Okay, it's a 97 d16y8... converted it to OBD 1 yesterday with a P28 chipped+socketed with a Hondata S200B. When I start it cold or cool, the idle slowly goes from 1500-2000 and back as it's warming up. I unplugged the IACV while it was doing that and it idled at 800rpm... big surprise.

What's been bugging me is this loud whining sound I hear as it's warming up that I can only hear from under the car toward the front as it's warming up. That sound will go away as soon as it's been on for a certain amount of time, about 2 minutes... and it will idle normally (with the IACV still plugged in the whole time.)

Now, today when it was whining, I unplugged the EVAP purge control solenoid (on top of the fuel rail... this:



When I unplugged that, the whining stopped and it idled properly, but the CEL was on. I turned the engine off and started it back up again and the CEL was gone, still idling good.

My question is: What do I need that plugged in for with OBD 1? I thought the OBD 1 ECU didn't have EVAP controls... Sorry that was so long.

 

you dont use that sensor

 

Why does the ECU try and control it then?

 

the obd1 iacv has two wires and obd2 has 4.

 

So what is going to happen if I leave the EVAP purge control solenoid unplugged? Will it waste gas or ruin the system or something? I don't want it to ruin the system, I have to get it smog tested in a couple of years.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jdmhonda &raquo;</TD></TR><TR><TD CLASS="quote">the obd1 iacv has two wires and obd2 has 4.</TD></TR></TABLE>

My OBD 2 IACV has 2 wires, I think only the auto has three. It seems to be running ok now, no CEL snd it's idling ok. I'll wait to see what happens when I start it cold tomorrow.

 

something you might be willing to try is what i did on my ls ... that same valve i have but becuz my car is obd1 i took a vacuum cap and capped of the ends of it and just unplugged it .... car runs great and i ctually have etter response from the car period.....


Hope that helps Good luck

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LSegHatchy &raquo;</TD></TR><TR><TD CLASS="quote">something you might be willing to try is what i did on my ls ... that same valve i have but becuz my car is obd1 i took a vacuum cap and capped of the ends of it and just unplugged it .... car runs great and i ctually have etter response from the car period..... </TD></TR></TABLE>

Vacuum cap? Please elaborate...

 

I just looked at the wiring diagram, and one of the wires goes to the ECU, the other to the alternator SP sensor... hmm.

 

what is it that connects too the evap?Is it a vacuum or wire?If its a wire,i would just unplug it and since you said its fine i would drive it like that for a few days.See how the car performs and gas mileage,etc.Its probably not a vacuum because the rpms would tend too go up...

 

I had mine unplugged before with an obd1 conversion and never threw a code.

 

I think the reason the CEL was on was because I tried unplugging the IACV before the EVAP purge control solenoid, once I plugged the IACV back in, it must have stayed on. I was going to pull the code, but the light was gone when I restarted.

It seems to be running ok now, I just wanted to know how that would affect fuel mileage and performance.

Does everyone who converts to OBD 1 from OBD 2 have to disconnect that thing?