94 Lesabre - Horrible Acceleration/Loss of Power

All of a sudden when I was driving my car I noticed I was giving it gas and noticing it not wanting to pull. It was getting to around 4000RPMS probably and pulling as though I should have been at 1000 RPMS. I had this problem before and the mechanic said I need a new oxygen sensor. I replaced the oxygen and it started running fine again! All of a sudden, this problems happened to me again yesterday. I took my oxygen sensor back to autozone and got a new one and installed it and it's still showing the same symptoms nothing changed. Maybe the oxygen sensor was hiding a more severe problem? I am about to take my car to the muffler shop to have them cut off my muffler and catalytic converter to see if maybe that is the problem.

Any suggestions?

Thanks a bunch in advance,
Jordan

1994 Buick Lesabre
104,000 Miles
Replaced Spark Plug Wires
Replaced IAC Valve
Replaced Oxygen Sensor (Twice)

Welcome to AF, where is the proper diagnostics being performed, fuel pressure tests, scanning for possible maf problems, back pressure test for cat performance just to name a few. The o2 would never cause this issue. How fast were you going at 4k, this would be 100 mph in overdrive, not clear what you are describing, also.

Welcome to AF, where is the proper diagnostics being performed, fuel pressure tests, scanning for possible maf problems, back pressure test for cat performance just to name a few. The o2 would never cause this issue. How fast were you going at 4k, this would be 100 mph in overdrive, not clear what you are describing, also.

Thanks a bunch! The diagnostics were performed at a transmission shop because the first time it started doing this I thought it was the transmission going out. He informed me that the transmission was perfectly fine that it was the oxygen sensor that was bad. He did say my fuel pressure was a little low.

To explain this a little better let's say I am sitting at a red light. The light turns green and I give it gas and can hear it revving to about 4000 rpms an I am only accelerating as if I am going a little quicker than idle speed. I can eventually get to about 45mph after about 4 cars have passed me from the light. I am just so boggled because I normally can google exactly what the car is doing and find an immediate answer but this sounds like it can be a number of things. Would you suggest me cutting the catalytic converter off and seeing if that fixes it?

As maxwedge mentioned, you have someone do a "back pressure test" to see if the cat is clogged rather than cutting the cat off. Stop by a muffler shop and ask them to do the pressure test. Do you have any DTC's? What is fuel pressure reading? BTW, a clogged cat will cause early 02 failure!

As maxwedge mentioned, you have someone do a "back pressure test" to see if the cat is clogged rather than cutting the cat off. Stop by a muffler shop and ask them to do the pressure test. Do you have any DTC's? What is fuel pressure reading? BTW, a clogged cat will cause early 02 failure!

I just called a muffler shop nearby and they said it's a free inspection, does that sound right or is it something that your normally charged for? I currently do not have a SES light on.

It's usually free, or it's a very cheap test.

The light turns green and I give it gas and can hear it revving to about 4000 rpms an I am only accelerating as if I am going a little quicker than idle speed.This is the part that is confusing, do you have a tach, or are you just going by the sound of the engine? Does it do this every time from a start, or just when cold? If the exhaust back pressure test ok, you may indeed have some trans problems. If this is the case, take it back to the trans shop and ask them to do a 'line pressure test' to see if you have proper pressure in all gears. If you have low pressure, you may have the typical failed input shaft seals. This was a common problem from 92-94 & IIRC, GM upgraded the seals in 95, or 96.

This is the part that is confusing, do you have a tach, or are you just going by the sound of the engine? Does it do this every time from a start, or just when cold? If the exhaust back pressure test ok, you may indeed have some trans problems. If this is the case, take it back to the trans shop and ask them to do a 'line pressure test' to see if you have proper pressure in all gears. If you have low pressure, you may have the typical failed input shaft seals. This was a common problem from 92-94 & IIRC, GM upgraded the seals in 95, or 96.

I am just going by the sound of the engine. My previous car (2001 Saturn SL2) had a tach on it and that's how I can kinda sense what I hear. It did it that one time and it has continued doing it. I brought it to a muffler shop and he put his hand over my exhaust then put his hand to his nose and smelled it. He said it is defiantly not clogged it seems as though it is working fine. He said he can do a fuel pressure test on the car tomorrow he just did not have the proper tools with him. I am thinking about just replacing the fuel pump because from what I hear you simply disconnect the line and then remove the hex bolts and that's it. If it is the input shaft seals, you know how much that runs to get replaced?

Thanks for the help so much!
Jordan

Gas tank must come out for the fp, do the tests first.

This is the part that is confusing, do you have a tach, or are you just going by the sound of the engine? Does it do this every time from a start, or just when cold? If the exhaust back pressure test ok, you may indeed have some trans problems. If this is the case, take it back to the trans shop and ask them to do a 'line pressure test' to see if you have proper pressure in all gears. If you have low pressure, you may have the typical failed input shaft seals. This was a common problem from 92-94 & IIRC, GM upgraded the seals in 95, or 96.

OK! Listen to these shenanigans (don't know if I can curse here so I will stay safe and will not)! I manage to drive my car to the bank, and I deposit my money in the bank and go to accelerate to leave and notice that the front of my car lifts up a little. Hrmmmm. I give it more gas, WALAAAH! The car is working perfectly fine now! WHAT THE HELL! Is god playing tricks on me, I do not understand this... Could it be those input shaft seals?

Thanks,
Jordan