Emmisions

[frogman68]

I hate emissions That being said I am at a total loss on a 88 Blazer 350 TBI either 97 or 197k on the engine.
Took it to emissions it failed with the following.

Hydro Carbons 7.0335 allowed is 2.4 Carbon Monoxide 9.5826 allowed 80 Oxides of Nitrogen 4.3030 allowed 4.2

Took it home and did the little computer check it gave error 13 for 20 bucks I just replaced the O2 sensor. While I was at it I changed the plugs checked the cap and rotor (less than 500 miles on this stuff) and did adjust the timing .

This truck is seldom used till my son starts driving. So before taking it back I ran it a few days seems ok rechecked the timing this morning and took it back.

Today it failed again

Hydro Carbons 11.4070 allowed is 2.4 Carbon Monoxide 18.1414 allowed 80 Oxides of Nitrogen 3.4058 allowed 4.2

Now it passed two of three but the CO2 has doubled and the hydrocarbons still are high since its TBI I can't adjust it not sure what to do to it next besides register it Historic and be done with it

[Stewart G Griffin]

Exactly; i was going to suggest historic plates.  Much cheaper too.

[VileZambonie]

Do you have the CO2 and O2 readings also? If you do I can point you in the right direction.

[frogman68]

Do you have the CO2 and O2 readings also? If you do I can point you in the right direction.

no they dont give that to ya just CO HC and NO

[VileZambonie]

What are your results in?

HC? PPM?

CO %?

[frogman68]

What are your results in?

HC? PPM?

CO %?

Hc first test was 7.0335 gpm allowed is 2.4 gpm second test 11.4070 gpm

co first test 9.5826 gpm allowed is 80 gpm second test 18.1414 gpm

Both times CO passed but for the second test it doubled and that is after a new set of plugs oxygen sensor and timing adjustment.

Thinking since this thing is 20 just change the Cat and see if that helps .

Might just be me but the exhaust feels hotter than "usual" for a chevy no scientific things just a feeling

[Jiggy]

I would suggest this.....rather than throwing parts at it (cat alone is going to be couple hundred installed), I would fing a reputable shop that has a scope, not just a scanner.  Around here there are a few shops that have a computerized scope and the average cost for diagnosis is $70 (about an hours work).  If you're not sure who to go to, I would suggest calling 1 of 2 people to find out.  Your local NAPA would know possibly (not just any parts store but NAPA because a good shop is primarily going to be using quality parts like NAPA).  Or the other would be the local Snap-On guy and ask him who has a scope.

I wold love to offer ideas based on numbers you can recite but changing one thing can alter others and without a scope you really can't see whats going on.  If you want more info let me know.

[VileZambonie]

Without the 5 gas readings I can't tell you what the most likely cause is. Well at least the HC, CO, CO2 and O2. If you can give us scan data also at operating temp that will help us otherwise like Jiggy said, you'll just be throwing parts at it.

[TexasRed]

And make sure the engine is hot when you take it to the emissions place. These engines don't run real clean when they're cold.

[Blue 82]

how did you set the timing?

[frogman68]

how did you set the timing?

Let the truck run for about 30 minutes (outside temp about 50 degrees Fahrenheit) hook the timing light up and disconnected the EST (Think that is what its called Brown/Black wire by the master cylinder) and set it to 0 degree's

this truck is seldom used I think I am going to run it this week to see if that will clear it up

[GoatBeard]

I thought 8 degrees was the factory setting?  I used to set mine at 10 -- made it run better.

[choptop]

I thought 8 degrees was the factory setting?  I used to set mine at 10 -- made it run better.

It's a TBI engine so the timing is set differently.

[GoatBeard]

AHH! 

[frogman68]

What is it called ?

I did a vacuum test I get 0 at 2000 Rpm at the EGR valve when I traced it back it goes to I have no idea what it is called but it has vacuum on the inlet from the carb but nothing coming out on the side that has the EGR there is wires there not sure if its the EGR Solenoid (the pic from Autozone doesnt look like it). Of course the camera is dead and no batteries and its Thanksgiving so I cant get any today

Btw when I push up on the EGR valve at idle it does want to die