Idle problem (irregular) on my hatch.

Well, my hatchback has been having idle problems lately. I can,t directly pinpoint what's going on exactly.
It idles fine when cold or if it's been sitting for some time. After it warms up, it's got a lumpy idle and will die randomly.
I checked for vacuum leaks and couldn't find any. Maybe a thermovalve is leaking but I have seen no hose or gasket leak so far.
My vacuum gauge reads 20 but will drop to like 18 when the rpm decreases and go back to 20 (like this, forever).
I adjusted the float lever on spec (was a little high) but it didn't solve the problem.
I cleaned the shit out of the carb but still the same problem occurs.
I turned up the throttle stop screw so it itles higher and won't die anymore. The idle is still lumpy and a bit of a pain to keep in gear at a stop light (automatic car)
I noticed that if I apply vacuum to the power valve (line #14), it's like there's nothing connected to it. Maybe I need to buy a real vacuum pump but if I suck with my mouth, there's no way it will hold vacuum. This rocedure has worked fine with other vacuum devices so maybe I'm doing this wrong hehe.
Anyone got an idea?
Edit:
I forgot to mention that if I place my hand on top of the primary barrel or partially manualy close the choke plate, the idle will raise (normal?)

Sounds kinda like the electric choke isn't working. My car had these same symptoms, and I found that the wire sending power to the choke on my carb had come unplugged. Hence the choke stays on all the time, and the car runs like crap when warmed up.

Yea check your choke. I remember when my car idled crappy, my brother told me it could be the choke.

In fact, the choke opens all the way after it's been warmed up. That's where it begins to act weird.

I noticed that I can feel some hesitation while driving on the highway at constant rpms. If I step on the gas, it revs like a champ without problem. I just can feel it jerk a bit going at constant rpms (like 2500 ish)

Quote:

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Originally Posted by carotman

In fact, the choke opens all the way after it's been warmed up. That's where it begins to act weird.

I noticed that I can feel some hesitation while driving on the highway at constant rpms. If I step on the gas, it revs like a champ without problem. I just can feel it jerk a bit going at constant rpms (like 2500 ish)

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How is your fuel pump? Mine jerks like you described as well but only when it is cold.

It is obviously leaning at idle and probably at part throttle as well. Sounds like you have crap in your idle circuit, and when the choke is applied, it increases the vacuum enough to pull adequate fuel to run the car. These carbs have an idle mixture screw? Maybe pull it out and check for aforementioned crap. Also, count the number of turns until it seats before you remove it so you can put it back. May have to break off a limiting cap.

Otherwise, it's symptomatic of a vacuum leak somewheres. I check for faulty lines and parts by running the engine and kinking each hose off one by one. If the engine suddenly runs right when you kink a certain hose, investigate further. I found a pooched distributer advance diaphragm this way.

I'm a bit dumb.

I just remembered that the PCV hose is cracked just on top of the PCV valve. I didn't bother with it but this may be the cause of a nice vacuum leak...

Quote:

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Originally Posted by carotman

I'm a bit dumb.

I just remembered that the PCV hose is cracked just on top of the PCV valve. I didn't bother with it but this may be the cause of a nice vacuum leak...

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That will do it!

another way to check for vacuum leak is get a can of cheap carb cleaner and use the small tube that comes with it, spray very sparingly around carb base, intake manifold mating surfaces, vacuum tees, etc. ..If you hear the engine rise rpm slightly while idleing , that is the area to look for leak.

Well, I fixed the PCV hose but it still does it. It didn't help much but it did help.

I noticed today that if I make a right turn and let the rpms drop, the engine will die ?!?!? Left turns are ok. Could it be the float that's acting up?

When I was trying to find a fuel problem on the car. I jumped the fuel cutoff relay and the pump came constantly on. Maybe this just busted the float somehow. The float level is fine tough so I don't know what to think.

I bought 60 inch of vacuum tubes and "HELP!" Vacuum caps today. I'll do the vacuum removal procedure and see if it helps in any way.

At least it doesn't randomly die on me anymore so it's drivable this way.

There is a bleed hole inside the powervalve, so it won't hold vacuum very easily untill it's strong enough to pull more then the small hole can bleed off, It's hard to say that the plunger ends up covering the bleed hole once it reaches the top.

You may want to try and push the plunger up with your finger and then suck on the vacuum line and try to hold the plunger in the up position by just sucking on it. :)

I think the hole is there as a way to let the plunger drop quicker once vacuum is low enough.




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Did you replace the PCV valve too?


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When you hold your hand over the carb you increase vacuum and richen the mixture by reducing air, so you may have a lean mix but it could be from a vacuum leak.

The air cleaner on and closed can help up the vacuum signal. but wont solve the lumpy idle

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Hmm, I plugged evey single vacuum hose on the intake and back of the carb. I just left the secondary barrel diaphragm connected and I still had a lumpy idle :(

This means it's not a vacuum leak from the hoses. I sprayed carb cleaner at the base of the carb where the EFE plate is but it didn't change anything. I sprayed on top of the intake manifold gasket where it meets with the head but still didn't change. There could be an intake leak under the manifold but that's a hard to reach area.

I didn't replace the PCV valve because it was functionning properly. One of the guys in the local Honda club is junking an 87 Hatch, auto (same car as mine). I know his carb works fine so I may just end up replacing the thing and the base gaskets. We'll see if it solves the problem.

Yup, I noticed it again tonight. Left turns makes the idle go UP by like 250 rpm, right turns make it drop by the same amount (and die)...

Very odd....

I'll take a video of this haha

Try cleaning out the carb.

Have you replaced any fuel filters?

I cleaned the hell out of the carb at the beggining of the week. I replaced the front filter in November and the back filter is about 2 years old.

I wonder if those cleaners that you put in the tank could help a bit.

Pump could be weak

Float could be stickng, not sure what else would cause the problems. I mean the car never will like turning right, but it shouldn't die completely.

What about the gasket for the top hat.

And none of your ABC is hooked to vacuum is it?

You can remove and clean the idle jet, or what I think is the idle jet, it's a long jet that sits between the float bowl and the primary barrel.

Have you made any adjustments to the A/F screw?

how is the Solenoid at the back of the carb?

not sure what else I can trow out there.

Hmmm I could check the solenoid at the back of the carb indeed! (never thought about that). I think the procedure is in the shop manual somewhere.

I don't have any ABC vacuums on that carb from the factory. I may try and clean the idle jet. Do I have to remove the top hat to reach it? ( I guess so) I could always rebuild the carb in the process too. I never touched the A/F screw and I don't plan to, that may cause even more harm hehe.

Thanks alot Mike for your help., this is really appreciated.

Quote:

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Originally Posted by carotman

I cleaned the hell out of the carb at the beggining of the week. I replaced the front filter in November and the back filter is about 2 years old.
I wonder if those cleaners that you put in the tank could help a bit.

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I used those cleaners and it helped my MPG and smoothed out the idle. I also noticed the engine is a bit more responsive after the treatment.

I had a similar problem a while ago and it turned out that the jets just needed to be cleaned.

I'll try the fuel cleaner soon.

The engine also wants to shutdown when I brake hard and come to a stop

I'd yard that idle mixture screw right out and spray the shit out of it's hole with carb cleaner. If you can't see fluid pouring into the primary bore with the throttle opened while you are spraying with carb clean, the idle circuit is probably at fault. Motorbikes are notorious for this after having sat for awhile.

Did you have figure this out yet?:huh:

Nope.

I got a complete intake manifold here (including carb and all the stuff). I'll end up swapping the whole thing and see if it still does it lol.

have you ever checked the egr, I dont remember if any body mentioned that . It would not explain your turning symptoms exactley but a bad egr gasket or stuck valve can mimick a vacuum leak at idle. Even if it is not connected ! You have made adjustments to compensate for a problem so any thing can be considered.

Hmm the EGR might not be 100% sealing but the valve itself is working. I applied vacuum to it and the engine wants to die at idle.

I'll order a new EGR gasket in the process and clean that valve.

FYI,

As may all ready know I have been experiencing Idle problems on my 86 accord. I have been trying to figure out what could be causing it. I have narrowed the majority of the problem down to a fuel problem. I changed both fuel filters and the one in the back was so dirty that it was amazing the thing ran.

However, it still didn't run right. So I pulled the fuel pump out and notice that the screen on the bottom of the pickup was completely stopped up. It's a square screen that sits basiclly directly on the bottom of the tank collecting all kinds of junk in these older tanks. I drained the tank (they have a drain plug) and put a new fuel pump screen on it and that made it run 100 times better. It still is a little rough but still allot smoother than before on idle and running.

This may be part of your problem. If you start the car and it runs at cold it could be because after the car sits for a while the sediment falls away from the screen and after its been running for awhile it starts to build up and clogs it bad enough to make it run bad. still ran rough. Just a thought.

I think that when people suggest that you change you fuel filter they should also suggest that you change this fuel pump screen as well because you probably won't notice a big change with just a new filter as the volume can't exist to with poor flow.

Also, I noticed that when the screen is replaced that the swoosh sound that you hear when you unscrew the gas cap is alot less intense than before. I think that if you here a big swoosh that it's because the fuel pump is pumping more pressure than normally required. So maybe to much swoosh could be a indicator of a clogged fuel pump screen.