Suburban failed emmissions

[Murphy]

89 suburban 350 202k miles

so it failed on NOx. I junking the truck in march, and we have til late march to get it fixed, so I really dont care about it passing. I'm more concerned about how it will effect performance/gas mileage. I'm thinking its probably a bad cat since the cat is probably original, or at least really old. would it be better to just straight pipe it?

[Subliminal]

Why not just cat it and get through emissions?

[Murphy]

cat cost money, emissions wastes a good morning. Its getting junked when winter is over cause i'm tired of dumping money into it, and its rusting away.

[Subliminal]

Then just run that pipe and skip emissions, I guess.

It only took me one $150 fine to keep my vehicles up to par with our state's emissions. I'm not really sure how it works in your state.

[black86glhs]

On that model, I'de look at the EGR valve and passages. More than likely the passages are plugged up. I've seen this many times on gen 1 small blocks and Olds 307 V8s. It might just be the valve. Start it and apply vacuum to the valve and see if the engine runs bad or stalls. When working properly it should be able to stall the engine.

[turbovanman²]

I bet the EGR valve is bad, common on older units. DO NOT buy an aftermarket one, they don't work, buy OE or AC Delco. I need to know whats written on the valve to help you test it, "N or P"

[turbovanman²]

On that model, I'de look at the EGR valve and passages. More than likely the passages are plugged up. I've seen this many times on gen 1 small blocks and Olds 307 V8s. It might just be the valve. Start it and apply vacuum to the valve and see if the engine runs bad or stalls. When working properly it should be able to stall the engine.

Ha, you beat me by a sec but you can't all test them like you just said, you have to know if its an N or P unit, ;)

[Pat]

Let me know when it's getting scrapped...my brother might be interested in it for parts.

[black86glhs]

Ha, you beat me by a sec but you can't all test them like you just said, you have to know if its an N or P unit, ;)Good point, look for a P to be stamped on it. If it is a P unit, raise the rpms to 2000 and apply vacuum to the valve. the engine speed should drop by 100-200 rpm.

[Murphy]

if he wants it for parts, he can have it for what the JY would pay, $300. I'm not really interested in parting if, but if its something easy or if its really worth my time I would be up for it. it runs and drives fine. My dad drove it to NJ and back a couple weeks ago. engine and trans are original(I believe) 202k miles. rear end was replaces no more than 40k miles ago. has 4wd, tow package, silveraldo so it has the nice interior with rear a/c. if he wants anything from the exterior, forget it.


I just looked at the valve, I didnt see anything written on it. where should the letter be? or the top or the base?

[turbovanman²]

I just looked at the valve, I didnt see anything written on it. where should the letter be? or the top or the base?

Its on top, you'll need a flashlight and wipe it down. There will be 8 numbers, IE 17083456 and then a N or P.

Can you post the readings?

[Murphy]

the lower set is 325 21N

[RoadWarrior222]

If it's high because it's running lean, you might get worse gas mileage when you fix it.

[black86glhs]

the lower set is 325 21NJust hook a hand vacuum pump to it and see if the RPMs change at idle when you apply vacuum.