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NEED EMISSIONS HELP

HI,I OWN A 2 WHEEL DRIVE 95 CHEVY TRUCK WITH A 305 WITH 149,000 MILES ON IT AND I HAVE TRIED TO PASS AN EMISSIONS TEST 3 TIMES NOW AND IT IS STILL FAILING AND I NEED SOME HELP FIGURING OUT WHATS GOING ON.THE TRUCK RUNS GREAT AT ALL SPEEDS AND DOESNT INDICATE ANY PROBLEM FROM A DRIVABILITY STAND POINT BUT IT BOMBS ON THE HC's AND THE Nox.HERE ARE THE ACTUAL RESULTS FROM MY LAST INSPECTION ATTEMPT.

HIGH SPEED EMISSION RESULTS (25 mph)

-------------STANDARD---------------CURRENT READING HC(PPM)--------143-----------------149 FAIL CO(%)----------1.60----------------0.70 PASS CO2(%)---------13.8 O2(%)-----------0.6 Nox(PPM)--------905----------------1572 FAIL DILUTION-------->6.0---------------14.5 PASS

LOW SPEED EMISSIONS RESULTS (15 mph)

------------STANDARD-----------------CURRENT READING HC(PPM)--------147-------------------152 FAIL CO(%)---------1.24------------------0.57 PASS CO2(%)---------14.0 O2(%)-----------0.5 Nox(PPM)--------990-----------------1537 FAIL DILUTION------->6.0-----------------14.57 PASS

ANY HELP WOULD BE GREATLY APPRECIATED,BY THE WAY I HAVE REPLACED THE EGR AND THE O2 SENSOR ALSO THE THROTTLE BODY BASE PLATE GASKET.THANKS

Reply to
QUADNUTS
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Hope this helps.... Immediately prior to taking the vehicle in for testing:

Replace PCV valve, change your oil filter and oil, new air filter and it should pass. Also, make sure ypur plugs/ wires are in good shape (good spark=good burn).

One other thing...are you in Ohio?

T.

Reply to
Terry Mosley

THANKS FOR THE HELP TERRY ,IM IN HOUSTON TEXAS.BY THE WAY I HAVE HAD SEVERAL PEOPLE TELL ME ITS THE CAT,COULD THE CAT CAUSE MY PROBLEM?

Reply to
QUADNUTS

Might very well be, I just read thru the report a little more and the high NOx count might indicate a catalytic conver that has lost it 's effectiveness...pricey, but the other things I listed are always a good starting point...

Curious about Ohio as we have only certain counties with e-check and some are a little more tolerant than others.

T
Reply to
Terry Mosley

Yes, it could be the cat... but when was the last time you checked your cooling system? I had a 305 that had *strictly* high NOx values, and poor cooling... one rebuilt water pump later, the NOx is nearly zero.

Just my 2 cents.

V Vuarra

Quid quid latine dictum sit altum videtur. (That which is said in Latin sounds profound.)

Reply to
Vuarra

THANKS GUYS FOR YOUR INPUT,IM GOING TO START WITH THE CHEAP STUFF FIRST AND GO WITH A NEW CAT AS A LAST RESORT.I REALLY APPRECIATE YOUR HELP,

ROBERT FROM TEXAS

Reply to
QUADNUTS

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