Volvo Owners Club Forum - View Single Post - S40 (New) Engine 2.0D :

Sidonas · Aug 18th, 2020, 08:59

I've made some progress since and have a request, so I've decided to update the thread. It's going to be a long one but someone might find it useful in the future.

As I wrote earlier, my first suspicion was a bad TCV (the brown solenoid valve on the right side of the engine when viewed from the front). I took it out and did a quick test on it, as per this video: [YOUTUBE]https://www.youtube.com/watch?v=lKnE0RDVXBU&t=492s[/YOUTUBE].
Since it behaved like a faulty one, I decided to swap it out for a new one - no change in performance. The next step wasto figure out whether all the vacuum hoses that control the geometry of the turbine were intact. Since I couldn't get my hand on a vacuum meter, I bought a 60 ml syringe for that.

For someone that might go through the same procedure, it would make sense to get familiar with the anatomy of the vacuum system. Someone on this forum has already drawn it out for the Euro4-5 (twin throttle body) engines: https://i.imgur.com/apNRBEJ.jpg. Euro3 (single throttle body) engines don't have the "C" valve and all of its connections, other than that it's the same.

I then disconnected each hose on both ends, plugged one side and used the syringe to both vacuum and pressure test it - all of them were intact. My next suspicion was the second TCV (tagged as "B" in the drawing). It is responsible for controlling the anti-shudder valve but shares the same vacuum source as the TCV, thus a failure there could cause a vacuum loss in the whole system. I took it out and tried the test shown in the video. However, even without any electrical or mechanical input, it couldn't hold any vacuum and was basically a straight connection to the atmosphere for the vacuum system. It got replaced as well.

After I fixed the vacuum system, the car is now more predictable and requested vs actual boost stays fairly close up until 3k RPM at which point the actual boost value starts to go down. This is of little consequence in longer gears (3rd and up), however, in 1st and 2nd gears, as soon as I get to feel the boost, it starts to go down (see graph - https://imgur.com/a/opFONbf).

At this point, there are two problems:
1) Turbo lag is too high (doesn't boost up to the "desired" value until ~2.3k RPM;
2) Loss of boost past 3k RPM.

Taken together, the car is only really working to its full capacity in a narrow 2.3 - 3k RPM range. I will get the car tested by a specialist on Thursday and update you on the topic.

Now to the request, I'd like to ask someone who has a normally behaving 2.0D and a VIDA/DICE to record a wide open throttle run from 1st to 4th, switching gears no sooner than 3.5k RPM, so I could see what I should be aiming for with this car in terms of turbo lag and boost control.

Aug 18th, 2020, 08:59	#3
Sidonas Junior Member Last Online: Aug 28th, 2023 13:55 Join Date: Oct 2019 Location: Kaunas	I've made some progress since and have a request, so I've decided to update the thread. It's going to be a long one but someone might find it useful in the future. As I wrote earlier, my first suspicion was a bad TCV (the brown solenoid valve on the right side of the engine when viewed from the front). I took it out and did a quick test on it, as per this video: [YOUTUBE]https://www.youtube.com/watch?v=lKnE0RDVXBU&t=492s[/YOUTUBE]. Since it behaved like a faulty one, I decided to swap it out for a new one - no change in performance. The next step wasto figure out whether all the vacuum hoses that control the geometry of the turbine were intact. Since I couldn't get my hand on a vacuum meter, I bought a 60 ml syringe for that. For someone that might go through the same procedure, it would make sense to get familiar with the anatomy of the vacuum system. Someone on this forum has already drawn it out for the Euro4-5 (twin throttle body) engines: https://i.imgur.com/apNRBEJ.jpg. Euro3 (single throttle body) engines don't have the "C" valve and all of its connections, other than that it's the same. I then disconnected each hose on both ends, plugged one side and used the syringe to both vacuum and pressure test it - all of them were intact. My next suspicion was the second TCV (tagged as "B" in the drawing). It is responsible for controlling the anti-shudder valve but shares the same vacuum source as the TCV, thus a failure there could cause a vacuum loss in the whole system. I took it out and tried the test shown in the video. However, even without any electrical or mechanical input, it couldn't hold any vacuum and was basically a straight connection to the atmosphere for the vacuum system. It got replaced as well. After I fixed the vacuum system, the car is now more predictable and requested vs actual boost stays fairly close up until 3k RPM at which point the actual boost value starts to go down. This is of little consequence in longer gears (3rd and up), however, in 1st and 2nd gears, as soon as I get to feel the boost, it starts to go down (see graph - https://imgur.com/a/opFONbf). At this point, there are two problems: 1) Turbo lag is too high (doesn't boost up to the "desired" value until ~2.3k RPM; 2) Loss of boost past 3k RPM. Taken together, the car is only really working to its full capacity in a narrow 2.3 - 3k RPM range. I will get the car tested by a specialist on Thursday and update you on the topic. Now to the request, I'd like to ask someone who has a normally behaving 2.0D and a VIDA/DICE to record a wide open throttle run from 1st to 4th, switching gears no sooner than 3.5k RPM, so I could see what I should be aiming for with this car in terms of turbo lag and boost control.