N75J on a standard 1.8T?

[gpk_gti]

come to think of it,thats another bit ill be selling!!!! forgot all about it!!!

[fuzion]

If you intend on chipping your car which im assuming you would be, grab a cheap one whilst you can before you do so. Put it on either way and slowly get everything together..

Its your choice int he end!

[schoona]

so is it like a re-circ BOV?

i say BOV as generic turbo speak, even though (if i understand correctly) it is en elctronically controlled DV?

[Blitzen]

so is it like a re-circ BOV?

i say BOV as generic turbo speak, even though (if i understand correctly) it is en elctronically controlled DV?

Not quite man. It has to do with the waste gate controlling, and nothing to do with the DV.

[Bug_racer]

Ok
lesson 2
I am not going to give my opinion just options !


The Mk4 Golf is drive by cable , most mk4 Golfs did not run the boost sensor which is located in the intercooler . Ive seen 1 so far with wiring hooked up , freak car maybe ? Anyway , with the mk4 due to the fact that the ECU does not know what boost is being made you can change the n75 to a J and it wont know you did so . In fact you could even run a manual boost controller and you wont get boost cut issues ! , but , the car does run a temp sensor in the intake manifold . The higher the reading the more fuel it dumps in to cool down the combustion . You need to remember that the lambda is also going to try and trim the fuel cause it will be running so rich but the factory maps will stop it cause its trying to protect the engine . Once you go over 10 psi its all hell , unless your chipped , thats the correct way to tune the engine , since your changing boost , fuel and ignition maps .

On cars which do have the boost sensor your restricted to about 12 psi before you hit hard limp mode . This is because when you have gone past a certain amount of boost that the ecu requests to what actually it is , it feels like it cuts ignition till it goes down to the max level . My assumption is its approx 3-4 psi more than what max stock level is , which is within the max amount that a upgraded n75j will give anyway . Im not completely sure on this as I hate "testing" a car this way to give optimum results with mbc !



I re-read what I wrote , sorry if I sound drunk ! I hope people have more of an understanding anyway

[No457 Snowy]

Thanks Seb, it's good to get some straight talk in layman's terms on this stuff. It sounds like you really need someone who knows what they are doing to see how an individual motor is going to react to something like changing the N75, otherwise you risk not really knowing what the hell is going on inside the engine?

Especially on a chipped car, by changing to a different N75 that it wasn't tuned for, wouldn't you be just messing up the remapped fuel/boost/ignition tune you just payed for? (Assuming you have a chip from a reputable company that is).


Snowy

[No457 Snowy]

Further interesting boost sensor related comments and photos in this thread for those interested:

http://www.vwwatercooled.org.au/newforum/upload/showthread.php?t=20021&page=2

Snowy

[spj]

Well decided to go ahead, against the advice on here...

Finally installed it this afternoon, cause i finally got around to wiring up my boost guage... lazy!

After a few runs and varying the type of driving my findings are as below...

Before, N75C (stock)
Boost - 8psi
Spike - 9psi
Boost would fall away in the top RPM range (4200rpm>) to 6.5psi.

After, N75J
Boost - 10psi
Spike - 11psi
Boost slightly falls away in the top RPM range, but then zips back up to 9.5-10psi.

22 degrees and sunny in Melbourne this afternoon, and had been driving the car alot so heat soak would be a factor (standard car other than Remus rear box), but have noticed an increase in power (as much as can be expected...).

Will have a nice drive tonight, in the cooler, turbo air =]

Worthwhile mod for $100 IMHO.

[gpk_gti]

I told ya!!!! just checked my dyno sheet and I was getting 9.5psi without and 11psi with it on.... cheap and easy power mod!!!

[spj]

I told ya!!!! just checked my dyno sheet and I was getting 9.5psi without and 11psi with it on.... cheap and easy power mod!!!

Finally some good advice... TRIED AND TESTED.

What where your power figures from those dyno runs? Mods?

Cheers,
Sonny.

[gpk_gti]

they were before chip ,just with exhaust and k03s.

[glidn]

Snowy i know what you mean, but the fact is N75J does actually come standard on the GTI as i have seen many here in New Zealand.

Also now the N75J is the only replacement unit you can no buy from VW in New Zealand.

SPJ - As for the replacement DV, do that, dont think. JUST DO IT.
Get the 710N DV. It comes from the Audi S3 unit, it should set you back around $80ish tops. It's even cheaper than the standard replacement unit.

I'm sure that the 75J is the difference between my gti and the girlfriends gti.
Hell her car is making almost 10Wkw more.

[spj]

SPJ - As for the replacement DV, do that, dont think. JUST DO IT.
Get the 710N DV. It comes from the Audi S3 unit, it should set you back around $80ish tops. It's even cheaper than the standard replacement unit.

I'm sure that the 75J is the difference between my gti and the girlfriends gti.
Hell her car is making almost 10Wkw more.

Hey mate,

So whats the difference with the S3 diverter? Will that stop my boost falling off in the top end more? will it run more boost just replacing the DV?

I have been told that the $350 APR DV wont do anything extra... just wont fail... Bit of a waste of money IMHO if my diverter is fine...

Your thoughts?

Cheers.

[No457 Snowy]

I think everyone agreed there would be some more boost, but as Seb pointed out weird things start to happen inside the engine when it dumps more fuel in to protect from the extra heat but at the same time it's trying to trim it back because it thinks the mix is too rich. Sounds like a recipe for problems without proper tuning.

My worry would be that you could damage the engine here because things are no longer tuned properly to account for the extra heat and boost you've just added. With a proper chip tune you get the timing adjustments the fuel maps and the boost all tuned to complement each other and not cause issues.

I'm not sure if this is the case, but just being "not sure" is enough to stop me from guessing and playing with a complex system and maybe running too lean and smoking my engine for 2 psi.

Maybe it's completely safe, I don't know.


Snowy.

[spj]

Well i found out today, my findings above were all written with a faulty diverter valve!

Car is in at Volkspower for a few things and they advised me of this after i requested them to check over it. Replacment one being fitted, will update when i get the car back.