I have a 95 civic dx with a d16z6 built swap and I have always had problems with my idle speed jumping up and down, mostly when it's cold , but sometimes always. It did it with my stock motor, and it still idles funky since I've installed my new motor. I've checked my iac valve and confirmed it's good and yesterday I connected a voltmeter to my o2 signal wire because i notice on my a/f gauge that it leans out when my idle speed increases. I found that my o2 signal voltage drops to 0 volts intermittenly as the idle speed flucuates, but it is a brandnew o2 sensor. What would cause the voltage to drop in the signal wire other than a bad o2 sensor. Maybe a bad ecm? Circuitry problems? Throw some ideas out because i don't know where to go from here. thanks

 

what kind of a/f gauge are you reading that get that lean reading?

 

this is really old... but im having the same problem and i would like to fix it..
thanks

 

help please... it's really annoying... it jumps from 2200 or so to 1000... up and down ....ALWAYS... when it's cold.. it idles really high... at like 2700 for 40 seconds... and then the up and downs... i checked the iacv it's fine.. changed the fuel filter...checked for vaccum leaks... but i havent checked the injectors... how do i know which on is bad ??
any more options i should look for..
thanks

 

put a new IACV on. or borrow a buddy's.
are you running uber or something??

 

NO.... not uber... stock ecu... i took the valve out and it seemed fine.. i blew through the holes and it was not clogged or anything(coolant takes really good btw..lol)... but im not sure if im checking it the way it should be checked...how do you inspect it for being good or bad??...also the FITV is located under the TB, or behind?? i dont think my car has a FITV lol...there is a hose that goes from the motor to the IACV... and one from the IACV to the throttle body.. but i thought there was a hose going from the IACV to the FITV... but there are only two... and one that goes to the motor and the other to the TB... im lost here..
help

 

spray wd40 inside the IACV to lube it up, could be dry and see if that helps.

 

check your fast idle vavle. its the thing attached to the bottom of the tb that has coolant lines running to it

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HaTcH_BmX &raquo;</TD></TR><TR><TD CLASS="quote">help please... it's really annoying... it jumps from 2200 or so to 1000... up and down ....ALWAYS... when it's cold.. it idles really high... at like 2700 for 40 seconds... and then the up and downs... i checked the iacv it's fine.. changed the fuel filter...checked for vaccum leaks... but i havent checked the injectors... how do i know which on is bad ??
any more options i should look for..
thanks</TD></TR></TABLE>

I had this exact same thing happen to me. It was so embarrassing at traffic lights. People thinking I wanted to race or something. Anyway...

It has been a long time so forgive my mistakes. I believe it is the Fast idle valve. The valve that has the coolant lines running to it. I took it apart and found that a plastic diaphragm had backed all the way out. It is the big plastic piece that treads into the body of the valve and compresses a spring. I threaded the plastic piece back into the body of the valve to compress the spring again and the problem was solved. Good luck.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 92bubblesi &raquo;</TD></TR><TR><TD CLASS="quote">

I had this exact same thing happen to me. It was so embarrassing at traffic lights. People thinking I wanted to race or something. Anyway...

It has been a long time so forgive my mistakes. I believe it is the Fast idle valve. The valve that has the coolant lines running to it. I took it apart and found that a plastic diaphragm had backed all the way out. It is the big plastic piece that treads into the body of the valve and compresses a spring. I threaded the plastic piece back into the body of the valve to compress the spring again and the problem was solved. Good luck. </TD></TR></TABLE>
same here.. everyone thinks im a ricer that likes to rev the car...lol..
anyways.. this is so stressful man... i took the FITV out... took it apart to see that the white plastic thing was loose... so i tighted it up... it idle fine for like 5 mins and then it started doing the same ****... the thing is that it doesnt idle as high anymore... but the up and downs are still there....
there is a nipple on top of the TB... is there supposed to be a hose in there... cause there isn't one... and where would it go to??
thanks

 

Ok Here a a couple of other things to check.

That nipple you are talking about should be hooked up to the charcoal canister. Try at least plugging it and see if the idle gets better.

Also the fast idle valve is factory adjusted so you may have to mess with it to get it right. According to my helms manual when the engine is fully warned up you should feel no suction on the lower port hole in the throttle body. This is the hole inside the throttle body right before the throttle plate. That is the hole where the fast idle valve would take in air if it were open.

How do the O rings look on the FIV?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 92bubblesi &raquo;</TD></TR><TR><TD CLASS="quote">Ok Here a a couple of other things to check.

That nipple you are talking about should be hooked up to the charcoal canister. Try at least plugging it and see if the idle gets better.

Also the fast idle valve is factory adjusted so you may have to mess with it to get it right. According to my helms manual when the engine is fully warned up you should feel no suction on the lower port hole in the throttle body. This is the hole inside the throttle body right before the throttle plate. That is the hole where the fast idle valve would take in air if it were open.

How do the O rings look on the FIV? </TD></TR></TABLE>
the o rings were fine... i adjusted the white plastic until the end...and it seemed like it worked... but then the up and downs started again... but this time a lot lower... and when i turn the car up... it warms up a lot lower than before... so that's good... what i noticed though? that when i took the TB out... the gasket was gone... but when i spayed carb cleaner like someone told me.. and it didnt surge.. i havent check the IM gasket... so i'll do that first thing in the morning tomorrow...
also what voltage should the tps read ??

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HaTcH_BmX &raquo;</TD></TR><TR><TD CLASS="quote"> what i noticed though? that when i took the TB out... the gasket was gone... but when i spayed carb cleaner like someone told me..</TD></TR></TABLE>

I would replace the gasket before doing anymore work.

 

I FOUND THE PROBLEM... it's the IACV... i put electrical tape on the two holes like harv told me and it idles super normal now... quick question though.. what will happen if i drive the car like this for a few days until i get a new valve?? coolant still pass through it... but the holes are bloqued now...
thanks

 

help

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HaTcH_BmX &raquo;</TD></TR><TR><TD CLASS="quote">I FOUND THE PROBLEM... it's the IACV... i put electrical tape on the two holes like harv told me and it idles super normal now... quick question though.. what will happen if i drive the car like this for a few days until i get a new valve?? coolant still pass through it... but the holes are bloqued now...
thanks</TD></TR></TABLE>i have the same problem too. lmk if it's ok to drive with the tape there for awhile...

 

yes it's ok.. but its just a quick fix.. you need to change the valve

 

reset your idle. make sure there is no leaks in the tb gasket.
start the car; unplug the iacv; set idle to 550 rpms; plug iacv back.

 

hey man.. this is pissing me off... i changed the the IM and TB gasket and nothing.. i realized that the IACV is working just fine... i checked with two wires connected to the battery and i heard the click click so it was working...i turned the car on... and placed my hand on the throttle body and the car didnt shut off... so i know for sure i have a vaccum leak... but i cant ******* find it... i can hear air coming off somewhere but cant find where... everything is connected... i took the IM out and made sure i put every single hose back in its place... but it's still doing the same annoying up and downs... if the master cylinder is fucked... can that cause the idle problem??? the knock sensor (i believe) was disconnected but i dont thing that is causing the problem...any tips on finding this vaccum leak.. the gaskets are not making the problem...the hoses are all connected... im lost...
thanks

 

Okay so i cant get my civic to pass emmissions, and i bleed the coolant, and just replaced the throttle postion sensor, my car still idles high. What can i do to fix this?? Please help!!

 

I have what sounds like the same issue. Mine's ONLY when the engine is cold, it bounces between around 3200 and 1000 rpms, if i let off the clutch, the rpms decrease, push it in, they go up. As soon as it starts to warm up it goes away so I was thinking maybe a vacuum leak that's just sealing itself with the expansion from the heat. Just wondering if someone with close to the same issues figured out their problem before i end up dumping a bunch of money on parts. Wasn't sure if everyone was only having this issue at cold idle or not...