Lift off accelerator in 1st gear, delay in clutch opening.

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Deylan
Finally has his VR6.
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Lift off accelerator in 1st gear, delay in clutch opening.

Post by Deylan » Tue May 03, 2011 8:04 pm

I was wondering if anyone has noticed this -- When I lift off accelerator in 1st gear, instead of the immediate freewheel like in all other gears, the clutch remains closed for a second or so and engine brake effect occurs briefly?

Holding gearstick to try and select neutral (activating gear lever switch) stops it from doing this.

Only happens in 1st gear.

Initial diagnosis: Sensor is causing this to happen. Possibly worn load signal potentiometer.
Things tried already: Adjust LSP 157 to correct spec, basic setting.
"I've been guilty of hanging around...."

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Hajo06
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Re: Lift off accelerator in 1st gear, delay in clutch openin

Post by Hajo06 » Thu May 05, 2011 4:33 pm

I do not know the problem.
Have you selected the display of the sensor LSP 157 with laptop?
Does the transducer indicate 0% if you take the foot of accelerator pedal in Measuring Block 1 Position 1?
How are the voltages in the Measuring Block 2 positions 1?
Greetings Hajo

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Deylan
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Re: Lift off accelerator in 1st gear, delay in clutch openin

Post by Deylan » Thu May 05, 2011 4:46 pm

Hi Hajo,

All that checks out to be OK, it only happens for a brief moment, as usual, it would be too quick to show up in VAG-COM :(

If I hold the gearstick switch it stops the car from doing this, ruling out mechanical reasons, I believe some sensor is causing this, it is quite strange, and also happens less once the car has warmed up.

Occurs between 5-10mph, if I am going faster and take my foot off accelerator, the problem does not occur.

I think this will be a difficult one to diagnose. :lol:
"I've been guilty of hanging around...."

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Hajo06
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Re: Lift off accelerator in 1st gear, delay in clutch openin

Post by Hajo06 » Fri May 06, 2011 12:48 pm

Deylan wrote: If I hold the gearstick switch it stops the car from doing this, ruling out mechanical reasons,....
This is logical.
If you operate Gear Operating Switch F191, the clutch opens.

You should determine the measuring value in the idleness (engine switched off, ignition on).
The display is almost simultaneous.
Also control immediately with the function of the switch F208.
Hajo

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Deylan
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Re: Lift off accelerator in 1st gear, delay in clutch openin

Post by Deylan » Wed Sep 21, 2011 7:39 pm

Aside from the mechanical engine "quirks" (shall we call them). This problem is what is annoying me the most.

For example, say I am creeping along in traffic, I will get up to 10MPH or so, and then traffic slows, I lift off the accelerator and instead of the car coasting, the clutch remains closed (connected) for 1-2 seconds, and then suddenly releases, this causes the car to jerk from the engine breaking effect in the 1st gear.

Holding gear stick (activating gear lever switch) - stops problem.

This is getting on my nerves a lot because when I lift off my accelerator I keep bracing myself for the car to jerk as the engine brake effect takes place, making my driving experience uncomfortable in town traffic.

This did not occur with old ECU, however, old ECU was defective anyhow and was causing clutch to slip too much.

This only occurs in 1st gear.

So what are people's thoughts?

My extended theories

1) Worn load signal potentiometer on injection pump giving poor readings to ECU - ECU is holding clutch closed under assumption accelerator still pressed until vehicle speed drops below threshold for 1st gear.
2) The accelerator pedal and/or cable is not fitted properly, therefore the "idle" voltage is fluctuating causing the ECU to not know properly at what voltage the accelerator pedal is at idle. Therefore it isn't recognising that the accelerator pedal has been fully lifted. - This said, when measuring on VAGCOM, I cannot see any evidence of this.
3) Defective ECU / Faulty memory, not adapting.
4) Problems with servo motor (I say unlikely, as this occurs only in 1st gear).
5) Intended behaviour (Unlikely, but I know of no other Ecomatic owner who is driving with a Digiswing revision E to disprove this.)
"I've been guilty of hanging around...."

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