2000 V70XC dead? Very rough Idle today

watsonjx · Post by **watsonjx** » 13 Sep 2025, 16:45

It drove fine yesterday. But today idle is very rough, jumping between 500 and 1000rpm. Push full gas and it only gets to 3000rpm. Engine shakes at 1000rpm.

Tried disconnect each ignition coil. Each time it bings down the top RPM to 2000. So all cylinders are still working?

Did big leak happen over night? Engine is too old? It is currently 242k miles so not a surprise?

Post by **volvolugnut** » 13 Sep 2025, 17:26

If you have good ignition and assume good compression, then the other variables are proper fuel and air.
Try to unplug the Mass Air sensor. If idle improves, the sensor may be failing.
Try to check fuel pressure if you can.
Try to remove a couple spark plugs and see if they are wet or black indicating too much fuel or not enough air.
Look for loose or damaged vacuum lines.
The air intake tubes after the mass air sensor may have a leak and the air flow reading if not correct for the fuel flow.
What is the general state of engine maintenance?
volvolugnut

watsonjx · Post by **watsonjx** » 13 Sep 2025, 18:01

MAF disconnected and it is slightly worse, not much difference. Engine has been fine in past years. Only regular syn oil change.

Spark plugs are replaced 30k miles ago. I believe it could be oil soaked but should not be so much difference overnight.

Maybe vacuum leak. I got small EVAP leak code recently. If the EVAP hose suddenly broke it could be this bad. Really don't want to work on it anymore.

watsonjx · Post by **watsonjx** » 13 Sep 2025, 18:22

There is a hose under the manifold, cracked to half open. I see it is attached to air pipe after MAF. Is it the problem? See the red marks on both ends of the hose.

But it could have been like that for long time.

Post by **scot850** » 13 Sep 2025, 23:02

Whilst I can't for sure say that is the whole problem, not having a sealed vacuum system from the manifold will affect how the system balances itself. Replace the pipe and see how the car runs then. May sure the pipe is oil resistant.

Neil.

Post by **abscate** » 14 Sep 2025, 01:10

Same evap pipe that brought my 1999 to its knees so many years ago. Generic hose will do to replace it

watsonjx · Post by **watsonjx** » 14 Sep 2025, 10:36

Thanks for confirming. The right end is on a T joint and all three hoses should be replaced I guess. Is it one part number for all the pieces? The joint looks like glued on permanently, no clamps on it.

Post by **abscate** » 14 Sep 2025, 11:08

I’ve got all the sizes documented somewhere, but the 2000 might be a bit different

melmaclifeform · Post by **melmaclifeform** » 19 Sep 2025, 19:09

watsonjx wrote: ↑14 Sep 2025, 10:36 Thanks for confirming. The right end is on a T joint and all three hoses should be replaced I guess. Is it one part number for all the pieces? The joint looks like glued on permanently, no clamps on it.

8MM hose should be the size you need. Get it on Amazon and just replace it in parts as they break. That's what I've done on my 2000.

Post by **abscate** » 19 Sep 2025, 19:28

Here’s the 1999 hose sizes