davidjoe007

I've been having backfire after the supposed warm up...the idle comes down way too soon...the idle comes down before it's actually warm. After it comes down it backfires on a slight rev and smooths out once its about 180 F. or accutally warm. The factory service manual says, "the air regulator by-passes the throttle valve to control the quantity of air for increasing the engine idling spreed at bimetal temp of below 176 degree F. A bimetal and a heater are built into the air regulator. When the ignition switch is turned to the "START" position or the engine electical current flows through the heater and bimetal, as it heated by the heater, it begins to move and closes the air passage in a few minutes. The air passage remains closed until the engine is stopped and the bimetal tem drops below 176 dregrees F." If the air regulator is not working properly it would effect the air/fuel mix causing the backfire. What do you guys think. I think changing the air filter might help too. By the way I'm enjoying my Factory Service Manual. There is still a slight hesitation once it's warm and accelerting fast. Could the air regulator affect the performance of the car once it's warm? Maybe by staying open. I took took the Air Regulator off and the valve was slightly open. With the car off I think it should be open and then close as it warms up. Maybe it closes early or not all the way? Anyone have any experience with this?

jfairladyz

Yeah it should close as it warms. It shouldn't affect the car too much if at all by staying open. The air is still metered by the AFM, so it's accounted for. The only thing it would do is cause a constant high idle when the throttle is closed. It's just there to help the engine at idle, and just as take it off idle. Once the throttle is opened, the AR is a non-factor in driveability. However, staying closed when it's cold will cause issues like stuttering, hesitation, and possibly backfiring. A clogged air filter will definitely cause a hesitation if it's bad enough. And I don't think the valve ever closes completely. I think it stays open ever so slightly just by the way it's designed. Take it off, and check it early in the morning while it's still cool and see how far it's open. Then put it on the car, let her warm up and check her again, the opening should be alot smaller. Another way to check is when the engine is cold, squeeze the hose between the regulator and TB and the idle should drop. Then with the engine warm, do the same thing and the idle should stay constant. If this checks out then the AR is probably good.