1998 V70 GLT IAC problem, will not smog

jgerhard45 · Post by **jgerhard45** » 10 Jan 2011, 00:10

I still cannot get my 98 V70 to pass a smog test. The car runs fine down the road but during the smog test after sitting at high rpm the IAC begins oscillating and the idle speed surging. I thought it was a problem with the cooling fan because the fan doesn't seem to come on when it should but I've checked every component in the system. I have tried three different ECUs and two IACs. If I watch the coolant temp on the OBD tool it goes into this fail mode at about 210F. Are there any valves that open at about this temp that could create a vaccuum leak to the intake manifold? I've replace the thermostat and coolant temp sensor. The thermostat regulates at 194F going down the road but when I'm sitting still climbs to about 210F, is that normal?
The only codes I've seen are P1505 and P1507, IAC signal high and low.

Post by **jimmy57** » 10 Jan 2011, 11:36

cooling fan operation due to temp when A/C is not triggering fan due to A/C pressure is at about 220. There may be nothing wrong with fan system. How are you reading the coolant temp?
Are connectors in IAC valve plug secure? the prongs may have spread and you have poor conections.
Has the IAC valve been cleaned? crankcase vapors can get to that and it can get gummy and stick a bit making for erratic idle.

FCPEURO · Post by **FCPEURO** » 10 Jan 2011, 18:03

If the connector is clean and connected securely, then you may just need to replace the IAC.