I have a '91 Prelude SI with the 2.1 L. I just replaced the Head Gasket, Timing Belt, Water Pump, Drive Belts, Misc. Gaskets, Readjusted the Valves. Now it has a rough Idle which was not present before, and when you put a load on the engine it dies. I called the local Honda dealership, and I've spoken with 3 people there and received 3 different answers. 1) The Main Computer was bad. 2) The Ignition was bad. 3) There was air in the block. Then I asked one of the Parts Guys @ Autozone and he suggested that I check the Idle Solenoid. This makes the most sense to me, but how do I check it, and is this really the problem? I would really appreciate an Honest answer!!!!!
THANKS!!!!!

 

welcome to the forum. suggestions, (due to replaced the head gasket,) take a compression check to see if you have low compression. ( can cause a rough idle ) readjusted valves can also cause a rough idle, recheck for proper gap per service manual. check your plug wires, being carbon, it can leak or crack and not be able to see. check at night to see if there is a spark jump. and It is possible the idle control valve is dirty or the solenoid is going bad, try cleaning the valve. Don't know an honest answer, need to trouble shoot the system first for cause.

 

Thanks for the suggestions! The Plugs, Wires, Distributor Cap, Rotor, Ignition Module, Exhaust Manifold and Flange Gaskets have all been replaced, But I'll check the wires for any issues as they have been taken off a few times. I'll check the compression and the valve tolerance. I cleaned the Idle Air Solenoid and it made a small change, and I tightened the White screw shaped valve inside the Fast Idle Solenoid and that made a moderate change. I also checked and released the air pressure in the Purge Valve. I was looking through all the posts and I noticed one on how to test the Idle Air Solenoid and according to the procedure if the solenoid is unplugged it should cause the engine to idle up and down. When I unplugged the Solenoid on the car it died, so if the test is accurate, then the solenoid is bad or going bad. I have found only one company that makes a new one. I don't have $200 to find out if this will cure the problem. I hope to find one in the salvage yard so that I can find out if the this really is the problem. If you can offer any other suggestions, I will truly appreciate it!!!

Thanks!!
Zem