VW Golf 2005 - PD BKD Engine

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STC
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VW Golf 2005 - PD BKD Engine

Post by STC » Mon Jul 17, 2017 11:05 pm

This throws a Manifold / Boost Pressure Sensor Signal Implausible fault at Ignition on. Won't Clear.

It has landed on me with the Parts Cannon Fired repeatedly and relentlessly :D

New Parts etc. ..........
1. MAP/ Boost Pressure Sensor.
2. Turbo Charger
3 EGR Blanked & Mapped Out

Engine not running I see 1306mB in measured values against 1020 mB atmospheric and desired. The Fault Code is accurate and Validated.

1. 5v Ref Voltage is steady at all times
2. Sensor Ground is steady at all times
3. Signal wire has no Volt Drop - Zero ! Wire cut both ends and substituted with known good.
4. Used Sensor Simulator to manipulate values below and above "Desired" ECU reaction is confirmed as Good. Dial it to match atmospheric and the Fault Clears.
5. Connector Pins (male and female) Clean, Shiny and Tight.
6. Un Plug Sensor plug and Fault code Changes to "Open Circuit"
7. Genuine Dealer MAP sensor fitted - No Change.
8. Vacuum Lines checked, Vacuum Block is Functioning, Vacuum Pump is doing its thing. Vacuum lines are correctly fitted and routed as per Elsa
9. Turbo Control Diaphragm can hold 500mb Absolute Pressure for 10 minutes.
Bosch ESi (this is a Bosch ECU and Component) specifies MAP Voltage to be at 1.4 to 1.8v at Ignition On and at idle - Yes same figures ?? I guess it won't be boosting at idle ?? I have 1.4v with 3 Boost pressure sensors - Original, Customer replacement and Mine from the dealer ( Sealed Package )

I am ready to throw a new ECU on this.

Question is: What will I do, what further testing will I do If the new ECU does not fix it.

BTW
A Global Scan of the complete vehicle throws up fault codes for a fog lamp bulb, 778 steering angle sensor, Left door speaker open circuit, Ambient Temperature Sensor - That was missing so I manipulated it to read 21C as per AccuWeather on my Samsung Guide to the Galaxy, also similar to Intake Air Temp with Engine Off. DTC Cleared and stayed away.

As always, all ideas, help, thoughts welcome and reciprocated where possible.

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Fat Freddy
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Re: VW Golf 2005 - PD BKD Engine

Post by Fat Freddy » Mon Jul 17, 2017 11:17 pm

Dial it to match atmospheric and the Fault Clears.
And at what voltage was that?

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Re: VW Golf 2005 - PD BKD Engine

Post by STC » Mon Jul 17, 2017 11:24 pm

Wow FF You are as sharp as a pin :D

1.4 Volts Confirmed with PP3 and Fluke 123 Scope - and stable, not an average.
Not fluctuating either. Confirmed!

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Re: VW Golf 2005 - PD BKD Engine

Post by steevegt » Mon Jul 17, 2017 11:37 pm

STC wrote:3. Signal wire has no Volt Drop - Zero ! Wire cut both ends and substituted with known good.
I guess this means that before cutting the wire the voltage at the sensor side is the same as the one reported by the communication tool.

What was the voltage at the sensor side before cutting the wire and after cutting the wire?
If the sensor is OK, without the signal wire connected to the ECU, with good ground and 5 volt, the sensor must output the right voltage, proving that it is the ECU (or the wire between the sensor and the ECU) that is pulling the signal voltage up.

What is the bias voltage value? 5 volt?
With the sensor unplugged use a multimeter in Amp mode, to short the bias signal to ground, and measure the current. With this you could prove that the ECU internal bias voltage resistor is faulty, if you could compare this amp measure with another good car. I guess that resistor should be the issue.

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Re: VW Golf 2005 - PD BKD Engine

Post by STC » Mon Jul 17, 2017 11:42 pm

What was the voltage at the sensor side before cutting the wire and after cutting the wire?
Same !
I guess that resistor should be the issue.
ECU Fault >>>>

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Re: VW Golf 2005 - PD BKD Engine

Post by steevegt » Mon Jul 17, 2017 11:44 pm

STC wrote:
What was the voltage at the sensor side before cutting the wire and after cutting the wire?
Same !
I made my thoughts before assuming that it was not.

Is the voltage measured the same as the voltage reported by the scan tool?

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Re: VW Golf 2005 - PD BKD Engine

Post by STC » Mon Jul 17, 2017 11:49 pm

Steeve

Scantool, VCDS, KTS, Snap On do not report Voltage. Only Pressure Values - Good point you make :D :D

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Re: VW Golf 2005 - PD BKD Engine

Post by steevegt » Mon Jul 17, 2017 11:51 pm

STC wrote:Steeve

Scantool, VCDS, KTS, Snap On do not report Voltage. Only Pressure Values - Good point you make :D :D
Not even standard OBD2 Pids?

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Re: VW Golf 2005 - PD BKD Engine

Post by STC » Mon Jul 17, 2017 11:55 pm

Nope - did look.

Readiness monitors .... Checked everything I know !

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Re: VW Golf 2005 - PD BKD Engine

Post by steevegt » Tue Jul 18, 2017 12:09 am

STC wrote:Nope - did look.

Readiness monitors .... Checked everything I know !
If the sensor is good, and nothing is pulling up the sensor signal, with the voltage PID it should be immediate to condemn the ECU. I guess the ECU is misreading the voltage!?
Do you think it could be caused by someone that messed with the software maps?

I guess you could also confirm (waveform library) that the MAP value of the same engine at Idle shouldn't be around 1.4 volts, but instead the voltage the sensor is producing now.

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