Quick question

[Inkara1]

I have a 1981 Honda Accord LX 3-door with the 1751CC CVCC engine. It has a 3-barrel Keihin carburetor (2 for the main combustion chamber, 1 for the CVCC precombustion chambers).

In the summer of 2000 I installed a K&N Filtercharger reusable high-performance air filter. At about the same time I also had to replace the carb floats.

Now, when winter 2000 came rolling around, I noticed that right as the car is first coming off the fully-closed choke position, if it's 40-45 degrees or below out, the car tends to die if you're revving it then let off the gas (for example, putting in the clutch coming up to a red light). If I use the brakes and don't push in the clutch until the motor gets down to 1500 or so, it'll drop to 600-ish RPM but not die. If I push in the clutch at higher RPM than that, it'll drop to 600 then to 0 almost immediately.

It only did this if I pushed in the clutch when the choke was in its "just coming off full choke" position, and only if it was cold outside. The problem went away in the spring.

Now it's getting to be winter again and the problem's back.

My question: Does the less-restrictive K&N filter have anything to do with that?

 

[Deanril]

No it doesnt ,your problem is the choke is not staying on LONG enough.Its quite possible the choke spring is now weaker then when new ,and the butterfly opens sooner then when new ,and the high idle is linked to the butterfly ,no choke butterfly valve and no high idle.

It needs to idle high to warm up the engine otherwise your situation will happen.I would look either into a new choke/choke spring or ,see if you can adjust the choke spring ,sometimes they have 3 screws you can loosen and you can twist the black plastic cover and put more tension on the spring thus causing the choke to stay on longer.Or it will have 3 rivets that you can pop out and then adjust it and put sheet metal screws back in.

Or this may work if you have a electric choke ,pop a resister inline to slow the flow of amps ,thus causing the choke to stay on longer.

 

[Inkara1]

Ah, ok. I'll have to take a look at it, it's a weird little carb. Of course, taking off the air cleaner involves removing a couple of hoses, undoing some bolts, that kinda fun stuff. The car was originally bought in December 1980, so the thing's old enough to buy me some beer.

Yeah, I think maybe it has something to do with having to replace the carb floats. My dad and I left the bottom half of the carb on the manifold, on the engine, in the car. We just took off the top and replaced the floats, so maybe the choke got set to not stay on quite long enough in the coldest of cold weather.

In any case, last summer the thing only put out 8 ppm of hydrocarbons at idle (940 rpm)(120 allowed) and 6 ppm at 2500 rpm (150 allowed), and CO2 showed 0.0% at both RPMs. This is with smog check 1, but does that seem pretty clean?

 

[jopes]

I would say it is clean.

My 78 bronoc has no cat on it and she just squeeked by with 289hc @ idle and was very clean 2500 with 55 ppm HC's


I think I may have a vacuum leak someplace on my engine. Where I have no idea. Might be under the intake.

 

[Deanril]

Co2 needs to be at 12-16 % thats efficientcy of the motor.HC can be 0 a new cat can cover up alot of stuff.

If your CO2 was zero the car wouldnt pass ,because the machine is smart enough to know that the hose isnt plugged into the car,your thinking of o2 thats usually around 0-1%thats how much oxygen is left over after the complete burn from engine and cat.

 

[Inkara1]

There are two things the test measures. Hydrocarbons are one of them, and the other is O2 or CO2 or CO or something along those lines. This is the original smog check, not the Smog Check 2 with the wheels under load. In either case, it showed 0.0% for that one, and the 8 ppm at idle and 6 at 2500 for HC. This is also the original cat, although I did put in a new cap and rotor and adjusted the valves a couple days before the test.

jopes--tried the test where you screw a blowtorch onto a propane cylinder and turn it on but don't light it, then move it around the engine while it runs and look to see if the revs increase?

 

[Deanril]

The 2-speed idle test ,grades you (pass/fail) on HC (unburned fuel) and CO(how rich its running) but also includes o2 and co2(effiecientcy).

With your results the car is running quite good ,and the fuel is being metered quite well,and the cat is working efficiently.

 

[jopes]

nope, this is the second time I have ever heard of ti and today was the first. I have never myself tried this way. I always poured water over the intake. you will hear the rpm's change if there is a leak. and the water is not going to hurt anything if a spark is to set it off like a torch could melt some much needed wires

 

[Deanril]

My way is DANGEROUS!!!

And I have set like 5 cars on fire (no damage put out quickly but they were BLAZING!!)........now I have a fire extinguisher with me when I do it!

But its the BEST..

You think vacuum leak in a gasket intake or carb ect.... spray carb cleaner in the area ,or over intake it will make engine speed up and run normal when you hit the spot ,works the best.

 

[Inkara1]

UPDATE:

I've found out why my car wants to die when it's cold and it's just coming off idle (that Haynes manual can sure come in handy). The thing has an electric choke, which is heated by electricity. Well, there is one positive lead going to the electric choke, then the ground goes through a switch located in the air intake line. When the ambient temperature is above 65 degrees, the switch sends the voltage through a straight path to ground. When the temperature is below 49, it sends the voltage through a different path, with a 5-ohm resistor. (I assume between those two temperatures it divides the voltage between the two leads.) As deanril described earlier, sending the voltage through a resisted path means the choke will warm up slower. Well, below 49 degrees is when the problem I describe is. Luckily the resistor is in a metal case bolted right to near the top of the firewall, so it's easy to get to.

My dad and I tested the resistor and it's not resisting. So, the air temperature switch is switching, but it's switching from a non-resisted path to another non-resisted path. So, problem solved.

Well, almost. Trying to find another one of those little fuckers is proving to be the bitch from hell.

 

[Deanril]

Honda sure does get all technical with their carbs....