Having to shift to Neutral When Stopped in Drive

VolvoS402006 · Post by **VolvoS402006** » 16 Jan 2025, 11:31

I have a 07 Volvo XC 90 3.2 FWD automatic transmission with 200K. Lately I can't leave it in drive at a full stop with my foot on the brake. This doesn't always happen but is very frequent. When I need to come to a full stop in drive the car struggles like it is under a heavy load, it doesn't stall or quit. I can put it in neutral and everything with my foot on the brake and it is fine, then I can put it in drive and it works fine until I come to the next light or have to fully stop. I do not have any codes or messages displayed and the car runs and drives fine, as I keep it well maintained. If there is anyone who has experienced I would really appreciate and help in understanding this.
Thanks!

Joel

Post by **volvolugnut** » 16 Jan 2025, 17:33

This might happen if the idle speed is very high and the transmission remains in gear. What is RPM in this situation?
volvolugnut

VolvoS402006 · Post by **VolvoS402006** » 17 Jan 2025, 06:33

The idle speed is 1000 rpm and drops to 800 when I come to a stop with the car in gear. Then when I put it in neutral it goes to 1000 and then I put it in drive when the light turns green and everything is ok. Until I get to the next light then I have to repaet the process.

Post by **volvolugnut** » 17 Jan 2025, 08:29

I think your idle speed should be closer to 700-750 in gear or neutral.
Others will need to confirm and comment how to correct.
volvolugnut

Post by **xHeart** » 17 Jan 2025, 13:19

volvolugnut wrote: ↑17 Jan 2025, 08:29 I think your idle speed should be closer to 700-750 in gear or neutral.
Others will need to confirm and comment how to correct.
volvolugnut

Suspecting it to be an idle control valve failure - perhaps a major vacuum leak along the intake. Please check hoses, connectors, clamps along the entire intake to isolate.

Post by **xHeart** » 25 Jan 2025, 08:32

Item 11 is a your idle control valve (aka Check Valve) when coming to stop in Drive. Be prepared to service all items, 9, 10, 11, 12, 15.

chitownV · Post by **chitownV** » 26 Jan 2025, 11:28

The 3.2 does not have an idle control valve (ICV, IACV, ISC)) and the ECU controls the idle via the throttle body. If you ever read the live throttle body opening, it will vary during idle to maintain ~ 650-800 normally, depending on engine temp, ambient temp, A/C, etc. The #11 item in the picture mentioned earlier is the brake booster vacuum hose connected to the vacuum pump, which operates independently of the engine vacuum. The brake booster hose should also have a one-way valve.

With 200k miles and unknown maintenance, the first thing I would ask is if you ever changed your engine mounts.

The next thing I would ask is if you have done transmission fluid maintenance with specific T-IV or JWS 3309 fluid (for a 2007 3.2). If you have to shift out of Drive, there could be a potential pressure build-up or sticking solenoid issue. The load from a transmission could affect the engine where it tries to maintain the idle, like putting a load with the A/C compressor on. Switching to neutral the engine revs to 1k rpm due to the load, and then it adjusts lowering the idle before you go into Drive again.

A transmission maintenance issue would not throw a dash code and cannot be read with typical OBDII generic scanners. This might not even throw a transmission code. The best way to approach this is to simply change the transmission fluid with specific T-IV or JWS 3309 fluid.

Of course, there are other maintenance items that could contribute to vacuum issues at idle, vacuum that could affect the load readings, IIRC one way the 3.2 does it is through the MAP sensor on the intake manifold (could be covered in oil/dirt or is reading incorrectly), loose intake tubing bringing in more air, injectors not closing fully, etc. Maintenance is key.

Good luck!