failed emissions test
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Junior User
Joined: Apr 2003
Posts: 57
Likes: 0
From: St. Louis area
failed emissions test
You guys did such a great job helping me with my idle problems, so I'm back with another problem. '88 XLT 302 Auto. I just did put in a new throttle position sensor and a new egr valve sensor to get the beast to run right (instead of stalling at stops). Now the state of Illinois sent me my notice to get my emissions checked. The only part of the test that failed was that the hydrocarbons were out of range. The standard was 1.60gpm and my bronco tested 1.78 gpm. My question is, does anyone know how I can get this to pass without dumping a ton of cash into it? Basically, is it a simple fix? Ineed to bring reciepts of any repairs to the next testing and I figure I'll use the ones for the TPS and EGR sensor if needed, but any other help will do! Thanks!
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
failed emissions test
There's some fuel additive that GUARANTEES you'll pass emissions, and I think many parts stores & Wal-Mart carry it. Also, what you do right before the test has a BIG effect: keep the engine HOT & running at least 15 min before the test, and don't let it idle very long at a time (hold it at hi rev for a minute or 2 every few minutes).
For a permanent fix, make sure you're not getting any oil into the cylinders (compression test) and make sure the HEGO, TAB, TAD, smog pump, & bypass/diverter valve are all working right. Also, change the PCV & breather filter, and clean any residue out of the intake/throttle body/IAC. Clean or change the plugs, cap, & rotor so you have good hot spark.
For a permanent fix, make sure you're not getting any oil into the cylinders (compression test) and make sure the HEGO, TAB, TAD, smog pump, & bypass/diverter valve are all working right. Also, change the PCV & breather filter, and clean any residue out of the intake/throttle body/IAC. Clean or change the plugs, cap, & rotor so you have good hot spark.
Mountain Pass
Joined: Sep 2002
Posts: 181
Likes: 0
From: covington
failed emissions test
We have an auto expert that I listen to on talk radio who is very good. He says that if nothing is wrong mechanically the #1 reason to fail an emission test is dirty oil. Change the oil before going to take the test. Run at least 89 octane and a can of fuel injector cleaner in the tank. I had a 1978 chevy with a 350 4bbl carb and headers. It passed what my 2000 crown vic had to pass following the above recommendations. As extra security a new 02 sensor wouldn't hurt. Hope it helps.
Senior User
Joined: Apr 2002
Posts: 279
Likes: 1
failed emissions test
If that additive your talking about is what I tried, It doesn't guarantee you'll pass, it guarantees an improvement. I think it's primarily a fuel system cleaner.
Hydrocarbons, essentially means unburnt fuel.
A tune up (plugs primarily), fuel injector cleaner, and an oil change. Dirty oil gets past your rings and burns up in the combustion chamber throwing things out of whack.
And as previously mentioned, make sure your car is warmed up completely. Catalytic converters don't work unless they are *HOT*.
Hydrocarbons, essentially means unburnt fuel.
A tune up (plugs primarily), fuel injector cleaner, and an oil change. Dirty oil gets past your rings and burns up in the combustion chamber throwing things out of whack.
And as previously mentioned, make sure your car is warmed up completely. Catalytic converters don't work unless they are *HOT*.
