I recorded some audio clips of my poorly idling Volvo. Two of them are the engine bay and the other is the exhaust. It is idling very poorly and I am wondering what could cause this issue? The only code I am receiving on my OBD is 121. I can hear a pop noise and when I put my hand on the intake it feels like it is backfiring into the intake. I took the off the hose that connects the exhaust to the intake but it still does it.

Also when installing the O2 sensor, are the 2 white wires interchangeable?

Your help will be greatly appreciated.
Engine 2

Engine 1

Exhaust



Thanks,
Garrett

 

Okay...

I'm going to point you to a rather long thread about a car I was involved with for a while. It had (and still has ) issues that it hunts (doesn't idle) well from time to time. The problem for the car is as of yet unsolved. HOWEVER, they go into nearly every possible thing that could be wrong and cause a car to hunt. Off the top of my head, I'd look for a vacuum leak. That can be an issue. Ignore the parts about the misfire, and look just at the thread about idle issues.

https://volvoforums.com/forum/volvo-...misfire-50499/

ALSO--what model car do you have? Is it a turbo or no? These details help considerably when trying to figure things out. I have most of my experience with 700s and 200s, and tend to bow out when questions about 900s come up.

 

yes, the two white wires are for the heater element, and don't care which polarity. one goes to ground, and the other connects to the same relay as the fuel pumps (so the heater is on when the fuel pumps are running).