RPM drop by 200 to 300 while decelerating

Tarek80 · Post by **Tarek80** » 13 Sep 2020, 09:23

Hello,
First of all, let me thank you all for all the useful information. I have learnt a lot

I have a 2001 C70 T5 Conv, it have about 104k miles that I just bought. The car drives good, needs work but over all well.
I have replaced the PCV system and did a tune up. This is my first Turbo car so I am still learning.
My question and I appreciate the help

. While driving at any speed and then take my foot of the gas, the rpm starts dropping in linear fashion. However, once the rpm drops to about 1500 I then drops about 200 to 300 at once. Is this normal?
Thank you

Post by **Sveedy** » 13 Sep 2020, 17:54

I read this post earlier and payed attention to my RPM's today. What your describing doesn't seem to happen too me. RPM's stay somewhat steady after I let off the gas. Then they slowly start dropping. I'm driving a turbo as well. I'm no expert but some will chime in.

Post by **wizechatmgr** » 13 Sep 2020, 20:05

Did this have the transmission flash done yet?

Tarek80 · Post by **Tarek80** » 13 Sep 2020, 20:18

Hi,
I am not sure. I will have to take it to the dealer or is there a way I can check?

Tarek80 · Post by **Tarek80** » 14 Sep 2020, 07:26

A quick video to show the issue

Post by **abscate** » 14 Sep 2020, 11:55

Throwing this out there

Are the engine rpms actually dropping or is it just indicating ?

Tarek80 · Post by **Tarek80** » 16 Sep 2020, 07:39

Thank you for the hint!!
I used Torque Pro to monitor the RPM and it also showed the drop.

Post by **wizechatmgr** » 16 Sep 2020, 16:52

Any misfire codes stored? I almost wonder if that's a throttle module getting iffy...

Tarek80 · Post by **Tarek80** » 18 Sep 2020, 09:48

Hello again,
I took the car to a local “ Volvo Specialist “ .. he checked for misfires and I also asked to update the TCM software. After couple of days I got the following
1. No misfire events
2. They couldn’t update the TCM software because they don’t have DICE bypass .. specialist if you ask me!!
However, they pulled the current ECU software part number 09480596A if that means anything ..
Now I need to take it to a Volvo dealer and see what they say.

Post by **abscate** » 18 Sep 2020, 10:27

I think the c70 stays P80 through 2004