GROSS POLLUTER - Failed Cali Smog test

[Nicholas7620]

Well the pump adds air to the exhaust so it will burn completely. You could try it. But keep in mind it only cleans up what little extra gas isn't burned in normal combustion. It can't fix a major problem

 

Hi Mike,

 

I remember my prior smog system rebuilds that there was good robust suction out of the AIR PUMP,  I'm going in for another smog evaluation in an hour with brand new plugs, meticulously gaped, guessing I'm going to be too high on CO percentage.

 

I'll next swap in the new smog pump.  This is going to be a process.

[Nicholas7620]

I just finished changing plugs.  The removed plugs were blackened up and black as coal.  The datsun is idling at 1600 right now warming up.  Hope I get lucky.

[Nicholas7620]

I'm back.  There was little improvement.

 

I'm at 10% CO emission, a problem is you can't smell CO.... the exhaust smells clean.  I should be at 1% CO

 

I'm planning to change out the smog pump on Monday and let the advice come from Datsun owners.  Smog tech wasn't overly impressed by suggestion to change smog pump.

 

I remember my airfilter openings produce more suction from the pipes in the airfilter openings .

 

 

The hole on the left has weak suction....the hole on the right has nothing.... the hole on the floor of the air filter has weak suction.

 

The EGR valve is old.  I'm in Study mode, not touching the Datsun until Monday.

 

Have a good weekend.

[DanielC]

It looks to me like the choke plate in the carb, in your picture is starting to close.  When the engine is warm, that plate has to be completely vertical.

[datzenmike]

 When they get hot, plugs are self cleaning. Sooty plugs could be from not enough driving distance or the choke on all the time.

[LenRobertson]

Roadster-ka is correct - unplugging the 12V to the choke will keep it closed, not open. However if you loosen the 3 screws on the plastic choke spring cover, I think you should be able to rotate the cover to the point there is virtually no spring pressure trying to push the choke closed. My  memory is that the choke butterfly is offset relative to the choke shaft so that it will stay wide open even if the cover and spring are entirely removed from the carb. But I'm not absolutely sure what happens at different manifold vacuum conditions. I think any time I've wanted to be sure of no-choke, I hay wired it open.

 

I can't resist doing my possible loose small venturi  rant once again. In the second pic in you post #11, I can see the venturis (one in each of the two carb barrels) down in the gloom of the carb throats. Just bellow the open choke butterfly for the primary barrel. If you haven't done so already, reach down with needle-nose pliers or a mini-seal pick and make sure neither of these is at all loose. Maybe just prying with a screw driver will be enough to get a wiggle if either is loose. The reason I'm obsesso about this is two of my three Datsuns came with carbs with this style small venturi holder and both had worked loose. Others on Ratsun have posted they have had this part come loose. My theory (which may be total nonsense) is if the venturi holder is loose, it can pull raw gas out of the one end where there is an O-ring, rather than through the tiny hole out at the small venturi where the gas is supposed to come out and be atomized as it is sucked down the carb throat. If your venturi holders are tight, that is wonderful. Ignore the prior rant.

 

You mentioned the EGR valve being old. I vaguely remember something about a stuck EGR being not a good thing but I have no idea what happens if the thing is non-functioning. Maybe nothing that will matter in a smog test. I've pulled off EGR valves that were gunky with carbon so maybe they can be cleaned rather than replaced.

 

Len

 

 

[datzenmike]

EGR dilutes the air fuel mix with inert (no oxygen) exhaust. It's only used with the engine under load, but not at full throttle. If the EGR tube has a leak, oxygen will get in and lean out the mixture. Last... there should be NO EGR at idle. If the EGR valve is dirty and can't close tight it will leak exhaust in and dilute the idle mix to the point it will hardly run.

 

If the EGR is stuck closed the engine will run fine but produce more NO.

[Roadster-ka]

I dont feel the egr is the problem. Egr stuck open, engine won't idle. Egr stuck shut, engine runs normally but with high NOx .

Carb is leaking fuel into venturi when throttle is open or choke is not fully open

[Nicholas7620]

I called the Technician in Florida who rebuilt the carb and he told me to tighten down the the idle screw adjustment all the way down and turn it out one and a half turns.  Hi also said the choke should have power and it does.  I haven't loosened the choke to leaner.  The setting is the same as the Florida tech's setting.  I might loosen it tomorrow AM because I'm going in for another dry run test.

 

After I made the idle screw adjustment recommended by Florida Tech, the engine idled a little rougher but still idled at the factory 750 rpm

 

Len -  I just came back in from checking for any looseness in the venturi tubes and they were firmly seated.

 

 

 

Mike - I took a temperature reading on the radiator, I'm at 180 running temp,  minutes after turnoff carryover heat pushed the temp to 200 before cool off.

 

 

I changed spark plug wires to high performance wire, they are a pretty blue color.

 

[Nicholas7620]

EGR valve stands for Exhaust Gas Recirculation and I changed into a new one 2 years ago when I had high NOx reading.  I'm very low and significantly less than smog allowance for NOx.

 

The exhaust smells clean but because CO is odorless and colorless I can't tell squat.  I'm supposed to be around 1% but the smog test machine put me around 11%.

 

I'll try to get another shot at the smog emission tester tomorrow AM and if I fail again.  I'll get the shop manual and retrace every vacuum tube tube and change out the smog pump to a rebuilt one I have from Cardone.

[datzenmike]

The idle mixture screw is to be adjusted in the field. A 1 1/2 out is merely a ball park place to start.

 

Engine hot, ignition timing set, valve clearances set.

 

Turn down idle as low as it will go

Turn idle mix in or out looking for the fastest smooth idle, Generally there is about one full turn where it runs well, just set in the middle.

Turn idle speed down with the idle speed screw.

Repeat the above as many times as needed till you cannot improve the idle quality and it is at 750-850 or what ever the factory recommends.

 

You idle mix is now correct.

[Nicholas7620]

I tested my choke connection and the plug was not live and I replugged the choke to a live plug.  I went to cold start and the choke opened as soon as the engine started.  I'm fast idling at 1400.

 

EVIDENTLY, my choke was connected to a ZERO voltage plug.  Yikes, I was screwed from the very get go. 

 

I've never played with a circuit tester before and I decided to take the plunge and pulled out my circuit tester and there was no voltage going to the choke. 

 

I tested a nearby plug and it had voltage so I switched the choke plug to the live plug and the start was smooth and yes the butterfly was closed and opened upon starting .... so there was no gagging by the engine.

 

I'm waiting for the choke to kick off ,  just checked, the temp is at 160 and idle is at 1550.

 

Recheck I'm at 170 in temp and idle is at 1550.  The idle is still at 170, 2 min later, rpms still at 1550.

 

10 min later temp is still at 170 idle is at 1700.  I accelerated the choke off and the idle is at 750.

 

I'm going to the smog shop and see what the readings are.

[Roadster-ka]

Good luck!!!!

[DanielC]

A electric choke works like this.  

When starting a cold engine, you step on the gas pedal.  Opening the throttle allow a fast idle cam to drop, and at the same time allows the choke butterfly to close.  Stepping on the gas pedal also squirts some gas from the accelerator pump into the manifold.

The engine starts, and on some cars, engine vacuum opens the choke a little.  On all cars, the heater should start to heat the heat sensitive spring that closed the choke in the first place, and the choke opens up gradually as it heats up, along with the engine.

As long as you do not touch the gas pedal, the fast idle cam cannot move, but the choke can open as the engine warms up.  the engine will stay at fast idle.  This is normal.

 

Earlier 510 cars, and 1972 521 trucks also had an electric choke.  These vehicles had a relay that applied battery voltage to the choke heater.  The relay got a signal from the externally regulated alternator to allow the relay to apply voltage to the choke heater relay.  The choke heater does not get voltage directly from the ignition circuit.  It used the alternator triggered relay to only apply current to the choke when the engine was actually running.

[Nicholas7620]

I didn't pass.  The advance was down to 5 degrees instead of 10.  It looks like the advance is moving around.  After I set to 10 degrees and checked it again.  The advance was up to 20.  So I lowered it back to 10 adjusted the idle to 700, then smelled the exhaust.  No smell. The B210 idles good. 

 

I'll go in tomorrow AM and bring my timing gun, tools and check everything  again at the smog shop and see what happens.

[Nicholas7620]

Where do I get smaller jets to decrease the size of the primary jet of my B210.  It's a Hitachi carburetor.

 

Found a website.  My Primary is a #104 and secondary is a #145.

 

http://www.jetsrus.com/a_jets_by_carburetor_type/jets_hitachi_main_4H7.html 

[Nicholas7620]

I failed again.  The smog tech and I couldn't get any improvement in CO emissions, I'm still at 11% at 15 mph and 6.8+ at 25 mph.

 

I've talked with Nat'l Carb and they're suggesting I try smaller jets.  Nat'l Carb is checking to see if they have smaller than a #104 but I'm wondering if I can swap out a #104 for the #145 from another carburetor because I fail at high RPM's.

[john510]

Why would a stock carburetor need smaller jets ? I know i mentioned it before but the Cat might be shot ? how old is it ? I ruined a cat on my 2000 Toyota Tacoma by driving only fifty miles with a cylinder misfire.This is on a V-6.One cylinder not igniting fuel destroyed it that quick.You said you've been running rich enough to have black sparks plugs.All the tuning and adjustment you could do won't fix an inefficient cat.

[Nicholas7620]

On 7/9/2018 at 3:58 PM, john510 said:

Why would a stock carburetor need smaller jets ? I know i mentioned it before but the Cat might be shot ? how old is it ? I ruined a cat on my 2000 Toyota Tacoma by driving only fifty miles with a cylinder misfire.This is on a V-6.One cylinder not igniting fuel destroyed it that quick.You said you've been running rich enough to have black sparks plugs.All the tuning and adjustment you could do won't fix an inefficient cat.

 

IF I was high on NOx then the CAT could be the problem and the EGR, PCV,  maybe SMOG PUMP would also be the usual suspects. 

 

Since the readings are high for CO then the intake side is the problem which could be  vacuum, carburetor, choke and too rich of a fuel mixture. 

 

Here is my new smog test for today after I put in a #104 carb jet for the Secondary thus reducing the secondary jet from a #145 to a # 104.  I also replace two suspect vacuum hoses and leaned the choke one setting.  As you can see I had significant improvement from GROSS POLLUTER to just Fail. 

 

I improved from ~11% CO at 15 mph to ~3% by reducing to a #104 secondary jet, I'm encouraged because of an 8% improvement.  However my CO% should be less than 1.52% at 15 mph.

 

I improved from ~7% CO at 25 mph to 2.10% by reducing to a #104 secondary jet.  Again I'm encouraged because of a 4%+ improvement.  Before changing jets I couldn't get any improvement in my CO readings no matter what I did.

 

Edited July 14, 2018 by Nicholas7620
to include a picture of Gross Polluter test

[Nicholas7620]

On 6/26/2018 at 6:17 PM, Nicholas7620 said:

Here is my Smog Test Result.

 

 

This is my GROSS POLLUTER fail.  Whew my CO% are very high because Gross Polluter is only ~3% and my reading is over 11%. 

[datzenmike]

At 25 MPH I can't see the secondary even being in use.

 

 

Is this the original carb??? Because it will be jetted properly. If running rich from having say, the choke on, re-jetting isn't really fixing the root cause.

[Nicholas7620]

On 6/26/2018 at 6:17 PM, Nicholas7620 said:

Here is my Smog Test Result.

 

 

 

 

44 minutes ago, datzenmike said:

At 25 MPH I can't see the secondary even being in use.

 

 

Is this the original carb??? Because it will be jetted properly. If running rich from having say, the choke on, re-jetting isn't really fixing the root cause. 

The choke is not on.  I can change the carb setting another notch to the lean.

 

No it's not the original carb.  I  may have returned the original for a core.  The carb is a rebuilt carb by NCI.  The carb is over 40 years old.  The jets could have been enlarged.  I don't know.  Changing the jets was the first improvement in CO readings. I did every thing else new air filter, plugs, rotor, cap, plug wires, change oil all these changes led to GROSS POLLUTER. 

I'm just in a fail category and NOT GROSS POLLUTER.

 

 

I have a 102 jet which NCI, the carb rebuilder, sent me.  I'm pondering whether it's worth the effort to change from a 104 to a 102.  Both the primary and secondary are #104 jets.

 

Which jet should I reduce to #102?  The primary or the secondary?  Is there a way I can make the jet smaller. 

 

I ordered just now several Hitachi jets #43's.  It might take 10 days to receive them.  Changing Jet size appears to be the only option.  If I could buy a brand new HITACHI DCH 306 - 11A, I would.  The DCH 306 - 11A is the California carb for a manual transmission. That original carb passed smog /was good for 30+ years.  These rebuilt carbs are good for two years and then fail.

 

[datzenmike]

Try for one in the high 90s for the primary. Secondary can be much richer as it's for full throttle use.

 

My 710 came with a 99 jet and while it ran very well, this was really for higher altitude where the air is thinner. Indeed the car is from Nevada average elevation over 5,000 feet. I got a 112 jet from a local L20B (sea level) and performance was actually increased! As Q-tip said.... more air needs more gas and with more power you can run it with less throttle. On holidays this summer I averaged 30 MPG US. Even got a tank @ 35.

 

Apples and oranges as far as engines go but it does show that they run best with the correct jets. I had a B-210 and I think the carb and the jets are correspondingly smaller. Did you ever take the plugs out and 'read' them? Overly rich will have darker plug tip porcelain with extremely rich showing as black or powdery black with carbon. Overly lean will be very light with dangerously lean extremely white. The Goldilocks color to shoot for is light brown/tan which is juuuuuust right.

 

If checking plugs, engine must be thoroughly warmed up so that the choke is off. You must also drive for 15-30 minutes, preferably on the highway at cruise speed so that the plug tip has time to heat up and self clean. Then pull over safely and remove the plugs. 

[john510]

Whatever cure you find to solve this problem make sure to let us know what it was.It might help somebody else NOT fix what isn't broken.

[Nicholas7620]

I'll let every one know what I did to pass.  I received my #102 jet  and #140 jets from NCI and I received a #108, #42 and #43 jets from jetsrus.com.  The #145 is the stock secondary jet.  Right now I have two #104's in my carb which resulted in avoiding the dreaded GROSS POLLUTER class to a lesser class of just FAIL.  I'm at 3% CO and I should be at 1%.

 

 

The #108 ... I received from jetsrus.com appears smaller than the #102 I received from NCI.  It's hard to tell.  I'm thinking of using the #102 and #43 for the primary jet and secondary jet, respectively.

 

 

Edited July 20, 2018 by Nicholas7620
add information for pictures