Chevrolet Repair: chev 5.3l pickup, chevron techron, top tier gasoline

Question
I have a 2004 Chevy pickup,it runs rough and sometimes stalls when cold,it also has a knocking or pinging sound when accelerating.I took it to the dealer and no codes came up. They cleaned the MAF sensor and did a fuel injection flush. The problem is still there,they said the next thing is to change the MAF sensor which I did,still didn't work. Your help wpould be greatly appreciated.

Thanks
Stewart

Answer
The first thing I need to ask, did the dealer tech expierence the condition? If, not you should leave the vehicle there so they can cold start and road test to see if the conditions can be duplicated. Using the TechII the tech could take a snapshot of data stream when the problem acts up. This would indentify and intermittent failure.

Also, are you using an aftermarket oiled air filter. These have been causing MAF sensor failures?

Injectors have been a problem. I would try adding Chevron Techron Plus to 20 gallons of gas. Don't add any gas until it's a quarter tank and then add another. Techron Plus is the only injector cleaner that GM recommends.
Always make sure your only using Top Tier Gasoline. Go to toptier.com.
Last there is a bulletin on poor engine ground:

Engine Controls - MIL ON/Misfire/Misfire DTC's Set

Bulletin No.: 06-06-04-046

Date: September 12, 2006

INFORMATION

Subject:
Information on Engine Misfire MIL/SES Light Illuminated or Flashing DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P0420 or P0430

Models:
1999-2007 Cadillac, Chevrolet, GMC Full-Size Pickup and/or Utility Trucks

with 4.8L, 5.3L, 5.7L, 6.0L or 6.2L VORTEC GEN III, GEN IV, V-8 Engine (VINs V, C, T, Z, B, 3, M, 0, J, R, U, N, Y, K, 8 - RPOs LR4, LY2, LM7, L59, L33, LC9, LH6, LMG, LY5, L31, LQ4, LQ9, L76, LY6, L92)

with Active Fuel Management(TM) and E85 Flex Fuel

If you encounter vehicles that exhibit the above conditions, refer to SI for the appropriate DTC(s) set. If no trouble is found, the cause may be due to an ECM ground terminal that has corroded with rust over time. Inspect the main engine wiring harness ground terminal (G103) for this condition.


 


The wire terminal (G103) attaches either to the front or to the rear of the right side cylinder head, depending on the model year of the Full Size Pickup and/or Utility Trucks. If the ECM ground terminal has been found to be corroded, then follow the service procedure outlined in this bulletin to correct the corrosion issue.


 


Remove either the nut or bolt securing the main engine wiring harness ground terminal (G103) to the right cylinder head. Refer to the above illustration to determine where the ground is located on the vehicle (1).

Remove all rust from the ground terminal, the cylinder head and the retaining nut or bolt.

Position the main engine wiring harness ground terminal and install the nut or bolt.

Tighten:

Tighten the retaining nut or bolt to 16 N.m (12 lb ft).

Apply some type of electrical moisture sealant to protect the harness terminal from further corrosion.

Hope this helps you!

Robert