompanied by the vibration is a very very slight backing-off of the throttle, not enough to be jarring, but just enough to hear the turbo whistle going quiet momentarily. This backing-off lasts a split second and normally happens about 3 times till the revs pick up and then it's pull till the red line!! Although if you set off aggressively in every gear, you don't notice it at all. It almost feels like TC is taking over momentarily, but highly unlikely in 4th gear at 1500rpm!! My first thought was the guibo is taking an extra battering because of the extra torque but that doesn't explain the strange throttle behaviour. The vibration also changes frequency depending on road speed, i.e flooring her at 1500rpm in 5th will produce a higher frequency vibration than same revs in 3rd gear. I've tried turning the tc off by holding the button down for a few seconds, but the vibration is still there but albeit to a lesser degree, is it ever really off?? Is it possible that the torque is stretching the guibo more and more, making the car think the wheels are starting to slip therefore releasing the throttle? Anyone know how the tc system senses wheel slip anyway?? Another thing that may be relevant, since I've owned the car, sometimes I would notice a slight judder on idle, not too bad but just enough to be noticeable, the gearstick will shake slightly. My old derv mondeo apparently took the timing from the flywheel and she did the same thing at times, possibly this is a clutch/flywheel issue?? Already spoke to the remap guy and i am taking the car back to him for a look, but thought I'd ask you guys if you've encountered anything similar. IMO the additional torque is highlighting a problem I was oblivious to before. My head hurts!!!! Link to comment Share on other sites More sharing options...
hughes330d Posted June 21, 2010 Report Share Posted June 21, 2010 I`d be very interested to hear the out come of this. I have the same problem. I have been to what was ment to be a specialist, and they said they couldn`t find anything wrong. My thoughts were that it was caused by flywheel judder, which is common on remapped VAG`s. I had the same thing with a remapped A4. Although I havent remapped mine yet. Also, what fuel are you using? I found mine much improved by using BP. Link to comment Share on other sites More sharing options...
Mcfly Posted June 21, 2010 Author Report Share Posted June 21, 2010 I only ever use maxol diesel. My car was sitting about 4bhp over standard before the remap, and my brother in law was getting his 320d remapped at the same time was using supermarket low sulphur diesel and his car was under the standard power by 7bhp! Might try some BP next fill for a trial. Link to comment Share on other sites More sharing options...
Singh Posted June 22, 2010 Report Share Posted June 22, 2010 Can just the fuel really be signaled as the reason for an 11 bhp difference between two cars? I figured that in non-highly tuned motors, fuel would not have any really measureable difference in performance/power output. Especially since these are diesels. Anyone else had expereince of this? (sorry for the slight topic tangent here!) Link to comment Share on other sites More sharing options...
Mcfly Posted June 22, 2010 Author Report Share Posted June 22, 2010 Can just the fuel really be signaled as the reason for an 11 bhp difference between two cars? I figured that in non-highly tuned motors, fuel would not have any really measureable difference in performance/power output. Especially since these are diesels. Anyone else had expereince of this? (sorry for the slight topic tangent here!) The two cars were different models, mine is a 2001 330d and his is an E90 320d, but mine was putting out 4bhp more than the standard figure before the remap, but I had literally just changed the fuel and air filters so Id say she was running on full song, plus I am running an EGR bypass valve so this possibly contributed to the gain. His car is completely standard, and was producing 7bhp below the standard figure stated by BMW and the first thing the remap guy asked was "are you running low-sulphur diesel?", I think he sees this a lot. After the remap she was producing a fine 193bhp, possibly if his filters etc were changed he would find a few bhp more.. Link to comment Share on other sites More sharing options...
Mcfly Posted June 22, 2010 Author Report Share Posted June 22, 2010 I`d be very interested to hear the out come of this. I have the same problem. I have been to what was ment to be a specialist, and they said they couldn`t find anything wrong. My thoughts were that it was caused by flywheel judder, which is common on remapped VAG`s. I had the same thing with a remapped A4. Although I havent remapped mine yet. Also, what fuel are you using? I found mine much improved by using BP. Just a quick follow-up.. Called in with the remap guy again today and he has a trained BMW mechanic working full time for him...handy! Took him a run in my car and wouldnt you believe it.... completely silent!! At last I got it to make the noise and the backing-off. He seems to have seen this many times before on modified and standard cars, we already knew about the 'clunk' on lift-off which is the doughnut (I looked at the doughnut last night and you can actually turn it round partially by hand - so its truly fubar'd!). The 'rumble-strip' like vibration is seemingly the driveshaft centre bearing, this failure is apparently brought-on by the dead doughnut, and can come and go depending on the position of the dodgy doughnut! He suggests sorting them both at the same time. Also he did say the bearing hanger which bolts to the underside of the floor is basically steel-on-steel, meaning any vibrations are transmitted straight up through the floor. He says when re-fitting the hanger should be mounted on a small piece of rubber sheet to act as a shock absorber. The throttle backing-off is a safety measure of the turbo, he says its more common in tuned cars, but says his mates standard 184bhp does the exact same thing. Im going to replace both bits and see what happens Link to comment Share on other sites More sharing options...
hughes330d Posted June 23, 2010 Report Share Posted June 23, 2010 I must get mine up to them to get it sorted. Thanks Link to comment Share on other sites More sharing options...
