!990 Volvo 740 2.3 210,000KM
I understand the IAC controlled by the tps. Also that it controls the idle, increases the idle when cold and maintain idle when warm. I took the hose off that comes off the air filter box and goes to the IAC, with the engine warm I increased the rpm to 2000. I still have air being sucked in through the hose. I thought that once the throttle is open ,the TPS cuts power to the IAC and no air is moving through it.
A previous post mentioned that a bad Iac could cause a louder exhaust sound, is this correct?

Thank you

 

Best bet is to pull the IAC and test it with 12v. See if the valve opens and closes. Right now it could be the IAC or the TPS or the ECU. Or you might have a leak in the accordion hose. Try to isolate the problem.