Question1994 GMC Sierra 1500 w/approx 170k miles.
I would appreciate any feedback on my problem...
I have had emissions problems for a few years now as can be seen in the following emissions transcript...
Emissions Inspection 6/4/2002
Hydrocarbons (HC) – Inspection 5.3095 – Requirement 2.7000 FAIL
Carbon Monoxide (CO) – Inspection 35.3126 – Requirement 60.0000 PASS
Oxides of Nitrogen (Nox) – Inspection 0.4853 – Requirement 5.7000 PASS
Carbon Dioxide (CO2) – Inspection 476.3944
Work Performed 8/2002
· Adjusted Timing to 0 TDC
· Replace Oxygen Sensor @ Catalytic Converter
· Replace Spark Plugs
· Replace Ignition Wires
· Replace Distributor Cap & Rotor
· Replace PCV Valve
· Replace Air Filter
Emissions Inspection 8/2002
Hydrocarbons (HC) – Inspection 0.1880 – Requirement 2.2000 PASS
Carbon Monoxide (CO) – Inspection 1.9014 – Requirement 60.0000 PASS
Oxides of Nitrogen (Nox) – Inspection 0.0070 – Requirement 4.2000 PASS
Carbon Dioxide (CO2) – Inspection 73.1697
Emissions Inspection 7/13/2004
Hydrocarbons (HC) – Inspection 6.7361 – Requirement 2.0000 FAIL
Carbon Monoxide (CO) – Inspection 62.4512 – Requirement 60.0000 FAIL
Oxides of Nitrogen (Nox) – Inspection 0.3481 – Requirement 4.0000 PASS
Carbon Dioxide (CO2) – Inspection 599.9200
Work Performed 11/2004
· Adjusted Timing to 0 TDC
· Replace Spark Plugs
· Replace Ignition Wires
· Check and Clean Distributor Cap & Rotor
· Replace Air Filter
Emissions Inspection 7/13/2004
Hydrocarbons (HC) – Inspection 4.6401 – Requirement 2.0000 FAIL
Carbon Monoxide (CO) – Inspection 18.6279 – Requirement 60.0000 PASS
Oxides of Nitrogen (Nox) – Inspection 0.2441 – Requirement 4.0000 PASS
Carbon Dioxide (CO2) – Inspection 609.0446
Still notice low throttle, low RPM miss (seems to get a little worse as engine temperature increases). No miss upon acceleration or at high RPMs that I can notice. After engine warm-up and when truck is parked, holding the accelerator slightly so that engine revs around 500 – 700 RPM (approx), the engine will stall, revs will decrease, engine will recover and surge back to 500 –700 RPM, stall, and repeat in a cyclical manner.
Work Performed 11/2004
· Check and clean EGR valve. Valve seemed to be fine, but cleaned.
I'm hoping that you can give me an idea as to what could be the cause of my problems...I'll gladly reply if further info for diagnosis is required...Thanks
AnswerOK, Here is what I would suggest:
In most cases there is a blackish sticky residue that builds up around and ON both sides of the throttle plate area as well as in the IDLE AIR BY-PASS circuit of which is usually seen as a little hole just in front of the throttle plate within the throttle plate bore.
using an appropriate aerosol cleaning agent clean the throttle plate area as well as spraying into this BY-PASS hole with the engine running IF possible. If NOT possible just spray these areas clean and start the engine and let the engine clear itself up by burning off this cleaning agent. repeat this process once or twice and do it as a maintenance item.
Tere are several products on the market that are referred to as TOP ENGINE CLEANER of which cleans off the carbo buildup that naturally accumulates on top of the pistons.
Follow the directives on the product and repeat it in about two weeks for a total of 3 or 4 applications.
This should resolve a lot of your emissions problems.
autohelp
