i think i have posted this like ten times already lol
no worrys....
hope it helps dude
I finally got the swap (b18a) in my civic but unfortunately when I started it up it idled at 3k. Then when it warmed up it had a hunting idle from 2k to 2500 rpm. I stood over that thing for 3 days, testing and scratching my head. On top of that I did a TON of searching on the h-t, hybrid boards, and on G2IC. I hope what is contained within helps someone. Maybe they wont have to go through as much work as I did.
The idle on our Hondas is a tricky thing. It is controlled by two main sensors: the FITV and the IACV. The FITV is a mechanical valve that is controlled by coolant temperature (there is no ECU plug to it). When the coolant is cold the valve is open and letting air into the IM through a hole in the TB before the throttle plate. This essentially creates a small vacuum leak which in turn lets the motor idle higher than normal (supposed to be around 1500-2k for warming up). As the coolant warms up the valve closes and no longer lets air in through the hole in the throttle body. All the while the IACV, which is ECU controlled, is letting small amounts of air into the IM through another hole in the TB. Any amount of extra air the ECU is not expecting will confuse it and you will get either a high idle or a roaming/hunting/fluctuating idle. On to the troubleshooting.
First things first, don't skip any of these steps. From what I have read (and experienced) usually small dumb things cause these problems so don't overlook anything. Also refer back up to the pictures if need be.
1) Check your vacuum routing. On the underside of your hood there should be a vacuum diagram. If there isn't a diagram under there, there is one in a Helms, Chiltons, or Haynes manual for your car (you should have one of these anyway). Remember, ANY extra air will confuse the ECU. Check for cracked or bad vacuum hoses. If in doubt just replace the hose, they are cheap.
The PCV valve could also be the culprit. Take it out and examine it. If it is cracked it could be causing a vacuum leak. Replace the peice if you arent completely sure it is ok (the helms/chiltons/haynes manuals tell you how to check it).
2) Check to see that your throttle plate is closed all the way. Take your intake off at the TB and check to see that nothing is blocking the plate. If nothing is in the way and it isn't closed all the way, loosen your throttle cable.
3) Check to see if the nuts holding the TB and the IM on are tight, this was the source of my idle problem. If they are loose, tighten them.
3.5) Check the Idle screw. Its on the top of the TB right next to the red vacuum line in the first picture. Its a flat-tip screw and most TB's have it epoxied over. If your screw is not epoxied over try adjusting it.
4) Bleed your coolant. Some air bubbles may throw the FITV off and keep the valve open.
5) Take the 3 10mm bolts out of the FITV (you don't have to take off the coolant lines). Then take off the 2 8mm bolts off the plate on the back of the FITV. Once the plate is off you will see a white plastic thing, screw that all the way in. This causes a TON of people's hunting idle problems (it's a source of a vacuum leak). Put the FITV back on and start the car up. If it still idles bad go on. Here is a writeup on the FITV. {Jacksont001 note: it is located below}
6) Clean the IACV screen(s). See Oz's write up on G2IC. {Jacksont001 note: it is located below}
7) Make sure your car is completely warmed up. With it running, take the intake off the TB. There are 2 holes right in front of the throttle plate, these are the holes that feed the IACV (top hole) and the FITV (bottom hole). With your finger, cover up the bottom hole (it should NOT be sucking if your car is warmed up). If the idle goes down the FITV is to blame, either get a new one or take it apart and screw the valve completely closed (I have only read of people doing this, so I don't know exactly how. Also, you will have to keep the engine speed up yourself when the car is cold).
Next cover both holes up with your fingers. The car should sputter and die (or almost die). If it does then the source of your crappy idle is the IACV. Replace it. If you want you can test the IACV. Shut the car off and put + battery voltage to the blk/yel terminal (on the valve) and momentarily touch ground to the blu/yel side. When doing this the valve should click, if it doesn't, replace it.
If, when covering both holes the car still has a high idle, you have a vacuum leak somewhere. Again check the IM and TB nuts. You can spray carb cleaner around those areas and if any gets sucked in (the engine will rev) you have found your leak. Another source of vacuum leaks are where the FITV and IACV connect to the IM. Either replace the gaskets or use silicone gasket sealant.
8) If nothing has worked you should test your TPS. Probe the middle wire on the TPS plug (with the key on but not running, and the plug still connected to the sensor) with the + probe on the volt meter, and the neg probe to ground. You should have .5v with a fully closed throttle plate and 4.8v with it wide open. If the TPS is off, replace it. My TPS was .425v to 4.55v and it idles fine now so I don't know how big the margin of error is. Also, it is pretty rare for these to go bad.
9) If, still, nothing has worked you might want to try a new ECU. This also is very unlikely, but worth a try.
10) If it still idles bad, go through the steps again.
It was a pain to have this mysterious problem and very little info on how to go about troubleshooting it. The idle problem is a real PITA because there are so many things that cause the same result (the hunting idle). When I had this problem I read through a ton of posts over at Honda-tech describing the exact same problem but when I PMed them, they all had different fixes. I hope this covers all of the possibilities. If I skipped over anything PLEASE let me know
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Quote: Posted by The Oz at G2ic.com
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Teg Tip: Idle Air Control Valve (IACV) Removal/Cleaning Procedures...
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NOTES FROM THE AUTHOR
Well, BR explained it pretty simply. So, when I was able to rent the digicam the other day, I decided to clean the IACV and post it up. This is pretty straightforward, with the coolant lines being the only hassle (probably because I'm just too weak ).
CREDITS
BR - Well, he opened the doors and pretty much explained things very well.
INTRODUCTION
Task: Idle Air Control Valve (IACV) Removal, Installation, Cleaning
Difficulty: Easy
Time Required: Actual work is 30 minutes. Drying time is 3 hours depending on your preference.
Engine Used in this Guide: 89-91 B16A
Engines Applicable: Other B-Series engines will differ, but the idea is basically the same.
TOOLS REQUIRED
- 3/8" Ratchet
- 3/8" 12mm Socket
- 12mm Closed-End Wrench (if Ratchet is not available)
- Assorted Long Nose Pliers
- Carb Cleaner (readily available at your local Automotive Store)
- Towels
- Air Compressor
- Compressed Gas Can such as "Dust-Off" (used for computers) can be substituted if Air compressor is not available.
NOTE: If the pictures do not show, click here for the album:
http://www.imagestation.com/album/?id=4291328805
STEP 1
Figure 1 shows the location of the IACV. Get yourself familiarized with what you're about to do. NOTE: It is highly recommended that you do the work with the engine COLD.
Fig. 1 - IACV Location inside Engine Bay
STEP 2
Take a 12mm socket or wrench and remove the bolts shown in Fig. 2. The IACV will simply detach itself from the intake manifold.
Fig. 2 - Remove Mounting Bolts
STEP 3
Once the bolts are removed, you need to remove the 2 coolant hoses and the 2P Connector from the IACV. Use long-nose pliers to loosen the clamps that hold the coolant hoses tight. Fig. 3 shows the IACV removed from the engine and I have highlighted the items for clarity. Be careful not lose that O-Ring!!
Fig. 3 - Where everything is
STEP 4
Refer again to Figure 3 in Step 3 for reference. Take the Carb Cleaner and liberally spray the inside of the 2 holes shown in Figure 3. It may be best to remove the O-Ring if possible as I noticed that the Carb Cleaner SWELLED the rubber. However, the swelling should subside in a couple of hours. Once you are finished with the Carb Cleaner, take the Air Compressor and inject compressed air in the holes to dry.
What I have done is this: Spent approx. 30 seconds per hole injecting it with Carb Cleaner. Then spent 2 min. per hole with the Air Compressor. I then flooded the 2 holes with Carb Cleaner again and laid it down on the ground as shown in Figure 3. I left it soaking like that for approx. 1 hour. After which, I pumped the air compressor again to dry it. Just to be on the safe side, I left it to "natural dry" for 2 hours before installing it back on the engine.
STEP 5
Installation is reverse. Do not mix the Coolant hoses around. Although, I do not see any forseeable damage if you do (just be on the safe side, though). Don't forget the O-Ring gasket. That is quite important if you want to minimize air leaks. Take your baby out for a spin!
CONCLUSION
As far as I know, the IACV does not operate unless the engine has reached normal operating temperatures. Until it does, the Fast Idle Thermo Valve does the work. Again, I could be wrong. In any case, it is better to test the IACV while the engine has completely warmed up.
My bouncing idle has been fixed previously. However, I have noticed I feel less vibration in the cockpit during Idle after this maintenance.
If you have any questions, either post 'em here or email me at
the_oz@hotmail.com
Regards,
Oz
