Throttle Down Delay On Newer Vehicles?

[David006]

not really a problem but was driving SILs relatively new Vigo yesterday and tried my usual relatively quick gear changes as I do on my old B2500.

Anyways I noted I had to slow it down because the rev drop was delayed when I released the throttle..is this normal on newer power trains or is it a mal adjustment?

[stevenl]

In my experience normal on diesels, have always had this, also on my old Peugeot 504. There always seems to be a slight delay compared to gasoline cars, but this does make me wonder since you normally drive an older diesel.

Edited October 4, 2012 by stevenl

[SoCalChris]

Yep, my late-model 5.9L Dodge Cummins diesel did the same thing, and it behaved like the throttle is stuck open for a second. I was told this is purposely programmed into the engine ECU to prevent turbo "bark" which can be damaging airflow reversal through the turbo. This happens when the throttle is released too quickly and turbo slows down too fast to keep the air flowing in the appropriate direction.

[David006]

Yep, my late-model 5.9L Dodge Cummins diesel did the same thing, and it behaved like the throttle is stuck open for a second. I was told this is purposely programmed into the engine ECU to prevent turbo "bark" which can be damaging airflow reversal through the turbo. This happens when the throttle is released too quickly and turbo slows down too fast to keep the air flowing in the appropriate direction.

ok good stuff thanks ..turbo "bark" hugh...my old truck don't have a turbo so that's probably it. Thanks for prompt reply all.

d

[stevenl]

Yep, my late-model 5.9L Dodge Cummins diesel did the same thing, and it behaved like the throttle is stuck open for a second. I was told this is purposely programmed into the engine ECU to prevent turbo "bark" which can be damaging airflow reversal through the turbo. This happens when the throttle is released too quickly and turbo slows down too fast to keep the air flowing in the appropriate direction.

ok good stuff thanks ..turbo "bark" hugh...my old truck don't have a turbo so that's probably it. Thanks for prompt reply all.

d

Neither does my old 504, but still it did this.

[BSJ]

It's to do with the exhaust emissions. Suddenly taking your foot of the pedal allows unburnt diesel to expel to atmosphere. Yer, I know it's ridiculous when you see the amount of exhaust emissions coming from.....every diesel truck, bus and old pick-up!