crazyz250

2000 Honda Civic lx d16y7 motor non-vtec. Bought the car for $900 and a motor for $300. Put the two together and i got me a nice car for cheep. I am having some problems with the IAC tho...

P0505 - Idle control malfunction is my CEL light.

I have so far tried 3 IACV's and non of them have worked (All of them have been sitting for atleast a month). I have extensivly cleaned all 3 of them, along with my throttle body and varios parts of the IM. The car idles as it should when cold (high idle) after driving around for a bit it then begins to go up-down-up-down (1000 rpms - 1300 and back down) when you really beat on the car it goes away. The part new is over $400 so that is out of the question. Also once the car is fully warmed up and if you give it about 1/8 throttle it will stutter (almost like a 2-step on a turbo car) and when it does that the CEL comes on and says the PO505 code so im pretty much stuck.... whats next?

EGTurboB16

Check your vacuum system, make sure all the hoses are hooked up correctly. Usually there is a diagram of the proper set up under your hood, but I'm unsure if the car and engine are OEM, you can check for your engines specific diagram some where on the internet I'm sure.

jdm_sir2

Alot of people always think that the erractic idle is only cause by the valve malfunctioning but it could be so many other things causing that exact symptoms!

Ok you replaced the IACV with a new one!
I'm guessing since u put the engine in you must be mechanical inclined!
Try checking the valve lash! It's always over looked by honda owners this is a simple adjustment that should be done anywhere between every 25,000 - 30,000miles.
So once you do that and you still have the same problem check for any vaccum leaks if the engine is more than 8 years old you might want to change the intake manifold gasket also replace any vaccum lines and fuel lines!
Another thing check your tps make sure it's working properly check what the volt output is usually .5volts closed and 4.5volts wide open if you get any crazy numbers than the TPS my have taken a crap!
If you've done all that and you still have those problem check the engines compression!
If you get low numbers all accross the engine is probably shot if you get low numbers in one or two cylinders you might have a blown head gasket!

This is all things you might want to look in to! It's all a simple process of troubleshooting!

I hope all this might enlighten you!

Electron Eg

Yea i have a d16z6 and mine does the same thing!!! but backwards, mine does the whole up and down until it is up to operating temp... i dont know why!! and its so annoying and driving me crazy

crazyz250

My motor is a d16z6 block/vtec head with y7 everything (vtec not hooked up)

It has a new IM gasket
i will check for vaccum leaks
where exactly is the TPS? easy to change?
Has good compression - it was a good running motor when it was pulled.

I know my volts may be low, the batt light comes on now and then it has a brand new batt. but the alternator is who knows how old. But that isnt going to caue it to not idle right. My friend had teh same EXACT problem. He bought a iac of someone online and it worked fine problem solved. So i'm thing these iacv's are very easy to go bad and i just need to find a good one...

94EG8

What intake manifold are you using? If using a Z6 manifold with Y7 ECU you'll never get it to idle right, easiest solution is to use an automatic Y8 manifold and throttlebody.

crazyz250

z6 block/head/dizzy y7 everything else (IM EM ECU etc)

CHR

CrazyZ250,
Did you ever find out the problem with your car? I have a similar problem with a 2000 Civic EX. I have replaced the IACV and TPS, car used to idle erratically. Now it only idles high (Around 2,800-3,000) and it's driving me crazy. Please help!

-__-

when u replace or mess with the TPS, you have to CALIBRATE IT afterwards. if not, your car will run shitty. but do what the other guy said first. did u change spark plugs/wires/cap/rotor and all the regular maintenance stuff? also check the timing. make sure the Mechanical timing is correct.

^^to CHR, if ur car is idling steady at 2800 RPM, u may need to adjust the idle screw on the throttle body and recalibrate the TPS

Former User

Also check whether the throttle cable is adjusted too tightly. There should be about 1/2" slack in the cable.

darrinbrewer

iTrader: (1)

i ran into a 3 wire- 2 wire issue, put a 2 wire ITR iacv in a auto dx car (converted to 5 speed)

just some info.....

CHR

Thanks, Darrin. I will keep that in mind.

CHR

After having tried everything recommended and nothing worked...I saved up and am about to buy a new throttle body from a local dealership. They parts salesman told me that I could swap the throttle body out myself without any calibration required.

Anybody had any luck with this?

JJDd16z6

darrinbrewer do you have a link to the page you got that info from...i need to wire a 3-wire IAC plug onto my old harness that has a 2-wire IAC

Supaslowsi

my 2000 si does this too..... when i step on the gas to take off from a light my engine pulses from 1600-1800 unless i push the pedal harder then its fine...seems like there is a dead spot..... any ideas

chope045

i just rebuilt my motor and the other day it was kinda pulsing from 2500-3500rpm cleanded my plugs and checked all my sensor connections the next day it just stoped but for a pulsing idle change the tps my car was doing that drove me nuts

motegicivic

I think all older vtec has dead spots before the vtec kicks in.

Do you have an aftermarket exhaust?

Also check your timing.

Supaslowsi

yes i have an aftermarket exhaust.... i have a dc header 2 1/2 inch catback to a flowmaster 40 series all of which were on the car when i got it... idles fine until the iac kicks in then it goes up to 1500 dosent move around really at all. when i try to take off from a light it pulses hard from 1600-1800 but once i get past that it revs all the way to red line great

EGscrapyard

SSame thing was happening to me with my b16 turns out the wrong plug was hookkked up to the iacv. So remember the stupid little things lol

redjones

Happened to me. Use that spray to check for leaks, my throttle body gasket had a leak.

Supaslowsi

So I have come to the conclusion that my car has a mind of its own... Had all these issues on Thursday... And when i wake up Friday car starts and runs perfect with cel still on drove around like thirty miles with no problems at all. Cleared codes and now idled at 2k til it warms up and has slight idle search but settles down to about 900-1000

motegicivic

So all the piping is 2.5? is that outside diameter or inside diameter?

With an exhaust too wide it kills the low end before say 3k rpms.

Supaslowsi

Car runs great now still don't have a.clue as to what the problem was but it hasn't been acting up since Friday

chope045

typical honda i was about to go insane getting my idle right but i got my p28 back from my buddy and my car runs like a dream i adjusted the idle down and it will keep running and not die

greenpalace1

Did you guys sort out your problems. My 2002 Odyssey has the same issue. If I take off the air intake and stick my finger in the IACV intake port on the throttle body, the problem goes away. This all happened after I replace the IACV. I think my next step is going to be to put back on the IACV that doesn't work. The only reason I changed it was to make the engine light go off. The engine wasn't stalling. I should have just left it alone. I think there is some sensor problem that is forcing the valve open when it shouldn't actually be open. I have seen some postings about the power steering sensor wiring. Thanks for whatever comments folks have.