Altea 2.0 TDi Sport 2004 - Seat Altea TDi cruise control

Honest John Back Room » Technical matters
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Tue 10 Mar 2015 17:48
Altea 2.0 TDi Sport 2004 - Seat Altea TDi cruise control - apriliajay

I have a 2.0 BKD TDi engine Altea, has 94k on the clock, nearly a FSH.
It runs pretty well apart for 2 issues; when on cruise if you get to a downhill stretch it will not keep a constant speed, it will apply, let off and then re-apply throttle. On a flat or uphill it is fine.
Secondly, when driving at any speed, if you let off the throttle, there is a delay and then a pronounced lurch into engine braking. It also feels as if there is engine movement, but have changed all gearbox dogbone mounts, which made no real difference. I believe it is throttle behaviour somewhere?
We also have a 1.9 TDi version, which behaves beautifully under the above circumstances.
Help!

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Tue 10 Mar 2015 21:20
Altea 2.0 TDi Sport 2004 - Seat Altea TDi cruise control - elekie&a/c doctor

May be an idea to get the brake light switch checked.These are a double function device that switch on the brake lights and send a signal to the engine control unit for foot on/off brake.

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Wed 11 Mar 2015 06:32
Altea 2.0 TDi Sport 2004 - Seat Altea TDi cruise control - Railroad.
Yes as above. Also check the clutch pedal switch operation too. The ECM needs a signal from that.
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Wed 11 Mar 2015 08:40
Altea 2.0 TDi Sport 2004 - Seat Altea TDi cruise control - apriliajay

Thanks to you both for replies, I willlook into those, but had recently had a brainwave and thought of checking wheel speed sensors, then last night HJ sent a reply and suggested the same and that one could be dirty or ineffective and confusing the ECU.

This morning driving to work I disabled the ESP system and while I could not check the cruise function downhill, it was fine on the flat, but more satisfying was the fact that letting off the throttle was night and day different to before, giving a smooth and normal transition between power and engine braking.

Have already checked the car on VCDS / VAGCOM and found no actual faults.

Going to get it up on a ramp and try to clean or test the sensors.

Edited by apriliajay on 11/03/2015 at 08:41

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Wed 11 Mar 2015 09:20
Altea 2.0 TDi Sport 2004 - Seat Altea TDi cruise control - elekie&a/c doctor

Checking and cleaning the sensors is a complete waste of time and effort.Any problem here would show as an abs/esp fault on Vcds.Have you checked engine for any faults?more likely to be a problem here.

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Wed 11 Mar 2015 17:25
Altea 2.0 TDi Sport 2004 - Seat Altea TDi cruise control - apriliajay

Yes you are correct, I realised today that they can be checked live and all 4 are spot on. Damn.

The only code we can find seems to be related to the steering wheel but we are a bit confused;

Address 16: Steering wheel labels.............

Part No. and so on and so on, then lower down -

Component: E0221 004 0060

1 Fault Found:

00002 - Transmission Control Unit

004 - No Signal / Communication.

Does this mean anything and would any of the specifics above need to be known??

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Wed 11 Mar 2015 18:18
Altea 2.0 TDi Sport 2004 - Seat Altea TDi cruise control - elekie&a/c doctor

Could be a problem with the air intake flap/actuator sticking.This can retstrict air entering the engine.It is also used as an air shut off when ignition is switched off to prevent run-on.

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Thu 12 Mar 2015 08:52
Altea 2.0 TDi Sport 2004 - Seat Altea TDi cruise control - apriliajay

This was the kind of thing I felt it would be, if it was a Petrol I would have said it feels like the throttle flap messing about, having a delayed reaction and snapping shut.

Does this flap move under normal driving to vary the air allowed in? I am still learing about Diesels really and just remember the old days people told you that they ran without any air restriction and it was just the fuel amount that varied, but that was in the mechanical pump days.

I have cleaned the EGR valve and the flap is connected to it on this engine, thing is it was almost straight after I got the car so I can't remember if this made the symptom happen or if it was like it already.

No fault code for it either, the car shuts off perfectly normally. This is an annoying one for sure.

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