Hi all,

I've got a '92 Volvo 240 that won't pass smog because of a high idle in park (as well as missing/failed thermostatic air cleaner). I've seen people ask for help on this issue but haven't found any results that show a working fix. The car idles fine in drive, but in park it's at about 1,500 rpm. I'm hoping a replacement of the idle air control valve would do it? But before I start buying more parts id like your advice..I don't think it's a throttle/idle adjustment though as it would likely stall if I set the idle lower. Thanks as always for your help,

Nick

 

warmed up, with the IAC unplugged, in park or neutral, and all accessories shut off, it should idle about 600 rpm. the IAC should bring this up to about 700rpm

make sure the throttle idle switch is working, it should be 0 ohms across the switch contacts with the throttle at idle, and open circuit with it even a hair off idle (measured with the engine shut off, and the switch unplugged).

if you remove the idle air control to clean or inspect or replace it, also inspect the rubber tubes that it connects to, if they are cracked, replace both of them.

 

I'm not sure I understand that second part.. With the car running there should be 0 ohms across the idle switch contacts (this has to be unplugged to measure?)

...and then with the engine shut off and the idle switch unplugged it should measure what?

Thanks for the clarification..

 

no, no, engine off, switch unplugged for both tests. the switch is closed when the throttle is at idle, and opens as soon as you give it any throttle (simulate by rotating the throttle 'spindle/drum'). closed switch should read 0 ohms, open switch should read infinite ohms.

 

Pierce, do '92 240's have any diagnostic capabilities? If so, he can do this and check the TPS, Idle Valve, Injectors, etc. -

https://www.volvoclub.org.uk/faq/EngineOBDCodes.html

 

yeah LH 2.4 has the same diagnostics as the 740/940's with 2.4, there should be a diag block near the left fender, under the cover this has 6 or 8 numbered holes, a push button, and a little jumper wire. follow those instructions to read any codes from the ECU (pin 2) and the ignition system (pin 6)