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high idle / bad brakes


Eriq

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hello all. i'm new here with a 92 accord lx (82,000 miles) bought 3 days ago =)

I am having some issues that I need some help with if possible...

the car has obviously been sitting for at least a year or two...

 

I immediately replaced the valve cover gasket, fuel filter, plugs, wires, air filter, and did a throttle body cleaning. New fluids, battery, alternator, and master cylinder are lined up for tommorrow. The issue is at hand is that my idle is waaay too high at about 1300-1500 in park, and 1000+ in gear. I'm thinking vacuum leak but all of the hoses seem to be good so far. I was leaning toward the brake booster because when I pump the brakes at idle the rpms shoot up to 2000+ and then it boggs down and dives toward 1000rpms...but when I took the booster vacuum line off and plugged it, there was no change in rpm's! I plugged it at both ends at the check valve and still nothing!!! Now I know that I need a new master cylinder because with the engine off and the brakes pumped and pressed the pedal slowly sinks to the floor. Without pumping the pressure up they're soft and squishy during driving too, they also sink to the floor...just quicker lol. Plus, I noticed bubbling where the master cylinder meets the booster and under the it...a tell-tale leak sign. Now I don't know if something like that alone would cause a vacuum leak and if i should just replace that, or if I have to spring for a booster also.......or if it might be something else all together =0 If the booster was like 30-50 bucks, like the MC, I would just do it, but these things are more like 150-200! Dont mean to ramble.....my first post lol :laugh:

Thanx every1...

Eric

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A vacuum leak will make your idle stumble or fall, not rise.

 

IMO...

You could have a dirty Fast Idle Thermo Valve (FITV) that is stuck open.

 

Check:

With your engine warm and idling, take your Intake Tube off and see if those small ports that bypass the throttle body are sucking air, you can do this with your finger by covering the holes one at a time.

 

How it works...

I believe on your model (someone else chime in here to correct me if I'm wrong) the FITV bypasses the throttle valve while the engine is cold to raise the idle; the Air Boost Valve bypasses the throttle valve after the engine is warm to keep the car idling steady. So, you should have both ports sucking while cold, and only one while warm. Covering one while cold should drop your idle (how much depends on which port you cover), covering the Air Boost Valve while warm should make the car cut off, the FITV should not be sucking* air after the engine is warm, though, I have a feeling you will find that it IS sucking air when the motor is warm given your issue. *My FITV doesn't really suck air while warm but I can feel a little vacuum on my finger, so I know it leaks alittle but still works.

 

The Fix:

The FITV works like your radiator cap so your ability to clean it is limited to the air passages, though this may be enough to resolve your issue. If your issue is the with the wax core you will need to replace it.

 

 

 

Have fun, check it out, let us know what you find.

Edited by James Matteu
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ok...so after replacing the alternator today I turned the car over and let it idle for a few minutes...it started with a high idle again but seemed to drop down to just below 1k rpms after a couple of minutes. I assume the car wasnt getting enough voltage to the sensors and computer to gather enough steady data to control the idle correctly. This is what I'm hoping anyway. I ran into some snags so havent done the fluids or master cylinder and booster yet...after all that hopefully the car will run like a top. I will keep posting on the subject, and thanx for the help...I will do that test just to make sure that is working properly also.

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ok...so after replacing the alternator today I turned the car over and let it idle for a few minutes...it started with a high idle again but seemed to drop down to just below 1k rpms after a couple of minutes. I assume the car wasnt getting enough voltage to the sensors and computer to gather enough steady data to control the idle correctly. This is what I'm hoping anyway. I ran into some snags so havent done the fluids or master cylinder and booster yet...after all that hopefully the car will run like a top. I will keep posting on the subject, and thanx for the help...I will do that test just to make sure that is working properly also.

...false alarm. after driving to the parts store and back it seems to be almost back to where it was. A pcv valve helped a little, but its still idling high.

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  • 4 weeks later...

After alot of work I am still stumped! I have now replaced the FITV and IACV after finding alot of debris in them (twigs and acorn bits and such!!!). I've replaced my alternator, intake manifold...throttle body....egr valve...and plenum gaskets. I've turned my idle screw all the way down. I've cleaned my egr and throttle body. My TPS tests within spec and gradually increases/decreases with throttle movement. I've blocked off my Idle boost valve with a make-shift plate (good ol' aluminum can). I've checked my throttle cable for slack and pretty much covered all bases I can think of. The only thing that helped a little was disconnecting the line to my cruise contol actuator...blocking the port in the intake plenum...along with tightening the idle screw all the way. With that being said...my idle is higher than I started!!! After finding all that junk in my air control valves and cleaning it out letting more air in it was idling around 1400rpms in gear!!! It has been a struggle to get the idle down since then. with all said earlier being done my idle is again down just above where it started...at like 1100rpms in gear.... I NEED HELP LOL! .....got any suggestions?

 

oh...one other thing. I dont know it it help any...but before taking off and plugging my cruise control vacuum to my intake plenum, if I disconnected my IACV at idle the rpm's would drop, but it would surge. Now, with my cruise control vacuum hose disconnected, it dropped my idle and doesnt surge when my iacv is unplugged, but it still idles high.

Edited by Eriq
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