Carb Tuning And A/C

[3rdCoast]

Hey ppl im new here. I just got an 88 accord Lx automatic (carbed). I got it for $700 cuz the guy couldnt figure out why it was idleing so bad. He put in a new pcv valve, new distro i think or cap cant remember exactly, new spark plugs, and a head gasket. This guy is a uti student and he put one of the plugs in real crooked and u could tell by lookin at it compared to the others it wasnt right (he lost his credabillity with me on that one). So i got that fixed it. The plug was stripped but just needed to be rethreaded and put in straight and it ran a lot better (the engine was misfiring cuz of the plug). Me being a perfectionist the car was idleing a lil higher than i wanted it to and when i put the a/c on the rpms drop to about 1000-1200rpms in park or about 900 in gear. In park with no a/c it idles at about 1500-1800 at full opperating temp. The car also diesles when u turn it off without the a/c on. Why is the a/c taking so much out the idle speed. The guy that i got the car from also tampered with the idle on the car i dont know what screw he used cuz theres about 3 on my carb, The plastic one on the back of the carb is a b!tch to get to and didnt seem to do anything when i messed with it. Then theres the a/c idle screw on the front right of the carb i messed with that some and that one seemed to have the most effect then i got another screw on the passenger side of the car in front next to the throttle cable (i didnt touch this one cuz i didnt know what it was at the time) I used this link to try to tune the carb myself here (http://members.fortunecity.com/accordex87/carb.htm) (i have that screw in #3 that that carb doesnt) thats the screw i didnt touch. The car doesnt stall anymore at stops with the a/c on but it does shake the dash up and steering wheel shakes a lot almost blurs the clock sometimes. any ideas on what to touch/tune/test? Also can somebody tell me what this white-ish offwhile colored valve or filter is. Its under the pcv tube that goes to the air intake on the driver side of the engine. I tried to read the tip of it but all it says is "denso" on it the rest r #'s. Well the hose that goes on this valve/filter is take off and plugged with a screw and can be reconnected cuz peice for tube to slide on is broken off. Is this of any importance??? :dunno: .......... i know these damn carb questions get old but all the others i read didnt seem fit my prob exactly though some were real close......... Thanx for any help u can give me

[lostforawhile]

Hey ppl im new here. I just got an 88 accord Lx automatic (carbed). I got it for $700 cuz the guy couldnt figure out why it was idleing so bad. He put in a new pcv valve, new distro i think or cap cant remember exactly, new spark plugs, and a head gasket. This guy is a uti student and he put one of the plugs in real crooked and u could tell by lookin at it compared to the others it wasnt right (he lost his credabillity with me on that one). So i got that fixed it. The plug was stripped but just needed to be rethreaded and put in straight and it ran a lot better (the engine was misfiring cuz of the plug). Me being a perfectionist the car was idleing a lil higher than i wanted it to and when i put the a/c on the rpms drop to about 1000-1200rpms in park or about 900 in gear. In park with no a/c it idles at about 1500-1800 at full opperating temp. The car also diesles when u turn it off without the a/c on. Why is the a/c taking so much out the idle speed. The guy that i got the car from also tampered with the idle on the car i dont know what screw he used cuz theres about 3 on my carb, The plastic one on the back of the carb is a b!tch to get to and didnt seem to do anything when i messed with it. Then theres the a/c idle screw on the front right of the carb i messed with that some and that one seemed to have the most effect then i got another screw on the passenger side of the car in front next to the throttle cable (i didnt touch this one cuz i didnt know what it was at the time) I used this link to try to tune the carb myself here (http://members.fortunecity.com/accordex87/carb.htm) (i have that screw in #3 that that carb doesnt) thats the screw i didnt touch. The car doesnt stall anymore at stops with the a/c on but it does shake the dash up and steering wheel shakes a lot almost blurs the clock sometimes. any ideas on what to touch/tune/test? Also can somebody tell me what this white-ish offwhile colored valve or filter is. Its under the pcv tube that goes to the air intake on the driver side of the engine. I tried to read the tip of it but all it says is "denso" on it the rest r #'s. Well the hose that goes on this valve/filter is take off and plugged with a screw and can be reconnected cuz peice for tube to slide on is broken off. Is this of any importance??? :dunno: .......... i know these damn carb questions get old but all the others i read didnt seem fit my prob exactly though some were real close......... Thanx for any help u can give me

[lostforawhile]

ok you are going to have some idle drop withthe ac on there is a throttle controller on the drivers side that opens the throttle some when the ac is on that keeps the idle from dropping too much i need moe information on which valve you are talking about i think i know but need a little more info. are you talking about on the drivers side where there are two valves? those are what the computer uses to control mixture the plastic screw is hard to turn i know. that directly opens the primary throttle plate if you are turning it so it compresses the spring. if it's open too much there won't be enough vaccume to pull fuel out of the idle port if it's not open enough not enough air. it sounds like you might have a vaccume leak. check one thing there is a valve on the side of the fuel bowl that vents the bowl, it has a small hose and a large hose that goes to the charchol canister. with the engine running pull off the small hose and plug it if your idle improves you may have found the leak. you can do this with most of these small diaphrams they spring leaks all the time. that particular one often goes bad because vapors from the fuel bowl eat the diaphram if yu don't know about it easy to miss.

[A20A1]

First off you have too high an idle... IMO the idle was set too high as a quick fix, but no one addressed the problems causing the bad idle.

Read what I wrote on the adjustment order...
http://www.3geez.com/showthread.php?t=44074

the reason the Throttle stop screw (black plastic screw) doesn't help any is cause the idle diaphragm (front, throttle cable side of carb) is set too high.

The A/C idle boost screw is at the rear of the carb by the firewall.

The white valve(s) you see around in the engine are for EGR and emissions related controls. If it's connected to the Air Suction valve it's becuase it uses the air suctions vacuum source.

[3rdCoast]

i checked the the hose that i said was disconnected and plugged with a screw, its hose #32 the what looks like a filter is broken where the hose connects on but is this hose or filter important to anything here?? Did you see what im going by i used the page i put up in my original post??? ........ here it is........http://members.fortunecity.com/accordex87/carb.htm also i messed with a/c idle screw some shown at the bottom of the page i linked and i have a screw on the throttle cable side under it where in one of the pix the one shown does not and i havent messed with that screw at all the be black one on the back of the carb and the one shown as the a/c idle screw shown in the link if this helps in any way.....and i cant tell u what the guy did and to what screws he used to change the idle to compensate for his overlooked screw-up with the crooked spark plug..

[A20A1]

Well the idle diaphragm is the one you want to adjust if you have too high an idle, the reason it's missing in the pic is cause that person is running a different version on the carbed A20. Different emissions controls.

The A/C idle boost is the very last screw to mess with and if you've ever tried to tug on the A/C idle boost linkage it onnly moves very slightly.

[3rdCoast]

Well the idle diaphragm is the one you want to adjust if you have too high an idle, the reason it's missing in the pic is cause that person is running a different version on the carbed A20. Different emissions controls.

The A/C idle boost is the very last screw to mess with and if you've ever tried to tug on the A/C idle boost linkage it onnly moves very slightly.
and the idle diaphragm is on the passenger side and is adjusted with that screw by the throttle cable right? Would i also go by that link and turn the black knob to its lowest position (compress spring, or decompress) then adjust the idle diaphragm screw??????

[A20A1]

http://www.3geez.com/attachment.php?attachmentid=4374

Yes turn the throttle stop screw out to close the throttle and lower the idle...

The idle diaphragm screw must also be turned out prior to adjusting the throttle stop or the idle diaphragm may hold the trottle open and you wont nottice the effects of turning the throttle stop screw.
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[A20A1]

Chances are the throttle stop screw may not need adjustment... turn the idle diaphragm screw out all the way first but not till it falls out and see where the idle drops to. Make sure the engine is fully warm.

If the car stalls before you pull the idle diaphragm screw off the throttle linkage where the screw hits the linkage then you can raise the throttle stop.

But remember to make sure you don't have vacuum leaks or any other problems cause then you'll be adjusting the idle for that problem... if later that problem ever is fixed or fixes itself then you'll end up with too high an idle, and you'll need to readjust it.

[3rdCoast]

oh see i didnt know there was a screw inside the black knob and i got some kind of metal tubes(maybe fuel lines) right behind the black screw that make it almost impossible to get to and nevermind gettin a screwdriver in there so i gues i gotta find a way to get those lines out of the way. In the pic u posted up, see where the nut is under the throttle cable with the yellow mark in it? On my carb there is a screw right in that area, and its not there on the carb in the pic u have provided. It looks similar to the a/c idle screw on the driverside im still workin on trying to get some pix to show this :(

[POS carb]

there's supposed to be an idle controller there, all it does is crack the trhottle open when vacuum drops (like when the engine is stalling)
You should be focusing on the one by the driver's side, it has two adjustments... Turn the screw on the front in till it makes contact, then on the rear you can adjust the ammount of compensation. I need to dig up some photos of my old carb to show you...

[A20A1]

I removed the idle diaphragm cause I didn't need the extra idle assistance.

The metal tubes are the hard vacuum lines.

http://www.3geez.com/attachment.php?attachmentid=4375
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[A20A1]

Eric, I always figured the A/C idle boost at the back to offer less adjustment and compensation then the idle diaphragm. I think the A/C idle boost was used as a backup when the headlights and A/C were on cause it only moves a little bit, where as the idle diaphragm moves a lot more.

Though I've never played with the screw at the rear. I figued it was a stopper.


Eric, I have a pic of your carb with you pouring tequila into it. :)

[3rdCoast]

yeah pix r good. so u r sayin to screw in the screw by the throttle cabel on the front till it makes contact then adjust the black knob on the back??? what about the screw inside the black knob?

[A20A1]

If the idle diaphragm is making contact then adjusting the throttle stop wont do anything till you raise the throttle stop idle above the idle speed set by the idle diaphragm.

You probably don't want to raise it if it's already high you just want to set the best lowest idle speed you can get with the throttle stop... thats why I said turn out the idle diaphragm screw till it no longer touches the plate behind it, that way it isn't interfering with the throttle stop screw adjustment.

If you notice the idle diaphragm screw always touches the plate no matter how far you turn it out, it could mean the throttle stop is opening the throttle plate too much... but if your at that point where the throttle stop is the only thing holding open the throttle and you still have poor idle, and can't close the throttle or else it will stall then something is causing the idle to drop... it could be a vacuum leak or dirty carb... etc.

You should have a steady idle around 800 rpm (+/-100) rpm with the throttle stop all by itself with no help from the other idle diaphragms... and you should nottice that when the idle diaphragm screws are turned all the way out that they do not touch the plate behind them. Just make sure A/C and headlights are off and that the car is fully warm when setting the throttle stop.

[lostforawhile]

the two white valves on the drivers side of the engine are not emisions i just posted a thread about this. the two white valves are used by the computer to adjust the air fuel ratio. the carb is factory set rich and the computer lets air in in pulses to the intake manifold. this leans out the mixture. it uses a bunch of different sensors and the o2 sensor to help set this mixture. we need to have a thread entitled those valves are'nt emissions so quit removing them!!! would you remove a big piece of your carb and expect it to run right? this is not a holley this is a very high tech computer controlled system of which the carb is only part of!! :pc:

[3rdCoast]

well i did some things tonight/this morning i guess to the adjustment screws and i got the parked idle down to about 1500 rms and at 1000 in drive, and when i cut the a/c on in drive it goes down to the mark right under the 1 and is a lil less shakey. I might have gone off topic with this whole thing see i wanted to adjust whatever needed to be adjusted cuz the car would shake pretty bad when stopped at a light with the a/c on. It wouldnt stall anymore after i got the bad plug fixed but it still doesnt run as smooth at i would like it to when im at a light with the a/c on. I know 1500 rpms is high for idle in park and warmed up and would like to fix that too so maybe this is a one thing at a time fix. Get the a/c to behave in drive while stopped and then fix the idle while in park. Would this be correct?? or is it all one problem?? If anybody has a somewhat close up pic of the engine i could circle the valve/filter (which is not connected in my car the hose is plugged with a screw, hose is #'d 32 if that helps identify it) thing im talkin about if lostforawhile knows what im talkin about and what he said about it in his last post could that be what is messin with my idle?????

[A20A1]

No one is saying to remove those valves...

[A20A1]

I think #32 went to a few different solenoid valves and to the box in the fender.

Did you turn the A/C idle boost screw in with the A/C on?
I usually overshoot the idle in park knowing that when I place the car in drive the rpms will naturally drop a certain amount. If it's too high I lower the adjustment.

[3rdCoast]

i take the air intake off the top along with the pcv filter and a hose to get it out of the way cuz i cant get to any of these adjustment screws with it on so i take it apart tweak a screw and then put all that crap back together cuz i dont know if turning the car on with all that stuff disconnected with effect what im tryin to fix... so no i havent done any adjustments with the a/c on i just make a tweak then put it all back and then turn on the car and see what i got then......

[POS carb]

lol post the pic!@

I agree the idle control diaphragm offers a lot of control however since it's vacuum operated it only really works when the engine is almost stalling and I can't live with the car shuddering, coming back to life, shuddering, back to life, etc... I thought the vacuum on the right side was turned on and off by solenoids

[3rdCoast]

i found an engine pic that shows that bastard valve/filter thing i been wanting to know about its not the same one but it looks just like it (in the pic its by the blue part of the air intake) and is right under where the pcv filter that connects to the airbox......http://3geez.com/attachment.php?attachmentid=3632

[lostforawhile]

lol post the pic!@

I agree the idle control diaphragm offers a lot of control however since it's vacuum operated it only really works when the engine is almost stalling and I can't live with the car shuddering, coming back to life, shuddering, back to life, etc... I thought the vacuum on the right side was turned on and off by solenoidsthey are, in the black box the computer turns them on and off at high speed thet controls the amount of air those valves let into the intake manifold. this changes the mixture depending on conditions. make sure your o2 sensor is good, if it's stuck the computer might lean the car way out or run it too rich, there are no defaults on the computer it's eithier right or wrong. modern cars have computers that can tell if a sensor is out of range. oh the sensor that plugs into the side of the air snorkel, the one with the two pin plug, that sensor is very important, it tells the computer what the air temp is and that changes the whole parameters of the mixture. just think, 20 years ago this was state of the art, now it's only state of the art on the space shuttle :lol:

[A20A1]

lol post the pic!@

I agree the idle control diaphragm offers a lot of control however since it's vacuum operated it only really works when the engine is almost stalling and I can't live with the car shuddering, coming back to life, shuddering, back to life, etc... I thought the vacuum on the right side was turned on and off by solenoids

http://www.3geez.com/attachment.php?attachmentid=4378

[3rdCoast]

hey that plug that lostforawhile is talkin about is broken on my car i was lookin at it the other day and noticed it the wires r still good just need to put a new female connecter on it and plug the wires back in.............

[3rdCoast]

i fixed those wires i noticed a lil bit of a difference but im not sure if its better or worse. I also got some carb cleaner can someone tell me where exactly to spray it to check for vaccumm leaks and if i sprayed some in the top of the carb it dont gonna make a fireball or anything if i turn on the car would it?.

[A20A1]

It wont make a fireball, you may make the car stall or not start for a little bit if you spray too much. You spray away from the carb opening so it doesn't get sucked in when checking for leaks, aim the nozzle where a vacuum line connects to a vacuum port and at the gaskets between the carb and manifold and manifold and cylinder head... it'll give you a general idea of where the leak is. Oh and do it while the car is fully warm and running.

[3rdCoast]

well i dont think i have a vaccume leak i spayed carb cleaner on sever spots nothing changed. Today before i used any carb cleaner, i was letting the car heat up and that fast idle turned itself off and car was idleing in park at mark right after 1000rms (1200?). So something i did dropped the idle some from 1500rpms the other day (i think it was fixing the broken plug on the airbox). Now i was thinkin somethin when i had the a/c on and just idling in park. When i pushed on the brake i noticed a small but noticable (when lookin at the gauge) drop in the rpms. At night the headlights and dash dim a lil bit to when i turn the a/c. Could a low battery/ old alt be why its doin this? In a couple weeks or so im taking my sound system out of my other 88 accord and puttin it in this one, and i got an optima yellowtop for a battery. So if i got my speakers and amps goin in this car i dont want the car shakin and almost stalling to peices cuz i have my a/c on at night............just somethin i think was worth some thought....tell what u guys think about it

[A20A1]

well you want a good alternator right? I dunno if having a better battery will help run more accessories.

As for the drop in idle when you press the brake... the brake booster runs off of manifold vacuum

[3rdCoast]

so ur sayin there may be a vaccume leak??? how would i test the vaccume on that?

[3rdCoast]

i found a pic of the valve/filter thing i've been askin about that isnt connected on my car. can somebody tell me what it is and if it should be corrected..... it's in the second to last pic its all the way on the right, right above to the small air filter on the cam cover, its dirty but its a white-ish color (it wont let me edit and paste the pic on here or i would circle it):dunno:
.........click here (http://www.3geez.com/showthread.php?t=37760&page=2&pp=20)

[A20A1]

Yes you should reconnect the white valve.

[njpeter]

As I duck the membership for saying this for the umpteeth time <ducking>, idle speed problem resolution requies either significant luck and the various bits posted by the members or a good eye for vac lines , AND the silver shop manual. Might be an idea to check engine compression first. You need strong kung-fu to make a carbed 3g idle well. Take it easy with the carb cleaner too, it's toxic.

[3rdCoast]

yeah i havent been messin with the carb cleaner much can u tell me what that valve is called so i can get a new one cuz the part the hose connects to is snapped off on the valve so it cant be reconnected :sad2:

[njpeter]

aha!, I've been there too...a good idle is not possible with the air control vlave inlet broekn off, the hose is really small and that plastic resists all the glue I ever tried ( I used some stiff wire to kee the airport open, but the glue always failed(even epoxy!), I actually ended up buying a junker to strip, as that air valve is brutal expensive at teh dealer, and quite a few in the boneyards have had the smaller nipple broken off already. I'm sure some EFI convert has one laying around or you can just keep hitting the yards..one tip, bring some clipper with you, do not try to remove the hoses at the yard, carful/gentle work with a razor on the bench will free the hoses without snapping off the nipples.

I can't say enough for the silver shop manual, the third party books don't cover the idle feedback system in any detail. Trust me on this..at $30-40, money very well spent, unless you've got more time then money, to be blunt, you're better off collecting deposit cans to buy the manual then to try to figure it out blind.

[3rdCoast]

silver manual? i never heard of it where do they sell it at?

[njpeter]

that's the official honda shop manual, you can find them on ebay, or maybe the section you need posted on some website ;~). the sell for around 30 used. make sure to get your model year, there are some subtle differences each year.

[3rdCoast]

I got my car back from the shop today and the guy checked it out and didnt know what was up with the car he said the plugs were firing ok and it was best not to try to take them out and try to fix them cuz it could damage the head and make a mess of the holes and that it wasnt missfiring. He said he thinks it could be the carb or a selenoid or other electrical part might be failing and didnt want to try to mess with those cuz of how expensive it gets and have it not be the problem. So heres what i got. The car seemed to start ok when i 1st got in it at the shop. Ran pretty bad when i put the a/c on maybe 500-600rpms in drive and stopped car shakes pretty bad. After driving the car around a lil bit and got it warmed up it seemed to run a lil worse actually stalled with a/c on a couple times. I noticed the rpms seem a lil jumpy when accellerating they were steady climbing from about 1500 then moved real quick to all lil over 2000 (it wasnt a transmission slip). Still idles at about 1200-1300rpms in park and diesles when i turn the car off....... Im taking it to another shop the the mechanic suggested would probably know more about it and be better equipped to diagnose it i just wanted to see what u guys think about this?????