Posted on November 21, 2011 - by Richard

2000 Chevrolet S10 Pickup Emission

Symptoms for 2000 Chevrolet S10 Pickup emission:

Got a complaint from a guy from ATS with a 2000 Chevrolet S10 Pickup emission. It has a 4.3L engine and  came in with a check engine light on. He got initially codes p0172 and p0175 having both banks 1 and 2 rich fuel mixture. He checked the fuel pressure and got above 55 psi which was not bad. While monitoring the scanner display monitor live stream, he noticed the fuel trims were way high which were about -21 respectively for both cylinder banks.

Knowing the ecm was telling the fuel injectors to add more fuel, he tried removing the pcv valve hose to make the fuel mixture lean. Final fuel trim came down to -10 to both cylinder banks. This is what he ended up checking and asking ATS how to fix it. He was reluctant to remove the intake plenum since it was a major job.

Analysis for 2000 Chevrolet S10 Pickup Emission:

The fuel mixture here is rich but there are few causes for this problem:

1.) Leaking fuel regulator valve located under the top engine intake plenum which connects to the fuel rails. This fuel rails feed all the injectors. Unfortunately, these fuel connections are hard to access. This leads us to the next step.

2.) Leaking fuel injectors can also do this and this can be scanned using the injector balance test. Each injector is cut off and engine fuel trim are observed every time and compared. Once a faulty injector is detected, the intake plenum can be removed to check the affected injectors. At the same time, test also the fuel regulators for leaks if it needs replacement.

3.) Defective oxygen sensors and this can be monitored also using a scanner live data stream. If the sensor is stuck at rich or lean position, it can upset the ecm to make a false command to the injectors. Oxygen sensor is normally changed at regular interval especially a faulty code would show it. In this case, the oxygen readings were normal as per his report.

4.) The final approach that can be used to check this emission problem is to do a step by step test of the fuel system including the evaporative system. This latter system monitors raw fuel coming from the fuel tank which is vented or purged back to the fuel injector lines. Using the vent and purge solenoids, and gas tank fuel sensor, it prevents raw gas vapor to leak from the vehicle to pollute the environment.

A complete pinpoint test is used to analyze this problem which can help a mechanic or ATS member decide which part of the evaporative system is bad. This pinpoint test is available from ATS which are supplied upon request to all ATS members.

Final Fix for 2000 Chevrolet S10 Pickup Emission:

A pinpoint test was received by this ATS customer which lead him to replace the purge solenoid of the evaporative system. Once replaced, the engine fault code was reset and code never returned.

Additional tip for 2000 Chevrolet S10 Pickup Emission:

1.) To prevent replacements of unwanted parts or major labor jobs, get a good scanner and checked with ATS. This will help get huge savings from garages who charged $100 per hour or more.

Thanks,

Richard