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How to get hc ppm down on 1991deville 4.9 - 1991 Cadillac DeVille

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Jackie Miles

Jackie Miles

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It could be from unburnt fuel. Try a new catalytic converter. Have the muffler shop install a Universal type converter not an OEM. Universal type is much cheaper. Be sure to keep your old converter. You can recycle it for enough money to pay for the new converter installation. Don't let the muffler shop have it. They recycle those things for big bucks. If they want it ,sellit to them. I had a universal converter put on my Buick Park Avenue for $150.00, including labor. Recycled the old converter for $197.00 the same day. The old original equipment converters are worth a lot more than the newer ones because of the platinum pellets inside.

Posted on Jan 22, 2011

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Reason for failing emmision hc ppm idle on a 1996 chevy suburban 454 truck
Hi!

First of all, HC (Hydrocarbon) are the residue of petroleum based product combustion. If your HC reading are higher than the OBD2 legal limit (220 ppm), the most common causes could be a leaking fuel injector, abnormal oil consumption, a faulty Oxygen sensor or worn out spark plug / distributor cap / spark plug wire. To be honest, I would need more accurate details such as NOx ppm, CO ppm, CO2 ppm and Oxygen ppm and if there is any repair that have been made on the car recently to give a proper diagnostic.

Warm regards

Mar 16, 2015 | 1999 Chevrolet Suburban

1 Answer

What dose HC (PPM) stand for how do you get the numble down
HC is hydrocarbons. This is unburnt fuel. PPM is the amount of fuel in the mixture and it is in PARTS PER MILLION.
There are a lot of possible causes:
1. Dirty air filter. Not letting enough air into the engine.
2. The ignition timing is bad. It is too advanced.
3. The ignition system has many parts that could be worn. Plugs etc
4. There is a vacuum leak.
5. The Catalytic converter is worn out.
6. Low compression due to valves or piston rings
7. Too much fuel being put into the intake manifold. Bad injectors or carburetor.

Jul 22, 2014 | 1995 Chevrolet Tahoe

1 Answer

Failed hc ppm& feul evap test
If I read your post right, you are over on Hc and that is all? Check the air filter, check the injectors. You are either not getting enough air or are getting too much fuel.

Apr 02, 2014 | 1993 Saturn SL

1 Answer

Hc ppm
I would google vehicle exhaust gases & do some studying

Given it is a 1992-- 22 year old vehicle & don't know how old
the motor is !

159 is HC & a lot of unburnt fuel

NO may be an egr issue along with overheating

Best study the gases & what is required to address them

You could go with the spark plugs,wires,synthetic oil, new air filter,
check out the egr system,pcv system & vacuum leaks,thermostat,
oxygen sensor,clean maf sensor

I'm NOT saying throw parts at it,I'm saying check it out & do some
testing, to find some problems

You have to take out a lot of fuel & bring down your misfire counts,
engine temp etc

I would guess after your best efforts ,you need to replace the
exhaust converter,I would, unless it is only 5 years old or newer

Apr 02, 2014 | 1992 Mitsubishi 3000GT

1 Answer

DID SMOG ON MY 1994 HONDA ACCORD FOR SECOND TIME AND FAIL THE ASM EMISSION TEST WHAT CAN DO PLEASE HELP
Any codes? any problem tune up, catalytic convener, burning oil.

Aug 19, 2017 | 1994 Honda Accord

2 Answers

Emission test failed HC (PPM)
i can be, only 2 things, or both.
1: engine running way too rich.
2: dead cat.
(both happens, too)
replace the cat, might be cheaper that full engine diagnosis and repair.
in a real shop we test the cat. using up and down stream tests.
with the 5 gas analyser.
but the truth is a new CAT can hide a very filthy running motor.

Mar 12, 2013 | 1995 Geo Prizm

1 Answer

I have a 93' Ford Taurus that failed emissions
run the fault codes to find the faulty sensor
sensors that control the exhaust emissions are the HO2S ( heated oxygen sensors in the exhaust manifold/s
the O2 sensor ( oxygen sensors after the cat converters ) and the EGR unit that recycles exhaust gas back through the engine to re-burn the gasses

Oct 17, 2017 | 1993 Ford Taurus

2 Answers

Need 92 toyota paseo to pass CA smog test ! What causes too high HC in smog test????
High HC means moisture in the system. Try driving it longer then take it to the smog shop. Otherwise it could be hard like a head gasket or easy such as a PCV not functioning. Any ways you should always drive it about 20 miles before smog check, longer when the weather is cold.

Nov 30, 2010 | Toyota Paseo Cars & Trucks

1 Answer

FAILED EMISSIONS
possible but could be head gasket or valves , or worn rings and is by passing the pistons going straight out the end ...or maby settings are wrong ? try carb cleaner and inspect visually air-filter etc.

Aug 26, 2009 | 1986 Ford Mustang

1 Answer

Emissions level HC (PPM) too high in truck. How to fix?
Do an oil change with 20W50 oil (or one grade higher) to prevent blow by during the test.

You current oil has HC from blow by though the rings.

Do a fresh oil change will lower the HC.

========
Change spark plugs,wires,cap and rotor if they are over 24,000 miles
========

Make the smog check appointment for the EARLY MORNING. Colder air will help the fuel burn better.

========

Clean or change the air filter and pcv valve.

Clean Mass Air Flow sensor with CRC Mass Air flow cleaner or electronic part cleaner.

========

Do a quick wipe down on the wires and cap to take the moisture off.

========

Check spark plug wire contacts for corrosion.

========

Fill the tank to around 3/4.......just in case your fuel pump is weak.

========

Ran the truck for 20+ minutes on highway before the test.

========

Do not carry excessive cargo on the truck bed.


These are the little things I would do to get the HC and CO down.


Please post more information on the comment window.

Jul 16, 2008 | 1990 Ford F250

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