Valve Replaced

[Witchfinder]

I had the N75 valve replaced today. Claybank Skoda did the other valve whilst they were at it, too.

The car is definately smoother. The surge/dropoff around 3000 RPM from the Jabba remap has gone. However, the rawness of the power delivery has also gone.

It still feels faster, although not as fast as it was. I'd be interested to get it back on the rollers and see what the curves look like now!

[DGW]

Rob, do you happen to know if the N75 was replaced with the same version?

[Witchfinder]

Good question, I never thought to ask! Do Skoda supply different ones?

[SkodiRS]

Probably replaced with the standard C version(?). Skoda probably won't have a different one but you can definately get a different veriosn from Audi.

I'm running a J and there is definite increase in response. However this really needs remapping because of the different (N75 valve characteristics.

May change back to standard once I've fitted the Milltek down-pipe and sports cat.

Decision, decisions..............

As a side point......will probably arrange a rolling road session sometime in the new year if there's enough interest.

[PaulAlex]

Hi guys,

I know this has been discussed in the past, but is it worth me upgrading my N75 valve before I get Jabba'd next month ? What are the benefits/disadvantages ?

Cheers,

Paul

www.alexrally.com

[skodaw]

Paul

As Adrian(SkodiRS) has said -- the different version available from Audi -- does give smoother response -- mainly because it's designed for a higher output than the standard part -- so YES I would change before remap -- better before than after,as it may have a impact on the remap characteristic.

Rob.

You are probably just missing the extra surge the overboost gives -- I suspect the power will be fine,poss down slightly -- but more than likely just the drop in overboost being felt !!

[PaulAlex]

All,

To keep you up-to-date, Jabbasport have just emailed me to say that I should stay with the standard valve.

Roll on October 3rd

www.alexrally.com

[Witchfinder]

Originally posted by skodaw in this post

You are probably just missing the extra surge the overboost gives -- I suspect the power will be fine,poss down slightly -- but more than likely just the drop in overboost being felt !!

That's what I suspected. For anyone with the 3000 rpm "spike" who is also considering a valve change or getting the spike mapped out, think carefully about it. Do you prefer smoothness, or can you live with the spike for a little more kick?

I'm not cerain I'm glad I changed the valve. The overboost was mental and I was really enjoying it. The car feels pretty sluggish now in comparison (even though I know it isn't really). However, the smoothness is preferable for when I'm carrying passengers.

[SkodiRS]

Rob,

I would give Mike a bell as I think you would need to have the original map remapped to take into consideration the new one's characteristics.

Cheers.

Adrian.

[Witchfinder]

When I spoke to Mike last week, he seemed to think I wouldn't need any alterations doing after the valve was replaced.

[SkodiRS]

Hmmm.....this is kind of at odds with what Elton told me.....however I suppose this could be if you're changing to a different type of valve.:confused:

That said I suppose although a remap is done to a certain N75 valve may be the map takes into consideration a certain amount of tolerance on the device.

I'm a little bit confused now.........who put me on this slippery slope anyway.

[DGW]

Adrian, I think the remap is only affected if a different version N75 is fitted. That said, if the remap was carried out on a car with dodgy valves, I guess the remap won't give the best results. But isn't the starting point a 'canned' remap (ie based on a number of similar cars) which Mike optimises for your car and preferences? I don't know how many 'canned' versions he has, but I did ask for the standard map as a starting point.

[SkodiRS]

Denis,

I was thinking the same thing as per the flaky N75 valve.

I'm pretty sure Mike has a baseline map he first loads and then as you say optimises per individual.

Not sure how he got to the baseline but may be as you suggest, it's an "average" over a number of cars.

Mike is pretty conservative on his maps and he won't give you anything other than his standard remap unless you can specifically say what you want i.e what sort of revs you want certain characteristics to happen etc.

[ncarring]

I think he has one baseline map per engine type. The thing he really wanted to know before doing mine was what engine code it was, then he used his standard AGU map to start from. He did say it ended up quite different from the starting point though - think that was for a Golf.

[Dutch4x4]

Originally posted by Witchfinder in this post

I had the N75 valve replaced today. Claybank Skoda did the other valve whilst they were at it, too.

The car is definately smoother. The surge/dropoff around 3000 RPM from the Jabba remap has gone. However, the rawness of the power delivery has also gone.

It still feels faster, although not as fast as it was. I'd be interested to get it back on the rollers and see what the curves look like now!

Very peculiar, Rob. Did you replace it because the old one was broken?

I don't see how your car's characteristics can change so dramatically by replacing one N75C with another. They can, however, by replacing it with another type such as Adrian's. So Denis' question is very valid: did you by chance get another type?

(Now where's that other N75 thread?)

[Witchfinder]

Originally posted by Dutch4x4 in this post

Very peculiar, Rob. Did you replace it because the old one was broken?

I replaced it because Mike at Jabba said it was sticking. He seemed to think a new valve would sort the problem out. Certainly the overboost characteristics and spike at 3000 rpm seemed to confirm that point, but now the car just doesn't feel as powerful.

I will be calling them again just to confirm one way or another - it's a full day out if I want to go back, and I don't want to make the trip unless it is definately wrong.

[Dutch4x4]

Ah, a sticking valve would explain the overboost alright!

(How to get a sports N75? Get it to stick! )

Mind you, in the long term it's better this way, believe me. You wouldn't want to overload the turbo with continuing overboost...

[Witchfinder]

Another call to Jabba has confirmed that they think adjusting the map will be unnecessary. To be honest, I'm not certain I agree. Pre valve replacement, it felt awesome (despite the power spike at 3000 rpm). Now it feels sluggish - almost like the original map.

The grin has gone... :(

[DGW]

Rob, sounds like you need to get your car checked on a RR to see whether the power really has gone, and for peace of mind.

[SkodiRS]

Rob,

get back on the phone and tell Mike that you're not happy with the performance now that you've had the N75 changed.

Jabba are good peeps so should be able to sort you.

[Witchfinder]

I have spoken to Mike last week and he seemed adamant that the sluggishness was a normal side-effect of changing the valve, and that the map wouldn't need altering. The call today seemed to confirm that.

I could do with getting it on some rollers, but I don't know anywhere local.

[SkodiRS]

I suppose you can really tell that the overboost surge/dip is gone now although I assume can turn up the overboost as well as turn it down.

Having gotten used to it I like it.

[Witchfinder]

Just been out with the lads for a spin at lunchtime, and the first response was "this doesn't feel any faster than before". OK, definately not right!

I've called Jabba and they've booked me in to get the map sorted out next Wednesday. Very professional and courteous - I can't fault them at all. Although their workshop could do with being about 100 miles further North

[ncarring]

Rob, I'm sure Mike will sort out your map.

Looks like others considering changing the valve should think carefully beforehand. This episode does illustrate the crucial role the N75 valve plays in the engine/turbo dynamics, and the dependence of the ECU mapping on the characteristics of the valve.