1999 Chevrolet 2 Door Tahoe, 5.7L, 4x4, VIN R, 122,200 miles
Original problem: Service engine soon light & Code P0300 only under heavy load. (Random cylinder misfire) Light would go out next day. Vehicle drove fine under normal driving circumstances.
1) Changed plugs, wires, rotor and distributor cap. Had timing and distributor set to proper settings
2) Changed inline fuel filter. Still thru code P0300
3) Installed new AC Delco spider injector kit. New problem: Missing (Stutter’s & Jolts @ varies RPM’s) Still thru code P0300.
4) Installed Delco reman/distributor and new Delco Platinum plugs. No improvement!
5) Fuel pressure test showed pressure drop from 60+ to 42. Installed new GM fuel pump and additive for excess water in tank.
6) No improvement…Throwing too many $ and parts with no results…fired mechanic! Need Help…
There is a GM TSB for this condition need to check and clean ground for PCM located on right cylinder head either front or rear. Any other codes?
February, 28, 2013 AT 7:33 PM
Cleaned the PCM ground. No improvement. No other codes except P0300.
February, 28, 2013 AT 7:51 PM
To solve problem truck needs to be diagnosed with a scan tool not a code reader. In drive mode to monitor sensors and output data. Do you know if MAP sensor was checked out? Was miss fire history checked?
February, 28, 2013 AT 8:01 PM
After I had the timing and distributor tuned, we checked the miss fire history. It showed a miss fire in random cylinders not any one specific cylinder. That is when we decided to replace the spider. The MAP sensor checked out OK prior to this.
February, 28, 2013 AT 8:05 PM
All can do is have checked on sacn tool and in drive mode. If truck was in my shop that would have been step one
March, 4, 2013 AT 5:29 PM
We cleaned the ground wires to the frame on passenger side of vehicle. Can you send me a more detailed description of the location of the PCM ground?