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Discussion Starter · #1 ·
Failed Emissions Test

1990 Astro (Z motor) mostly original @ 343,584 miles (552,944.8488960001 Canadian)

Before the test:

Replaced all plugs (3&5 were completely crusted over all others were clean).
New AcDelco O2 sensor.
Changed oil (put in 20W50 (the usual) and 1 bottle of No Smoke/No Leak) (Oil PSI is waaaay up there now.)
Set timing 2-3* after TDC ( I was having bad pinging/knocking).
Ran 1 whole can of Seafoam thru a vac line.
Put 3 cans of Seafoam in the tank with premium grade gas.
Ran the tank out and refilled with premium gas for the test.
Engine was at normal temp.

25/25 Test
Item / Allowed / Actual
HC / 184 / 205 fail
CO / 2.29 / 0.28
NO / 1195 / 247
CO+CO / 6.0min / 14.6
RPM / 2500 max / 1300

50/15 Test
Item / Allowed / Actual
HC / 188 / 207 fail
CO / 1.69 / 0.36
NO / 1300 / 269
CO+CO / 6.0min / 14.6
RPM / 2500 max / 1327

Ya'lls thoughts ????
 

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I'd guess the blow-by is causing the the high HC level???

I'm likely wrong here though....

Check the EGR valve...make sure it moves freely...maybe remove it and make sure it isn't all coked up...
 

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Failed Emissions Test

1990 Astro (Z motor) mostly original @ 343,584 miles (552,944.8488960001 Canadian)

Before the test:

Replaced all plugs (3&5 were completely crusted over all others were clean).
New AcDelco O2 sensor.
Changed oil (put in 20W50 (the usual) and 1 bottle of No Smoke/No Leak) (Oil PSI is waaaay up there now.)
Set timing 2-3* after TDC ( I was having bad pinging/knocking).
Ran 1 whole can of Seafoam thru a vac line.
Put 3 cans of Seafoam in the tank with premium grade gas.
Ran the tank out and refilled with premium gas for the test.
Engine was at normal temp.

25/25 Test
Item / Allowed / Actual
HC / 184 / 205 fail
CO / 2.29 / 0.28
NO / 1195 / 247
CO+CO / 6.0min / 14.6
RPM / 2500 max / 1300

50/15 Test
Item / Allowed / Actual
HC / 188 / 207 fail
CO / 1.69 / 0.36
NO / 1300 / 269
CO+CO / 6.0min / 14.6
RPM / 2500 max / 1327

Ya'lls thoughts ????
Catalytic converter gone bad?
 

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Discussion Starter · #5 ·
I'd guess the blow-by is causing the the high HC level???

I'm likely wrong here though....

Check the EGR valve...make sure it moves freely...maybe remove it and make sure it isn't all coked up...
Replaced the EGR late last year.
And cleaned out the port also.
 

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Discussion Starter · #6 ·
Blowby shouldn't be too bad... pcv should eat most...

might just be a deaded catalyst but the CO proportion seems low, if you can turn it a bit lean should go ;)
I'll check the PVC.

For some people, the numbers don't point to the cat.
It is the HUGE pancake style.
I'm pretty sure it is the original.

Puttin' a cat on it will double the value of my van.

Besides, in Atlanta, people are stealing cats from vehicles in parking lots for the metal in them. They are using cordless saw-alls in less than 5 minutes.
 

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Discussion Starter · #10 ·
Know what? I'd just try advancing the timing a degree or two and see what she will do at the inspection.
One plan I had was to move the timing to 2-3* BTDC and put 2 bottles of octane boost in the tank to hold back the pinging/knocking.
Also, to place the trans in D and not OD.

I had moved the timing after TDC to reduce the ping/knocking.
I also figured that with the engine being (almost) all original that the timing would be jumping all over the place, but the timing light is fairly steady. I did replace the dizzy late last year because the top bushing wore to one side causing the star points to hit the pickup. What a sound that made. Took me a few weeks to figure that one out.

I did replace the cap/rotor/coil/wires last year.

Please keep thinkin' out there.
 

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It sounds like you either have a lot of carbon on top of the pistons/and or a fuel issue. 2-3* ATDC is a big part of the problem. Premium fuel and true octane boosters will slow the burn rate which will require even more advance to burn properly. I'd be willing to bet that you're fuel pressure is low, especially under load, creating a lean condition, heatnig the carbon, causing the knock, and the higher HCs.
Your NOx numbers are low so I don't think the cat is bad and the EGR seems to be working. Normally retarding timing will drop your NOx and increase the HC/CO, so if you can run 0* advance without a ping, run more top-end cleaner, or other method of choice to clean it up.
Rent a fuel pressure tester from Autozone, snake it up past the hood seal and tape it to the windsheild, run it on the road and see what the fuel pressure is. I bet it drops under load. If it does replace the filter first, then the re-check. If it can't maintain fuel pressure check the wiring to the pump for full voltage and check the wires for corrosion. Replace the pump after you've verified that the voltage is there.
Worst case install a vacuum pump and connect it to the PCV and pull the crankcase down with the pump and don't put it back into the engine. Hide this cause it isn't legal. Excessive blow-by can peg your HC, but given your pinging issue, I don't think that is it.
 

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Discussion Starter · #13 · (Edited)
Ok, for you visual people, here are the pics of the plugs I pulled out.


18,000 miles (28,968.192 Canadian) on plugs 3+5 35,000 miles (56,327.04 Canadian) on 1,2,4,6


Close up of 3+5
 

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Get a leakdown tester, and do a leakdown test on 3 and 5. Looking at those plugs, I'm curious if you have burnt valves?
 

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Discussion Starter · #15 ·
Minor update.

Last week.
Added 4 cans of Seafoam into the tank and have run most of it out.
Today....
Changed timing to 0* TDC or maybe 1*BTDC (was hard to tell).
Replaced PCV.
Cleaned out the PCV tubing. It was maybe 50% or less airflow.
Replaced the air filter.
Checked voltage in the fuel pump harness (near the fuel tank) and it reads 13-14 volts with the motor running.

Tomorrow....
Test the fuel pressure.
Run a can of Seafoam thru the PVC port.
The last can I ran in it was thru a vac line that is ported near # 4 so may not have helped # 3 + 5.

Any other thoughts ? ? ?
 

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I don't know if its this simple, but can you put new plugs in it right before you have it tested?
 

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Wow! If those are the plugs, think of the pistons!
You need a leak down test on 3 and 5.
I'd bet you have a wasted set of rings, bent/burned valves, and/or bad springs.
No matter what though, that is your problem.
New, fresh plugs the day you go to smog check and run 91 octane premium, but all that carbon will get hot and it will still ping.
 

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Discussion Starter · #18 ·
Thanks for the ideas......

Now, to expand on the situation.
I need it to pass emissions in the next 10 days so I can get the tag renewed.
I had planned to sell the van last year but things didn't work out.
Well, the plan, again, is to sell it in the next 60-90 days for $500.00.
So, I need to get past the emissions for now.

Again, thanks for ya'lls thoughts.
 

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Sell it anyway and tell the person it needs to pass smog.
Start at $1,000 (if it looks nice), take $500.
They'll feel like they got a deal, you'll get what you want.

Believe it or not, it works. Lots of people won't look at cars listed under $1k.
 

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in places like california- the owner/seller is responsible for the smog check......
yeah I know many people sell the car without getting a smog test.......the problem is that the DMV will not do the transfer of ownership until the car passes smog. Unless its going to be a non-operational vehicle.
so if you sold the car to some scumbag and he cant get it smogged------- yet is driving the car around getting parking tickets etc- the person liable is the owner of the car........
 
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