Failed emissions test... help

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Failed emissions test... help

December 05, 2006, 11:08:10 AM

If I remember correctly I'm reading too high NOx at 25mph, over 1000 above average. At 15mph I passed. The people at the inspection place couldn't begin to tell me why. Said either maybe egr or cats, but I put 2 new high flow cats on back in 04 and a new EGR and EVP about a year ago. Any suggestions? How well does that pass inspection in a can stuff work? I got 15 days to get it fixed...

Failed emissions test... help

Reply #1 – December 05, 2006, 11:26:44 AM

Also forgot to mention i'm sure i'm still throwing the same lean codes I've been chasing for a couple years...

Failed emissions test... help

Reply #2 – December 05, 2006, 05:39:58 PM

Make sure your timing is set at 10 BTDC. Use the lowest octane fuel you can get and I've also heard that running some alcohol in the tank can help but I haven't tried that yet.

I also failed in TX for NOx with a new MAC cat pipe and new EGR valve and EVP so I'm in the same boat. My timing was at 12 BTDC and I was running mid grade gas. I tried the guranteed to pass in the can and my 2nd test was even worse. I havent been back since but I'll be giving it another go soon... I may just try and bribe someone.

Let me know what you figure out!

Failed emissions test... help

Reply #3 – December 05, 2006, 05:53:23 PM

Quote from: Metal Matt;117028

Also forgot to mention i'm sure i'm still throwing the same lean codes I've been chasing for a couple years...

Actually, being lean is your problem. I'm sitting here looking at a chart in my Ford Fuel Injection book that shows the effects of A/F ratio on pollutants and it shows that if you get even the slightest bit past 14.7:1 ratio the NOx skyrocket. CO and HC will be be fine, they'll only rise if you're rich but not near what a lean condition will do to NOx.

You just have to figure out why you're getting lean codes and fix it (easier said than done). I bet you'll pass after that.

Failed emissions test... help

Reply #4 – December 05, 2006, 10:56:43 PM

It's gotta be your lean condition. I have two high flow cats and dual exhaust (one cat on each side) with headers and I passed the Illinois smog test fine.

Failed emissions test... help

Reply #5 – December 06, 2006, 08:24:14 AM

Quote from: Dogcharmer;117079

Actually, being lean is your problem. I'm sitting here looking at a chart in my Ford Fuel Injection book that shows the effects of A/F ratio on pollutants and it shows that if you get even the slightest bit past 14.7:1 ratio the NOx skyrocket. CO and HC will be be fine, they'll only rise if you're rich but not near what a lean condition will do to NOx.

You just have to figure out why you're getting lean codes and fix it (easier said than done). I bet you'll pass after that.

that’s what I was thinking but he did a better job explaining it.

Failed emissions test... help

Reply #6 – December 06, 2006, 03:21:58 PM

Thanks guys. Guess its time to get to work. Maybe its a bad/clogged injector? I've cleaned 'em a bunch before with different stuff and it never seemed to fix the problem. I'll check those and for vacuum leaks as well.

Failed emissions test... help

Reply #7 – December 06, 2006, 10:22:43 PM

what code number you getting?

also i have heard to lower your fuel pres prior to inspection.

Failed emissions test... help

Reply #8 – December 10, 2006, 04:22:46 AM

Fill it with high octane fuel... 91-94'sh... run the tank dry then fill it again... if it doesnt pass after that... come on, everybody knows somebody that knows somebody

Failed emissions test... help

Reply #9 – December 10, 2006, 08:34:40 AM

found this it might help
http://www.jason.fletcher.net/tech/sniffer/sniffer.htm

Failed emissions test... help

Reply #10 – December 11, 2006, 09:06:00 AM

Will running a higher octane fuel really help it not run lean?? Right now I just use regular 87 octane.

Also, I just thought, I'm using an HO TB/spacer, with the SO upper intake. Is the extra air possibly creating the problem?

Failed emissions test... help

Reply #11 – December 13, 2006, 04:18:34 PM

Alrighty, about to take it back up for a test. I found 2 things...

First off, one of the 3 wires going to the plug that the 02 plugs into, was pulled out about a centimeter. Grabbed some needlenose pliers and shoved it back in...

Secondlyness, a light green (olive?) colored tube going from the egr to something on the rear of the strut tower had a bit of a crack in it. Granted, I noticed this a while back and repaired it the best I could with some electical tape and a prayer, but it seemed like it had a kink in it that might have either been choking it or a leak. Got that straightened out and hopefully it will pass and they will give me a really sweet 80s like high five. The kind were you have to jump. Or just passing would be good.

Question, what actuates and tells the egr to open? Does the evp give it some electical signal, or does a vacuum pull it open ie that stupid cracked olive colored tube? Also, if its exhuast gas returning, where is it returning from, the tube that goes under the plenum?

Failed emissions test... help

Reply #12 – December 14, 2006, 08:55:31 AM

Well I passed.... because the guy doing the inspection stuck a screw driver in the egr to get it to open up during the high rpm part of the test... Its got a new egr and evp on it. I'm guessing the wiring to it is messed up? part of it where it tee's off looks exposed and somewhat rusted. I guess that could be it? I got a year to get it fixed and sorted out before next inspection.

Failed emissions test... help

Reply #13 – December 14, 2006, 09:05:59 AM

The computer controls the EGR by "dithering" the control solenoid. It applies pulses to the solenoid to either suck some more air out and open the EGR a bit more, or let a little air bleed back in so the valve closes a bit.

Don't take this drawing as gospel, even though it shows green to the EGR valve. I just used the different colors to separate the functions and make it easier to follow.

Failed emissions test... help

Reply #14 – December 15, 2006, 03:50:59 PM

Thanks for the diagram!