mysterious loss of power

[Yokolo]

Hello everyone, I'm was wondering if anyone could give me some pointers in how to approach this strange power loss problem I've been having lately.

I'm driving a 95' nissan 240sx with about 175k 5spd. The car starts great with no apparent problems and it will drive fine for a while and all of a sudden the car loses power and responsiveness.  There aren't any strange sounds, nothing audible at least. The car then still drives but slowly and it doesn't seem to respond to  the throttle. What I mean is that even if I floor it, it really doesn't seem to go any faster although the engine still seems to rev  fine.

I'm not very experience in the garage, my experience doesn't extend beyond  changing brake pads, calipers,  fluids and installing stereo components so any advice would be highly appreciated.

Thanks everyone

[S204STi]

This one is for the pros.

It sounds like the engine runs fine as long at it is in open loop, but as soon as it goes closed loop it runs like a dog.  You have some sensor acting up.

[Yokolo]

Thanks R-inge, I will look into the sensors and hopefully it's just a simple bad sensor. When you talk about the open/closed loop though, what do you mean? I'm not familiar with the term.

[Tave]

This one is for the pros.

It sounds like the engine runs fine as long at it is in open loop, but as soon as it goes closed loop it runs like a dog.? You have some sensor acting up.

No possibility it could be a clutch on its way out?

[S204STi]

No possibility it could be a clutch on its way out?

Good thought.

[GoCougs]

What I mean is that even if I floor it, it really doesn't seem to go any faster although the engine still seems to rev fine.

Does this mean that when in gear and when applying throttle, that the engine revs normally, but that the car doesn't respond?

If so, sounds like a worn clutch to me.

[Eye of the Tiger]

Perhaps the clutch cable is adjustable.

[S204STi]

The fact that it drives fine for a while but then gives up the fight is what I am betting on being the more significant piece of info.

[Tave]

I suppose it depends on how long the problem has been a problem. A worn clutch would do something similar to what he described, but for a relatively short window of time. At least that's what happened to me.




And a worn clutch would also never be making full-power, but sometimes you don't notice it bleeding off untill it's about ready to go under (again, what happened to me ). Kind of like you don't notice a dog getting bigger but people who come over every once in a while do.

[Yokolo]

Thanks everyone. it sounds like it might the clutch, so I'll have it looked at. It's really strange though, once I stopped at a light to make a left turn. Once the light turned green I gave it gas and the car would barely go. The clutch engages rather nicely still and it feels pretty much the same as it's always felt though, so I didn't think it was the clutch but I guess it could be after all.

[Soup DeVille]

Thanks R-inge, I will look into the sensors and hopefully it's just a simple bad sensor. When you talk about the open/closed loop though, what do you mean? I'm not familiar with the term.

Replace closed loop/ open loop with smart, normal mode and safe, dumb mode.

When many ECUs sense a sensor problem, they will go into a 'safe mode' that reduces power but rus at levels it knows should be safe.