Main Relay -> erratic idle?

[jkrolikowski]

Like the title says... I'm not sure, but... thoughts?

Naysayers, check two things:
1) 90-93 Accord, Haynes manual says to check main relay and its connections if after testing the IACV and all tests indicate that IACV is ok. (it is a note in italics, after the section in the Haynes where it tells you how to test your IACV)

2) See schematic at back of Haynes manual. PGM-FI/Main Relay is wired to the IACV (note the schematic has the IACV labeled as EACV - perhaps it is a generic diagram..). I'm not good at reading schematics.. but looks like the main relay receives parameters from the ECU and based on this info and the main relay's own regulation of the fuel pump, the main relay will send voltage to the IACV accordingly.

I'm going to remove/inspect/fix/solder/replace in the next few days. I'll let you know what happens. I've done just about everything else, so I have nothing to lose.

[deevergote]

The main relay turns the fuel pump on when you start the car. That's it. It has nothing to do with your idle. If the car starts, it is working just fine. Don't mess with it.

You checked the IACV and ensured that it's functional, but did you adjust it properly? How about the FITV, which is another common part that influences the idle?
Check the "read this first" thread at the top of this section. In there, you will find instructions on properly setting your base idle.

Don't go grasping at straws and replacing or "fixing" random parts on your car. That's only going to create more problems, as every part you touch then becomes an additional variable in future issues.

[jkrolikowski]

The main relay turns the fuel pump on when you start the car. That's it. It has nothing to do with your idle. If the car starts, it is working just fine. Don't mess with it.

You checked the IACV and ensured that it's functional, but did you adjust it properly? How about the FITV, which is another common part that influences the idle?
Check the "read this first" thread at the top of this section. In there, you will find instructions on properly setting your base idle.

Don't go grasping at straws and replacing or "fixing" random parts on your car. That's only going to create more problems, as every part you touch then becomes an additional variable in future issues.

Both the IACV and FITV have been inspected, cleaned, and then replaced when they still did not work. In my extensive research about these parts, I have seen nothing about adjusting the IACV. Please tell me how I can do this.

I definately agree that fixing random parts can potentially create more probs./addt'l variables, but I change nothing on my car without researching it first and reasoning that it could be a source of the problem.

At this point, I'm nearly convinced that the problem is a vacuum leak, and I think it might be the intake manifold gasket. Question: I hear a hissing sound there, but I've always thought that this is the fuel injectors. Do the fuel injectors make a steady hissing sound? They're in the same general area as where the intake manifold meets the head.

I'm going to extensively check for vacuum leaks this weekend. I've been reluctant to use carb cleaner w/o an extinguisher handy, and I'm reluctant to buy an extinguisher, but i suppose I should have one around anyway. I think I have a propane torch and fuel line, so I may try this method as I hear it's safer than carb cleaner. Anyone know a method that is not flamable? I'd like to use smoke, but I'm not sure how effective this is or how it affects the engine when the smoke is sucked in... Can't find much info online regarding a smoke method.