Hello, club members

I have a bad brake booster that is plug off for now and a fast idle problem.Can these be link together? The Honda has (1500) 1.5LT Japanese motor with a Keihin 3 barrel carburetor and it is a manual 4 speed if this helps.I wasted money putting two carburetors on the car and I still have the same problem.The problem is that it has a hard start up and the idle is high at start up.The car runs great after you start to drive it, but when you come to a stop it's back up there.It also diesels a bit on shut off.I replaced the cap, rotor, wires, plugs and set the timing just in case.I check with the carb cleaner trick to check for vac. leaks, but I found no leaks.It might be a sensor also, but which thermovalve would it be? The head one? The block one?, or the radiator one? The fan works and the gauge works inside, so I don't know what to do next.Can anyone help? I would be greatful. Thank you!

 

while parked try plugging up the vacuum to the brake booster, i havent come across a brake booster leaking vacuum but if it does then its letting air in the motor which would cause the higher idle and surging problems.

 

Thank you for your reply to my post. I plug off the booster with a rubber cap, but it might be leaking out of the cap. With the booster hooked up it makes a loud air leak. I will replace it soon and hope to fix the problem. I have another question if you can help. Is it normal to have back pressure when you open the gas cap? It make a loud swoosh noise and air blows by.I wonder if the gas tank vent has a problem. Thank you again for your post!