imported_winner007

I just had my cousins Audi 1.8T engine replaced. It came with a stock turbo. The problem is, after the engine is replaced i still dun feel the turbo kicking in. The engine was dead and had no compression, but anyways. When i drive the car now. I go around 2000-3000 rpm and when i let go of the gas, i hear a sound like the bov sound, but the stock 1.8T doesn't have a bov put in. So is that a sign on the pipe leaking or something because they had to remove all the stuff inorder to get the engine out, so i know something they did was not right. What is the best way to check to see if it is working? How do i know how many pounds of psi i am running? There are no guages inside the vehicle that tells me how many psi.

So basically i just want to know that sound is not normal and i want to know what is the possibility could cause this to make this noise.

When u give gas and then let go the gas pedal, u hear like a small hissing of bov sound but it is not bov. I dun feel the turbo.

I hope someone hear knows about turbo and can help me out thanx.

imported_chris_v2

it has a bov.....

anyways, just bring it back to the shop? I don't see why your asking us, it's not like your going to fix it yourself. Bring it back to the shop!! they will fix it.

imported_winner007

it is still in the shop. I didn't take it home yet. They said they will check it out on Mon and hopefully i can get the car back on Mon. I dunno if they can fix it though, i hope it is just loose clamps on the pipe or something. But how can u tell if it has a leak? Would there be any noise? So the noise i hear might be a bov? but i was only at like 2000-3000rpm. I shouldn't be hearing that noise at that low rpm.

imported_starboy869

I would assume rev it up by hand from under hood and listen / feel for leaks. I think if the shop installed the engine they can fix your turbo problem alot better than you can.

dingus888

sounds like a leak they shoudl be dead silent they have diverter valves not BOV

definatly is a boost leak. easy way for a shop to test woudl be a smoke test probobly if they don't have a boost leak tester their really isn't too much piping on those they have like 2 rubber hoses adn a hard pipe going behond the bumper area if I remeber correctly when I ahd to fix a exploded IC pipe on my moms 1.8t

bbarbulo

iTrader: (2)

lol cars don't make boost without load. like when you just rev the engine it doesn't make boost.

if it was a loose boost tube, it would have shot off by now. I'm assuming your car isn't making any boost at all, so that hissing noise you hear is an open vacuum tube, more than likely the N75 valve that controls the VNT (internal wastegate) for the turbo. so basically check to make sure the VNT control tubing is connected.

imported_starboy869

hmm How about when you have high rev it at idle then you hear the psst sound of the bov. I mostly work with DDEC IV and cat engines and yes they make boost when when rpm increase and in N.

I'm trying to see it from your view and I can't!!! ie. stomp on throttle, engine speed goes up, exhaust gasses turns the turbine faster, now the compressor turns faster.

Now if Audi has there ECU programs to make no boost at 0 km/h then I can see it. ie. whatever they use BOV, Wastegate, etc is opened @ 0 km/hr

VTEC_Thunder

...My turbo cavalier would make 5-7+psi revving it in neutral....but thats a different car.

The 1.8T will have a by-pass valve (similar to a bov, only the air is sent back into the turbo to be reused instead of dumped into the atmosphere) and like everyone else said, there is probably a leak somewhere. The mechanics probably forgot a vacuum line somewhere or something.

You want to know how much boost it's making? Install a vacuum/boost gauge.

brianmcgaugh

audi map or maf??
What size turbo do they have?

You can build boost on small turbo setups with a free rev. maybe not much but some..and enough to make a bov/bpv sound

also you can also build boost with a free rev with any car/turbo, but to much of it and your turbo will hate u...anti lag

imported_starboy869

anti-lag?

dingus888

anti lag..?? no that's generally only an aftermarket option....tons of fuel super low timing = big spool out of turbo without any load put on it

and a detroit and cat might make some boost free revving because of the amount of exhaust velocity and shear cubic inches pumping tons of air and heat from exhaust, but generally speakign no load = no boost. Tiny hair dryer on huge engine = maybe some boost

HD mechanic I take it..? I always liked the sound of a V671 2 stroke detroit

bbarbulo

iTrader: (2)

MAF

it's a small turbo, depending on the year it'd be a *** or a Garrett VNT.

why can't STOCK turbo setups make boost?? because they're not supposed to, they're designed correctly so that the wastegate stays open until there is enough load on the engine (therefore a lack of vacuum) to close the wastegate.

all those making boost under freerev conditions need to adjust your wastegates.

starboy, read my next reply

think this way... the wastegate is vacuum operated. so think about an N/A engine that has maximum vacuum when the throttle plate is closed. opening the throttle plate to WOT at no load condition (watch the vacuum gauge) only makes the vacuum decrease slightly for a moment, then it returns to full vacuum. now, drive the car and observe the vacuum gauge, if you punish it through all the gears, the vacuum will be close to 0 in every gear. now, add a turbo to that setup and think what the wastegate will be doing. the wastegate will open when vacuum is high, and close when vacuum is low. so a properly tuned wastegate won't let you make boost w/o load. now, in addition to all this, VW/Audi uses a Bosch valve called an N75 valve which controls how much vacuum actually gets to the wastegate (VNT)... so not only does the engine NOT normally make boost with no load, there is ALSO an electronic failsafe that ensures the wastegate remains open at no load.

bbarbulo

iTrader: (2)

has nothing to do with it at all... I think you're referring to starboy's post???

starboy, diesels as you know don't have a throttle plate, therefore they do not make vacuum. diesels have a vacuum pump exactly for that reason, they're incapable of vacuum.... that's also the reason you can see a runaway diesel that self destructs if the turbo seals blow.

dingus888

^^ diesels wont' runaway if the seals go on the turbo they run away if the fuel rack get's stuck or setting the fuel setting wrong aka full fuel, or if they have some type of vacuum pump controlling how much fuel they get and if it get's a vacumm leak then it will runaway. Their are 2 many types of pumps and fuel setups ie cumming pt detroit unit body rotory pumps inline pumps. The worst is a 2 stroke detroit you need to know what you are doing whileworkgin on them. Never been afraid till I did a tune up on a v671

bbarbulo

iTrader: (2)

ya you're right it depends on what design it uses, but both oil and diesel is combustible in a diesel engine, so yes it will runaway if you have engine oil in large quantities getting into the cylinders. it happens on VW TDIs like my dads all the time, thats why I know... I had to tell my dad so he knows what to do if it happens so we don't lose the whole engine if the turbo does ever blow.

imported_starboy869

thanks for the info bbarbulo

imported_winner007

Yes bbarbulo is right. You can't make boost without load. Well i tell them to check and see if there is any leak, if not i tell them to check the N75 valve thanx.

brianmcgaugh

I fixed that for ya

imported_fotoboy0806

that "BOV" like sound you're hearing is the sound of the Diverter valve! almost ever single euro motor has one! if you take out the air filter you'll actually hear it! of if u have an intake kit! it's pretty loud! i've changed many of those for my friends! the one for the 1.8T Audi are right behind your rad on the left hand side of the motor!