Is the Pre-heat hose really necessary to pass Emission? I have to take my 1988 240 Volvo Wagon A/T for the first time here in Phoenix,Az. It's running good, took take of the overheating issue(new radiator, new water pump, new thermo), all fluids changed, getting about 22-24 MPG city(FREEWAY TO JAMMED IN A.M. AND P/M). I noticed my pre heat hose is cut off and connected where is should be. Does anybody know if this could have an affect on the Emission Test? Im going to order it anyway but I need to get the emission done ASAP to get my registration. Thanks

 

It shouldn't affect the readings of the test but my fail a visual inspection if they are that strict.

 

Exactly. Here in Dallas county, they do a strict visual inspection but really don't know what to look for except missing parts. If they see the heat box on the header pipe missing the hose they could fail you. I simply removed the heat box from the header pipe so nothing appears missing.

 

if you reconnect that preheat hose make sure the thermostat activated flapper valve thing in the bottom of the airbox is working or permanently jammed shut, or you may end up frying your MAF.

 

Jammed shut? As in OPEN to the front for the cold air or jammed shut on the cold air side? It would seem you want it open to where the cooler air is coming from in front of the radiator as opposed to the dryer hose side that goes to the manifold. Is that correct Pierce, jammed shut on the warm side?