1990 Cadillac Seville V8-273 4.5L
Symptoms: No power. Will slowly accelerate to driving speed. Slightly rough idle. Smooths out when accelerating. Runs fine at cruising speed but still is slow to accelerate when at speed. When given too much throttle the transmission downshifts hard.
The car was running fine when parked for two days. When next started the car it had no power and lost power as the engine heated up. Problem was caused by a bad catalytic converter. A piece of the honeycomb ( 2" X 3" ) had broken off and was blocking the inlet side of the converter. Lack of power persisted even after changing out the converter and muffler.
Work recently done. From most recent:
1. Replaced wiring harness to TCP - some frayed wires and broken insulation.
2. Replaced ECM - symptoms did not change. Runs slightly better.
A. Tried first with EEPROM chip from in service ECM.
B. Currently has EEPROM chip that came with replacement ECM.
3. Ran a fuel pressure test and fuel pressure readings are good at idle speed and under driving conditions. Scan tool showed all sensor readings were perfect.
4. Replaced battery - bad cell
5. Replaced spark plug wires - 1 wire had insulation worn off from fan blade
6. Replaced spark plugs - all plugs showed normal, light wear with no abnormalities
7. Replaced distributor cap - spark wire terminals had movement in them
8. Replaced positive cable connector to alternator - broken inside insulator.
9. Repaired damaged wire harness to starter - 5 wires had worn through insulation on transmission support.
10. Replaced muffler - small leak
11. Replaced catalytic converter - piece of honeycomb had broken off and was blocking inlet.
12. Replaced and set TCP - flat spots throughout travel range
13. Replaced ICM - general principles
Work done within last 3,000 miles:
1. Replaced timing chain and cam gear. Crank gear showed no wear. Chain had some moderate slack and cam gear showed some minor wear. Replaced camshaft dampner bushing ( reduces end play in camshaft ) at end of camshaft.
2. Replaced water pump - bad seal
3. Replaced water pump inlet pipe - would not seal to water pump
4. Oil and oil filter change - Pennzoil 30W and Slick50
5. Fuel filter
6. Air filter
All sensor readings are ideal. No ECM/BCM codes. Fuel pressure is excellent at idle and throughout driving range. Timing is dead on and advances under acceleration. Returns to set timing after letting off gas. According to all the tests performed to date, the car should be running perfectly. Any ideas? Anyone?
Thursday, April 9th, 2009 AT 8:05 PM