Running issues

[mcleemo]

Hi all got a 2.0 TDI 06 Passat, has no eml light on, just limiting itself to 3.5k revs, I've unplugged the maf sensor but no change! If I accelerate slowly it's ok but put my foot down and it's lumpy with no power.. Could anyone please help shed some light on the issue. Many thanks.

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[DMitch16]

Hi all got a 2.0 TDI 06 Passat, has no eml light on, just limiting itself to 3.5k revs, I've unplugged the maf sensor but no change! If I accelerate slowly it's ok but put my foot down and it's lumpy with no power.. Could anyone please help shed some light on the issue. Many thanks.

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Lots of things make a 2.0 PD lumpy. What's your mileage and engine code? Engine code should be on white printed sticker in boot wheel well under carpet. Also there may be fault codes that are recorded but which do not throw up a dash warning. A fault code scan with a VW capable scan tool (VCDS, VAS or higher functioning scan tool) would be advisable. There are engine parts that cause 'limp mode' some of which will not register a warning light until more serious.

[mcleemo]

Thanks for the reply bud, sorry it's a bkp I think, 113000 miles, I have vcds will plug it in when I have a chance. I used torque Pro app first off but nothing came up.
Think I need to work the actuator free, could I do this on the car? Thanks.


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[DMitch16]

When you say work the actuator free? Is it rigid with no movement? A fair few VNT turbos get clogged up with carbon and soot preventing the vane actuator ring from rotating but this normally throws up under / over boost fault codes, limp mode and often the dash fault light. Has it already had its first timing belt change (due at 95k on this year of PD)? Also a deteriorating Dual Mass Flywheel can separate and the front plate jam causing vibration and poor power. Almost feels like a cylinder isn't firing, pickup from stationary would be awful and possibly with an engine 'shudder' when accelerating. Clutch bite could get much further down as it gets worse.

[mcleemo]

When you say work the actuator free? Is it rigid with no movement? A fair few VNT turbos get clogged up with carbon and soot preventing the vane actuator ring from rotating but this normally throws up under / over boost fault codes, limp mode and often the dash fault light. Has it already had its first timing belt change (due at 95k on this year of PD)? Also a deteriorating Dual Mass Flywheel can separate and the front plate jam causing vibration and poor power. Almost feels like a cylinder isn't firing, pickup from stationary would be awful and possibly with an engine 'shudder' when accelerating. Clutch bite could get much further down as it gets worse.A little stiff on movement but now you've told me about the eml light I'm thinking it's something else. I plugged my vcds and I have one code
• intermittent implausible signal Injector 4.

So I'm looking for a new Injector and fit it right?? Cheers bud, awesome reply, thank you.

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[DMitch16]

More likely to be the loom than the injector although the injector itself can't be ruled out at this stage.

New loom is around £120 but used ones are around for less.

The test is to swap injectors 3 and 4 and see if the injector 4 fault moves with it to injector 3. If it stays at 4 it's the loom not the injector.

[mcleemo]

More likely to be the loom than the injector itself although the injector itself can't be ruled out at this stage.

New loom is around £120 but used ones are around for less.Just your help may have saved me £££, thank you. Well that sounds less stressful (I hope) Is the loom a DIY job?

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[DMitch16]

Depends on your mechanical proficiency. It's a medium difficulty job but does not need any special tools as such as long as you have a reasonable tool kit. A loom change is recommended when you change injectors anyway as the old one would be more brittle and subject to possible damage upon removal. A few tricky bits such as not losing the red loom collar plastic locking pin, being careful not to break the injector or glow plug connectors or drop anything into the head. Also the connector 'collar' is in 2 parts outer and inner collars. The inner one has a retaining clip on the inside part of the head which needs to be removed and the collar may be very, very stiff. I use a rope or strap to undo it (coiled around once, pulled tight and then using a push-me-pull-me type motion with each end to undo the collar) but do not feed it through as the loom rail needs to be unbolted first iirc 3 hex head bolts, with female hex heads. Then remove the loom from out of the head mounting hole.

[Crasher]

When you read the fault codes with VCDS you will have no idea if your Air Mass Meter is faulty as you ran the engine with it unplugged before checking the codes.

[mcleemo]

Hey pal, I ran it when off and on, made no difference. I remember while idling it was reading between 240-270. The injectors were
0
0
-29
0

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[Crasher]

The ECU can tell if the AMM is faulty due to a wiring fault or other (not all) reasons, now you have run the engine with the AMM disconnected you will have a fault code stored to say you have an AMM open/short circuit and so you now have no idea if it was there before or not, you should always read the codes before carrying out any tests. Just because the AMM being disconnected does not make any difference to the way it runs does not mean the AMM is not faulty, that is an old wives tinterweb tale.