Engine Performance problem
1999 Chevy Suburban V8 Four Wheel Drive Automatic 76,461 miles K1500 5.7 L Vortec Engine
Engine will start and runs fine when cold.
After1-2 miles driving engine, it will not come up to
speed. It backfires through the intake as if lean fuel air mixture, bogs down and no power. I've read about a "limp home mode" that seems to fit what the car goes into. I shut the engine off and it immediately restarts and everything fine for a few minutes and then it reverts back to same problem.
Fuel pump first replaced Dec 5-08 after showing signs of being noisy and engine not starting one day. This new pump became noisy after a couple of days and then lost power on December 25th. It was then replaced Dec 29th with a fuel pump with a different style with modified connector. There have been problems with the original fuel pumps. The fuel filter changed again, 60-65 psi fuel pressure at test port. Fuel pressure regulator, spark plugs, cap, rotor and cool sensor replaced. Intake manifold gaskets replaced. O2 sensors replaced at shop after their codes read needed replacing. The shop not able to diagnose, only that the intake manifold had a severe leak that was then leak fixed at our home. The shop scan codes read P0131 O2 low voltage P0151 O2 low voltage, P0405 EGR Sensor "A" Circuit low, P0102 Mass Air flow low input. The Mass Air Flow sensor was cleaned with "Sensor Kleen" before going into the shop. This nightmare has been going on for almost 2 months. The next step might be to replace the Powertrain Control Module (PCM), I have been reading that all too often technicians tend to blame that which they understand least and if the engine is not running right and the cause is not obvious they may blame the computer. No codes are showing from the hand held scanner we put on the car after taking it out for a test drive yesterday. My husband is retired and our funds are getting low for fixing this vehicle. We would appreciate any help you could give us.
Friday, January 30th, 2009 AT 9:55 PM