I have a mental block against OBD1 carbs

[nipper]

Good news - Justy has a working exhuast system

Better news - valves all adjusted runs quiet

Best news - IT RUNS

 

not so good news.

 

Has a very loopey idle. Easily stalls. Prefered Idle speed someplace between 1200-2000 rpm.

 

There is a random miss at all rpms. Trust me this is a huge improvement over what it was. I think pouring gas straight down the manifold was more effecient then the old carb.

 

Justys really do not have complicated emissions systems, the carb has a duty solenoid.

 

All new ignition parts.

 

The miss is driving me a little nuts as iggy timing doesnt doesnt affect the miss (does effect the engine rpm so that is ruled out).

 

Car will run smoothly for the first 10 seconds it is started.

 

The only known carb issue is that the evap vent valve in the carb really doesnt exist. The rubber seat on the piston is 1/2 gone. I havent ruled this out yet as the issue.

 

I am thinking duty solenoid due to what happens at the cold start. Car does fire up every time easily it doesnt labor or putput like it is flooding.

 

This carb came off a perfectly good running justy. The previous carb was rebuilt and royally ruined by a rebuilder. Oddly I am not the first justy person to have this issue.

 

30,000 original miles, engine is tight. I don't think it has anything to do with the car sitting for many years, but I am open to reasons.

 

I do GREAT with the nightmare 1970's and 1980's emissions and carbs, kick but with Fuel Injection. This is my black hole of induction.

[nipper]

1989 Subaru Justy CVT 30,000 miles

engine tight.

 

been through 2 1/2 carbs (dont ask)

 

Second one is the best so far.cars runs smooth for ten seconds then starts popping with idle anywhere from stall to 2000 rpm (650 normal). It has a random miss with the freq of popcorn. no backfire through carb just pop ........pop....popopop ................pop...........popop rough idle. Rpm levels out it still popps.

 

New plugs etc

New filters etc

Newly fabricated exhaust pipe sadly with an open air injector port

I am nt sure if there is an issue with the duty solenoid, but I am going to use a dwell meter to find out. I wonder if my sears eng analyzer will be a low impedence meter.

 

I am going to try this

Monitoring the MC solenoid's average duty requires (for most people) the use of high impedance dwell meter. A low impedance dwell meter may be used unless it affects engine operation; my recommendation is to not use a low impedance dwell meter (that is, stay away from self-powered dwell meters). Following the GM procedure, set the dwell meter to the six cylinders scale REGARDLESS of the number of cylinders in the engine. At this setting, 30 degrees will correspond to a 50% duty cycle, 60 to a 100% duty cycle, and 0 to a 0% duty cycle. Run the engine until closed loop operation is present; this will be indicated by a varying dwell (see footnote 1 for deviations from this procedure). Once the engine is hot, not the average dwell -- the reading should vary equally above 30 degrees and equally below 30 degrees. The following is a brief trouble listing:

1. DWELL NOT VARYING: system is operating in open loop.
   
2. DWELL STUCK AT 10 DEGREES OR LOWER: full rich command is present; the computer is compensating for WHAT APPEARS TO BE a massive fuel flow reduction (check for dirt in carburetor, air injection system stuck in upstream position, vacuum leaks, improper a/f mixture setting...).
   
3. DWELL STUCK AT 50 DEGREES OR HIGHER: full lean command is present (check for float stuck low, valve seat damage, oxygen sensor's sense lead shorted to battery voltage, etc.)
   
4. DWELL OSCILLATING, BUT AVERAGE READING IS BELOW 30 DEGREES: average rich command is present (check for vacuum leaks, dirt in carburetor's jets, improperly set a/f mixture...)
   
5. DWELL OSCILLATING, BUT AVERAGE READING IS ABOVE 30 DEGREES: average lean command is present. Check for incorrectly set a/f mixture, float stuck low, valve seat damage, clogged air filter, etc...).
   

Based on the above descriptions, it should be fairly clear on how to set the idle a/f mixture: merely set the mixture so that the average dwell is 30 degrees. Now, suppose the system's dwell is not varying, but the sensors are working properly, the upper radiator hose is hot...

 

Several cars with small engines have the oxygen sensor mounted fairly far away from the engines. Indeed, during idle conditions, the sensor may cool off to the point that it will not operate (I had this experience in a 1986 Mustang with 2.3 liters engine and EEC-IV system). My recommendation is that all electrical accessories be turned off (so as to provide a minimal load on the engine) and use the idle stop screw on the carburetor to gradually increase the idle rpm until the sensor begins oscillating. Ensuring a negligible load on the engine guarantees that the carburetor will be operating mostly on its idle circuit. Now, set the a/f mixture so that the average dwell is 30 degrees. On the Mustang, this was done at about 1500 rpm. Note that the a/f mixture setting procedure assumes that NO fuel delivery problems (vacuum leaks, clogged carburetor, etc.) are present.

 

Otherwise i am sort of clulees. i am much better with a full mech carb, obd with all those millions of hoses, throtte body FI or full blown FI.

 

Suggestions?

[bheinen74]

timing?

loose spark plug

bad cylinder?

[nipper]

Timing is ok (still tyriong to set it but doesnt help at all). I cant get it running smooth enough to really get it settled.

New plugs

Tight engine.

[bheinen74]

this is fitting, for it sounds like popcorn you say.

 

maybe someone dumped popcorn in the intake.

 

I am not much help but will keep checking in you need to get it going..

 

bad valve perhaps.