Help me understand my incident on Nordschleife

[fuscobal]

Hello guys,

I just came back from the Nurburgring trip and although it was a beautiful experience, it was not without incidents. A friend of mine with 1.8T had oil starvation and the oil pump sucked dirt from the bottom of the pan. From this he also blocked the turbocharger. For me, something very weird happened and I'm going to describe it on detail. On Saturday there were also no less than 10 incidents on the track. Here it goes :

- Thursday : In the 3rd lap, right after exiting the carousel, my "coolant agent" light came on so I had to slow down thinking my engine boiled and I had no coolant in the engine. I drove very slowly for 40secs when the light went off by itself and still managed a 9'20" (this would have been a 8'50" lap). In the parking lot, I opened the hood and saw my coolant was 2 thingers more than the maximum and I took out about 0.5L until it reached the maximum line.
- Friday : In the first lap, after exiting the carousel, in the wide left-corner that is not at all so difficult, the car suddenly pulled left towards the interior of the corner. With 4-5 seconds before, I was just changing 4th gear so at that momet I must have had like 160kmh. Before saying anything, let me tell you I didn't touch the kerb (my left wheels were at about 1m from the kerb) and I didn't brake (I was not at full gas either, just medium accelerating). When the car pulled left, I counter-steered but being so close to the kerb it touched it and the went to the right. I counter-steered again and made the back slide a little hitting the barrier with the rear-right corner and then with the front-right corner out of inertia. At the moment at the impact I don't think I had more than 40-50kmh so only the front and rear bumpers + headlight/stoplight were damaged. I quickly opened the hood and there was no cooling agent in the tank wich seemed strange being the engine lookedgood. Engine seemed to be ok and also the wheel alignment.
- After reaching the garage, I've put the Vag-com on the car and I had only one error : "ESP sensor G419 defective - intermittent" (ESP was off on the track). Unfortunately I erased the code by mistake instead of saving it.
- Going back in time for 2 month, I remember something similar happened when I was accelerating on a straight line. on the first lane. The car suddenly pulled right but at that time I was having about 80-100kmh so I managed to bring the car back. On the right side, the road was pretty dirty. After talking to some of my frinds, one of them had the same issue with his Cupra and he was pretty sure the LSD tricked him.

Possible causes from what I gathered until now :

- ESP/ABS sensors faulty or got tricked by the LSD/suspension/brakes
- LSD got tricked by a dirty spot on the left side of the track and the wheels spinned at different speeds
- Engine boiled because there was no cooling fluid left and this somehow influenced the wheels (less probable but still can't understand why I had no coolnt). The coolant tank was at the max position and that was the first lap on Friday so how could it dissapear so fast if not by boiling and going out as steam ?

The blue circle shows where it happened  >

[Richn83]

Was the coolant cold before you removed 0.5l, as the maximum line is based on cold fluid and if you removed hot or warm fluid then this would have contracted under cooling.

And I suppose that if the ESP had a fault it could have caused the front left brake to apply causing the car to Veer off at a funny angle (as even with the switch in the off position it will still intervene in extreme circumstances.

[fuscobal]

The coolant was warm when I removed it but I took this in consideration and I still left it at maximum position so when it was cold it would be over the minimum. When I entered the track the next day, the coolant was between the min and max position so nothi9ng to worry about. Another thing is, My coolant was pretty concentrated because of the heavy winter and my mechanic told me during summer it should be thinned with more water for a proper engine cooling. He said this could have caused those large variations in volume for the cooling fluid !

[RedRobin]

....

You mention "LSD" a number of times and so seem suspicious of it. Just to clarify, do you have a Quaife ATB differential installed? If so, when it comes into play, it's best to keep it in play with your throttle.

ESP off? - On the Nordschleife you're a braver man than I am! Having it on can be an intermittent nuisance but it might have saved you, or are you uber experienced with it off? I was strongly advised that if you want to drive the Nordschleife without ESP in an ESP equipped car you should learn by doing lots and lots of slooow laps and only build up faster laps very gradually. But that doesn't help your question what went wrong.

This incident must have cost you a pretty pfennig 

[QD MBE]

....

You mention "LSD" a number of times and so seem suspicious of it. Just to clarify, do you have a Quaife ATB differential installed? If so, when it comes into play, it's best to keep it in play with your throttle.

ESP off? - On the Nordschleife you're a braver man than I am! Having it on can be an intermittent nuisance but it might have saved you, or are you uber experienced with it off? I was strongly advised that if you want to drive the Nordschleife without ESP in an ESP equipped car you should learn by doing lots and lots of slooow laps and only build up faster laps very gradually. But that doesn't help your question what went wrong.

This incident must have cost you a pretty pfennig 

When my LSD was not playing the game correctly, it would snatch and was not nice to drive.  on the power violent twitches were frequent, hence my wish to 'have it fixed or removed'. 

have you been having problems with your LSD Fusco?

[RedRobin]

^^^^
Let's hope for Quaife's sake they didn't produce a bad batch.

Try testing the LSD in a safe wide open environment, Fusco? See if you can induce/reproduce the snatch.

[Nikiforos]

Maybe the problem is more simple than you think.
My theory is that when the car is under pressure(high temperatures),you might have coolant loss from a damaged coolant hose,
so the tires step on the coolant and loose grip.(thats why ESP seems fault)
When the engine get colder everything might seems ok.
So check all the coolant hoses and get some silicone ones .In hard track conditions,reliability is No1 for me

[danishmkvgti]

Maybe the problem is more simple than you think.
My theory is that when the car is under pressure(high temperatures),you might have coolant loss from a damaged coolant hose,
so the tires step on the coolant and loose grip.(thats why ESP seems fault)
When the engine get colder everything might seems ok.
So check all the coolant hoses and get some silicone ones .In hard track conditions,reliability is No1 for me

Sounds right in my ears 

[RedRobin]

So check all the coolant hoses and get some silicone ones .In hard track conditions,reliability is No1 for me

....Oh dear, another mod to add to my never ending list!

Good points you make, Niki  [Thinks: he must be a Greek]

[Richn83]

The coolant was warm when I removed it but I took this in consideration and I still left it at maximum position so when it was cold it would be over the minimum. When I entered the track the next day, the coolant was between the min and max position so nothi9ng to worry about. Another thing is, My coolant was pretty concentrated because of the heavy winter and my mechanic told me during summer it should be thinned with more water for a proper engine cooling. He said this could have caused those large variations in volume for the cooling fluid !

Ahh ok, so the mechanic is saying the higher concentration of coolant, will cause the variance of volume based on temperature to be more dramatic.

If what Nikiforos is saying were true would the sudden application of a single brake by ESP cause some unusual behaviour with the LSD? which could exacerbate the problem, I have no experience with LSD but if one wheel suddenly braked would it shove the power over to the other wheel so for example inside wheel breaks, LSD shoves power over to outside wheel, and this shove the car off in a funny direction?  Maybe with some torque steer chucked in for good measure?????

[Nikiforos]

So check all the coolant hoses and get some silicone ones .In hard track conditions,reliability is No1 for me

....Oh dear, another mod to add to my never ending list!

Good points you make, Niki   [Thinks: he must be a Greek]

Totally Greek

@RICHN83:
In the track or under very fast road conditions, the ESP might be off,because for example when  a wheel
get "on air"for a while, the esp ecu thinks that something is wrong and turns the esp off.
I have seen this with my previous car(Swift Sport)several times.
Because of the hard and sudden spinning of Fusco's GTI in the Ring, the ESP might diagnosed fault.
In my opinion it has nothing to do with the LSD which is 100% mechanic.The only problem is that it makes torque
tranfer more violent.

[tony_danza]

I'm voting wheel slipped, LSD counter'd by sending all power to other side and it skewed the car's direction.

Saw it at Oulton with a mate's car a while back, he lost the back on a right hander, he semi caught it by counter steering, it gripped the outside and speared him off into the outside barriers on the left.... non-LSD and it would have just oversteered around in a circle or hit the inside barrier.

[laurent.d]

Maybe the problem is more simple than you think.
My theory is that when the car is under pressure(high temperatures),you might have coolant loss from a damaged coolant hose,
so the tires step on the coolant and loose grip.(thats why ESP seems fault)
When the engine get colder everything might seems ok.
So check all the coolant hoses and get some silicone ones .In hard track conditions,reliability is No1 for me

Sounds right in my ears  

Yes! It's what I was thinking too.

....
ESP off? - On the Nordschleife you're a braver man than I am! Having it on can be an intermittent nuisance but it might have saved you, or are you uber experienced with it off? I was strongly advised that if you want to drive the Nordschleife without ESP in an ESP equipped car you should learn by doing lots and lots of slooow laps and only build up faster laps very gradually. But that doesn't help your question what went wrong.

For me, driving fast ESP ''on'' sound weird. First it will burn your brakes and it often react much too soon and not accurately. Or I should say driver réaction and ESP correction don't match together.   Or you drive, or électronic drives.
I always drive fast ESP OFF on the road or at the Ring.

I'm voting wheel slipped, LSD counter'd by sending all power to other side and it skewed the car's direction.

Saw it at Oulton with a mate's car a while back, he lost the back on a right hander, he semi caught it by counter steering, it gripped the outside and speared him off into the outside barriers on the left.... non-LSD and it would have just oversteered around in a circle or hit the inside barrier.

I don't have much experience with LSD as I have got mine since only 2500km, but even at the Ring I didn't experienced such violant reaction, that you loose the control of your car. Even with one front inner wheel in the air. It does steer into the curve when pushed hard and you have to manage the steering wheel, but not much.

[tony_danza]

Sadly all we can do is guess.

Can you take it somewhere safe and see if you can make it do the same again?

[Hurdy]

Possibly could be the steering alignment sensor

This could bring the ESP in when it shouldn't be really needed.

A mate of mine had this issue on his ED30 and all 4 wheels locked in his case and put him on the grass after a corner (not me, I hasten to add!)

Worth checking anyway, even if it is just to eliminate it as a possibility.