86 Honda Accord LX-i Code 12?

[crod3]

I recently purchased this accord and I think i'm getting a code 12. The light under the driver side seat blinks 12 times pauses and then blinks 12 times again so i would assume that's a code 12. It runs a high idle.

The car idles high and the PGM light comes on after about 20 minutes of driving it. I checked all the vacuum lines and found a problem. According to the manual (fig. 1 below) there is a vacuum line that goes from the intake to the A/C Idle Boost Valve but I can't find it.


The line from is plugged


The A/C idle boost valve also has a plug


What vacuum lines go where and how should it be connected?

Here is a pic with the plugs removed.

[Oldblueaccord]

I recently purchased this accord and I think i'm getting a code 12. The light under the driver side seat blinks 12 times pauses and then blinks 12 times again so i would assume that's a code 12. It runs a high idle.

The car idles high and the PGM light comes on after about 20 minutes of driving it. I checked all the vacuum lines and found a problem. According to the manual (fig. 1 below) there is a vacuum line that goes from the intake to the A/C Idle Boost Valve but I can't find it.


The line from is plugged


The A/C idle boost valve also has a plug


What vacuum lines go where and how should it be connected?

Here is a pic with the plugs removed.

The 86 EFI motors are a bit differant than the other years. Most dont have that valve.

Try a google search images sometimes might find a diagram.

[Dr_Snooz]

I can't speak to your car specifically because I have an '89 and the A/C boost is integrated in the IACV. In general, however, the vacuum line will run from the manifold to some kind of electrically activated control solenoid, possibly in the black box or mounted on the firewall. From there it will go to the boost valve. Basically, when the A/C is powered on, it will open the electric solenoid and allow vacuum to operate the boost valve.

That won't fix your code though.

[Fixedit]

I have an 86 EFI with the a/c idle boost valve. The port on the intake and one the valve are plugged on mine as well. Being as my previous owner was not a mechanic/didn't mess with things, I had assumed the car came from the factory with those two ports plugged. I later confirmed the theory by looking at the vacuum line diagram under the hood; I can see the port on the intake covered with a cap. Also, I believe if the two ports were connected with a hose, nothing would happen as it looks like they would both have manifold vacuum. I don't think this is your issue. Also, code 12 should be the EGR code (computer senses the EGR isn't operating normally). That could be any number of things (inoperative EGR valve, EGR position sensor gone bad, etc.) but I also don't think this is causing your high idle (if anything it would lower it, if the valve was stuck open).

I recommend trying to adjust your Fast Idle Control Valve. This is located on your intake close to the firewall, right around the area of the throttle body. The top has two screws, remove one and loosen the other to swing the top around. You'll then have access to the adjustment; it is essentially a screw but you'll need something with a long skinny flat blade (I have successfully used a cheap ruler/straight edge). Downwards (clockwise) should lower the idle, upwards should raise it. Go ahead and let the engine get to operating temperature before adjusting this (it uses coolant to heat up and control how much air bypasses the throttle plate into the engine to keep it idling). After adjusting the valve and you cold start the engine (next day/after work etc.) and your engine starts surging at idle (900-1800rpm back and forth) the Fast Idle valve may need cleaning or to be replaced. I don't know enough to say which, but I had this issue until I adjusted it, I only got rid of the surging by bottoming out the adjustment and giving myself too low of an idle. If you're already maxxed out to the bottom and still have a high idle, I'd suspect an intake leak but I figure you've already checked for that.

As for your code 12, I'd use a hand held vacuum pump with a gauge, connect it to the port on the EGR valve, and see if it holds a small amount of vacuum. If not, replace it. If it does, use a multimeter and backprobe the position sensor (three wires right out the top of the valve). Positive lead to the signal wire and negative lead to good ground (the car battery is easily right there, can use the negative terminal). Then use the vacuum pump again, slowly apply vacuum and observe the voltage output of the sensor (key should be on in ignition). With the valve closed, I believe voltage should be closer to zero/0.5 volts. As it opens the voltage should approach 4.5 to 5 volts. A graphing meter would point out faults more clearly. If it all checks out fine, the valve may just be clogged with carbon and requires a cleaning for the EGR system to work properly. I do not know how to test whatever controls the vacuum applied to the EGR valve (it's in the magic black box with the MAP sensor).

Sorry to write you a book, I know I have trouble reading through long posts myself but I hope this helps

[Jafir]

After testing the egr valve, clean the ports on the white chamber inside the black emissions box to fix the egr code. 9 out of 10 on an 86 or 87 lxi that is what causes the code.

As for the idle, make sure the adjustment is set. The screw on the throttle body can back itself out. I would only mess with the fast idle valve if you don't get good result following the normal adjustment procedure.