So I have been dealing with idle issues on my 93 honda del sol since the day I bought it. I think I finally fixed it with a new FITV but I decided to be thorough and go ahead and clean up the IACV. When I took it off I noticed that between the IACV and the throttle body there was a piece of paper. I'm not sure if the belongs there or not but it looks like some random piece of paper put there to block off the IACV. I didn't wanna mess with it since it was running fine but I just wanted to see if I should remove it or what is actually supposed to go there.

Another thing I wanted to ask was about the ECU and CELs. I've had this CEL since I bought the car but finally got around to pulling the codes. When I got to the cable I noticed that it already had a paper clip left in it from the previous owner. I took it off, started the car up then turned it off and shorted it again to see if it would give me the code but nothing came up. The light came on again without blinking. I reset the ECU and took the car for a ride and the light remained on, no change. I know that the engine isn't the original one, it is a d15 now so I don't really know how that affects stuff especially the ECU and CELs.

The last thing I want to ask is what sensors should this car have? It's probably a dumb question but I am just getting into cars and don't have much experience. I noticed there was a cable leading to nothing near the radiator area. I don't have a camera on me to take a picture but a list of the sensors would be good so I can look for them one by one to make sure everything is there.

Sorry for the wall of text and possibly stupid questions but I really want to fix up this car to the best of my abilities. Thanks!

 

No, there should not be a piece of paper under your IACV.

Take the paperclip out - you shouldn't have one in there unless you're pulling a code. If it stays solid with a paperclip in, that means there are no stored codes. What trim Del Sol do you have? The D15 actually is one of the original available motors.

What are the colors of the wires going to the plug, and what shape is the plug?

 

So I should remove that piece of paper? Is there supposed to be some sort of gasket between it and the throttle body? Well the paper clip was taken out but the CEL stayed solid still. I was told by the old owner that the engine was replaced. I'm honestly not super sure on the trim. How do I check that?

Let me go check the plug I don't really remember.

 

Okay the plug is white with green and brown wires running into it.

 

Yes, remove the paper. Yes, there should be a funny figure 8 looking rubber gasket on the IACV - you should be able to get one at your local dealership for cheap. Do you have a friend with a similar ECU that you can try out? That will help rule out a wiring problem, or a failed ECU.

Post your VIN. Leave out the last 6 digits for security.

 

It does have the figure 8 gasket. I'm just curious why they would put that paper there...I don't have a friend with a similar ECU but I'll try shorting it again tomorrow. It's dark here and I don't have a nice bright garage to work in XD

 

The PO probably had a problem with the IACV, and couldn't be fucked to diagnose and fix it correctly. Regardless, if you have any IACV problems after removing that absolutely stupid blockoff paper, they're all relatively easy to diagnose and fix.

 

Well thanks a lot. I will take look at it again tomorrow morning when the sun comes out. Hopefully there isn't any issues.

 

So I took the paper off this morning and the idle went up pretty high ~3000 rpm. I remembered that I had replaced the FITV and when I did the idle went really low so I unscrewed it almost all the way to the top to raise the idle. So I went back in and lowered the FITV again and now the idle is nearly perfect (as per the sticker under the hood). It starts a little higher when it is cold but goes down to the right RPMs after a few minutes of warm up. Still can't get the ECU to spit out the code though so any suggestions there would be good.

 

Solid code 0 for master relay?

 

Could that be it? I tried to follow the instructions for pulling codes as faithfully as I could and when I turned on the car the CEL just turned on solid. Is there a chance I am doing it wrong?

 

Good, so the PO had a minor IACV problem, ghetto rigged it, and you found it and fixed it properly. See? Told you it would be easy! The car is supposed to idle high while warming up.

Let's go back to step one with the CEL.

1 - Remove any paperclips, and reset the ECU. To reset the ECU, disconnect the battery completely and try to start the car, then reconnect the battery. After reconnecting the battery, start the car.

Does the CEL come back on? If it doesn't, good. If it does, continue.

2 - Turn the car off, then insert the paperclip. Turn the key to ON(II). Does the CEL blink, or does it stay solid?

If the CEL blinks, good. Go to the FAQ's sticky to find the list of CELs, and figure out what codes are being thrown. If the CEL continues to stay solid, continue.

3 - Find a friend with a matching ECU. Lacking in friends, find a junkyard or online vendor (eBay is great for this) and buy a second one. After replacing the ECU, follow the aforementioned reset procedure. Is the CEL back on?

If the CEL is off, good. Your previous ECU is fried and needs to be replaced. If your CEL comes back on, return to step 2. If, after returning to step 2, you get pushed to step 3 again, you have a wiring problem and should either start inspecting your entire wiring harness (time consuming and complicated) or just replace it with a known good unit.