My idle went crazy today...

[87DXHatch]

Ok, I am pissed. This is probably the third or fourth time I have posted on my idle but I am just triple checking things.

I went to the post office and let the car run while I did my thing. It's about 70¡ here and I took about 30 min. When I get back to my car, the F***er is doing 3000 Rpms! I tap the gas and the B**** jumps to 4000!!! I am just like "Damn it! It is happening again!!!!!!"

<Finishing story> So I shut it off and it takes like 7 seconds to spin down and then diesels like a Motha. I wait a little bit and quickly turn it on and slam it into reverse at the same time. Ca-Chunk! I get into gear and I get on the road. When I let off the brake it was idleing so fast it felt like I had the accelerator pushed down! When I came to a stop, it was idleing at 1500 Rpms in Gear!!! So I got home and decided to shut it off in gear and not have to deal with the high rpm shutdown/dieseling. Wrong! I shut it off in gear and it dieseled for at least 10 seconds!! It was just like "Sputter, Sputter, Sputter, etc, etc."</Finishing story>

<Real question>Is it my PCV valve? If I idle around it doesn't help but if I actually press the gas and drive around it gets better after a while; Like me pressing gas is making the valve open and close until it gets back to normal.

I already kind of checked for vacuum leaks but I couldn't find any.

Also, if I let the car sit for like 1-2 hours, it is back to normal and I can drive again.

Please I need some major help. I don't want to go through this again, and it seems to happen more often as it gets hot outside.

[BoredRec]

Check the throttle cable where it comes thru the firewall. The cable makes a sharp turn, and they like to break, or get kinked there. The cable could be getting stuck, causing it to keep the throttle open.

[87DXHatch]

I don't think you understand my problem. This is not a unique event: this has happened to me before and I am 99% sure it has nothing to do with the throttle cable because when I got out of my car it was doing 1000 but when I got back in it was doing 3000 and the accelerator had not been touched.

Thanks anyways

[ACCORD EX]

ok ! i would change the pcv valve ! and then check the thermostat !
any way the car diesels @ shutting down at high rpms ! ( that's normal )

MIKE

[rocky2]

Check these .....engine temp...idle until fans come on. Maybe be running cool not allowing the choke butterfly plate on carb to fully open.
Take off air cleaner and carb screen and get a good look at butterfly plate to see if its open fully when hot....and soak down linkages with :lube

[rocky2]

Check these .....engine temp...idle until fans come on. Maybe be running cool not allowing the choke butterfly plate on carb to fully open.
Take off air cleaner and carb screen and get a good look at butterfly plate to see if its open fully when hot....and soak down linkages with :lube...

[1988starter]

Go buy a new PCV valve I got mine for about $2.50 and according to the package they should be replaced every 10,000

[James]

My car does that sometimes too. Usually I turn the A/C on, then it stops. Or if I have to, I pull the accelerator back with my foot, so I can put it in gear without hurting the transmission. It does this every once and a while. Somtimes I start the car, it automatically jumps to 1000rpms (I am happy). Other times, it jumps straight to 2400rpms (I am not happy), if you push the gas, it just increases. I have found that if I rev it to around 5000rpms for like 2 seconds, it will just fall back to around 1000rpms. I want to fix this, but I have no clue how. It just seems to have a mind of its own. Also I have noticed, that when I first start driving, for the first 4 or 5 minutes, if I stop in drive, it idles at around 1300 w/ ac, 1500 w/o ac. Then after that first five minutes it idles like so. 720 w/ ac (Steering wheel vibrates) 1000 w/o ac. Very strange. I just want to convert to EFI. I even had a dream that my car magically changed to EFI. It was great!! It was so much quicker and I was so much happier.

Later,
James

[1988starter]

Get the carb cleaner out for some summer cleaning guys and replace that PCV valve

[87DXHatch]

Well I have already hosed down the outside of the carb with carb cleaner and that didn't do much. I read you're not supposed to spray it down the opening that appears when the airbox is off so I didn't.

I have made two attempts to remove my airbox, both ending in failure. I can get all the screws and nuts off just fine, the part that stops me in my tracks is seeing all the vacuum hoses I have to remove. Those suckers are on tight and seem like if I take them off, they're not going back on! So one of these days (I.E: as soon as I can muster the courage) I am going to throw caution to the wind and take the whole airbox off.

Does anyone know exactly how many vacuum hoses are connected to the airbox? Can vacuum hoses easily be replaced if I mess any up?

[87DXHatch]

My car did it again! This time my parent's were driving it in the city...

I replaced the PCV valve and that did nothing to help the problem. I need some serious help here, folks! My dad says I need to take it to a shop where they know what they're doing but I want to fix it myself.

Has this not happened to anyone before? I know it isn't the PCV valve, that I just replaced, what the heck else could it be?!?!?! I'm pretty much at the end of my rope here and I may end up giving up and giving it to my mechanic...

The problem happens when its hot outside and I have been driving for a while 10 minutes min. When I start the car after shutting it off, it jumps to like 3000 rpms and doesn't go down for anything! The only remedy I have found it to let the car sit for like an hour and then it works OK again.

Any help would be appreciated...

[TeKKnoTeKK]

have you tried changing your thermostat?

[locknload68]

You only have to take off one vacuum line to move the airbox out of the way.

It is on the driver's side on the back of the box. You can either take it off the box or follow it to the metal tube it comes from. Take the line off by pulling and twisting it back and forth.

Once you have that one off, just tilt the box to the left and try to prop it up out of your way.

If you happen to break any vacuum lines, just go to the parts store and get one of the same size.

[87DXHatch]

Do you think I could order a thermostat from Napa? How hard would it be to install?

Locknload68, obviously if I have changed my PCV valve I've removed the airbox before...

Thanks

[locknload68]

Sorry, I didn't see the date.

[88WhiteLX-i]

First off I would check my spark plugs and make sure they are still good, real shitty plugs causes dieseling in cars, well atleast the old beasts my dad had. Then I would get a timing light and check your timimg. Well atleast that's my suggestions, I would def. check the plugs though....

[LX-biker]

Hi,
I had absolutely same problem when bought the car. Problem was glued !!!! (busters mechanics) thermovalve mounted on the intake with 3 pipes coming. But my car with carburator engine. With injector same problem could be from cloget small air filters around intake.

[87DXHatch]

Well, I was very surprised to see that this had resurfaced because I was planning on resurrecting this thread today...

Anyway, I am pretty sure I solved the problem. My uncle came over and looked at my car (he was the previous owner of my brother's '85 Prelude and a very good mechanic). We whipped off the airbox (hmm, first time I did it it took me a good 20 min to get off... this time about 30 seconds...) and started looking around.

Well it turns out my choke plate doesn't go completely 90¡ when I turn the car on warm. My uncle said that it should have like NO play in it and it has a little bit of play in it so we think that it gets stuck when my car gets hot. Anyway, I oiled it up Seafoam style and let my car run for a while. When it got to the point that it would have started idleing crazy I shut it off. I immidiately turned it back on, expecting the idle to hit 3000 but it went up to 2k and then dropped to 1k.

Problem solved! I hope... anyway, I am surprised no one on here thought it could have been the choke plate... oh well.

[rocky2]

Wait a minute DXHatch I did say that.

[87DXHatch]

Why am I allowed to live?! I just went back and read that post... I guess I should have heeded your advice earlier, sorry. Well, my car is not running perfectly yet. I think the electric choke needs to be replaced... anyone know where I could get one? Majestic Honda maybe?

But I have found a surefire work-around... anytime it starts idling crazy now, I just open the hood, open the airbox, open the carb screen, and move the choke plate back to straight up and down by hand and that solves it every time.

[rocky2]

My thing to do with carb problems such as a choke.would be go the "you pull a part" in your area and come out with 2-3-4 carbs and put em on till you find one that works,to me this is the best way and cheapest and less headachs.

[87DXHatch]

Well I think I blew it again. The other day my car did it again, so I popped the hood, took off the air box lid, took off the carb cover and proceeded to mess with the choke. But it was straight up. And when I messed with it, almost nothing happened with my idle.

So then I flashed back to two weeks ago when I was giving my carb a very thorough cleaning with the engine running and the air box off. I now remember the RPMS jumping when I sprayed a part of the carb.

How hard is it to find a vacuum leak and how hard are they to fix? Is there any where where I can get like a complete set of blue vacuum tubes, and replace them one by one until its fixed?

Thanks