Posted on December 16, 2009 - by Richard

Saving Money on 2002 Silverado Emissions

Symptoms:

This 2002 Silverado Emissions problem came to me when I got a call from my ATS customer last week. According to him, his truck runs rough intermittently, stalls and seems to have a rich fuel condition: thick black soot can be found on the tailpipe and his fuel consumption was bad. He wanted me to help and fix this problem before he takes it to the dealer which will be expensive since the truck is out of warranty.

Vehicle Specifications:

2002 GM Silverado 1500 with 5.3L 8cyl. fuel injected engine with 4 speed electronic transmission and OBD2 compliant including a SFI fuel system.

Diagnostics on 2002 Silverado Emissions:

I took the vehicle for a spin and I confirmed that this engine ran rich because of the occasional black smoke at the tail pipe. After the road test, I scanned it for codes and found P0101 stored which referred to mass sensor fault code. I serviced the mass sensor and probed the ground, power and frequency readings and all were found to be normal. Since it has not been replaced before, we bought a new one and installed it but it did not change anything. I checked the fuel regulator for leaks and found none.

To check this 2002 Silverado emissions, I monitored the scanner live data and these were my findings:

Common fix for 2002 Silverado Emissions problem:

Reading the ATS database, the common fix for these symptoms were:

1.) plugged air filter ( a new one was installed)
2.) defective ecm (the ground, power and reference voltage were all normal, maybe ecm could use reflash or reprogramming).
3.) 02 sensor (no code and readings were normal at live data)
4.) defective egr (no code and rpm slowed down when pintle rod was raised in the egr valve)
5.) bad CAT or catalytic converter but there no post oxygen sensor code that monitors the CAT efficiency which reads normal in the scan graphics.

Final fix for 2002 Silverado emissions:

Since most of the common fixes could not resolve this problem, my customer suggested about sending the vehicle to the dealer to reprogram but at the last moment, I thought about what I was missing here. Looking at the basics and what I have found so far, it seems there is a problem with fuel because of the bad fuel trim and injector pulse width readings. Measuring the fuel pump pressure readings, I found out the pressure reading was 53 psi. The vehicle fuel specs calls for a reading between 55-62 psi. Replacing the fuel pump fixed the problem. (Also, because the old fuel pump was weak, the ecm was compensating which resulted in higher fuel trim and injector spray ms readings).

For more 2002 Silverado emissions tips, please visit my ATS site.

Thanks!