Jump to content

Throttle Valve Replacement EA189 Tdi Yeti 4X4 @50K


voxmagna

Recommended Posts

Skoda EA189 CFHC Common Rail in Yeti 4X4 TDi @ 50k miles:  Fault code P0120 G69 implausible signal:

 

There are a few fault codes that relate to the diesel throttle valve (T.V) which sits between the intercooler and the inlet manifold. In a gasolene engine, the TV(A)
controls airflow in sync with the accelerator. In a diesel engine its only purpose is to produce a controlled vacuum to purge bad gases and reduce emissions by
recirculating them. If this flap valve were to stay fully open free of gunk, the engine would be a happy engine and the only consequence of not having it would possibly be
slight engine run on at shut down and increased emissions.

 

However, The EA189 engine gets feedback of the flap angle and if it isn't what it expects, you will get the MIL light on. In my case implausible signal I think
mean't the flap was sticking, but some have had teeth on plastic gears in the gearbox break. When the flap motors to that bad position, it stops and the system
puts up a fault error. Another fault error occurs if the flap motor is faulty and blows fuses. MIL light on does not put the car into limp mode for TV faults.
However, there's another problem waiting to happen: If the MIL light is on for any reason, all regeneration of the DPF is stopped and the longer you drive the
car, the more sooted up it will get. Your next warning after the MIL will be the DPF warning and that is expensive bad news.

 

My first step was to change the accelerator pedal. Easy swap but my P0120 fault came back 3 days after reset, proving it wasn't an accelerator problem.  Next
step order a 'nearly new' VW TV assembly part number 03L 128 063 R and plan the repair in between sleet, rain and cold weather. I didn't know what I would
find or whether my T.V would be repairable. If it was repairable it could be a useful clean spare.

 

I couldn't understand the shop teardown procedure, but I could see the TV at the front but it had bolts that would be difficult to get to and there was very little
space for tools. My mindset was to just replace the T.V Job done, I guess a dealer would do that? I was WRONG for 2 reasons: Removing the TV with the manifold and top stuff still in place sounds logical, but it's a sheer pain getting to bolts and getting the T.V out. Removing the engine tray doesn't help much except to get the things you drop. Secondly, if your T.V is badly gunked up like mine was at 50K, you should also clean out the plastic inlet manifold. Leave it alone and you have only done half the job. Here's my check list: (sorryI don't do YouTube!)

 

1. Tools, spline torx tools + various length 1/4 extensions, torque wrench, dental mirror, telescopic magnetic pickup, fuel hose clip remover.
2. Remove the under body engine cover to rescue things you drop.
3. Remove dipstick and bolt holding it to the T.V.
4. Disconnect 3 fuel rail hoses from their steel distributor so this part can be lifted clear.
5. Unclip the top loom from its tray all along and at the left bend.
6. Pull straight up and wiggle the 4 glow plug connectors to one side to pull them clear of obstructions.
7. Remove the steel high pressure fuel line between the fuel pump (that's the lump in the right corner) and the fuel rail.
8. Remove and tie up the changeover valve assembly on the left side.
9. Slacken 4 nuts on each fuel injector.
10. Remove 2 bolts holding the fuel rail.
11. Remove 2 bolts on block holding solid breather pipe.
12 Remove clamp bolt at the other end of this pipe and carefully spread the clip to remove the pipe.
13.Remove this steel pipe but don't lose the steel gasket!
14. Remove various connectors like the fuel rail connector which could get in the way of lifting up the manifold.
15. Note: You don't need to actually remove the fuel rail or the wiring loom, you just need to move these parts to create space, get to the inlet manifold bolts and allow it to be pulled up
and out towards the front.
16. Slacken the large hose clip screw holding the hose on the bottom of the T.V assembly, Remove the T.V plug. Leave the bottom hose clip alone.
17. Using a blunt blade screwdriver, work it around the top of the hose to loosen the hose on the T.V body.
18. Remove all torx bolts holding down the plastic manifold cover use a magnet tool to lift the bolts out
19. Push away any clutter above the manifold and gently tap it upwards from underneath with a soft hammer. Note: It has plastic alignment pegs underneath
and will not slide!
20. Remove the manifold complete with T.V attached, taking care not to damage the orange gaskets.
21. At this stage the large hose is open and vulnerable to soot, gunge and parts or tools dropping inside it. COVER THE HOSE WITH AN OLD SOCK as soon as
possible.
22. Whilst the glow plug terminals are exposed, check each glow plug for low resistance.

 

Now take your manifold with T.V attached to your workshop. Remove the T.V and its gunk.  I used a set of small spiral wire brushes sold for servicing heating
boilers. DO NOT FORCE THE FLAP, it should be fully open and can only be moved by the motor (worm drive?). If the flap is closed, at an angle, or can be moved gently with your finger it is bad. Remove the steel flow bush in the side of the manifold and clean it up. If you want to refit it 180 degrees, now is the time to file a small notch in the opposite corner. After using the fine wire brushes I finished cleaning mine with kerosene (paraffin). The gunk is black and smelly, but quite soft, unlike hard combusted carbon. If you are planning to refit your old T.V you need to go further in to it (I didn't). You won't be able to fix a motor or electronics problem, but there's a fix for a broken gear tooth which involves moving a gear wheel around to good teeth, since the gears only move the flap through 180 deg.

 

I chose to fit new and use my old unit as a plaything. You can temporarily strap it to the top somewhere and watch the flap move as you blip the throttle. The brightest amongst you will spot that a serviceable spare T.V can be connected, produces no errors or MIL and the installed unit sits there with its flap fully open.Reverse the procedure and put everything back. With everything connected you can turn the ignition on and check for faults or connectors you left off with vcds. Then crank. But your car probably won't start! You disconnected all the high pressure fuel lines and now you have to do some simple bleeding to purge out air. It helps if you have a second person. Start at the fuel pump on the right and crack open the union nut about 3 threads where it connects to the fuel rail. Now short crank until some diesel fuel comes out and close the union nut. Repeat for each fuel injector one at a time. With all union nuts tight it should start.

 

Torques:

Fuel rail bolts (2)         22Nm
Intake manifold bolts      8Nm
Dipstick mount (1)        10Nm
T.V bolts (3)                   8Nm
EGR pipe flange (2)       9Nm

 

When you have finished, do a 40 minute drive to force a DPF regen if your MIL light has previously been on. Listen to how well your TDi is now breathing, warnings should be off after clearing and note the
improvement in fuel consumption!

 

Hope you find this useful.

 

TVJ338, where it is.jpg

TV gunked up @ 50k miles.jpg

EGR gas inlet on manifold.jpg

Bad gas entry inside manifold..jpg

TV+manifold assembly.jpg

Manifold assembly topside.jpg

Edited by voxmagna
typo
  • Like 1
  • Thanks 1
Link to comment
Share on other sites

That's where I read it, but I'm never 100% convinced by what I read? I thought it couldn't do much harm. However, with the amount of gunk in my TV and manifold, the real problem is the emission control/EGR loop itself and short journey driving. I always try to design out a problem, but in this case it is designed in to this diesel engine. If they got rid of all the emissions hardware and put in Adblue injection at the start I think that might have been a better solution. Instead, somebody came up with using the same old system design and tweaked the ECUs to pass tests.

 

I have to say it's like driving a different car now, so much more responsive and smoother.  But to be fair, the first 40K was put on by the PO and I don't know how they drove it?

Edited by voxmagna
Link to comment
Share on other sites

After cleaning up my TV 'plaything' I thought I would open it up and share. If you are considering checking your TV to save money you need to do some testing to avoid replacing a faulty unit. The TV assembly is much simpler than many Skoda/VW electronics modules. I can't guarantee my tests will stop fault all codes.

 

I don't advise doing flap motor checks at the connector alone because you don't know if there is internal damage. How it works; The flap is turned by a motor and plastic gear assembly under the cover (5 torx screws).  Apart from what I think are anti suppression components and possibly a fuse, I can find no other hi tech electronics in the main body. The black plastic quadrant gear turning the flap has an enclosed magnet on the end. The motor is connected to 2 bronze connector clips which mate with two blade contacts in the cover. There is no electronic connection between the motor gears and the connector socket. The TV needs to know the position of the flap quadrant. In the lid of the cover there is an enclosed  Hall magnetic effect sensing circuit which picks up the angle of the flap and sends it to the connector. There are 5 pins on the connector- 2 are motor, and 3 including ground and a +5V supply are reserved for the position sensor as follows:

 

Pin1 +5V

Pin2  Position sense output

Pin3 Sense ground

Pin4 Motor M(0)

Pin5 Motor M (+5V)

 

To prove a unit is good you need to know the motor is good, the gears turn and the position sensor gives an output. Visually inspect all the plastic gears. The internals should be clean. The motor resistance measured either with the cover off or on pins 4 & 5 should be about 6 ohm. If it's a short circuit the motor is probably dead and you go no further. When testing the motor there is no protection circuitry to limit its stall current. You must use a 5V power supply with current limited to < 1 amp. The flap quadrant gear is spring biased to fully open. It should always be in the fully open position with no power applied. Apply power from the bench supply and the flap quadrant should move 90 degrees to the fully closed position. Remove the d.c supply once the motor is stalled and the flap should return to the fully open position.

 

In theory flap position sensing should be very reliable because it doesn't use potentiometers. I haven't done it, but you could apply +5 volt to pin 1, ground to pin 3 and see what comes out of pin 2. I doubt it's digital and would expect a (small?) changing analogue voltage. Nothing at all or stuck at ground or +5V would suggest a bad position sensing detector. Finally, spray switch cleaner on the motor connections and the connector socket pins. If yours are oiled up, clean first with meths alcohol.

 

After thoroughly cleaning the TV and doing the fettling tests you should be ready to go. Plug the TV into the loom (you don't need the engine running) , switch on the ignition and check the flap is moving as you blip the throttle. The flap should be fully open with closing and opening as you blip the accelerator. Clear any stored faults with vcds and rescan with the repaired TV connected. You should get a clear scan.

 

TV cover ID.jpg

TV cover.jpg

connect 5V less than1A to motor.jpg

Bench testing.jpg

Underneath the hood.jpg

  • Like 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Community Partner

×
×
  • Create New...

Important Information

Welcome to BRISKODA. Please note the following important links Terms of Use. We have a comprehensive Privacy Policy. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.