EVS90

so i bought this 1995 honda accord with manual transmission. i test drove the car before i bought it and everything seemed to be ok. i drove the car to work the next day (about 20 miles) and back home with no problem. when i got home i decided to clean the throttle body because it was a little dirty even though it didnt have any idle problems. right after i cleaned it i turned on the car and the idle was the same. 15 minutes later i decided to go buy some things, on my way over, after driving for 5 mins at a stop light, i noticed the idle going up and down between 750 to about 1300 rpm. when i got home i checked for anything that i might of left disconnected but everything was connected. the car starts fine and idles fine at about 750... until i press on the gas then the rpms go back down to 750 and then up to 1000 and stays there. if i turn on the AC the rpm go down to 750 as long as the compressor is running. the idle going up and down only occurs after driving the car. One thing i noticed is that when the idle is going up and down and the fans kick in the idle stays at 1000 rpm until the fans shut off and it starts going up and down again... Has this happened to anybody else? what do you guys think it is? i already checked for vaccum leaks and didnt find any... could it be the tps that got messed up when i moved the butterfly to clean it? map sensor? idle control valve??

EVS90

when i bought the car the check engine light was on. they told me it was for an O2 sensor. never checked the codes until the problem started. the codes i got after the problem were 7, 17 and 41 (heated element in O2 sensor, tps angle and vehicle speed sensor) i reseted the ECU by disconnected the negative battery cable for 10 mins. and the high idle problem and idle going up and down problem are still happpening. so far only the O2 sensor code and vehicle speed sensor code had come back.

MAD_MIKE

If the idle is fluctuating it may be that the FITV is out of adjustment, there is a write up at the top of the forum in the 'Accord FAQ' on how to adjust the FITV and clean the IACV.
Backprobe the TPS with a volt meter, if you somehow blasted the TPS, you may have wiped a section of the carbon tracking with cleaner.

holmesnmanny

heated sensor code means u need a new oxygen sensor ... only buy Denso oxygen sensors

EVS90

Ok so i did what Mike said and yea, the FITV was out of adjustment (the plastic part turned like 3 times before it was tight) but i put it back together and turned on the car and it idled at 1500 rpm and slowly went down to 750 rpm like it usually does, But as soon as i pressed on the gas it reved up and went to 1000 rpm and stayed there... so that did not fix the problem. So i went back to check the throttle body with the car idling and noticed that the hole for the FITV still sucks in air with the car warmed up... and as far as i know the engine should not do that.. right?.. is the valve broken?
now my question is.. if the car idles at 1500 rpm when cold and slowly goes down to 750 rpm as it warms up that means the FITV is doing its job... or am i wrong?

EVS90

i havent been able to back probe the tps yet, ill get a volt meter tomorrow and check that out. as far a what holmesnmanny is saying it makes sense but the thing is that the code for the O2 sensor was there way before the idle problem started. and the problem started right after i cleaned the throttle body, so i dont think the O2 sensor is causing that problem. i know the idle problem has something to do with the throttle body for 2 reasons; 1 because it happened right after i attempted to clean it and 2 because as far as i know in order for the engine to maintain a high rpm without surging or choking, it needs air coming in and that air need to pass by the MAP sensor in order for the computer to be injecting more gas to mix with the air...thats why i dont suspect the tps. but i dont have that much experience with hondas so i might be wrong...

holmesnmanny

yes seems like the fitv is fine but when you cleaned the throttle body you might have created a vacuum leak...warm the car up completely and then spray some throttle body cleaner gently around the throttle body until the idle changes and you have found the vacuum leak

EVS90

i read that there should not be air coming in thru the FITV hole when the engine is warmed up, is that true? i think that might the extra air coming in. i did spray the intake and throttle body with Brake cleaner... i didnt have carb cleaner, and did not find any vaccum leak.
is the rpm suppose to go up or down a little when you turn on the AC? as far as i know the engine should rev up a little to compensate for the load, but on my car the idle goes down and even when its reving up and down it gets steady when the ac is on.

MAD_MIKE

When the FITV is fully warmed up it should not allow any air to bypass the throttle blades. If it does make sure you did not over tighten the FITV. This can happen if you tighten it up when it is cold. Warm up the engine, let it cool down a bit and recheck the FITV. Back off the screw and then snug it down. You do not want to force it.

If the FITV is not working properly it will be hard to diagnose other issues with idle.

holmesnmanny

Get some really strong tape and warm the car up and tape up the fitv port with a big strong piece of tape. I've used the big clear type before just as a test. Just make sure it's one piece and it's not going to get sucked into the intake. Then see how the engine idles. If it idles fine then you know where the issue is. If not, you've atleast isolated the fitv.

nus_dogg

If anything, I bet some of that carbon crap must've went down into the IACV hole and into the IACV causing the pintle not to seat all the way when it's told to. Happened to a car I did awhile back when I still work for the dealer. After a fuel system cleaning service, car idles high as **** thinking I may blew the IM gasket. Turns out that some of the carbon went down into the IACV passage and causes the pintle to not seat all the way when you tell it to using the GM scan tool.

Clean out the IACV if you haven't.

MAD_MIKE

^ What they said.

*Holy Hell, its nus_dogg!*

EVS90

i removed the IACV and cleaned it as much as i could but that didnt fix it. if the car idles at 1500 when cold and then drop to 700 rpm like its suppose to, that means the FITV is working even though it sucks in air when after the car is warmed up, but i already tried to adjust and clean it completely... the tps has .5 v when closed and 4.5 at WOT. so the tps is working too. if i disconnect the MAP sensor the car dies so i guess that means the map sensor is working...

ej7attack

the fitv should not be sucking in air once warmed up. fast idle thermo valve its called. your iacv doesn't know where to go once you open the throttle. adjust the fitv again. iirc your supposed to turn it all the way in and then back it off a quarter turn. someone please correct me if im wrong.

EVS90

i thought i had found the problem when i found that the throttle plate was not sealing completely and the car didnt die when i close the FITV and IACV holes and posted it, i thought the only air getting to the engine at idle was thru the IACV hole. but mike already answered my question.

am going to try to clean the IACV again. do you guys think i should take it apart to clean everything inside better or thats a bad idea?

EVS90

i tried adjusting it twice. and cleaned it very good. could it be that the O ring is not sealing properly? tomorrow am going to try to bleed the coolant system again... maybe it still has some air in it and theres not enough coolant getting to the valve..

ej7attack

that is an acute possibility. no coolant flow, no bueno!

EVS90

Does anybody know what the voltage should be on the IACV? am getting 12 v on the positive and 3.4 on the ground. am using a cheap tester. also if i check the resistance of the IACV i get 3.5 and it slowly went up little by little to 12.4... is that normal? or the tester am using is not good? or does that mean the IACV is bad?

Today i bled the coolant system, tried to clean the IACV as much as i could, and i was told it could be the map sensor so i changed it but nothing..... i taped up the FITV hole and let the car idling and the problem was still there... i dnt know what else to try... the only thing left is changing the IACV which is $180... it would suck if i change it and that dsnt fix it...

MAD_MIKE

Can you do the same as with the FITV. Remove the IACV after the car has warmed up and let the car idle on its own.
The idle may be low, but the engine should idle, or you should be able to throttle it a bit. If the idle doe indeed drop then you know the IACV is the culprit.

EVS90

well what i did was let the car warmp up start surging up and down and partially plug the IACV and the surging would stop... i ordered a IACV, i should be getting it on friday, ill replace it and let you guys know how it went.

EVS90

i just dont get why would the computer command the the IACV to stay open after you throttle the car a bit. or sometimes the idle would be normal and increase little by little until it reached 1300 rpm. why would the computer command the IACV to open more and more little by little...

MAD_MIKE

The ECU is probably NOT commanding the IACV to do that. Since this all started after you cleaned the TB, most likely one of two things happened.
One, a chunk of carbon/soot/gunk is lodged inside the IACV not allowing it to close, it may just need a good cleaning.
Two, the throttle cleaner got inside the IACV motor and it is no longer able to function correctly.

EVS90

i got the IACV, installed it and nothing... so i got to the conclusion that in fact the computer was commanding the IACV to open more than it should... One of the inputs for the ECU to control the IACV is the TPS... so i got a better volt meter and rechecked the TPS and and hen it was closed i was getting .58 volts... so i calibrated the TPS to read .45 v when closed and played with the idle screw a little.... and BOOM!! now it i have a normal idle again!!!

EVS90

Now, the only problem am having is that when i turn the AC the idle drops below 500 rpm... which is not that annoying but it shouldnt be like that. The ECU should raise the idle to compensate for the load.... just like when you use the power steering... and in my car the ECU does detect the load of the power steering but not the AC... what could it be?

holmesnmanny

pull the radio/back up fuse for a minute...put it back in and idle the car til the fans cycle on .. turn the headlights on .. idle for one full minute ... turn rear defogger on idle full min ... then start making a video and while video is running turn on ac ... upload video to photobucket and let us see