brockscivic

My 92 LX Civic has a 95 d15b7 in it and when i first crank it up it idles at 1500 but its like it is trying to kill itself. If u watch the tachit drops about 50-100 rpms and then comes back up. It only does this when it is cold.

ddong2lee

yea..i have somewhat the same problem...
i have a gsr ek coupe...
when i start it in the morning, its at like 1500rpms then goes to 2000rpm very slowly...then after like 5mins or so it goes down to like 800-900...
ionno if theres something wrong with my car but thats how my is...i would like to know why this happens as well...

dantastic

when its cold, your motor is supposed to idle high to help your motor warm up faster.

if your cold idle is fluctuating, try cleaning your iac valve, or just swap it out with the one off ur stock motor.

vinuneuro

I have the same exact problem with my stock H23a. Is IAC the idle control valve? How much does it typically cost to fix the problem. This actually also happend to me after a long highway trip. Most of the problem is when the car is cold.

Good ol' Screwtape

IACV = Idle Air Control Valve.
And yeah...that could be your problem. Check your CEL codes. If it's throwing code 14 it's indicating a problem with the IACV.

IACVs run about $80 new from Honda, but you can probably dig out a working one from a junkyard for a lot less $$ than that.
And yeah, like they said, just take it out (it's like..two bolts or something) and clean it. It's simple.


- or, to be overly technical and know for sure -

Testing Procedures :
- Reset ECU
- Start Engine
- At this point if the CEL IS NOT indicating code 14, rev and hold the engine to 3,000 RPM (with no load. i.e. neutral/park) until the radiator fan comes on, then release and let the engine idle.
- (If it IS STILL showing code 14, Scroll down to Part II)
- With the engine running and the gas pedal released, disconnect the 2P connector from the IACV.
- If the engine speed drops when you disconnect the 2P connector, it might just be poor connections or loose wires at C409 (left side under dash), C304 (left shock tower), C115 (IAC valve), and ECU.
- If engine speed doesn't drop...swap in a known-good IACV and retest. If the problem goes away, you need to replace the faulty IACV...or just clean it maybe.

Part II:
- If you reset the ECU, start the engine, and you're still throwing code 14...
- Leave engine running, disconnect 2P connector from IACV
- Measure voltage between the Yellow/Black wire and body ground.
- Is there battery voltage?
- No? Repair open in Yellow/Black wire between the IACV and PGM-FI main relay. Done.
- Yes? Turn engine off and reconnect the 2P connector to the IACV.
- Connect test harness "A" connector to the main wire harness only, not the ECU.
- Turn engine on.
- Momentarily connect the A9 terminal to the A23 terminal several times.
- If the IACV clicks, substitute a known-good ECU and retest.
- If the IACV doesn't click, check for on open or short in Blue/Yellow (Grn/Wht) wire between IACV and ECU (A9). If the wire is ok, replace the IACV.

ej1civic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by brockscivic &raquo;</TD></TR><TR><TD CLASS="quote">My 92 LX Civic has a 95 d15b7 in it and when i first crank it up it idles at 1500 but its like it is trying to kill itself. If u watch the tachit drops about 50-100 rpms and then comes back up. It only does this when it is cold.</TD></TR></TABLE>

I have the same problem! Could it be a something like a chipped ECU? Ever since I put my chipped ECU in, it started doing this.

Evs-One

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ej1civic &raquo;</TD></TR><TR><TD CLASS="quote">

I have the same problem! Could it be a something like a chipped ECU? Ever since I put my chipped ECU in, it started doing this.</TD></TR></TABLE>

your car doesn't like you....plus it's slow

anyways....if the CEL isn't coming on....you may be able to get away with just cleaning the IAC. When you pull it off, you'll see a little screen...which is basically a filter. When this gets dirty, the IAC opens up more to allow for air to squeeze past the dirt, and then shuts fast because too much came in...thus you have the up and down idle.

It could also be a vac leak, or a bubble in the coolant. All of these must be checked. If you have a vac gauge/boost gauge, check and make sure vac should be about 20 to 22 at idle.

Clean out the IAC,reset ecu, and see if that helps.

civiceg9

can someone just point out where is the IAC
a picture would help

JDMlyfestyle

It could be your TPS (Throttle Position Sensor) Mine is doing the same i did a CEL tonight and its throwing a code 7 which is the TPS

SLeePeR012

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civiceg9 &raquo;</TD></TR><TR><TD CLASS="quote">can someone just point out where is the IAC
a picture would help </TD></TR></TABLE>
You should search.
Its a metal piece thas behind your intake manifold and is attached to the manifold by 2 10mm bolts. Its on the firewall side of my manifold but in other manifolds it can be located in front of the manifold. Anyways it has 2 coolatn lines coming from the bottom jus clip them off and take the metal peice off. You'll see 2 screens in there they should both be dirt black because of your nasty idle. Take some CARB cleaner spray it in there a few times untill its nice and clean let it dry for a few hours and you should be set.

If you're having problems at a light where the idle drops at complete stops then it's your IAVC not geeting enough Oxygen.

As for the TPS I have not a clue, if someone wants to fill us in about it that would be cool.

DaX

iTrader: (1)

check to see that your fast idle valve hasn't come apart on the incyde.

Jstue

what if you idle fluxuates from 1000-2500rpm and back down.. i have a d16y8 running off an d15 ecu.. i think thats the problem. but until i get my p28 i have to live with it. i think im gonna try cleaning the IAC. p.s. im also running off a dx(d15) wireing harness.. it idles at the normal cold postion (1200rpm) but once it gets to normal operating temp it starts fluxuating. GETS REALLY ANNOYING!

Jstue

anybody had this problem before?

vinuneuro

I have noticed that after having the idle problem described by many if the users here, my engine has also felt rougher. Not just at idle! My Lude has a stock H23 with 57k. If the engine seems rougher during driving also, could it still be the IAC?
Should I be throwing a code?

Jimmy

iTrader: (5)

Clean your IACV or try adjusting your idle?
Any questions PM me

C uR eX

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civiceg9 &raquo;</TD></TR><TR><TD CLASS="quote">can someone just point out where is the IAC
a picture would help </TD></TR></TABLE>

usually it right behind the intke manifold next to the throttle body, it has to bolts holding it and has to hose running to it..

these are the problem you might wannna check out whne this kinda idle problem...
1) IACV
2) TPS
3) ECU (chipped one's)..i had this problem casue of a chipped ecu..change the ecu and the problem was gone.

DaX

iTrader: (1)

FAST IDLE VALVE

causes jerkiness in part throttle, "hunting" idle, high idle

civiceg9

Clean out the IAVC and still the same,
start my car and it goes to 2500rpm.

anyother method of fixing this?

civiceg9

oh yeah can someone point out where is the
Fast Idle Valve?? Thanks

vinuneuro

I also had the rev flux problem when the engine was hot. Could this still be one ofthe idle vavles or the TPS. Could the problem also be a bubbles in the coolant due to a leak.

DaX

iTrader: (1)

FAST IDLE VALVE

It should be under the throttle body...it has no electrical connections going to it, has one or two coolant hoses going to it [depending on engine]. Should be like 3 bolts holding it on...take it off [plug up your coolant lines that you pull off], take the plate off the end, and make sure the white plastic thing is screwed in and not loose in there.

Your fast idle valve is 10 times more likely than your IACV to go bad.

vinuneuro

Couldl the problem be caused by bubbles in the coolant due to a leak? Would fast idle valve still show its problem at higher engine temps. What could be the problem if i have the same problem as others when its cold at idle, but also the engine doesn't seem as responsive and rougher than normal.

civiceg9

I change a new IACV
and still does the same

may have a vacum leak somewhere, I am guessing
so leave it to the Honda guys and see they can do about it

JDMlyfestyle

did you do a CEL code check. Do that first before you go to honda itll save u alot of time and money

vinuneuro

The honda dealer told me that somebody had messed around with the base idle ( i just bought the car). If the base idle was off, would the idle always be kind of wierd or just sometimes? It kind of felt like the car was worse when it was cold outside?