F*$&!!! Boost leaks!!!!
#1
11-05-2008, 10:27 PM
F*$&!!! Boost leaks!!!!
2000 b5 s4. finding more broken things everyday. drove today after i installed the new aux. water pump that pretty much fell apart, and coolant leak is gone, but i think i have a boost leak. when i had the intake off i looked at the f-pipe and it seemed to be in very good shape still. and i just installed a new throttle boot that was torn in 3 places. i could not see any other things in there that were cracked or damaged that would cause a boost leak. so i am beginning to think that i may have an intercooler leak. what are the chances of that?? these are oem with 133 k on them, running the 93 octane tune from apr. i cannot think of anything else that the leak could be coming from. i am going to install a boost gauge tomorrow for diag purposes to make sure what my boost/vacuum is . it feels at stock like it is running perfect and only at around 3000 and up do i notice the noise(a high pressure air escaping noise) while running the 93 octane tune. ill install the gauge during the day and run it and see what i come up with. if anyone knows otherwise where my leak could be would be awesome for some ideas.. the leak sounds like its coming from the passenger side..
Last edited by bigern45; 11-05-2008 at 10:28 PM. Reason: didnt mention what yr/make/model
#3
11-06-2008, 12:57 AM
they are stock.. but i am looking at an FMIC that comes with silicone ones.. but thatll be a week or two down the road.. unless i find another boost leak.. when i set the gauge up.. i know im supposed to get 8 or 9 psi in stock mode but how much in the 93 octane mode? ive heard 17 psi but i wanna make sure.. again its APR ..
#4
11-06-2008, 07:32 AM
I just installed my boost guage. Full boost comes on fast and is pretty steady all the way through the revs, iv got APR by the way
Stock mode i spike to 7 or 8 then hold 6+
Chipped mode I spike 17, hold 16+
What i didnt know is that even after you shut off your car it stays in whatever mode it was last in, i always thought it reset after being shut down. I always had trouble telling the difference between stock and chipped mode because i was always in chipped mode! Now i can tell it keeps pulling ALOT harder when im at 16psi lol
Intercoolers have pressurized air in them so if there is a leak in one its a boost leak. Stock coolers have plastic end tanks IIRC so maybe they could be the source of your leak. If you allready checked f-hose and the TBB your DV's might be to blame if theyre stock on the APR program. Pressure testing could help you find the exact location.
Stock mode i spike to 7 or 8 then hold 6+
Chipped mode I spike 17, hold 16+
What i didnt know is that even after you shut off your car it stays in whatever mode it was last in, i always thought it reset after being shut down. I always had trouble telling the difference between stock and chipped mode because i was always in chipped mode! Now i can tell it keeps pulling ALOT harder when im at 16psi lol
Intercoolers have pressurized air in them so if there is a leak in one its a boost leak. Stock coolers have plastic end tanks IIRC so maybe they could be the source of your leak. If you allready checked f-hose and the TBB your DV's might be to blame if theyre stock on the APR program. Pressure testing could help you find the exact location.
Last edited by SourDieselS4; 11-06-2008 at 07:35 AM.
#5
11-06-2008, 07:16 PM
okay.. i took all of the turbo connecting pipes and hoses from the turbos to the intercoolers and such and cleaned them all and retightened the clamps holding them on so i know that i have no boost leaks from the intercoolers to the throttle body and no leaks from the turbos to the intercoolers. the throttle body boot is brand new even though it is stock ( i have a silicone one on the way) . one of the diverter valves is brand new, not sure about the other one..
now.. for my boost issues.. in stock mode the apr chip gives me right at 8 to 9 psi and it holds that.. when i switch to the 93 octane tune in first gear i get 15 psi of boost and i hear a whooshing noise (what i think is my boost leak)... but then in second and third gear boost peaks at over 20 psi and then flutters down to 15 psi and then levels back up to 17psi. it almost feels like the ecu is stepping in when it spikes at 21 psi, dumping fuel and retarding the timing for overboost protection.. ive had the same issue before in a T6 volvo S80 and someone had adjusted the wastegates to allow for more boost spike. does this sound like the same thing has happened with this car?? and how difficult is it to adjust and get to the wastegate actuating rods and adjusters?? and if its not a big deal.. i really like the push in the back the 20 psi of boost gives.. but im worried about what type of strain on the turbos and the engine all of this boost is causing.
so does it seem like someone has tampered with the adjusting rods on my car?? and what type of boost will the engine handle without doing damage to the connecting rods and such?? and how can i tell what type of turbos are in my car? i really dont know what type of mods are on the car but i know someone has been into the ecu due to screws missing from the cover, so im assuming theyve had a tuned ecu in the car and removed it when they sold it.. and finally.. ive got an APR chipped ecu in the car but i have an option to go with the GIAC tune.. which is the better/stronger tune?? im looking for performance wise, not worried about gas mileage and such...
any help with my dilemma with the possible boost leak and over boost problem as well as which tune i should go with would be greatly appreciated..
now.. for my boost issues.. in stock mode the apr chip gives me right at 8 to 9 psi and it holds that.. when i switch to the 93 octane tune in first gear i get 15 psi of boost and i hear a whooshing noise (what i think is my boost leak)... but then in second and third gear boost peaks at over 20 psi and then flutters down to 15 psi and then levels back up to 17psi. it almost feels like the ecu is stepping in when it spikes at 21 psi, dumping fuel and retarding the timing for overboost protection.. ive had the same issue before in a T6 volvo S80 and someone had adjusted the wastegates to allow for more boost spike. does this sound like the same thing has happened with this car?? and how difficult is it to adjust and get to the wastegate actuating rods and adjusters?? and if its not a big deal.. i really like the push in the back the 20 psi of boost gives.. but im worried about what type of strain on the turbos and the engine all of this boost is causing.
so does it seem like someone has tampered with the adjusting rods on my car?? and what type of boost will the engine handle without doing damage to the connecting rods and such?? and how can i tell what type of turbos are in my car? i really dont know what type of mods are on the car but i know someone has been into the ecu due to screws missing from the cover, so im assuming theyve had a tuned ecu in the car and removed it when they sold it.. and finally.. ive got an APR chipped ecu in the car but i have an option to go with the GIAC tune.. which is the better/stronger tune?? im looking for performance wise, not worried about gas mileage and such...
any help with my dilemma with the possible boost leak and over boost problem as well as which tune i should go with would be greatly appreciated..
#6
11-06-2008, 10:59 PM
If it is a boost leak then
a possible scenario is that your Charge Pressure Sensor isn't seeing the actual boost for
a short moment due to a leak.
Thus causing the Charge Pressure Sensor to tell the ECU and
N75 to hold the actuators and WGs closed a little longer to satisfy the requested boost from the ECU, and this is in turn causing a spike higher than requested.
Leave your WG actuators alone, they aren't the problem so adjustment isn't necessary.
The spikes are a strain on your turbos, especially if you still have k03s.
The engine can take it so don't worry about it. These things love boost.
These engines won't dump fuel and retard timing to compensate for overcharge, but rather use a throttle cut which is anything but subtle and you would definitely notice it.
It sounds as if you may have a minor leak under high pressures giving false readings from the sensors so they are causing the turbos to be erratic.
Like HP said, those diverter valves could be problem also, so I'd replace them ASAP with upgrades. Sometimes the springs aren't strong enough to hold higher boost levels and will give you symptoms of leaks.
a possible scenario is that your Charge Pressure Sensor isn't seeing the actual boost for
a short moment due to a leak.
Thus causing the Charge Pressure Sensor to tell the ECU and
N75 to hold the actuators and WGs closed a little longer to satisfy the requested boost from the ECU, and this is in turn causing a spike higher than requested.
Leave your WG actuators alone, they aren't the problem so adjustment isn't necessary.
The spikes are a strain on your turbos, especially if you still have k03s.
The engine can take it so don't worry about it. These things love boost.
These engines won't dump fuel and retard timing to compensate for overcharge, but rather use a throttle cut which is anything but subtle and you would definitely notice it.
It sounds as if you may have a minor leak under high pressures giving false readings from the sensors so they are causing the turbos to be erratic.
Like HP said, those diverter valves could be problem also, so I'd replace them ASAP with upgrades. Sometimes the springs aren't strong enough to hold higher boost levels and will give you symptoms of leaks.
Last edited by RED_01; 11-06-2008 at 11:04 PM.
#7
11-07-2008, 12:28 AM
I agree with red, leave the WG actuators alone they arent the problem.
K03's are not going to last long at all over 20 psi id try to avoid going that high untill its fixed, however your stock motor will love 20+ psi on K04's.
Throttle cut just reduces the throttle angle regardless of pedal position, it also happens with the esp on if you try to launch or spin the tires like on wet pavement in 1st or 2nd.
If theres a small leak in the line from the n75 to the wastegates they(WG's) could stay closed longer making you spike. You can unhook the N75 and blow into the line going to the WG, it shouldnt open untill 4 psi is applied IIRC
Id might test the n75 too just to make sure its working properly, this is the instrustions from the bently manual. Even though it seems like its working normally in stock mode. Also i would reccomend getting a vag-com if you dont allready have one.
How to test the n75:
Turbo & WG
N75
This is the n75 (not my car)
K03's are not going to last long at all over 20 psi id try to avoid going that high untill its fixed, however your stock motor will love 20+ psi on K04's.
Throttle cut just reduces the throttle angle regardless of pedal position, it also happens with the esp on if you try to launch or spin the tires like on wet pavement in 1st or 2nd.
If theres a small leak in the line from the n75 to the wastegates they(WG's) could stay closed longer making you spike. You can unhook the N75 and blow into the line going to the WG, it shouldnt open untill 4 psi is applied IIRC
Id might test the n75 too just to make sure its working properly, this is the instrustions from the bently manual. Even though it seems like its working normally in stock mode. Also i would reccomend getting a vag-com if you dont allready have one.
How to test the n75:
With power off, the long connector is closed. Both short connecters are inter-connected. When triggered, the connection between the long and both short connectors is opened.
Check for leaks
Check for leaks
- Remove wastegate bypass regulator valve N75.
- Re-connect removed wastegate bypass regulator valve to wiring harness.
- Start output Diagnostic Test Mode (DTM) and advance through test program to select wastegate bypass regulator valve N75.
- Blow into long connector during DTM to check whether valve opens properly.
N75
This is the n75 (not my car)
Last edited by SourDieselS4; 11-07-2008 at 12:41 AM.
#8
11-07-2008, 07:07 AM
okay... funny thing is .. i just had my intake off 2 days ago to install an auxiliary water pump.. the valve you just pointed to has a few vacuum lines installed on it that go behind the intake and have a tee that splits up the flow.. well that tee broke and i installed just a generic tee in its place.. i could check the connection and make sure that its installed properly, i could also make sure that i didnt forget to plug back up the electrical connection to the solenoid or didnt damage the connector period.. thanks alot and ill check that today.. by the way.. how can i check to see what kind of turbos i have on this car? on both of these turbos there are blue stamped plates and i cant really make out any numbers on them.. a group of two or three sets on the top row of the plate and a long number on the bottom...
#9
11-07-2008, 07:48 AM
Definitely check those connections out and test the n75. It sounds like they may be the culprit.
Don't forget about those DVs either.
I beleive the easiest way is to see what material your turbo inlet pipes (the pipes connected to the center of the silver compressor housing on the turbo) are made from.
Cast aluminum (silver and somewhat rough to the touch) = k03s
Mandrel bent aluminum (usually black and smooth to the touch) = k04s
Don't forget about those DVs either.
I beleive the easiest way is to see what material your turbo inlet pipes (the pipes connected to the center of the silver compressor housing on the turbo) are made from.
Cast aluminum (silver and somewhat rough to the touch) = k03s
Mandrel bent aluminum (usually black and smooth to the touch) = k04s
#10
11-07-2008, 09:27 AM
Id put money you have k03 still. k04's couldnt touch 20+ psi on stock fueling, well they could youd just run super lean because your stock fueling cant support em.