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I have a Audi a3 1.8 T 1999 I am having boost problem car feels like I'm driving a 1.1 :(! I have changed n75 valve swapped my maf with someone else still no power.. Sprayed WD-40 all over engine which there was no disturbance.. Really is doing my head in, if anyone can help would be so thankfull :D

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6 Suggested Answers

6ya6ya
  • 2 Answers

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Posted on Jan 02, 2017

landsend
  • 1066 Answers

SOURCE: Intermittent boost pressure

a bad pop off valve.  Or boost controller.  Sadly with 100K on the speedo things are far from mint.

Posted on Mar 30, 2009

  • 1 Answer

SOURCE: My Audi A3 2.0 tdi limp mode/turbo overboost

i also have done a diagnostic test and it states a turbo overboost condition and it drives fine locally but loses power on the motorway and struggles to reach 80mph? any suggestions please email me at shiz86@hotmail.co.uk

Posted on Sep 14, 2009

abauto
  • 353 Answers

SOURCE: boost(?) problem audi tt

It is probably either the N75 valve(Diverter Valve) or the wastegate actuator. Usually a significant boost leak will set a DTC, still check all hoses and clamps.

A bad wastegate actuator or flap would cause no boost but not necessarily the air-sound.

____________________________________________
Testing N75

Air Bypass Valve: Testing and Inspection
With Generic Scan Tool
Wastegate Bypass Regulator Valve, Checking
Recommended special tools and equipment e.g.:
- VAG1526 multimeter or VAG1715 multimeter
- VAG1594 connector test kit
Test sequence
- Switch ignition off.
- Disconnect connector at solenoid valve for boost pressure regulation.
517f5c6.jpg - Measure resistance between terminals of valve.
Specified value: 25...35 Ohm
If specified value is not obtained:
- Replace Wastegate Bypass Regulator Valve -N75-.

________________________________________________

Testing N249

Exhaust Bypass Valve: Testing and Inspection
With Generic Scan Tool
Recirculating Valve For Turbocharger, Checking
NOTE:
Valve opens between connection to intake manifold and connection to deceleration shut-off valve with no voltage. Connection to vacuum
reservoir is closed.
Test sequence
- Switch ignition off.
- Disconnect connector from Recirculating valve for turbocharger -N249-.

9dfbfb9.jpg - Measure resistance between terminals of valve.
Specified value: 27...30 Ohm
If specified value is not obtained:
- Replace Recirculating valve for turbocharger -N249-.
If specified values are obtained:
- Connect test box to control module wiring harness, connect test box for wiring test.

1a741bd.jpg - Check wire between test box socket 105+2-pin connector terminal 2 for open circuit according to wiring diagram.
Wire resistance: max: 1.5 Ohm
- Also check the wire for short circuit to B+ and Ground (GND).
If no malfunctions are found in wire:
- Check wire between 2-pin connector terminal 1 and the Fuel Pump (FP) Relay -J17- for open circuit according to wiring diagram.
Wire resistance: max: 1.5 Ohm
If no malfunctions are found in wires:
- Replace Engine Control Module (ECM).

____________________________________________


To test the wastegate, locate the wastegate linkage rod and verify that there is no play and that it is closed. You can apply compressed air to the actuator to see if it opens and closes. (not more than 30 psi)

___________________________________________


2bd307e.jpg
Vehicle: Vacuum and Vapor Hose Diagrams
System Diagram
Vacuum Diagram
1 From fuel tank
2 EVAP canister
- with Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-
3 Check-valve for EVAP canister
- Between EVAP canister and intake manifold before turbocharger Installation position (light/dark side): Arrow points in direction of flow, as
shown
4 Turbocharger
5 Pressure unit for boost pressure regulation
6 Mechanical recirculation valve
7 Brake booster
8 Check-valve
- Between brake booster and intake manifold
- Installation position (light/dark side): Arrow points in direction of flow, as shown
9 Wastegate bypass regulator valve -N75-
10 Mass Air Flow (MAF) sensor -G70-
11 Air cleaner housing
12 Pressure control valve for crankshaft housing ventilation
13 Vacuum reservoir
- Bolted on at cylinder head
14 Charge air cooler
- With charge air pressure sensor -G31-
15 Fuel pressure regulator
16 Throttle valve control module -J338-
17 Intake manifold
- With Intake Air Temperature (IAT) sensor -G42-
18 Crankcase ventilation
19 Check-valve
- Installation position (light/dark side): Arrow points in direction of flow, as shown
20 Recirculating valve for turbocharger -N249-
- Component location Fig. 1
21 Check-valve
- Between EVAP canister and intake manifold
- Installation position (light/dark side): Arrow points in direction of flow, as shown
22 Charge air cooler

Posted on Oct 02, 2009

  • 5 Answers

SOURCE: boost pressure problems for audi A6 the car lacks

what is your actual psi? check into the other divertor valve or the n75 valve(electronic)

Posted on Nov 29, 2009

  • 11 Answers

SOURCE: 2003 Grand Am: Just replaced egr valve car has and cleaned maf se...

Symptoms....car throws a check engine code for the EGR valve.... car has noticeably less power (especially on the highway)and fuel mileage is noticably worse.
Cause....catalytic converter.

Posted on Sep 18, 2010

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1 Answer

1998. Can I install a boost control valve, and, If so, how?


your car (if it is turbo) already has a boost control valve. It is the N75 valve.

Dec 31, 2015 | Audi A3 Cars & Trucks

1 Answer

AUDI A3 OVERBOOST 20. TDI 04 SAFE MODE ISSUE


Code P0234 Check N75 boost control solenoid and all vacuum hoses to and from N75.

If performance returns after brief ignition key cycling, Off /On.....check for vacuum to turbo dump valve canister.

If performance is always low, check turbo vanes for sticking or 'snow screen' in snorkel to air filer is not restricted..

Oct 30, 2013 | 2005 Audi A3

1 Answer

On the audi a4 2003 what are the codes P 0135 and P0234?


Code P0135 -
Oxygen O2 Sensor Heater Circuit Malfunction (Bank1, Sensor1)

P0135. Turbo boost pressure too high.

O2 sensor heater malfunction: ...Check all fuses. If good, replace O2 sensor.

Over boost: Check N75 Boost control solenoid and all vacuum hoses to and from N75.

Oct 30, 2013 | 2003 Audi A4 Cabriolet

1 Answer

I have a 2000 audi a4 1.8t and seems to run sluggish over a 100kms, no engine light on, any possible reasons why?


If it runs well but is low on power it is possible that you are not getting any turbo boost. The wastegate actuator may be bad. The n75 valve that controls the actuator could be bad, also the N710 diverter vave may be bad.

Jun 27, 2011 | 2000 Audi A4

1 Answer

Turbo problem...dealer replaced valve...still


If you have a problem that isn't caused by something obvious, you need a Ross tech VCDS cable. This is a laptop computer diagnostic cable to talk to the car's computer. Without it you cannot do the more advanced tests.
Note about generations - some generations have similar engines: Mk3= 1996-1997 3rd generation Passat TDI or 1996-1999 3rd gen Jetta TDI Mk4= 1998-2006 New Beetle, 1999-2005 Jetta, 1999-2006 Golf, 2004-2005 Passat TDI Mk5= 2005.5-2010 Jetta TDI Mk6= 2010+ Golf TDI
Remember, an engine needs fuel, air, and compression to run. Low power is related to a lack of one of these or a sensor problem making the computer thinking there's a lack of these. Any sensor problem could also be caused by a bad ground or broken/chaffed wire so also check every section of the wiring of the suspect sensor for breaks.
Bad MAF sensor - very likely cause on the mk4 TDI. Not common on the mk3 TDI (1996-1999 Jetta/Passat). Early mk4 MAFs failed often.Error codes normally do not show up with a faulty MAF since the signal degrades instead of going out completely. Through VCDS, checking MAF actual vs. specified at idle, high rpm, and high load will quickly show a bad MAF or other problem causing a low MAF reading.
Clogged intake manifold - carbon buildup chokes the intake manifold, starving the engine of air. Only ultra low sulfur diesel is sold in North America now so there should be much less buildup in the future. Always use good quality synthetic engine oil on your TDI..
Anti shudder valve shut or almost shut (does not apply to mk3 TDI, more for mk4 TDI) - there is a spring loaded valve right before the intake manifold. Newer TDI use an electronic valve and are not as susceptible to sticking. If there is excess carbon buildup, it could shut in a partially closed position.
Clogged snowscreen/air filter - a clogged air filter will starve the engine of air. A clogged snowscreen (large debris air pre-filter) shouldn't block off all air unless the aux-intake flap is also clogged.
Clogged fuel filter - change interval is 20,000 miles but biodiesel use (cleans out old buildup) or bad fuel could clog it early, resulting in fuel starvation. Algae or bacterial growth in the fuel tank could also clog the lines.
Boost leak - a cracked hose or loose connector lets measured air out. No air or major leaks = poor engine running or stuttering. A visual inspection may not reveal all the possible or hard to see spots where leaks can form.
Hose inside ECU (mk3 TDI only, does not apply to mk4 or newer TDI) - this hose leaks and normally sets a check engine light,
Vacuum lines to/from turbo and n75 solenoid - these dry out over time and crack or can rub through. It's possible they are clogged. The n75 solenoid controls the turbo wastegate or VNT vanes with either vacuum or pressure. b4 Passat - on firewall above coolant reservoir, a3 Jetta - on pass side near air box, a4 Jetta/Golf - on firewall above brake fluid reservoir.
Problem with the n75 solenoid, VNT actuator, VNT vanes, or vacuum lines. You should have already checked the vacuum lines, the below test will inspect the entire system. Start the engine and through VCDS, click on "engine"-->"measuring blocks"-->hit "up" until you reach "group 11". Compare Specified vs. Actual MAP. This compares what's actually happening and being observed from the boost sensor (barring a faulty sensor/plug/wire) to boost the computer is requesting (what should be happening). They should be relatively close. If they are far off this normally results in limp mode but it could also be contributing to the problem. If you have a mk3 you have a conventional turbo but you can still use this test to check the n75 solenoid, the wastegate, and vac lines. However, wastegates are much less susceptible to sticking vs. VNT vanes. The videos below show how it works. The lever on the outside is welded to a lever inside the turbo housing. This is how it moves the VNT vanes. See the below videos to see how smoothly and free the lever should move. It should not stick or bind at all. Vacuum is being applied to the can, not pressure.
If the test shows poor response or no response at all, it could be sticky VNT vanes/actuator (mk4 and newer TDI only), The vanes or actuator can stick or fail to function, the lever should move freely.
If the actuator is fine, also check the n75 solenoid and vac lines. The n75 solenoid controls vacuum or boost to the vacuum line going to the turbo wastegate/VNT actuator. To test, apply voltage to the solenoid or swap with a known good unit. If you have a mk4 TDI, you can swap it with the EGR solenoid to test. Also check the plug for corrosion and the wiring harness for chaffing. If those are good, disconnect the VNT actuator rod and move the vanes by hand. If the vanes are stuck then remove the turbo and clean the inside of the exhaust housing to free the stuck vanes.
Faulty injection pump's fuel injection quantity adjuster - these are occasionally set wrong from the factory or after seal replacement. It's also possible the fuel pump's internal quantity adjuster is faulty. Applies to 1996-2003 TDI only or TDI that use a Bosch VE injection pump (not pumpe duse or common rail). Injection quantity should be 3-5 at idle and up to 36-38 at full throttle.




Feb 01, 2010 | 2004 Volkswagen Jetta

2 Answers

1999 tdi 1.9L eci code p1550. loss of power on hills


Its not your clutch. Its one of three things which is regards to your turbo.
17958/P1550/005456 - Boost Pressure Controle Valve (N75): Control Deviation

Possible Symptoms
  • Irregular behaviour
  • Reduced power output
  • Limp mode
Possible Causes
  • Hoses/Pipes incorrect connected, disconnected, blocked or leaking
  • Charger Pressure Control defective
    • Solenoid Valve for Boost Pressure Control (N75) defective
  • Turbocharger defective
Possible Solutions
  • Check Hoses/Pipes to/between Components
  • Check Charge Pressure Control
    • Check Solenoid Valve for Boost Pressure Control (N75)
  • Check turbocharger

Nov 14, 2009 | 2000 Volkswagen Jetta TDI

2 Answers

Boost(?) problem audi tt


It is probably either the N75 valve(Diverter Valve) or the wastegate actuator. Usually a significant boost leak will set a DTC, still check all hoses and clamps.

A bad wastegate actuator or flap would cause no boost but not necessarily the air-sound.

____________________________________________
Testing N75

Air Bypass Valve: Testing and Inspection
With Generic Scan Tool
Wastegate Bypass Regulator Valve, Checking
Recommended special tools and equipment e.g.:
- VAG1526 multimeter or VAG1715 multimeter
- VAG1594 connector test kit
Test sequence
- Switch ignition off.
- Disconnect connector at solenoid valve for boost pressure regulation.
517f5c6.jpg - Measure resistance between terminals of valve.
Specified value: 25...35 Ohm
If specified value is not obtained:
- Replace Wastegate Bypass Regulator Valve -N75-.

________________________________________________

Testing N249

Exhaust Bypass Valve: Testing and Inspection
With Generic Scan Tool
Recirculating Valve For Turbocharger, Checking
NOTE:
Valve opens between connection to intake manifold and connection to deceleration shut-off valve with no voltage. Connection to vacuum
reservoir is closed.
Test sequence
- Switch ignition off.
- Disconnect connector from Recirculating valve for turbocharger -N249-.

9dfbfb9.jpg - Measure resistance between terminals of valve.
Specified value: 27...30 Ohm
If specified value is not obtained:
- Replace Recirculating valve for turbocharger -N249-.
If specified values are obtained:
- Connect test box to control module wiring harness, connect test box for wiring test.

1a741bd.jpg - Check wire between test box socket 105+2-pin connector terminal 2 for open circuit according to wiring diagram.
Wire resistance: max: 1.5 Ohm
- Also check the wire for short circuit to B+ and Ground (GND).
If no malfunctions are found in wire:
- Check wire between 2-pin connector terminal 1 and the Fuel Pump (FP) Relay -J17- for open circuit according to wiring diagram.
Wire resistance: max: 1.5 Ohm
If no malfunctions are found in wires:
- Replace Engine Control Module (ECM).

____________________________________________


To test the wastegate, locate the wastegate linkage rod and verify that there is no play and that it is closed. You can apply compressed air to the actuator to see if it opens and closes. (not more than 30 psi)

___________________________________________


2bd307e.jpg
Vehicle: Vacuum and Vapor Hose Diagrams
System Diagram
Vacuum Diagram
1 From fuel tank
2 EVAP canister
- with Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-
3 Check-valve for EVAP canister
- Between EVAP canister and intake manifold before turbocharger Installation position (light/dark side): Arrow points in direction of flow, as
shown
4 Turbocharger
5 Pressure unit for boost pressure regulation
6 Mechanical recirculation valve
7 Brake booster
8 Check-valve
- Between brake booster and intake manifold
- Installation position (light/dark side): Arrow points in direction of flow, as shown
9 Wastegate bypass regulator valve -N75-
10 Mass Air Flow (MAF) sensor -G70-
11 Air cleaner housing
12 Pressure control valve for crankshaft housing ventilation
13 Vacuum reservoir
- Bolted on at cylinder head
14 Charge air cooler
- With charge air pressure sensor -G31-
15 Fuel pressure regulator
16 Throttle valve control module -J338-
17 Intake manifold
- With Intake Air Temperature (IAT) sensor -G42-
18 Crankcase ventilation
19 Check-valve
- Installation position (light/dark side): Arrow points in direction of flow, as shown
20 Recirculating valve for turbocharger -N249-
- Component location Fig. 1
21 Check-valve
- Between EVAP canister and intake manifold
- Installation position (light/dark side): Arrow points in direction of flow, as shown
22 Charge air cooler

Oct 01, 2009 | 2004 Audi TT

4 Answers

My Audi A3 2.0 tdi limp mode/turbo overboost


i also have done a diagnostic test and it states a turbo overboost condition and it drives fine locally but loses power on the motorway and struggles to reach 80mph? any suggestions please email me at shiz86@hotmail.co.uk

Apr 21, 2009 | 2005 Audi A3

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