'06 Jetta Intermittent Throttle Response

’06 Jetta TDI BRM has an intermittent issue where the throttle is not responding and engine speed is reduced to idle rpm. This occurs while driving and in park revving the engine. Once the accelerator pedal is released then response returns. Typically occurs when the engine is in the 1500 to 1900 RPM range.

No CEL indication or other abnormal indications. VAG-COM shows there are no DTCs.

Monitored the accelerator pedal input for Throttle Position Sensor and no issue as the indication increases throughout the range of 0 to 100% without signal dropout.

I read that an ASV problem could possibly be the cause but unsure of this. The ASV cycles when the key is turned off as it should.It may be a coincidence but I unplugged the ASV, revved in park as well as drove the car and the “no throttle response” did not occur. Could it be the ASV position signal to the ECM is an issue prompting the engine to go to idle speed?

This evening I plan to monitor the brake switch input to rule it out. While in park I did not notice the green pedal indicator light on the panel going out but I want to monitor the input to make sure.

Ready to purchase a new ASV but would like a bit of input from you guys if there is anything obvious I am missing or additional checks I should make.

Get or find VCDS and do a full scan really hard to say if it electronic or mechanical off the top of my head.

If the ECU sees a brake pedal input while driving under certain circumstance it can reduce RPM to idle.

In Park I am not sure what the BRM's rev limit is (lots of cars do not allow the engine to run at full speed while in Park). But I know it is more than 1800 RPM.

There could also be something in the M-unit requesting idle speed.

N.CaTDI said:

Get or find VCDS and do a full scan really hard to say if it electronic or mechanical off the top of my head.

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The VAG-COM tool I am using is the Ross-Tech VCDS with HEX-V2 interface module. With the initial full scan no DTCs are present. I will run another scan and post the data to see if anything stands out.

Pncsmith said:

The VAG-COM tool I am using is the Ross-Tech VCDS with HEX-V2 interface module. With the initial full scan no DTCs are present. I will run another scan and post the data to see if anything stands out.

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Sorry did not read carefully. Did you try the output test for the turbo boost N75? If you only got this when driving I would think Ziptie mod but in that you are getting it when not under load does not appear likely.

Reconnected the ASV valve and could not get the throttle response issue to re-occur while parked or driving

Verified pressing the brake pedal while driving will disable the accelerator but it will resume on it's on. Definitely not the issue I have been experiencing.

Performed the N75 output test as suggested by N.CaTDI and checked out good. The turbo vane rod cycled up and down physically and 10 to 90% duty cycle. The rpm increased to 1400 during the test with a boost pressure of 980(10%) to 1142(90%)

When I was watching the turbo vane rod cycle I noticed the vacuum line going to the actuator was split! Ah ha! Was this my smoking gun causing the throttle response issue?

Repaired the vacuum hose and took a drive, acceleration is noticeably better from takeoff through 3rd gear and can feel more power. No throttle issues during this drive.

Could this leaky vacuum hose be the cause of my intermittent throttle response? I'm still a bit hesitant to get on the freeway not knowing for sure if I have fixed the issue.

So far the vacuum leak fix has resolved the issue. Thanks for input!

Pncsmith said:

So far the vacuum leak fix has resolved the issue. Thanks for input!

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I was in Mexico a few years ago and another TDI member was having turbo loss. I had my VCDS cable with me so offered to help but found out his older car would not work with my cable. Looking at the engine we found a split vacuum line which was the cause of his problem very common problem I think for long-term replacing most vacuum lines every 5-10 years or so is good insurance.