No idea why this is happening.

[Netrover]

I’ve had my MY10 R36 for four years and absolutely love it. About once every 3-4 months a curious thing happens when I am driving on one particular section of road on my way home. It happens on this 5km stretch of road, and only in the one direction. From memory I have experienced this in other places, but I would say 99% of the time it is on this stretch of road.

I live about 30km from work, and the way home consists of the following terrain:
- 5 km of flat city driving. Stop/start up to 50km/h, followed by
- 3 km of uphill winding road to an altitude of about 300m, maximum of 70km/h, followed by
- 2 km of slightly steeper downhill winding road, maximum of 80km/h, followed by
- 20 km of mostly smaller hills and winding roads back to home

When I am driving up the 3 km uphill section, and when I apply the accelerator after rounding a corner, the engine dies for a second causing the car to slow down as if I had applied the brakes, before power resumes and it speeds up. It never happens in the first section of the hill, always in the top section. Sometimes it does it a couple of times in quick succession, say over 3-4 seconds, and sometimes again on following corners. It very occasionally happens going down the other side, I guess because I am just coasting down and not using the accelerator much. I have noticed it happen a few times right at the bottom when I have stepped on the gas. It doesn’t happen again for the remainder of the journey home.

I drive to work on the same route, but it has never happened in that direction.

It never happens on the open road at 100km/h (and faster when overtaking!) or under hard acceleration. Just completed a round trip of about 600 km on open roads with no issues.

I always use 98 octane fuel and stick to the service schedule with the local VW dealer.

Had about 30k on the clock when I got it, and has about 75k on the clock now.

I have no idea why this happens, and would be very interested to hear your thoughts. Thanks in advance.

[Passat R36]

Any error codes?

[Lucas_R]

Im wondering if you are (without realizing) pressing the throttle pedal while your foot is still partly on the brake - which on these cars cuts the power to the engine temporarily.

I used to do this occasionally in my Golf GTI and it drove me bonkers. Easy enough to do in a situation where you are going up a hill where you are on and off the brake and throttle all the time.

[Netrover]

Any error codes?

Workshop have not advised me of any, but I will ask them specifically at the next service.

[Netrover]

Im wondering if you are (without realizing) pressing the throttle pedal while your foot is still partly on the brake - which on these cars cuts the power to the engine temporarily.

I used to do this occasionally in my Golf GTI and it drove me bonkers. Easy enough to do in a situation where you are going up a hill where you are on and off the brake and throttle all the time.

interesting possibility. When it happens next I will check it out.

As as I said it only happens in that small stretch of road, and I drive lots of hills elsewhere.

While I hardly ever let the fuel tank get below half full, I did wonder if this is a fuel supply issue created by a long uphill drive and twisty turns. Again odd that it happens mainly in one stretch of road.

[Lucas_R]

interesting possibility. When it happens next I will check it out.

As as I said it only happens in that small stretch of road, and I drive lots of hills elsewhere.

While I hardly ever let the fuel tank get below half full, I did wonder if this is a fuel supply issue created by a long uphill drive and twisty turns. Again odd that it happens mainly in one stretch of road.

If the tank was quite low then it could certainly be a possibility, but anything more than say 1/3 of a tank then i cant imagine it would be an issue.

[Lucas_R]

Also refer to this thread as it might be the same/similar issue: Low fuel pressure and misfire?

[Netrover]

If the tank was quite low then it could certainly be a possibility, but anything more than say 1/3 of a tank then i cant imagine it would be an issue.

Thanks for the reference. I will pass this on to the workshop next service.

[befau]

(deleted)

[Guest001]

One thought is clutches

Scenario Going up hill take foot off going into corner, car slows due to uphill.

Go around corner no throttle Car thinks you are slowing and has gearbox ready to change down again. However you hit the loud pedal and woops, gearbox has to change to other clutch to change up which take a small bit of time.
Just a thought

[sn809]

Lol seems similar to injector failure issue in the 125KW diesel passat. Atleast that is what happened once to me, shortly after VW issued a recall so did not have to worry about it too much.
Going up hill the power just went and then suddenly kicked back in.

[shaunbags]

+1 for mechatronic shinannigans.
I think hillbilly is onto it.

Drive the section of road in manual mode next couple times to see if that does anything different?

[Netrover]

+1 for mechatronic shinannigans.
I think hillbilly is onto it.

Drive the section of road in manual mode next couple times to see if that does anything different?

i always use manual mode on the hills, and slide shifter back to auto when in town.

In saying that, I think when it started happening a few years ago I did slide it back to auto on the hills to see if it made a difference, but it continued to happen. When it does happen, it’s not just once. It happens multiple times in a short period of time.

I don’t think it’s happened again since my original post.

[shaunbags]

oh well hopefully it stays as one of those minor niggles!