revs drop on clutch slip?

[mark21]

hi, experienceing clutch slip after remap, esp in 3rd and 4th from 2k to 3.5k. i know this is a talked about topic but my quiery is that when i do boot it and the clutch seems to slip, the revs either stay at the given figure on the rev meter they are on or they drop a little bit and hoverup and down slightly. abit like when you boot an automatic. acceleration decreases during this but dusnt completley drop. i thought when a clutch slipped the acceleration decreases as the revs raise quicker????? any suggestions or advice?

thanks

 

[Muttley]

What you describe isn't clutch slip. Clutch slip is where the engine gets faster but the car doesn't.

What you describe sounds a bit like loss of boost. What do you do to provoke this behaviour, and how does the car behave afterwards? Does it pick up again and eventually accelerate?

 

[mark21]

thats what i thought but i had a friend in whos a mechanic as a passenger and he suggested clutch slip. im baffled. it started bout a wk ago. usually happend when the car was cold. 1st and 2nd seem fine. put it in 3rd or 4th with 2k revs and floor it it goes to accelerate and puts you back in the seat then next second the pull dies then starts and stops. if i was to describe the feel it would be like i was accelerating over dry road then a patch of ice then dry then ice. as for the revs it builds then hovers around 2k then flutters to 2.5k hovers then to 3k. once 3.5/4k is reached theres no problem. the speed increases during this palarvor but not as quick as when it was working fine. if i keep flooring it the revs do eventually reach the limiter then i change up. it only happens when im full throttle in 3rd, 4th, 5th and 6th from 2k to 3.5k revs. the speed does increase (but at a slower rate then usual) but its weird cos when i look at the revs hover and not increase with the speed i wounder where the powers comming from. i thought it was a safty device at first which stops you blowing the engine by to much hard driving.

 

[cupra-rich]

sounds very similar to what my car is doing. what car you got? need more idea's on what might be causing this?

 

[mark21]

its a leon cupra tdi 150bhp. got it remapped to 188bhp and 278 torque. the revs seem to act normal under boost then its as the the needle flicks up 1k revs then bobs up and down a little and stays at a given range then increases. speed does raise but not as harsh as when this isnt happening. my mate thinks its early signs of clutch slip but i just dont understand why the revs hover like an automatic whilst the speed increases.

 

[cupra-rich]

same car as me,remapped too.sounds like the same problem? hopefully having it vagcom this weekend might shed some light on it.will let you know if we find anything mate.

 

[Muttley]

Hmm. Remapped car, and the problem occurs when you're demanding a lot of power. A shot in the dark, but it might be the EGR valve? Although when this sticks it usually results in limp mode, maybe it's just being a bit slow to close? Don't know how you'd test it other than by disconnecting the electrical connector to the N18 valve, the EGR control valve. You'd get the engine warning light to come on while it was disconnected.

 

[mark21]

thanks guys, i wouldnt have a clue where to start with disconecting the valve you mention. its due a service soon so i might get it looked at then. will look forward to your news victor... if it is the clutch would ppl recommend the sach (think thats how you spell it) clutch and what else needs replacing or upgrading whilst the engines in bits? iv got a warrenty but wudnt know if theyd honor a heavier duty clutch. might have to pay for it myself but get them to cover the cost of the job (if im lucky!)

 

[Carcrazy]

Due to clutch slip only your engine is consider to go faster instead of the car. This is usually happening when the car is cold.

 

[mark21]

there is a loss off acceleration as soon as the revs seem to loose their uniform raise rate and "let go" and raise quicker but as they hover and bob around the car begins to accelerate again (no where near the proper rate tho) the revs act feel and sound like an auto during this hesitaion phase. this happens when the cars warm now. im starting to think its clutch slip as now that its worse its acting like the problems associated with clutch slip.

 

[geoffrodriguez]

My FR 150 does something very similar to this at around the same rev range, but it's got me stumped. It can't be clutch slip.

 

[cupra-rich]

well had the car vagcom'd no faults showing,so mechanic took it for a drive, definitely clutch slipping, says theres no need to uprate clutch just stick with oem?

 

[geoffrodriguez]

Blimey. But you definately need a new one? How much do you reckon it'll cost?

 

[muddyboots]

put it in 3rd or 4th with 2k revs and floor it it goes to accelerate and puts you back in the seat then next second the pull dies then starts and stops. if i was to describe the feel it would be like i was accelerating over dry road then a patch of ice then dry then ice. as for the revs it builds then hovers around 2k then flutters to 2.5k hovers then to 3k. once 3.5/4k is reached theres no problem.

The starting/stopping doesn't sound like clutch slip to me.

My money is on an EGR valve or MAF/MAP sensor problem.