Carb Adjustment?

[newsance]

Here's the deal. I recently picked up a 1987 DR wagon with a carbed 1.8. I believe it should be a hitachi carb? Non computer controlled.

 

I'm having trouble getting the car to pass emissions. Hydrocarbons are within spec. The car runs and drives normally.

 

However, CO (carbon monoxide) emissions are way too high. These are caused by a rich fuel mixture. This vehicle also gets worse fuel economy than my previous subaru (1985 dual range- basically the exact same car).

 

I'm thinking the carb was calibrated to sea level. I am at 6500 feet.

 

I have had both an enhanced "dyno" test and a normal idle and 2500 rpm test. The enhanced test had it maxing the scale for CO emissions at 30 mph+. On the normal test, it passed at idle, but failed at 2500 rpm.

 

What I need to know is how to adjust the carb for a leaner mixture at off idle on up to full throttle. The carb is running fat up in the thin air.

 

Please note that it idles perfectly, bith in the low emissions sense and the drivability sense. I am not talking about adjusting the idle mix, I am talking about setting the carb up to run leaner when off idle.

 

Is there an on vehicle adjustment for this? Will it require diiferent jetting? If so, where the hell do I get it?

[erik litchy]

tell us the values for NOX CO and HC

[newsance]

HC- 40ppm, max 400. This is for both idle at 2500.

 

CO- max 1.5, tested .1 at idle, 1.55 at 2500.

 

However, the "dyno" results are more telling. CO was off the scale from 35 mph on up. They use a grams per mile measurement, so I can't make an apples to apples comparison. Lets just say it was way too high.

 

I only need to pass with the basic test, but I would like to fix the problem rather than fool emissions. Fuel consumption and CO output both indicate I should lean it up a bit.

[Snowman]

You probably have to get different jets if it's running rich under load.

[newsance]

Any idea where to get jetting from?

 

 

Also, how can I check the float setting? I don't think that is the issue, but just to make sure...

[rwaterhouse]

Hi;

 

THis is from the Alldata website. I have a subscription and was reading up on emmission controls as mine are half removed and saw this. Hope it helps:

 

High HC & CO - at High RPM

This condition is indicated by abnormally high carbon monoxide AND hydrocarbon emissions during cruise (2500 rpm).

 

 

 

POSSIBLE CAUSE ACTION Electrical misfires Check ignition system Vacuum leak Check vacuum lines and routing in

"Vacuum and Vapor Hose Routing"

in Emissions - Check intake manifold

and vacuum components Faulty bowl vent/canister purge system Check Evaporative System in

"Testing Procedures" in Emissions PCV malfunction Check PCV system in "Testing

Procedures" in Emissions EGR malfunction Check EGR system in "Testing

Procedures" in Emissions Restricted exhaust Check Catalytic Converter in

"Testing Procedures" in Emissions Initial timing incorrect Check Ignition Timing in "Adjustment

Procedures" in Emissions Incorrect Spark Advance Check Spark Controls in

"Fuel Injection and Computerized

Engine Controls" Verify vehicle remains in Refer to "Fuel Injection and Closed Loop at steady throttle Computerized Engine Controls" for (2500 rpm), oxygen sensor operation

is working Self-Diagnostic procedures Fuel metering malfunction

 

 

 

Carbureted Check carburetor passages, bleeds

and restrictors, internal leaks,

float level, metering rods and gaskets

Replace or rebuild if faults are found Fuel Injected Check fuel pressure

Perform injector balance test

Test regulator operation

(check vacuum line and return hose),

Service Fuel Injectors (pressure clean)

 

 

So I see the formatong is COMPLETELY messed up. This sholuld be in two columns, hopefully you can make sense of it.