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87 K5 not passing emissions in Denver

garlicbreath

garlicbreath

1/2 ton status
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So, my brother in laws 87 K5 350TBI won't pass emissions. He has had it in 2 different shops and spent over a grand. Has to rent tires for each E test cause they can't handle 33's or larger, it's becoming a pain in the ass.
It failed today for high nox's or no2's. Not sure which is the right word.
He is scanning the receipts so I can post what was repaired/replaced.
I haven't dealt with emissions in 12 years, (in NY now) but suggested the usual, new oil, plugs, filters, pcv, etc. He said they changed sensors and other stuff, had a bad gasket causing a vacuum leak and high idle, now it's dying at intersections and idles really low when he puts it in drive. He should drive it a while to let the computer adjust right?

Any suggestions besides the usual make it a trail truck or register it outside of Denver at billy bobs trailer park?

Also, how old does a truck need to be in Colorado to not need emissions? I thought it was 25 years, which would be next year for an 87.
 
Kind of hard to say until we know what has been repaired/replaced.


In Colorado 1975 or older, one e-test and that's it. If in an e-test area. No longer 25 years or older. I'm in Springs so, haven't had to do a test in a while. Post up what all has been done and maybe we can help from there. High NoX usually means high combustion temps. Or a bad Cat. But, not always.
 
Yup need to see gas.numbers.

Could be important cat, EGR or Evap issues also. Sounds like the shop working on it is a bunch of morons.
 
here in CT,if u bring it to a shop and spend over $600,and it wont pass,they just write it off. so ur good forever. is there any such thing like that in his/ur state? and x2 on the shops,they seem like morons. it should have NO problem passing with a cat.
 
I had a Nox failure on my mothers '94 once, everything else passed fine. Brought it home, I removed the EGR valve, cleaned it real good with brake cleaner, reinstalled it, had it tested again and everything passed with good numbers.
 
K5_4x4 said:
Kind of hard to say until we know what has been repaired/replaced.


In Colorado 1975 or older, one e-test and that's it. If in an e-test area. No longer 25 years or older. I'm in Springs so, haven't had to do a test in a while. Post up what all has been done and maybe we can help from there. High NoX usually means high combustion temps. Or a bad Cat. But, not always.
Click to expand...

HIJACK!!

Do they do any testing in the springs? I'm moving there at the end of this year and I keep the Blazer street legal even though it's only had 2K put on the street in 2 years.
 
Yep, it needs to relearn idle, but the base idle may be set wrong.
Sounds like he has EGR problems. The main purpose for an EGR is reduction of NOx, and it can also cause stalling at intersections.
 
X3 on the EGR. If the cat is good and the HC ppm (Hydrocarbons) are within allowable range, the EGR is the culprit.
 
OK, I'll have him scan his receipts and test results when he gets home and post them.
 
OK, here is the receipt from yesterday. Looks like they did the intake manifold gasket, the egr valve, an O2 sensor, oil change, rebuilt the throttle body, and replaced some vacuum hoses.
I'll see if he has the emissions report.

SO, the egr has been replaced.

He did say the cats are about 5 years old, aftermarket high flow units.
He also said for a while the only way he could get it to run was unplugging the map sensor, which made it run really rich, but it ran. He said the shop smelled fuel in his oil.
Would excess fuel like that burn up cats?

And how does unplugging the map sensor make it run rich?


Well I can't attach it. It's a PDF, photobucket won't upload it, is there another hosting site that works with PDF's?
 
Recon! said:
HIJACK!!

Do they do any testing in the springs? I'm moving there at the end of this year and I keep the Blazer street legal even though it's only had 2K put on the street in 2 years.
Click to expand...

No testing in the springs since the end of 06.
 
garlicbreath said:
Here's the work from yesterday. Found a site that will host a pdf for 30 days.
http://freepdfhosting.com/1cdc3f54b7.pdf
Click to expand...

Well they rebuilt the throttle body, replaced EGR valve, and repaired some vac lines.

But it would help to see the report of gasses. If they even give that to you. I haven't seen a Denver (IM240) inspection sheet
I'm a little rusty, but did a lot of emission work in Phoenix and in the springs when we had it. I was licensed when I was 16
 
Well, rich will burn up a cat. by giving it more fuel than it can handle and make it run hotter than it can stand.

If he has fuel in his oil, he needs to address that before it ruins his engine.

If they repaired some vacuum lines, they may have hooked them back up wrong. Or messed something up when they fixed the EGR.
 
Also, I have had luck with Zipping a PDF file, because the forum will allow a much larger Zipped file than a PDF.
 
Here is the emissions report. He is SO close to passing!

Brentsemissions.jpg
 
Here is my advice take it for what its worth.

High nox is normally caused by improper EGR function, running lean or bad cat, but not so much bad cat, but a cat not burning off excessive gasses as it should. Maybe like an aftermarket cat.

The EGR valve may be good, but the passages could be clogged/blocked. The EGR valve may not be commanded to open by the computer at the right time either (normally the computer will ground the solinoid)

A quick test of EGR passage is to unbolt it and start the engine. It should sound like a major exhaust leak and even more are throttle is snapped, obviously.

Lean, normally not an issue I've seen on tbi trucks, but the o2 sensor could be slow or lazy. Maybe someone else can chime in on lean tbi issues.

And well the cat, many of the cheaper universal cats do work as they should.

If it were mine I would play with EGR passages 1st and see if there is any carbon built up in intake manifold or worst car the passages from the heads.

But like others have said, see if there is a waiver for the amount of money be has spent
 
carbon buildup on the pistons will also cause a high nox reading. de carbonizing the engine helps reduce the nox levels somtimes. google decarbonizing an engine with water.

the cats may be used up as well.
 
Yeah I failed to mention anything about the carbon build up.
Was also thinking about engine temp, it could be running a little too hot
 
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