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  #1  
Old 07-09-2011, 03:30 PM
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Join Date: Jul 2011
Location: Cherry Hill, NJ
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Hmm....87' 420 SEL failed emissions (NJ)...what to do?

This morning, I took my 420 through NJ's emissions test. Judging by the way it was running (slight sputtering, exhaust had an odor to it, but not of rotten eggs), I had a feeling it was going to flunk. As a last ditch effort, I threw in a bottle of 104 Octane boost and a bottle of Heat into the gas tank, opened it up on the highway, and ran it through. These were the results...

IDLE - FAIL

GAS READING STANDARD

HC ppm 1878 220 FAIL
CO% 0.23 1.20 PASS
C02% 7.6
02% 9.5

HIGH IDLE - PASS

HC ppm 217 220 PASS
CO% 0.72 1.20 PASS
C02% 13.1
02% 1.6

I'm almost wondering if the octane boost and dry gas did more harm than good. When I purchased the car, it had a slight hesitation to it when you'd hit the gas, and the idle is ever so slightly on the "sputtery" side. However, it never feels as though it's going to stall out. What should I look for? What should I change? I can't say that I've paid much attention to the gasmileage, as it's not my daily driver. The inspector at the DMV told me to try "the cheapest fix [I] could first", as he's seen people "spend hundreds of dollars, only to still fail". Sage advice.

Any suggestions?

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  #2  
Old 07-09-2011, 04:11 PM
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Well high hydrocarbons would mean that the engine is running rich, which is supported by your observations of a rough sputtery idle. This could be any number of things, but means that there is an amount of unburned fuel in the exhaust. Personally I would begin by adjusting the air/fuel mixture, which is free if you're willing to do the work and read through the Bosch injection troubleshooting manuals/DIYs. IIRC you'll need a digital multimeter capable of reading duty cycle.
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  #3  
Old 07-09-2011, 04:39 PM
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Join Date: May 2011
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Checked your oxygen sensor(s) lately? The voltage between the output line and chassis ground should oscillate between ~0.2 and ~0.8V 1-2x per second at idle with a warmed up engine.
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Old 07-09-2011, 05:33 PM
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How many miles on the car? You say the car is sputtering as in misfiring? That could definitely cause high HC readings. When was the last time all of the ignition items were changed out? Start with the basics and then move along to checking the duty cycle.
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  #5  
Old 07-09-2011, 08:15 PM
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Location: Cherry Hill, NJ
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It doesn't feel as though it's misfiring...it just feels as though the idle is not as smooth as it should be...

The car has 190K miles on it. I just purchased it. I don't think the 02 sensor has been checked, but shouldn't the 02 sensor light come on?
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  #6  
Old 07-09-2011, 08:47 PM
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Quote:
Originally Posted by bier79 View Post
It doesn't feel as though it's misfiring...it just feels as though the idle is not as smooth as it should be...

The car has 190K miles on it. I just purchased it. I don't think the 02 sensor has been checked, but shouldn't the 02 sensor light come on?
Nope, the O2 sensor light is just a timer that illuminates after a certain mileage, to remind you to check or replace the O2 sensor.
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  #7  
Old 07-09-2011, 09:10 PM
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Join Date: Dec 2010
Location: upstate SC
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Its been like forever since I've had to deal with "gas" readings.... No inspection laws here in SC. Looking at the readings I'm thinking you have a lean missfire condition. Check for a vacuum leak......fwiw
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  #8  
Old 07-10-2011, 11:28 AM
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Vacuum leak....this was actually something that came to mind. As I've never turned a wrench in my life...whereabouts should I start looking for this leak?
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  #9  
Old 07-10-2011, 01:11 PM
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Location: upstate SC
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ok......Trying to explain how to find vac leak.......hmmm.. I guess best place to start is by checking all the smaller vac lines coming off the intake, trace them to their respective locations. Theplastic ones can become brittle and break in half. The rubber ones tend to rot/split right where they attatch to the port on intake. Be sure to check the one going to trans vac modulator coming off right (pass) side rear of intake. Also check idle air valve hoses. This would be a good place to start. Also you can spray some choke cleaner (cold engine) on the suspect areas and look for a change in engine idle quality.... Lot of places to leak; hopefully just a hose. Remove the breather first and go hunting. Looking at the 4 gas readings once again I believe that this is your problem. Oh, most of the time if the leak is somewhat large you can hear it, a mid/high pitched whistling noise..........good luck

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