I am new to the Honda-tech site so if I am doing something wrong or posting in the wrong place correct me. I have a 1996 civic 5 speed DX so the d16y7 engine and I have been having fluctuating idles when parked. I do not have a tach so I don't know the exact rmps in which it goes up and down. I plugged the whole TB and the engine idles at the correct rpms and does not fluctuate. I also replaced the IACV, throttle body gasket, the intake manifold gasket and swapped TBs and still have had no luck and I am at kind of a loss of where to go from here. If someone could walk me through the troubleshooting process I'd be more that happy.

 

What do you mean you plugged the whole TB? Have you adjusted the screw at all?

 

I took off the intake system so I could see the top of the throttle body and place my hand over the whole TB. And no I haven't adjusted the screw.

 

Bleed the cooling system of air per factory service manual.

 

I will tomorrow and I'll keep you posted

 

I have done the same thing and I have had the same problems. Fluctuating idle still after I have cleaned and adjusted the IACV and the FITV, replaced the TB gasket and checked for vacuum leaks with carb cleaner. I guess I'll have to try that next.

 

Post the CEL codes.

 

I got to be the noob and ask. I know by looking at your link that CEL is the Check Engine Light. But if the CEL is not on while my car is on, does that mean there are no codes? And if there are, how do I read them?

I have a 94 Honda Civic EX (I believe it's from Canada, since some of the threads say they are different).

 

It means that either there are no codes or your CEL is not functioning properly. To figure that out, does the CEL turn on with the key at the ON(II) position and then turn off after 3-4 seconds? If yes, then it is functioning and there are no codes.

 

So I just went outside and turned on the car, engine running. The CEL didn't turn on, it barely even flashed. I caused some of the lights around it to turn on; Seat Belt, trunk, etc. to see if it was the bulb, just now thought they are all seperate bulbs, haha, dumb idea. But then I turned off the car and turned it to the On position but no engine running (like when you hear the fuel pump turn on and the blower fan turns on) (I don't know the names of the key positions, lol) I then saw it come on for just under 3 secs then go off, along with an SRS? light come on then go off. So does that mean everything is working and no codes?

 

Yes your CEL works. If it doesn't come on while the car is running you have no codes.

To read them IF you did have them. You have an OBD1 vehicle, so you would pull the plug out from the passenger side under the dash. Then use a piece of wire or something to jump the connection. Turn on the car and your CEL will begin to flash. Long flashes are the first number, short ones are the second number.


Idle rundown usefully goes like this:
Bleed coolant
Clean IACV (Most likely your problem with a surging idle, try taping it with a screwdriver while its surging)
Clean FITV (And adjust cold idle)
Check you didn't create any vacuum leaks doing the above
Then adjust idle per FSM (Warm up car, unplug IACV, start car, adjust idle accordingly, turn off, replug IACV, unplug battery to reset computer)

Clean your TB while you there because you already have it all apart anyhow.

 

Thanks, that's a relief to know that there are no codes, since I just bought the car at 200k miles and not TOTALLY sure everything is copostetic. Sorry for asking seperate questions on your thread, Dziegler92, I'm new here too and read yours trying to learn. Thank you all.

Hope you get the issue fixed. I too have a flucuating idle but it only happens occasionally. Haven't figured out when it happens or done any of the things you have done like cleaning the IACV. I'll be starting a new thread on that asking people but first I want to read other's and see if anyone has the same situation. So I'm curious to see how your's turns out. Especially the "bleeding the cooling system of air", let me know if it works.

 

There are many MANY threads about this exact problem. I am honestly not sure if creating a new one would help. Try what was listed above and if that doesn't work THEN you can think about making a new thread. No offense but the tech section is already overrun with idle threads as is.

 

None taken, thanks for the advice. I'll have to search around to see if anyone else has my exact same issue and look for write ups on how to bleed the cooling system. Don't want to add fuel to an already huge fire, lol

Still let me know if that fixes it...

 

Don't worry as long as you are getting help that's all that matters. I solved my issue. When i replaced my TB gasket autozone sold me the wrong gasket and it was even labeled "D16 96-00 manual trans." Ill post pictures.

 

This was the original TB gasket autozone sold me. It was missing the a little extra gasket on the edge to cover the IACV air passages in the TB which would cause a vacuum leak and create the fluctuating idle I had.




This was the second TB gasket I bought(the right one). The part I'm pointing to was the part of the gasket that was missing from the original gasket.

Unfortunately I still have one code that is being thrown. P0105 which is that MAP sensor. So if someone could help troubleshoot this new problem that would be great.