Has anyone found out how the fix the jumping idle problem? I have already cleaned my idle control valve, does anyone have any other ideas, or fixes. I really don't want to take it to the dealer, my helms doesn't even have anything on this.
thanks matt

 

try the idle screw on the tb yet? if it's set to low i think it will do that. also not sure, but maybe a vaccuum leak could do that

 

it is more than likely your warm up regulator. It is underneath the TB. Take it off and you will see that there is a valve inside. Shake it up and down and see if anything is loose or broken off. That is what happened to mine. It would idle up and down, up and down until the car warmed up. The idle adjustment screw would not likely cause this problem unless it is hanging out or missing.

 

There is a section in the helms about this, and ways to check for the problem. I know I have read it before, but my manual is at home so I can't give you the page.

The main 2 things to check are the fast idle valve, and the idle control valve.

 

find the vacuum line that is leaking. I've fixed the jumping idle on three ludes everytime it's from a vacuum that wasn't connected.

 

Not so true, i had this problem for the past few years and i took it to honda and ended up paying a amount i donot wish to talk about to have some dumbazz mech look at my engine, in the end all he did was clean out the Fast air idle control valve. It still did it, i just gave up on it and did not feel like talking to the people at classic nissan again about it because they suck, so i installed my AEM and u know that little plug they give you that gos on the intake manafold, it came off and when i had it back there for the same problem they said it was because of that when i just got done telling them that i just installed that the day before. so two years down the road i donot even care anymore, this summer i cleaned out the throttle body and cleaned out the idle air control valve and it still does it.. im thinking it might be time to replace the IAC. not sure whats your input

 

By the way. Mine wasn't even a visible vacuum line. Spray carb cleaner all around the intake manifold. the idle will change when you're spraying into the area of the vacuum leak. That's how I found mine. I tightened everything down and it solved most of it. (nuts weren't tight enough on the intake manifold - also careful not to OVERTIGHTEN.) I wanted to beat the car. Next problem was so simple it killed me when I found it. The screw was too tight on the throttle cable holding the throttle open slightly. giving it a 1600rpm idle. Two problems in one. Either way. One of the problems was a vacuum leak. But not a vacuum line. try the carb cleaner thing. I think you'll finallly get it fixed.

 

Yeah I have already cleaned out the iac, so it's not that, vacuum lines possible I'll check this weekend.

My idle jumping is wierd, it will do it when it's cold, warms up then it will stop, cruise around for a while, come to a stop light or something then it will do it again for the rest of the time I'm driving the car, even though it's warmed up, so that clears up the only when it's cold theory. I'm gonna look for vacuum lines.

 

well mine did that the other day when it was really cold, my car was warmed up, u have to drive it for a while, and cleaning out the IAC valve might solve it or not, u might need to replace it...


I know this morning i started up my car and dissconnected the IAC and the idle stayed steady but then i got a check engine light, the helms list the IAC as one of the problems if you have a bouncing idle problem. ill see if i can find the part and ill post the info

 

ok i cannot copy and paste it for some reasion so ill manual type in what it has to say:

Troubleshooting procedures:
Symptom chart
Listed below are symptoms and probable causes for problems that do not cause the malfunction indicator lamp to come on. Troubleshoot each probable cause in the order listed (from left to right) until the symptom is eliminated. The probable cause and troubleshooting page reference can be found below.

cold fast idle to low 7,8,9,6,17
cold fast idle to high 7,8,9,11,10
idle speed fluctuates 9,7,8,11,10


6. Intake air temperature sensor circuit (IAT)
7. Idle air control valve (IAC)
8. Fast idle thermo valve
9. idle speed adjustment
10. throttle body
11. throttle cable
17. air cleaner

if anyone needs to know what (IAT) is heres the info on that: The IAT sensor converts intake air temperature into voltage and singnals the ECM. when intake air temperature is low, the internal resistance of the sensor increases, and the voltage singnal is higher.

also it gos on to say Possible causes:
-IAC valve Mechanical malfunction
-fast idle thermo valve malfunction
-throtle body clogged port improper adjustment
-intake manifold gasket leakage
-vacuum hose leakage
-ect sensor incorrect output

Checking the IAC Directions:

disconnect the 2p connector from the iac valve ( which is grey)
Does the engine speed drop or the engine stall.

-no = Replace the IAC valve.
-yes = Adjust the Base idle speed. clean the ports on the throttle body:


(Questions i have when i started up my car this morning the idle went up and down and when i disconnected the IAC connector the idle was steady and i got a check engine light. Now this talks about speed drop does that mean that it stops going up and down, this manual is confusing.)

Checking the fast idle thermo valve directions:

turn the ignition switch off, remove the intake air duct from the throttle body. start the engine and let it idle, put your finger on the lower port in the throttle body. Does the engine speed drop?

-yes = check engine coolant level and for air in the cooling system. if ok replace the fast idle thermo valve.
-no = put your finger on the upper port in the throttle body

does the engine speed drop?

-no = check for vacuum leaks, make sure the throttle valve is completely closed, and repair as necessary.
-yes = adjust the idle speed, if its impossible, replace the IAC valve.


Modified by specalk at 8:06 PM 12/20/2003

 

I made a thread about this on po a couple of months ago. Mine was doing the same thing, I diagnosed it to being a faulty fast idle vavle. It's the valve with coolant lines going into it, underneath the tb. The way you test it is to pull the intake pipe off of the car and start the engine. You should have your surging idle. There's a small hole right before the butterfly plate on intake pipe side of the plate. Plug it up and if the idle goes back to normal, you have a bad fast idle valve. Just order a new one from some place like http://www.hondaautomotiveparts.com and replace the old one. That's what I found to be the problem on mine, and the new valve fixed it.
Good luck Matt.

 

alright, just checked that, and its the fast idle valve, cool finally. that was so annoying, I am gonna order one from honda on monday.
thanks guys
matt

 

so exodusfx it took care of it, how hard was it ti install it and how much does it cost for the valve,, i think i might just replace both of them and not take any chances..

when i was looking at the IAC valve i was sitting there wondering how the heck it could go bad