slipping clutch?

[Aussie-Ben]

hi guys,

I have a question about clutches, i was driving back on a long drive and i felt that my 2001 vrs was reving smooth but then around 3000rpm it would sit for a second as the engine caught up (like it had been slipping slightly)

a few times it would creep faster to 4000rpm and if i backed off a tad it jumped back down to 3000rmp on the tacho (i assume highly its the clutch as the engine did not sound like it droped 1000rpm) more likly in the higher gears also. however fine in the revs over 4000 - no slip

Question is, would it most likly happen around 3000 rpm? is this the peak torque or atleast a sharp change in torque?

and roughly how many miles do you get out of your clutch, my car has 43,000 miles however driven semi tame, and the owner prior was a older gent that looked to have looked after it and drove it kind.

I guess i will have to book it in for a service/clutch sooner than latter

[TeflonTom]

i would expect to get nearly double that milage from a clutch.

[Aussie-Ben]

yeah i was thinking it was a tad to fast! however my other cars despite having similar power, where much lighter and i thought maybe this was a factor.

My miles are also mostly on the motor way, so it seems very strange however in 5th gear if i put my foot down at 3000 rpm it seems to slip slighty

again only around the 3000-4000 area

Normally however when i had a clutch slip it would slip and not grip unless i backed right off the power
This one however seems to climb to say 4000rpm and with the foot still flat, it will sit on 4000 for a seconds or so then continue to climb, or it may even drop back a bit then continue to climb.

I wasnt sure if it was some fancy computer controlled ignition thing or now, I did however use some premium fuel that was marketed at ferarri made fuel (it was all they had)

maybe i will try again on the next tank with normal prem fuel.

I have a huge road trip coming up and would be in trouble if it plays up or fails then (4 people in the car with bags, for 2 weeks)

[TeflonTom]

have you had the fault code read off of it yet?? if any??

[Aussie-Ben]

Ok i got around to looking at the fault codes and there was none.

so i guess its a mechanical reason, and not a electronics/controlled issue

do you get a fault code if it pings?

[TeflonTom]

Originally Posted by Aussie-Ben

do you get a fault code if it pings?

i'm not sure on that one.... it depends which ecu it has?? if it's got a octane coding sensor it will (i think??)

that's what the knock sensor is for anyway, to retard the ignition timing before it starts pinking...

my guess is that if you are getting ping then it is because it's overboosting or because the quality of the fuel is a bit dodgey.

[Lummox]

Originally Posted by TeflonTom

that's what the knock sensor is for anyway, to retard the ignition timing before it starts pinking...

It needs to pink first so the knock sensor knows something needs adjusting, much like ABS needs to lock up to know to release.

[TeflonTom]

Originally Posted by Lummox

It needs to pink first so the knock sensor knows something needs adjusting, much like ABS needs to lock up to know to release.

i was under the impression (after seeing it on the screen of an oscilloscope) that it doesn't actaully have to pink to make it retard the timing..... well not on the magnetti marelli ecu's anyway... not sure about the bosch ones tho ..... i think what it does is kind of has a set threshold of 'allowable pinkyness' which it wont go over.... all the knock sensor does is sense vibration in the engine block and compares it to the signal from the crank sensor, and if they occur at different times to each other it pulls back the ignition timing untill both signals are the same

[Aussie-Ben]

i dont think..... infact i am sure its not ping

i used to run a jap motor in a modified car (engine swap) and runnin on standard fuel it would ping and its a feeling of total loss of power and revs drop, this however is a rise in revs then hold and continue to climb or it drops back....seamingly as the clutch re-grips

the fact it regrips is the bit that i find strange, normally once they slipped it would never re grip untill the power was removed


also i thought the knock sensors worked via looking for high frequency vibration as present in a ping and then adjusted the timig back rather than being predictive, thats only based on my past engine that were older efi jap motors

[TeflonTom]

Originally Posted by Aussie-Ben

, this however is a rise in revs then hold and continue to climb or it drops back....seamingly as the clutch re-grips

it might be a problem with the clutch slave cylinder.... or it might just need bleeding

[Aussie-Ben]

just thought i would update for the guys that were helping me

I took it to the shop and it needed a new clutch and flywheel (dual mass) grrr

£645 fitted, very much upset about it all since its only 43,000 miles
however this should see out the car i hope, and either way i will have the time to get myself setup and able to change it myself next time - non dual mass next time

on the good side, the gear box feels much better and its driving like a dream now

thanks for all the help posters

[TeflonTom]