Hey guys n gals,

As some of you may know, I currently have awful boost stutter and surging on my car, following the making of a very bad decision, and getting a generic (crap) remap.

As well as plans to have the remap removed and going back to the stock map for now, I have also ordered a brand new OEM N75 boost valve, just because I know I am on the original (11 year old car), and in case it is also a factor in the awful boost stutter/surge.

I got so fed up with the stutter/surge today that I unplugged the electrical connector to the N75 valve, which opens the valve and thus means that boost is controlled only by the wastegate spring, meaning that the car will only boost to 5psi.

Now, I have a beautifully smooth, stutter-free (underperforming) car !!

Clearly, this is and was only ever considered as a temporary measure. As above the car now has max boost of 5psi, but otherwise drives and feels fine, with no CEL, and no codes thrown.

My question is; considering I am only running 5psi, is it safe to run the car with the N75 unplugged in this way? ... clearly I am not going to harm the turbo itself (only running at 5psi!), but could this action damage the wastegate spring, actuator, etc ?

Will be interesting to hear any views.

This may be a temporary 'fudge' but I am actually enjoying driving my VRS for the first time in 3 weeks..... that tells you how bad my boost stutter/surge has been !!

Edited 5 June, 201214 yr by Longyear

Yes it's perfectly safe

Many thanks

Safe but slow huh!

I having similar problems to u mate an I'm just wondering are u putting blame down to the map or the n75? I want to keep mine remapped but I'm having the stutter/surge effect u are having . Mine does it between 3000-6000rpm .. Will unplugging my n75 reveal that the n75 is acutally at fault ? If u get me

Unplugging the electrical connector (in the way I did above) will not tell you whether your N75 is faulty. It will just effectively de-activate the N75 completely and instead the wastegate of the turbo will just open up at it's passive pressure level (5psi). This makes the car mega smooth to drive, but mainly because you now have approx half the turbo boost pressure of the stock mapped car!

To test the function of the N75, you can disconnect the central hose connection, and drive the car VERY carefully (go nowhere near wide open throttle and keep boost low). This will tell you if you have a N75 problem, because it will keep the N75 connected (electrically) but will disable it's ability to control the wastegate ........... so if the car boosts cleanly with this pipe disconnected, you probably have a N75 problem. If the car still surges, the problem is elsewhere. Be very careful though and don't keep the hose removed for more than a quick test, or will risk detonation and a new turbo and/or engine! .... if your brief and safe though, it's a relatively safe test.

Newsflash! : After 3 weeks of misery I have just completely cured my surging, by making a small adjustment to the N75. See my "Remap/Demap" thread for more info PS... a new N75 (which I have on order) will possibly give the same result as what I have done today.

Edited 5 June, 201214 yr by Longyear

Here:-

http://www.ebay.co.u...#ht_1438wt_1139

..but before anyone sees the word 'ebay' and kicks off about cheap parts, it's an original OE part. I have used these people lot's of times, for all my BMWs and VAGs and their parts are always genuine OE, and I've never had any problems.

As you can see from above I decided (all things considered) to go for a 'F' model.

Edited 5 June, 201214 yr by Longyear

Where did you get your N75 from?

When i was down at r-tech someone was running an ebay big turbo at 550bhp on a 1.8t and it was passed the 12 month mark

...It exploded 2 days later.

Nah, seriously though ebay can be a decent place for a bargain still if you know what you're looking at. The problem is more often than not the people selling if they know it's good will charge the going rate (or more)...

That's very true Chris ........ there are many false bargains on there.

In fact "Awesome GTI" is a classic example : buy their coil pack tie-downs from their website and get free P&P ..... buy the same thing from their eBay shop and the price for the product is the same, but there's £6 extra to pay for P&P !!

Edited 5 June, 201214 yr by Longyear