boost gauge....

So my car (99.5 golf tdi 5 speed) has an aftermarket nuspeed or whatever brand, boost gauge, on the steering wheel housing/shaft? i lifted it up a little, and its a wired gauge. Where does this wiring usually go? I'm trying to really find out what all was done to this car, because my turbo is boosting higher than i think it should? i'm getting 20+ psi of boost under hard acceleration. It was boosting like this with the stock VNT15, and its still boosting like this with an autozone "Rotomaster" brand turbo (also a vnt15 replacement). I read that it should be about 15-18 psi max boost, but i'm getting higher than this... I'd like to figure out the boost gauge, because i imagine its tapped into the MAP sensor, and if thats the case, i may put a new sensor in for maximum accuracy. Car runs great, and is getting 38-41 mpg in town... depending on how much of that turbo boost i use :-D.

Thanks for any advice...
other than a VAG-COM is their a way to determine if my car is tuned as well?

You will have to trace where the wires go.
Only the installer would know where he ran the wires and the pressure sensor.
The sensor could be anywhere in the pressure tube from the turbo to the EGR valve, in the intake manifold, maybe even in the EGR tubing.
I don't know if taping into the MAP sensor would work.

You could try lengthening the actuator arm to lower the boost.
Turn the adjuster nut 1/2 turn at a time and go for a ride.

I hd every inch of intake piping off, when the orirginal turbo blew, to clean it all out. Their is no sensor. It blows my mind

Follow the wires back from the MAP sensor, possible they tapped in there or near the ECU.

It's overboosting hard! 25-30 psi, it's freaking me out bad. I'm worried it's going to blow something up. Tknigjt I'm going to try to lengthen the rod as a poster above stated.

WELL, the VNT actuator rod on this aftermarket turbo didn't have an adjuster wheel to spin... the rod was threaded, so their is an adjustment, but its probably from removing the vnt rod off hte turbo itself, and adjusting. however their is a stop screw, 8mm head, with a 2mm "grub screw" so to say, functining as the stop screw. I turned it way in. Got the turbo down to spiking at about 20 psi, but holds about 18. The turbo lag is pretty noticable... where as before it boosted near instantly, just overboosted to extreme... the motor sounds solid, and turbo doesn't sound like its going to self destruct...

Thoughts? Opinions????
Edward

Do you want the good news or the bad news...? By lengthening the stop screw the turbo has exhibited the appropriate response: slower spooling by bypassing more of exhaust gasses around the turbine instead of through it.
Let me see if I can ask this question correctly: the threaded rod that is attached to the vacuum pot passes through the actuator arm and has one nut on the vacuum pot side and one nut on the "far side" of the actuator arm, is this correct? If there are any threads showing on the "far side" of the actuator arm you need those to lengthen the rod by using up the excess threads on the "end". If for some reason there are no available threads available, you might want to consider putting the stop screw back where it was and installing a $9.95 ebay boost valve set at 18 psi.

I don't quite get what your asking me NV. The VNT vacuum actuator, from what i could tell, has the threaded rod coming from it, into a larger arm, which uses a c-clip to hold it to the actuator arm. their is a knurled area on the arm, which appears to be a turning adjuster, but it doesn't turn, or at least i couldn't get it to do so, when i loosed the lock nut, the threaded rod seemed to be fairly loose inside the larger arm, so i wouldn't think of loctite at all. Either way, lengthening the rod, and adjusting the set screw should have the exact same effect right? limiting the VNT vanes travel.

Now... using a boost valve, would vent excess pressure, however, i want to keep the turbo alive... wouldn't overspooling still damage it? even if the excess pressure is venting off... I don't see how a boost drain valve would save the turbo... but i could be wrong... i don't quite know how these things work.

a Link for the boost valve would be greatly appreciated.... my first real go at these cars... my turbochbarged experience is ecoboosts... and we never got into this type of work.

doing some research, i think i understand. But not sure. I really think i'm getting too much fuel... i do blow sooty smoke past probably 2/3 throttle depending on what gear. I don't want a race car... i don't want MPG. thats why i bought this car. how can i determine if i have aftermarket nozzles. are they stamped somewhere... Can i remove an injector to see whats going on? The car has WAY more power than i ever thought possible for a 90 hp engine. The diesel torque is intense. and i love the way it drives. I am dealing with the turbo lag for now, as to keep the motor and turbo alive.

That's where you really want a VCDS type device. So you can measure those things.
I was always able to chirp the tires from 1st and 2nd, no mods. It's got like 155 '/lbs of torque when it's running right. Our older models have a stronger clutch also, if I can believe what I've read here.
Decent chance it has some add-ons (cause he put that gauge in), maybe nozzles and/or chip.

Not a blow-off valve which is what I believe you first thought, one of these units also know as a Dawe's device: http://www.ebay.com/itm/VMS-RACING-...ash=item3ab0a7b392:g:Gi0AAOSwDNdV6LGX&vxp=mtr

This one is not $9.99 but they are available for $9.99.

These valve do not blow off boost like a gasser does, they prevent the full vacuum signal from getting to the actuator preventing an over-boost situation. Al turbos are going to spike a tiny bit when at WOT, but usually within a second or two the level out to where they should be. The vanes in the turbo need to be able to travel as much as is possible during operation to help prevent soot from clogging up their operation. By closing down the amount of travel in the actuator arm it is not unlikely you have sooty exhaust, the computer says to provide a certain amount of fuel based on drivers demand (throttle position) and it leads the boost a bit with fuel to help get the turbo to spool faster. Making the set screw longer is never a good idea and now you know why. With a boost control valve installed in line the turbo will not over boost anymore, but it will allow the actuator arm to travel it's entire lenght.

Ok! Thank you! So now, if I lengthen the rod, does that have the same effect as the stop screw? Will it also cause the vane soot problems you listed?

I bought the controller you linked. Two lines. One goes to the vacuum line between n75 and turbo, other goes to intake somewhere?

Stop Screw

Gamikatsu said:

Ok! Thank you! So now, if I lengthen the rod, does that have the same effect as the stop screw? Will it also cause the vane soot problems you listed?

Click to expand...

In the end, yes you will get the same effect. Lengthening the actuator rod will help to control spikes and over boost like lengthening the stop screw did.
The first order of business is to shorten the stop screw to where it was originally; that is if you remember where it was set before you turned it.
What you DO NOT want have to happen is the the actuator arm to pull the vanes to a "snap open" position as there is always a possibility of them sticking in that position causing excess overboost and potentially over speeding the turbo causing it to explode.
Setting VNT turbo charger set screws is not a job for the beginner as there is too much that can go wrong ( usually BOOM!).

I have a non-standard turbo that makes boost if the barometric pressure drops across the input of the actuator so stop screw length and actuator rod rod length settings are fairly critical. IF you don't remember exactly where the stop screw was set, try this: take the thickness of two paper matchbook covers (0.060 or so) and pull the actuator rod all the way towards the stop screw and place the "spacer" between the arm and the stop screw. Nudge the stop screw until it bumps the matchbooks and set the lock down nut. This may not be a "perfect" setting but it should work until you figure out something else.

I want to clear something up: I initially thought you had a different turbo in your car and that is why my description of your actuator rod and mine did not match up.

Installing Boost Controller

Gamikatsu said:

I bought the controller you linked. Two lines. One goes to the vacuum line between n75 and turbo, other goes to intake somewhere?

Click to expand...

The way the Boost Control Valve (hereafter referred to as BCV) is like this: the bottom of the valve is where the positive pressure coming from the turbocharger is applied--somewhere past the IC--and the side port is where the pressure vents into the turbo vacuum line. There is a spring inside this check-valve, as that is really what it is, and when the pressure in the intake manifold rises above what the spring pressure inside the BCV is set at, it lifts the check ball slightly reducing the vacuum available to the actuator, thereby controlling the amount of boost. Once the maximum boost is set by the BCV, the chances of over boost are almost non-existant. Almost, but not never, unless there are dirty, sticky vanes in the turbo and then a BCV really isn't going to be of guaranteed help.
Is this pretty clear to you? I don't always explain things the best...

See if you can cancel your BCV order, that valve doesn't come with hoses or brackets or anything. This $9.99 does though:http://www.ebay.com/itm/BLACK-ADJUS...id=100005&rk=4&rkt=6&mehot=pp&sd=252071883666

It's fine. I already purchased it. I can get some new vacuum lik, which I should change them anyway! I'll also need one T and a nipple fitting right?

Yes, a threaded nipple to go into the intake pipe to pick up the boost, and a tee along with vac hoses and call it a day.

Just doing my homework... the "Arrow" side, which would probably be the straight inline to the screw, would go to the pressure side of the intake correct? and then the Side nozzle would go to the "T" in between the N75 and the VNT valve?

Makes a LOT of sense, once the boost goes over the set 18 psi, it would vent into the Vacuum side, releasing the vacuum actuator,

I have a question. Why is the N75 system so bad at controlling the boost? I feel like my car has more power than it should stock, and I still believe i have some kind of nozzles installed aftermarket. Which would make sense to me... more fuel = more exhaust pressure, which would mean faster turbo spooling. Then the PCM/N75 just can't react fast enough???????

I just really like to know how this stuff works.

Ed

Mr. Nevada_TDI, THANK YOU!!!!

So the BCV showed up today. after a run to advanced auto, for Vacuum T conectors, and vacuum line, and then a trip to Fastenall for a 1/4NPT Nipple, breaking out the drill bits and Snapon Tap and Die set... I drilled a hole in the intake pipe about 6" away from the MAP sensor, installed all the hoses and the valve. I guestimated on the setting, and got it set to 15 psi right away. adjusted it to about 17 psi steady and 19-20 spike. It works beautifully!!!!

Thank you so much for the help!!!!! Now i just get to go down and adjust the stop screw out another turn. I moved it close to max setting, but about one turn down. It was (before the BCF) boosting to about 20, with 24 spike... and was just driving it real gently.

Again, Thank you so much!

Edward

I am very glad I could be of help to you and you had good results. The only reason my car doesn't go to the stealership or anywhere else is because of the members on this website; I am happy I could pass along what was passed on to me. I always do what I can to pay it forward for these TDI's and the new owners of them.