Engine rev but no traction?

[ang12el]

Think I know the answer but just had my engine remapped and gone from 16 - 18" rims now when my accelerator is pressed beyond 3/4 way down the fuel is dumped into the engine and the rev counter shoots up but f all happens in the car .. ie it doesnt accelerate it just stays at the same speed .. the ESP light doesnt come on .. so whats the deal ? Is it due to crappy tyres I have on the wheels or is there something more worrying happening.

I didnt have this issue when the 16s where on it but seeing as the wheels dont spin I dont know what the problem is .. engine sounds as though it has just been reved in netural.

 

[quattrojames]

When you say the rev counter shoots up, I take it the actual engine speed increases accordingly? If so assuming you are definately getting no wheelspin then it sounds like your clutch is slipping.

 

[ang12el]

Thanks for the reply - I agree with you to a certain point. However why didnt I notice it on the 16" alloys and why is it that it happens at@ 3000rpm and not at low revs. Is this due to the extra torque being put on the clutch ? As you say the symptoms sound like the clutch just a bit confused as to why it is happening now . sorry if this sounds a daft question by the way ..

 

[quattrojames]

I would think the clutch slip is as a result of the increased torgue from the remap rather than the increase in wheel diameter.

Did you get both done at the same time?

 

[ang12el]

No I got the remap done and things were fine as far as I noticed but now with the larger wheels the problem has become apparent very quickly.

 

[ScottyP45]

it takes a LOT more force to spin an 18" rim than a 16" rim, the extra force required is breaking the grip of the pressure plate in the clutch I reckon mate.

To test the clutch - pull the handbrake on solid, press the brake and hold it, clutch, select second, keeping the brake on - use your right heel to rev the engine and let the clutch in smoothly but smartly. It should stall if the clutch is good even with revs, if its ****** it will slip immediately, and since its stationary that eliminates the wheels as being the sole cause of the problem.

You dont say which model you have but if its a tdi then your clutch will be the first to go as soon as you get a remap, as the standard clutch isnt that tough and a remap puts you way over its torque limit.

 

[quattrojames]

No I got the remap done and things were fine as far as I noticed but now with the larger wheels the problem has become apparent very quickly.

Sorry I got the impression from your first post you had got both done together. My bad.

it takes a LOT more force to spin an 18" rim than a 16" rim, the extra force required is breaking the grip of the pressure plate in the clutch I reckon mate.

 

[ang12el]

Thanks for the replies peeps - Ok so if its over the torque limit as it is a TDI does that mean I have to go for a better clutch (one that is more up to the task?) wasnt mentioned when looked for side effects of remap :sign_omg:

 

[ScottyP45]

try the slip test i mentioned earlier first to confirm it is the clutch, but a lot of guys with tdi's in all makes (bmw, audi, alfa etc) have had to uprate the clutch to the next stage up after a remap as the torque increase is huge and the standard clutch is only rated just beyond standard torque figures when new, if its a bit worn it won't hold more than it was originally intended to and will slip much easier.

Usually the worst case for a remapped tdi clutch is the low down grunt from say 2k in a high gear......turning the ESP off might alleviate the clutch slip in favour of wheel spin but if its gone already it will just get worse, and with bigger rims the chance of wheel spin is even less so the clutch is getting asked to work harder.

A mate with a scooby that was juiced up to 300bhp used to do 6k starts at Knockhill race track, had monster wheelspin even in an AWD, so he fitted bigger rims and high-grip soft compound racing tyres, stopped the wheelspin, so then he started burning out clutches constantly.....he uprated the clutch, then the force had to go elsewhere and it broke the gearbox! He then fitted a race spec gearbox, so it started snapping driveshaft couplings. Now obviously thats an extreme use, but shows how the forces are transferred to the next weakest component, in your case the clutch.

 

[Siena]

Mapped TDI's will definitely develop an unhealthy appetite for clutches.

In extreme cases, dual mass flywheels have been known to fail.
I've got a client with a 2004 Passat TDI 130 - it's had a lot of work, bigger injectors, FMIC, larger turbo and remap.

Last figures were 192ps / 298ft-lbs.

It was recovered to me last Tuesday, upon stripdown, I discovered the DM flywheel had failed. Both parts were freewheeling within each other.

I have fitted a custom SM lightweight item - oddly enough, the clutch was fine, but for the work involved, it made sense to fit an uprated one.

I have tried to break it, I did punish her hard, with my client beside me, but try as I could, she gripped.

It'll take a lot to break this set-up.

 

[ScottyP45]

oh yeah, I forgot about the DM flywheel.....hmmm....thats the other possibility which can only be determined by a stripdown

 

[ang12el]

Well thanks for the update peeps - got a price for replacment clutch from local Audi specalist repair centre Cost of a standard clutch is £300 fitted - however f me the price of the fly wheel is 232+ vat - whats it made of titanium!

All in all they can do it for £500 providing it needs a flywheel .. Thing is do I go for the standard rated clutch or ask for a more robust version.. if there is one available .. I only have a 100BHP engine that was remapped and is now 136..

Thanks for looking in

 

[Siena]

I can supply you with a light weight, single-mass flywheel for £240 inclusive.

Not stupidly light, but @ 7,2 kilos, about 8 kilos lighter than stock.

It's also a steel item, I don'n subscribe to the aluminium ones, with a steel friction surface riveted to the aluminium faces.

I can also supply a matching uprated clutch.

 

[Siena]

136PS may not sound much, it's the torque that's a killer.