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mcl311
03-15-2009, 01:31 PM
Hey guys, i just bought a 3g as my first car. its an 88 LX. the only problem with it is that it dies when it idles. my friends dad is a genius mechanic, and after doing tests he found there was no power going to the idle solenoid. he wanted me to find a diagram or something of the solenoid so he can trace it to the problem tomorrow. any info or anything you guys would help. thanks

russiankid
03-15-2009, 01:56 PM
I had this same issue. There is one single wire running to the solenoid with a connector near the EGR valve. The wire sometimes breaks off from the connector. Its a green and yellow wire and it runs to the back of the carburetor. To find it, look from the passenger side of the car towards the back of the engine. It sits on a metal bar, and its a yellow connector. Its kind of hard to see but its there.

It actually sits under a lot of vacuum lines, so just look around for a single wire with a connector.

3rd Party
03-15-2009, 01:59 PM
for now have you tried maybe adjusting the idle screw on the throttle body? on my Z car as well as other Z cars, when we replaced the intake plenum with a modified one we didn't have ports for the idle solenoid valve dealio. so just tinker with the idle screw, see if it makes the proper adjustments for the time being. BUT you'll want to turn it counter-clock wise to back the screw out of the throttle body allowing so much unmetered air into the plenum

3rd Party
03-15-2009, 01:59 PM
is this for carb'd motors? 'cause i didn't see a specification here...

russiankid
03-15-2009, 02:08 PM
LX=carb.

3rd Party
03-15-2009, 02:10 PM
wow...i fail'd hard on this one

3rd Party
03-15-2009, 02:10 PM
wait...there's still gotta be some screw to adjust on the carb for idle control, is there not??

mcl311
03-15-2009, 02:11 PM
yeah its carbed. i didnt do any of the work myself so i dont know what he tried and didnt try. he said the solenoid has no power going to it. he ran some speaker wire from the battery to the solenoid giving it power, and it idled just fine. he just asked for a chart so he knows where to find where the problem starts

3rd Party
03-15-2009, 02:14 PM
lemme find it, i think on the shop manual i have there's a diagram for the carb'd motors and their electrical nonsense

russiankid
03-15-2009, 02:14 PM
wait...there's still gotta be some screw to adjust on the carb for idle control, is there not??
There is.

yeah its carbed. i didnt do any of the work myself so i dont know what he tried and didnt try. he said the solenoid has no power going to it. he ran some speaker wire from the battery to the solenoid giving it power, and it idled just fine. he just asked for a chart so he knows where to find where the problem starts

I am 99% positive the wire just broke off. Thats what happened to mine. Not fun when you're going down hill, braking hard, and the car stalls. :uh:

Since he hooked power to it, he knows where it is. Trace the wire for it and you'll run into a connector.

mcl311
03-15-2009, 02:19 PM
There is.


I am 99% positive the wire just broke off. Thats what happened to mine. Not fun when you're going down hill, braking hard, and the car stalls. :uh:

Since he hooked power to it, he knows where it is. Trace the wire for it and you'll run into a connector.

k ill have him do that tomorrow. thanks for your help man

3rd Party
03-15-2009, 02:23 PM
well what about the people who remove all their vacuum nonsense out of their carb'd motors??

russiankid
03-15-2009, 02:36 PM
well what about the people who remove all their vacuum nonsense out of their carb'd motors??

The solenoid is electronically controlled.

3rd Party
03-15-2009, 03:17 PM
The solenoid is electronically controlled.

but the idle is something that can be changed through an idle screw, or choke...or am i wrong?

russiankid
03-15-2009, 05:42 PM
The idle speed can be changed using the throttle stop screw. The solenoid that we are talking about is actually the "primary slow mixture cut-off solenoid valve" that supplies fuel on idle. If the wire to it is broken or is not getting any power, it won't supply any fuel thus engine dies.

I bet if you spray carb cleaner into the barrel when the engine is about to die it will catch and stay running.

3rd Party
03-19-2009, 11:37 PM
heh, i guess i am glad after all i don't have a carb'd motor...EFI isn't that bad to deal with i suppose... :D :D

Dr_Snooz
03-20-2009, 07:50 PM
heh, i guess i am glad after all i don't have a carb'd motor...EFI isn't that bad to deal with i suppose... :D :D

EFI rules the universe!!! All bow to EFI!!!!!

lostforawhile
03-20-2009, 07:54 PM
EFI rules the universe!!! All bow to EFI!!!!!

don't think so carbs rule :rockon:

AccordB20A
03-20-2009, 09:12 PM
depends on what u like doing, but oem honda carbs SUCK ASS

u cant up the idle screw to fix the idle u have to apply power to the solenoid, adjusting the idle screw will make the car idle but very roughly at 2000rpm any lower and it will stall, dunno what that solenoid does

Civic Accord Honda
03-20-2009, 09:46 PM
EFI rules the universe!!! All bow to EFI!!!!!

only if its multi point fuel injection! direct port/TBI can suck my ass!

carotman
03-22-2009, 05:57 AM
I have a similar problem on mine. There's just no power at the solenoid control box itself. I don't know what trig it to send power to the solenoid. Maybe it's related to the tach singal or something.

George89
11-22-2014, 03:45 PM
Bumping this thread bc my car is doing this exact same thing and I believe this is the problem, will be looking into checking the idle solenoid and posting here again if I fix the problem and this was the cause.

88Sleeper
11-23-2014, 08:37 PM
George, I have 2 of these at home from 2 carbs & a weber swap, if you find the solenoid itself is bad.

Testing it is easy, just be careful of fuel spilling, etc.

Basically, unscrew the solenoid from back of carb (need to remove air cleaner box thing on top of it)

Then, with it sitting off to the side, turn ignition key to on position. Now, for the actual test, touch the body of the solenoid to a chassis ground somewhere where a potential spark wont light up the spilled fuel, or worse, light a pilot flame over your choke (and you almost crap your pants as you realize you will die if that flame goes into the bowl... [jk, but srsly be careful, I did that, & it's scary as hell])

If the solenoid works, the metal tip will retract whenever the circuit is completed to a ground. If it doesn't, test that you're getting 12v from the wire that the solenoid is plugged into (rubber bump about 8-12" from the solenoid is the plug)

88Sleeper
11-23-2014, 08:39 PM
Fyi, for future reference, signal to this solenoid comes whenever ignition is in on position, and dies when car is shutdown

88Sleeper
11-23-2014, 08:42 PM
You could also just have shi* clogging up that passageway, Amgen you have it off, spray sine carb cleaner into the hole (be careful for backspray, it's a small hole) and flush it out a few times.

DON'T BLOW COMPRESSED AIR INTO THIS HOLE (that's how I lit my pilot light in the first place :-/

g.frost
11-24-2014, 06:41 PM
I've had my 88 DX since new and it has ALWAYS had a very intermittent problem with the

"primary slow mixture cut-off solenoid valve".

It only happens on my car very rarely (like maybe once a year if that and only lasts for a day or 2, (no kidding, for the last 26 years!) and seems to happen when 'Jimmy' gets his temperament up about something. The last time several years ago now, I was teaching my daughter to drive stick. After Jimmy had enough, of the bucking and stalling, he pulled the " I'm not going to idle" trick to end the lesson.

It is the signal to this valve from ECU that sometimes fails to hold it open when the engine should be at idle.

The control logic is a bit more complicated than just Open when ignition on and Close when ignition off.
It also closes the valve when decelerating, to save gas & avoid fart pops in the exhaust.

A while back BUZO made an (AMAZING) diagnostic board for our carb ECU and had posted a bunch of data showing the cycling of this valve (and so much more). I used this data for clues at the time. Sadly, looking up that thread I see all the pictures are gone... There is also some theory of operation on this in the manual I stumbled on years ago when looking into this issue.

As the problem is only very rare on my car, I have never had a chance to fully diagnose: The power to the valve would go off, then as soon as the engine died, it would re-energize, OK to start again.. only to shut off again as soon as the engine started. My last suspect cause was the engine RPM sense: the valve should always be open below a certain RPM and I suspect this signal to ECU was the problem (sensing RPM higher than it was)....

Anyway, I don't know if this describes your symptoms at all, but this has been a long standing issue on my car that has never occurred long enough to fully diagnose and fix.. It would be great if I could find a fix after 26 years!

I had it into the Stealership with under 12,000 warranty: their (lying) diagnosis was 'bad gas' and they tried to rip me off for $500 to clean the fuel tank and carb. (never had that done in 26 years.)

Edit to ADD:

Forgot to note the last time this happened (years ago) I was able to 'reset' it's little pea sized brain by:

Don't try this at home kids, Illegal in all 50 states and not approved by the NTSA, I cannot recommend this:

While decelerating, foot off the gas pedal, in gear,(won't work on auto tranny) turn off ignition for a second or 2 and then turn back on.

George89
11-26-2014, 02:02 PM
Was able to work on it today! I removed the top breather box as well as some hoses and lines and gazed upon the 89 Keihin carburetor and its ridiculous vacuum hose jungle for emission regulations in all its grandeur. Anywho, I removed the primary slow-mixture cutoff solenoid valve and tested it with success it retracted each time I gave it ground which was several times. Reinstalled and checked all my vacuum lines taping the ends of a few that were splitting. Went to crank her up, immediately fired up fast idled, and once it was time to drop to idle speed after warming it died.

Soo I decided to screw with the idle adjustments, raised the breather box with a long wrench and tweeked with the Throttle stop screw, Adjusting screw A and Adjusting screw B until luckily I found an adjustment that kept it from stalling out even in gear with my foot on the brake! Its a little rough in gear while stopped (shaky around 750 or so rpm) and a little high in park or N (1100 rpm) which is fine by me as long as its not stalling all the time like it was. In fact the couple times I had it adjusted by a mechanic who knew what he was doing, it was always a little high in park a 25 year old carbureted engine with the original carburetor just will not run like new! Ever again! lol but thank you for all the advice, I now have a basic understanding of the idle screws and there adjustment effects having studied the service manual as well.