Help with erratic revving up and down

hajjat · Post by **hajjat** » 15 Jun 2021, 10:11

Howdy Volvo experts!

When I started the car today, it wasn't as smooth as usual. Felt it was choking. Then had this continuous revving up and down. It continued for a while then went away (sometimes it doesn't go away and continues actually). I tried to start the car again multiple times and got the same behavior.

Anyone had a similar behavior? Any thoughts what could be the problem?

Here's the video I recorded:

cleven · Post by **cleven** » 15 Jun 2021, 17:15

I’m almost in the same boat

.

Post by **jonesg** » 15 Jun 2021, 17:31

Only had it once when the weather was very hot, drove 45 minutes and it was idling that when I arrived, 3 hrs later after cooling down it was normal again.
Only happened the one time.
You might want to check for codes.

hajjat · Post by **hajjat** » 15 Jun 2021, 20:04

No error codes. Yeah in the past it happened when the weather was very hot; it's close to 90 these days in CA, so...

Post by **RickHaleParker** » 15 Jun 2021, 20:17

hajjat wrote: ↑15 Jun 2021, 20:04 Yeah in the past it happened when the weather was very hot; it's close to 90 these days in CA, so...

Ambient Temperature related ... Ambient Temperature sensor?
Try cleaning the MAF sensor which does double duty as the Intake Air Temperature sensor.

Post by **kcodyjr** » 15 Jun 2021, 20:42

Sounds like what happens when the IAC is on the fritz. Do P2's have one?

Post by **cn90** » 15 Jun 2021, 22:52

You have 173K miles on the odometer.

You should clean the throttle body.
I wrote a DIY in forum, basically you can slide the TB out to the driver side for cleaning.
No need to remove the Intake manifold to remove the TB.

hajjat · Post by **hajjat** » 15 Jun 2021, 23:20

You should clean the throttle body. I wrote a DIY in forum, basically you can slide the TB out to the driver side for cleaning

Cool. Found your DIY post viewtopic.php?f=10&t=78629. I'll give it a shot and see if that solves the issue. Never done it before, hope it goes smoothly (n00b here)!

Sounds like what happens when the IAC is on the fritz. Do P2's have one?

No, no codes.

Try cleaning the MAF sensor which does double duty as the Intake Air Temperature sensor.

Never done that before either. Let me buy a cleaner and try it out.

Thanks everyone for the great insights, I'll try these out and let you know how it goes!

Post by **RickHaleParker** » 15 Jun 2021, 23:52

hajjat wrote: ↑15 Jun 2021, 23:20 Never done that before either. Let me buy a cleaner and try it out.

Not a cleaner. MAF cleaner and nothing other them MAF cleaner.

Post by **abscate** » 16 Jun 2021, 03:55

On a turbo , that’s probably loose induction somewhere. Start at the air cleaner, and work your way through each clamp and hose looking for loose stuff. Then go back and remove each piece looking for holes

This will take about 2 hours, total.