Exhaust (Jake) Brake

Resurrection

I realize this is a super old thread. However, I'm reading it today so some one else is also I'm sure. My TDI (2004 bew 5spd 3" turbo back exhaust, otherwise stock) does choke down the vanes. Today I was descending a good hill. Let off the foot feed and watched my boost gauge go to 0psi and then climb back up to 6psi. This was in 3rd gear at about 2000-2500rpm. A little more back pressure in the exhaust would be good I think for long hill descents.

I don't think there is back-pressure [if so, extremely minimum] in the exhaust pre-turbo when the Turbo is not providing boost. During no boost, the Vanes in the Turbo are at an angle that doesn't make the Turbine spool-up to an RPM level that will make boost. Also, at no-boost level, there is some vacuum going on during the intake strokes of the pistons.

Any back pressure would be counter-productive to the intent of maximum fuel economy ...... doubt if VW engineers would have intended that to happen. No back pressure contributes to TDIs coasting good in gear.

Oddly, my ALH Vanagon has something going on that causes the ASV to close occasionally when I let up on the accelerator. The boost gauge will show in excess of 25 inches vacuum during such episodes. The engine obviously holds back while the ASV is closed. Once I press the accelerator the boost gauge and power of the engine spring back into action.

Yes I am very curious why you need better engine breaking? I have gone 160k on the same set of pads and I am still at 50%. I have done plenty of mountain driving and 4th gear gives me plenty of engine breaking on rarely do I need to use 3rd.

I think you guys just need to adjust your engine breaking start points

Sometimes I turn the A/C on while descending a long hill. You can actually feel the extra resistance it creates (car slows down a little bit).

In the winter, if you have the A/C on and the heat turned up, it'll basically act as a dehumidifier, which isn't a bad thing. The car won't get cold...the heater is more powerful so it wins.

I get a fair amount of engine braking for my needs.

Wind up replacing pads when rust gets under the material, after 5 years or so. The fact that it still has half material is irrelevant.

I am starting to think 3rd syncro is going, though. It is starting to catch a bit funny, and I'm noticing that I get gear grinding a bit more often. Like, I miss the shift more often. All of a sudden. I do lots of engine braking in 5th (no wear) and often drop to 3rd to finish slowing down--I'll burp the motor but 3rd is still seeing lots of shifting.