Colorado emission test woes for an '80 L20B

[datzenmike]

 

                          2500                   Idle                Limits

HC PPM             289.3                  866.6             400

CO%                  2.83                    6.02               1.50

CO2%                13.35                  11.01              -

RPM                   2541                   748               1000

 

So another another fail. At least I have a comparable baseline though. Here's some pictures of the truck:

 

 

 

 

 

 

 

Proof of Colorado origination:

 

 

Another potential problem is the previous owners "fix" to the exhaust pip from the stock muffler back. It's tiny!

.

CO is carbon monoxide? This is gas is produced from the incomplete burning of carbon and oxygen. Seems to me you are running too rich or plugs not firing properly. Tail pipe is sooty from the carbon left over.

 

HC (hydro carbons?) is another clue of being over rich. This is simply unburned gas or burnt oil from worn rings.

 

Tail pipe is fine has no effect at that size.

 

 

 

Your truck may have a sticker from Colorado Springs but was is brought there or bought there new???? It could be from anywhere and Colorado has a higher altitude. Higher altitude will mean the air is 'thinner' and a normally jetted carb as sea level will run much richer as you go up.

[Buzzbomb]

At least you have two tests to go by now, and the 2nd one didn't cost you anything.

 

Are you using a vacuum gauge to troubleshoot this? Did you change the PCV valve? It looks like the original to me? Did you use the RPM drop method to set your idle mixture to lean best idle? You could easily tell if the exhaust had too much backpressure with a VG. I don't think the exhaust size matters, but you could also verify if your cat is plugged up with the VG. What condition are your plugs in? I'd have jacked up the idle speed to 1000, because in my experience, it works. The limit is 1350 RPM. I don't know what kind of tools you have at your disposal, but a VG is worth the money.

 

I personally don't believe the emissions stuff on an '80 is that big of deal. It seems to me that it is just a lot of valves, orifices, etc. Go through the diagram in the PDF I linked and make sure things are where they are supposed to be. They are pretty much the same. There are a ton of tests in there, but I would make sure the EGR valve is working ok AFTER replacing the PCV valve.

[Bill_P]

Those stencils were usually installed where the truck was originally sold. Common in the '80s. Now dealers have license plate frames with their name on them. Some truck dealerships still stencil a lot of the cheaper work/farm trucks.

 

It could have been bought out of state, but highly unlikely.

[datzenmike]

That decal could be 6 months old and the truck traded in on a new one. Agree it's only a possibility.

 

Check the emissions sticker under the hood. Literally, on the under side of the hood. It will say if high altitude emissions system.

[Bill_P]

Im not here to argue. I would bet $1000 its the original dealership. Take it how you want it.

[Buzzbomb]

That decal could be 6 months old and the truck traded in on a new one. Agree it's only a possibility.

 

Check the emissions sticker under the hood. Literally, on the under side of the hood. It will say if high altitude emissions system.

 

 

You know what..I forgot all about that because my truck was hit and I replaced the hood. Great point, Datzenmike. That truck more than likely has the sticker under the hood still. That has the diagram for all the hoses too, IIRC.

 

Thoroughbred Datsun is an OG Nissan dealer from that area MANY years ago, FWIW. The most important thing here, though, is the sticker under the hood. That truck has all the emissions stuff EXCEPT the air pump and CA only stuff if it's original to CO, which I believe it is. The only bearing on where it's from, I think, is whether or no it has an airpump. Otherwise, it's not running well enough to pass regardless of where it's from. Could a valve adjustment be needed and help this too, DatzenMike?

 

Use the FSM I linked and start eliminating possibilities.. The emissions stuff on an '80 is easy to check. Once again, a vacuum gauge, if you don't have one, is a great investment. Not sure what kind of tools you're working with, but that would be on my list. I'd say a vacuum pump of some sort, but you can always suck on the hoses, as illustrated in the FSM for the '78.

[elmerfudpucker]

Dump premium in, add a can of BK44? or is it 44BK? fuel treatment from napa to the gas, it looks like a little soup can, drive for 20 min at highway speed then try again. It should pass, always worked for me on even crappy running rides.  :ninja:

[datzenmike]

I've seen lots of Datsun/Nissans sporting local Chevy dealer decals because they were traded in and put on the lot for sale. Not saying it's from out of state only that it's possible. The decal could be anywhere up to 33 years old.

[MikeRL411]

 

What is Japan like? I would imagine they are strict with the population density. Kinda like SoCal with so many people.

  Even stricter than California. When US Military are deploying to Japan they are advised to attempt to import ONLY vehicles built and certified for the California market. Even then, no guarantee that those vehicles can pass Japanese import vehicle checks. You might have to go through an expensive upgrade, scrap the vehicle or have it shipped out of country at your expense.

[Bill_P]

People love to argue the stupidest shit on forums. Gotta love know it alls.

[nerdistmonk]

that decal has to be from when datsun was a used name, obviously there wouldnt be any datsun dealerships if nissan retired the datsun name, nissan would require them to alter the name to nissan and send them new advertising kits and flags,

 

 

Also heres the proof, cant believe i found this, heres a lawsuit against that very dealership from 1982 (just before datsun's trademark was retired, man you should be glad you didnt have to deal with this place lol):

 

http://co.findacase.com/research/wfrmDocViewer.aspx/xq/fac.19820218_0040528.CO.htm/qx

[Buzzbomb]

I can guarantee to those that care that Throughbred Nissan did in fact exist in Colorado at the time that truck was sold, used or new, as I stated earlier. 

 

Your EGR passage looks odd to me.. It looks like you're missing the hardline that goes from that threaded hole in the passage to the hose at the bottom of the BPT valve. It looks like there's a hole there with nothing around it. Then again, it might be below the point in the picture where it can be seen. Sure looks different than my EGR passage, though.

[nerdistmonk]

Whoa i just noticed that, ummm i would do something about that. What a hole.

[datzenmike]

People love to argue the stupidest shit on forums. Gotta love know it alls.

.

You know, Bill for 44 posts it's a little soon for being an asshole. 

[Viror]

I bought it from the original owners but didn't remember to take a picture of the original title, thus, the tailgate being my only photographic proof. One of the technicians at the Toyota dealership I work at offered to help after I told him I failed. Using his nice tools and better knowledge, we determined that I have a leak at the base of my carburetor, my accelerator pump is toast and my butterflies aren't returning to the same spot everytime.

[Z-train]

.

You know, Bill for 44 posts it's a little soon for being an asshole.

No kidding.

 

 

And for the record,there is a Throughbred Nissan here in Tucson also.

 

And what's even funnier is the people that think the no emission testing means you don't have to keep the SMOG gear on the vehicle and in proper order.

[nerdistmonk]

well the point being that the label wouldnt say datsun if it was put on there 10 years ago, it may as well say 'sold in the early 80s'

 

and these Thoroughbred dealerships seam to be all over the western half of the US, the one this car came from just happen to be sued for exceptionally crooked service.

 

(no shock, back in 1985 my parents had owned a nissan and it had the 'hopeless chokeless' computerized carb on it, it wouldnt run right at certain times, and the dealership instead of fixing it did absolutely nothing to it then billed them $500 for a new carb and tuneup that never happened, they wouldnt give them the car back till they paid. I cannot get them to drive or own a nissan to this very day. Sad because i could have fixed it if it were sitting here today)

[Viror]

I've ordered a carb rebuild kit and I'll retest after going through the carb and maybe some new spark 'em up plugs. Also, that "hole" under the EGR valve is actually plugged. I'll look around and see if I can find where that could link up to.

[darrel]

I have a '79 620 with unmolested emissions control on it. I don't know if there's a difference between the  '79 and '80 L20b, but you can compare if you want to. I live in broomfield.

 

Mine passed with flying colors last december.

[Viror]

It would certainly be nice to have a reference point. I couldn't get much access to the emissions diagrams from a '79 620 at work but I don't think it would be too terribly different. Do you work anywhere near Autonation Toyota/Go Toyota? It's just East of I25 on Arapahoe road. I really don't have much money to drive anywhere beyond my commute right now. Two old vehicles and college really sucks a bank account dry.

[Viror]

There is a special level in hell just for this model of Hitachi. I've used the Hitachi models on the Mazdas and the Ford Lima engines with much more ease than this one. Also, does the red spacer go between the carburetor and the heat shield or between the manifold and the heat shield? I think it's the former but I've been known to be wrong quite often.

[datzenmike]

Carb

Heat Shield Gasket (thin)

Heat Shield

Insulator Gasket (thick)

Intake Manifold

[Viror]

Well the carb is rebuilt and on the truck, runs great for the most part. Just need to tune the idle a bit and maybe lube the throttle cable. We'll see what it does for emissions here soon.

[Z-train]

You don't lube throttle cables.Clean them out make sure they're dry and if there is still an issue,it's junk.At the most use powdered graphite.

[elmerfudpucker]

You don't lube throttle cables.Clean them out make sure they're dry and if there is still an issue,it's junk.At the most use powdered graphite.

 

^^truth!!! had a damn cable try to kill me once from lockup at WOT, not cool, not cool at all.