hey guys this is a first time post for me sooo hii. but anyways im at a loss here i just bought a 1995 civic lx with a d15b7 motor and a manual tranny. well when i bought it it had the cel on and it would vibrate around 1400 rpms hot and cold. so i did a little troubleshooting and come to find out some one put a screw in the larger hole in the throttle body butterfly(smart huh) so i removed it and then started it up and then it started to idle high until it warmed up then it would flucuate rpm from about 900 to 1400. ahhh. so i went on this site and searched around and read about all the problems other people had and tried them all. i checked for vacuum leaks, bleed the coolant, changed the iacv, changed and the fitv - the fitv was new and i got a couple iacv's from the junk yard. and nothin has fixed it. except the iacv made it a lil smoother. when i first start it up and its cold the cel comes right on and it idles at about 1200 rpms and runs like crap. if i turn the heat on at his time it will smooth down to 700 rpms but it still doesnt run right. also if i hold down the brake at this time it smooths out a lil and idles at about 1000 rpms until i release the brakes. alsoonce iget going and im cruising along if i let off the gas just a lil bit then get on it again it jerks like its either gas on er off its kinda weird. then itll warm up and run like that until i shut it off then start it up again. so once warm and restarted the cel doesnt come on or at least not for a while but it flucuates rpm from 900 - 1400 rpms and runs fairly smooth once i get outta the idle range. until the cel come back on after a while (ie 20 mins or so) then it will still flucuate but it wont run as smooth. also once the cel comes on it does the gas on/off thing again. im at a total loss for this thing. its really starting to drive me nuts so if someone could please help i would greatly appreciate it thanks everyone and sorry for such a long post

 

What CEL code(s) have you retrieved? If you haven't retrieved the code(s), do so by following the instructions at this website:

http://www.honda-tech.com/zerothread/1901557

The code(s) is likely to be informative. If you wish, post the codes in this thread to receive more feedback.

 

i comes up with code 14 and thats it. thanks for the reply

 

Code 14 indicates a problem with the EACV (IACV) or its circuit (see pictures from the service manual).

I recommend that first you try cleaning your EACV with carburetor cleaner -- search this forum for how to perform this cleaning.

If cleaning doesn't help, then troubleshoot the EACV circuitry as detailed in the pictures.

If the circuitry is fine, then you might consider purchasing a new EACV.

 

cool thanks. i already tried cleaning the original iacv with no luck and i replaced it with a different one. which seems to work. but iam goin to test the wires just to make sure. were exactly is the test harness "A" that the diagram talks about. thank you so much for your help

 

Your replacement EACV was used so it could possibly be a little dirty/clogged up. Therefore, I recommend that you first clean it with carburetor cleaner before testing the circuitry.

You would need to purchase test harness A. You could probably purchase it from Honda or from some other online source.

Good luck with the troubleshooting.

 

There should be no holes in the throttle plate. Someone has modified it. I would suggest replacing the throttle body assembly as the most straightforward way to deal with it. Otherwise, stop up the hole again.

Very likely the previous owner has also tampered with the adjustments on the throttle body. The stop screw that limits how far the throttle plate closes needs to be adjusted so the plate just barely touches the throttle body (fully closed). It's only purpose is to keep the plate from slamming shut. This screw is NOT to be used to set the idle speed. Set it and forget it.

Then make sure there is slack in the throttle cable when no one is pressing the gas pedal, so the throttle plate does indeed close fully at idle.

Hopefully he did not tamper with the TPS (throttle position sensor) on the back of the throttle body. This is set at the factory and secured with screws that the heads break off. If you find it attached with regular screws you have to deal with the possibility of a misadjusted TPS.

Now with the engine idling, disconnect the electrical plug from the EACV. The idle speed should drop very low or perhaps even stall. If not there is something letting too much air into the engine, causing it to run faster than it should. Note that if this is the case, the ECU will be unable to control the idle and it will throw a code 14. Code 14 does not automatically mean the EACV is bad, as it is only one of the parts that could let too much air bypasss the throttle plate and get into the engine.

There is also an air bypass screw on the top of the throttle body, it is a large flathead screw facing toward the hose from the air cleaner. With the EACV plug disconnected and the engine warmed up, adjust this screw so the engine barely stays idling (400 rpm). Now when you reconnect the EACV the idle should increase to normal.