Question about Volkswagen New Jetta

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2004 jetta tdi, has engine miss & lack of power, has p0101 present, if unplugged has less power, but misses less, already cleaned extremely clogged egr valve, changed engine oil/filter, checked maf connector/wiring. also checked for vacuum leaks. the miss is a harsh stammering, worse under load in higher gears, studders the entire car, any advise?

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TdiPWR

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Running rough?? If i took a guess I'd say there's a faulty injector. Does it smoke like hell ?? Does it also miss at idle?- If so get a line wrench and a rag handy. Start the car and while idling wrap the rag around the base of the fuel line connector on injector 1 and crack it just a bit until fuel comes out. It might spray, thus the rag. If the miss gets worse, that ain't the injector to blame. Continue with the other 3. If you crack a line and there is no or very little change in the miss then you found the guilty party.

On a long shot it could also be a stuck valve.

Did that get it?? It sounds like an issue other than MAF but.... get a multimeter and try probing the connecter to the MAF. When you find out what it is , please let me know. I'm curious

*The key must be on*

pin 1- ignore it
pin 2- gnd = 12-14v
pins 2- 3 = 12-14v
pin 4- gnd = 5v
pins 3- 4 = 5v

P0101 - Mass Air Flow Sensor (G70): Implausible Signal

Possible Symptoms

  • Loss of Power
  • Erratic Idle
Possible Causes
  • Mass Air Flow Sensor (G70) faulty
  • Air Leak(s) after Mass Air Flow Sensor (G70)
  • Intake Air Filter dirty/faulty
  • Ground Spots corroded or Paint Residue
  • Wiring and/or Connections from/to Mass Air Flow Sensor (G70) faulty
Possible Solutions
  • Check Intake Air Filter
  • Check Mass Air Flow Sensor (G70)
  • Check Ground Spots
  • Check Wiring and/or Connections from/to Mass Air Flow Sensor (G70)

Posted on Dec 14, 2009

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1993-2005 Volkswagen Jetta, Golf, GTI, Cabrio (A3-A4) Hatchback & Sedan Workshop Repair Service Manual - 350MB PDF

1993 2005 Volkswagen Jetta Golf GTI Cabrio A3 A4 Hatchback Sedan...

This is a COMPLETE Service and Repair Manual for your 1993 1994 1955 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 VW Jetta, Golf, GTI, Cabrio (1.8L turbo, 1.9L TDI and PD diesel 2.0L gasoline, 2.8 LVR6) (A3, A4 Platform) Hatchback & Sedan. It covers every single detail. All models, and all engines are included.

This QUALITY manual is 100 percents COMPLETE and INTACT, no MISSING/CORRUPT pages/sections to freak you out! Detailed illustrations, exploded diagrams, drawings and photos guide you through every service repair procedure. This manual can be viewed on any computer, as well as zoomed and printed. All repair procedures are covered A-Z. This manual for VW Jetta, Golf, GTI, Cabrio makes any repair job easy to do with very easy to follow step-by-step instructions & pictures on all areas of repair.

1993 1994 1955 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 VW Jetta, Golf, GTI, Cabrio (1.8L turbo, 1.9L TDI and PD diesel 2.0L gasoline, 2.8 LVR6) (A3, A4 Platform) Hatchback & Sedan
===========
Format: PDF
System: All Versions of Windows, Mac, iOS, BB, Android, etc..
Requirements: PDF Reader.
Printable: Yes

TABLE OF CONTENT (example)

GENERAL INFORMATION *

ENGINE *
engine mechanical
engine lubrication system
engine cooling system
engine control system
fuel system
exhaust system

TRANSMISSION/TRANSAXLE *
clutch
manual transaxle
automatic transaxle

DRIVELINE/AXLE *
front axle
rear axle

SUSPENSION *
front suspension
rear suspension
road wheels & tyres

BRAKES *
brake system
parking brake system
brake control system

STEERING *
power steering system
steering system

RESTRAINTS *
seat belts
supplemental restraint system (srs)

BODY *
body, lock & security system
glasses, window system & mirrors
roof
exterior & Interior
Instrumental panel
seat

AIR CONDITIONER *
air conditioner system

ELECTRICAL *
wiring diagrams
starting & charging system
lighting system
driver information system
wiper, washer & horn
body control system
lan system
audio visual, navigation & telephone system
auto cruise control system
power supply, ground & circuit elements

MAINTENANCE *
maintenance

INDEX *
alphabetical Index

1993 1994 1955 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 VW Jetta, Golf, GTI, Cabrio (1.8L turbo, 1.9L TDI and PD diesel 2.0L gasoline, 2.8 LVR6) (A3, A4 Platform) Hatchback & Sedan

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check for bent axle or missing vibration rubber damper that is usually on the axle.

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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.




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