Hows it going everyone, Im very much so new here, and having problems with emissions here in cali(I'm from Hawaii but here for school).

Heres my situation; I recently bought a 1985 Blazer 4x4 with an automatic transmission and the 2.8 v6, and odometer just hit 100k. Its a really clean truck, with very little visible wear inside and out. I Picked it up for dirt cheap, and knew it wasn't passing emissions, figured I could sell it for scrap and almost make my money back if i couldn't get it to pass. Or ship it home to hawaii where smog is not required.



As far as the engine goes its only noticeable problem is that cold starts are a bit rough, need to give it some gas to fire it up, then some white smoke/evaporation of some sort for a minute or two, and the engine feels very rough and shaky. But as soon as I rev it up, it seems to cough out whatever is wrong, smooth out, and run perfectly fine for the rest of the day, with a faintly noticeable surge at idle.

Transmission wise, when I test drove it, I drove it on the freeway so was in overdrive the whole time. But now when I just drive it around town I am in drive, and when I am coming to a stop there is a very noticeable jerk coming from the transmission down shifting. Its always right before I come to a complete stop. But this jerk does not happen in overdrive. And I have read up a bit and it seems that it will poop out at some point in the not too distant future, which isn't the end of the world as I hope to swap it for a 5 speed by then. But for now I will baby it and need to work again this summer for funds in order to do anything like that. The transmission fluid did seem a little bit burnt, so I changed it, and it definitley dampened the jerk. I was also surprised to find that there was no drain plug, so I had to take off the whole pan.

Now for the emissions, the gentleman I bought it from provided me with his service records and past emissions tests. Which when he first bough the truck a couple years ago it passed no problem at all, but in the two year time period since then he did a carb overhaul, and got new oxygen sensors, and serviced it regularly. When he just recently went in to get it smoged it failed grossly. When I got it from him it had fresh oil and fluids, I replaced cap, rotor, plugs and wires, and pcv, and wanted to see how it was doing, got a cheap pretest and It failed again, but not grossly.

Here are the results:

Original test where It passed:
co2: 13.2, 13
o2: 2.2, 2.5
Hc:112, 58 Max:131, 103
CO:0.46, 0.01 Max:0.61, 0.77
NOx: 162, 448 Max:760, 784

Most recent pretest:
CO2:11.6, 8.6
O2:3.1, 7.4
HC: 173, 189 Max:131, 103
CO:1.82, 2.11 Max:0.61, 0.77
NOx:975, 949 Max: 760, 784

So you can see it still failed pretty bad in EVERY section. The mechanic told me to get a new cat, but the one on there now is not the original, pretty shiny and new welds compared to the rest of the exhaust system. Been thinking maybe egr valve? O2 sensors? or some internal flaw in the carb.

Well that pretty much it, my plea for help. Any guidance or similar situations input would be greatly appreciated. And I cant figure out how to upload pictures. Ive been a old volvo k-jet kind of person, so even carbs are newish to me.

God I wish I had a 4bt

-Justin

 

Welcome to the forum. Really clean truck with a tough looking stance. I'd start by finding the best carb. guy around and have it gone through. It's cheaper than a cat and has the highest potential to pay for itself in fuel saving. The mechanic may be right about the cat. Even though it doesn't look very old there's some cheap cats that last just long enough to punt the car.

 

Thanks for the reply, i will definitley get my carb fully checked out, and also maybe invest in the cat.

And today i found this wire, not hooked up to something, I have no idea what it does, but its on the drivers side near the rear of the engine. Any idea what it goes to? Or what is back there on that side that has connections. Tomorrow i will search more thoroughly for the plug in.

 

Well I couldnt find what it went to but I pulled a code 42, EST?

 

Electronic Spark Timing circuit. Code 42 is usually caused by a bad ignition module in the distributor.

 

How does the air filter on it look?

What were the spark plugs gapped to?