Cadillac Seville No power

The engine is the LBO-2B 4.5L. The spark plugs and wires have about 30K miles on them. I changed the air filter, oil and fuel filter about 2K miles ago. The cap, rotor and coil about 5K miles ago. I have not checked the cap and rotor. - Running lean sounds like it could be the problem. What would make the car do this from running good to shutting it down and then restarting it two days laters and the problem arises? Wouldn't I be getting a code if the engine was running too lean?

Racefan966,
I was advised to check the catalytic converter and a piece of the honeycomb had broken off (3"x2") and was partially blocking the inlet side of the converter. While I am certain that this was a problem, restricted exhaust flow, I am not certain it was the only problem. When the shop went to start the car it was as if the it had no battery. The battery has both side and top posts. A meter reading shows 12+ V for the top posts and 10+ V for the side terminals. I use the side terminals. Disconnecting the battery cables and reading from (+) side post to (+) top post reads 1.6 V and 0 V from the (-) side to the (-) top post. With the battery cables connected to the side posts I read 1+ V from the (+) side post to any ground point. Me thinks me also has a battery problem! I will get back to you with the readings you asked for once I have resolved the battery problem.

Racefan966,
Let me bring you up to date. I have replaced the battery, catalytic converter, muffler, spark plugs, spark plug wires and distributer cap. The battery was bad as was the catalytic converter. The distributer cap had loose spark plug wire terminals. One of the spark plug wires had gotten into the fan blades and wore the outer insulation off of it. The plugs looked great and I will be able to clean them up for later use.
I also found that the positive cable to the altenater had a bad terminal connector and I replaced it. There was also a wire harness that had been rubbing against the transmission mount and I had to repair 5 wires and re-wrap the harness.
I have about 250 miles on a new TPS and ICM. The TPS was set at +.2 with the ICM backed off the throttle. I have about 500 miles on a the throttle body since I cleaned it and replaced the throttle body gasket and the air intake gasket on top of the throttle body. I have about 1000 miles on a new cam gear and timing chain ( the crank gear was fine with very little wear showing ) and the sdame amount of miles on the water pump and water pump inlet pipe. The only reason I changed the timing chain and cam gear is because I was nearly there changing out the water pump and they were showing signs of some wear.
OK, that is what has been done. I still am not getting any codes that are current or in history. One thing that has changed is the ICM is now functioning properly where as before it would not let the engine idle below 1000 RPM. It now idles properly. The car no longer has a hot smell to it, even though it was never running hot when it did smell hot. Changing out the catalytic converter solved that problem.
I am still having the same issue with no power. The car idles rough enough to cause the steering wheel to shake. There is no dead miss and the engine smooths out some when accelerated. Gas milage is down to about 8 MPG. Acceleration is slow, but steady. I do not hear any mechanical issues with the engine. No rod knocks or lifter rattle. The car starts easily and idles without any attempts to die. The car performs like the timing is retarded too far or a bad vacuum leak, but I doubt either of these are causing the issue. The exhaust does not have any strange odors and I do not see any indication of burned valves as the exhaust does not try to suck in a cloth that I dangle over the exhaust pipe and there is no unusual popping of the exhaust. The car sounds like a four cylinder with a bad muffler.
I have a 4.5L engine with 208,000 miles on it but the engine is still rather tight and normally runs quite well. To refresh your memory, the car was running fine when I parked it, even with the issues I found while trying to resolve this problem. The next time I tried to drive it, two days later, the car was performing as I have described. With all of the work I have done so far the car performs only slightly better than it did after it lost power.
Should you need any further information please let me know.

Racefan966,
I took the car into a shop and they performed a fuel pressure test, both at idle and under driving conditions. The fuel pressure was fine under all conditions. He also performed a scan and all sensors are in ideal range. The only errors he got pertained to the computer. The 52 error shows the computer has lost memory. I changed the ECM and used my eeprom chip. No difference. I put in the eeprom chip from the replacement computer. No difference. The only codes I have gotten now are are in History. E052, B448 and B552. I cleared these codes and they have not reappeared, but the car still performs the same. What should I do next?

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?

User comment: YES, I WISH I GOT HERE SOONER, YOUR PROBLEM IS THE FUSE FOR THE INJECTORS UNDER THE HOOD, FUSE BOX NEXT TO BATTERY.

OK, here is what I have found. #1 cylinder has 0 PSI. The needle on the conpression gauge does not even move. The other cylinders have 75-80 PSI. The car is not burning oil. There is no blow by or blow back through the throttle body. The exhaust is not smoking or sucking back into the tail pipe. There is no oil in the water. There is no water in the oil. Using a mechanic's stethoscope I am can not hear any unusual noise from the valve covers and all of the injectors are firing. The engine is running slightly cooler than normal. An open intake valve should produce blow back through the throttle body. An open exhaust valve should be producing a sucking of air into the tail pipe. A cracked cylinder or head would mix oil and water some place. A blown piston should produce enough smoke to hide the car. A blown head gasket between cylinders should cause a low compression reading between the two adjoining cylinders. A blown head gasket on that one cylinder should be audible or causing blow by. Bad piston rings should also create a lot of smoke. A broken connecting rod would be easy to detect just from the sound of the engine. The spark plug has no fouling and looks normal. The car is slow to respond to the throttle but will run smoothly at 65 MPH and has only a slightly rough idle. Removing the spark plug wire on #1 cylinder has no effect on the way the car runs. How can I have a cylinder that has no compression and yet shows no other symptons other than a loss of power?

Check the fuses for the injectors. There are 2 fuses that power 4 injectors each. They are located in the underhood fuse box on the drivers fender

1979 Cadillac Seville 350 5.7. Owner poured gas down the carburetor to start (car is injected, no carb). Would start, but stopped. Replaced computer, fuel pump, distributor, throttle position sensor & injector trigger module. Now it will start & idol but now it w ill not accelerate.

Car has no power. Lights won't come on. But the battery is charged (side post). And the ground cable is still conected. Corrosion doesn't seem to be the problem. What do I do?

Engine Performance problem
1990 Cadillac Seville V8 Two Wheel Drive Automatic 15677 miles

when running over the speed 40 to 60 lose power