I recently failed emaission in the NOx test. I have 4 grams when 2 is the limit here!!! i dotn think this is being caused by my broken exhausy manifold studs, but they are being fixed int he shop right now anyway. I guess tha car is running lean at higher throttle. It runs really strong so I dont think its an injector. Could it be an O2 sensor? The car has 110000 miles on it.

 

Egr ???

.....

 

Get a leaky exhaust!
I passed with one

 

Seafoam! Not only is it fun, but it helps lower your emissions.

 

It's the EGR system. I failed NOx 3 times, and bought a replacement cat, which did me no good. Some part of the EGR system is failing. First, with car idling, rev the engine and make sure the EGR valve is opening. If it is, then it may be clogged. Craig's site has a write-up on how to clean it. If it isn't opeing, then either the EGR solenoid valve (or EGR temp sensor if you have a Cali spec car) is malfunctioning or not receiving proper vacuum. On my car, the vacuum line going to the EGR solenoid was bad, so I used another vacuum line and a T-junction to give it a good vacuum source. Now my EGR valve opens just fine.

 

I don't think Seafoam will be enough if he is double the limit. I used Seafoam, and noticed a better idle and fuel economy, but it certainly didn't cut my NOx in half.

 

I'm sure it would help a little, and it sounds like he could use all the help he can get.

Has anyone tried that stuff at autozone that you pour into your gas tank and it "guarantees you to pass emmissions" ? I don't remember the name, but they stock it by the fuel injector cleaner.

 

I think I've heard of people using the G2P guarranted to pass stuff and saying it worked...

 

Again, not to be the pessimist, but NOx are caused by excessive combustion temps, and G2P is mainly used to pass CO and HC's, as it contains lots of oxygenators that will give a slightly cleaner burn. And I wasn't suggesting he not use Seafoam, I was just saying don't expect to put a can of seafoam through your car and then just pass. If your NOx are double the limit, it is 99% the fault of the EGR system. Believe me, I spent weeks researching all types of solutions to the problem. If someone can search, there was a pretty good thread I started about this back in the winter when I first failed.

 

whoops, I should have just said that people liked G2P in a totally unscientific sampling, but I don't know why they failed-but it looks like mizeree x has done some good investigating. So get to work on the EGR... and post your findings.

 

I'm only looking out for people so they don't spend money needlessly on things that won't help them pass.

 

check the temp sensor connector for corrosion.
You can also clean out the EGR valve, and check all the vacuum hoses especially those associated with the egr.

 

I'm all for not wasting money -luckily they don't test in KS, and only in St. louis in MO. Judging by the smell of my exhaust, I'd probably get my car impounded...

 

i agree with the others: EGR. i had to replace it on my dad's bronco for it to pass. once i did, it passed perfectly.