Help! Strange engine problems, not sure what's going on.

[thewizard16]

Well, I don't know much about engines, so I'm hoping someone can give advice.

The car's been acting a little strange lately, but nothing too severe. Well, today something changed, evidently. Throughout my drive it got worse. At first, when I was moving slowly I'd feel the engine jump a little bit, that is, a moments "thunk", it'd lose a few revs and then catch back up. Well, it got to doing it more regularly throughout my errands. Then, towards the end, the engine got to where it sounded like it was working too hard to do everything. When I'd stop at a light, it'd be idling and then drop down to 500 RPMs and struggle a bit. Taking off it revved higher than it normally needs to to get going, acceleration was terrible, and it sounded like it wasn't happy. I'm sure it's something with the engine, it does this knocking thing regardless of what, if any, gear it is in. Also, it's not overheating, and the check engine light is not on, it just sounds really unhappy and is acting badly, making what is normally leisurely or regular driving difficult. I got it home and everything, but I'm not pleased with this, and I'm supposed to be driving a couple hundred miles within the next week.

Ideas? Suggestions?

[The Pirate]

I'm honestly not sure what that is, but check the basics first.  When was the last time you replaced the spark plugs, wires, and air filter?

[Soup DeVille]

Do your car has a lock up torque converter?

What is this car anyways? And what motor/tranny?

[thewizard16]

Sorry, I should have said that.

It's the 92 Camry XLE V6/4spd automatic overdrive transmission.
I have no idea if it has a lock up torque converter.

[thewizard16]

I'm honestly not sure what that is, but check the basics first.  When was the last time you replaced the spark plugs, wires, and air filter?

It was serviced less than 300 miles ago. Everything was checked, and I've had good luck with the mechanic. Oil change/air filter change was done, wires and plugs were checked, tires, tranny was checked, etc.

[Soup DeVille]

Sorry, I should have said that.

It's the 92 Camry XLE V6/4spd automatic overdrive transmission.
I have no idea if it has a lock up torque converter.

It sounds as if you're having transmission difficulties, not engine ones. No CEL?

[Eye of the Tiger]

Did the torque converter asplode? 

[Eye of the Tiger]

Well... I guess the first thing to do is check the transmission fluid.

[thewizard16]

It sounds as if you're having transmission difficulties, not engine ones. No CEL?

How can it be transmission problems if it still shifts normally and it does the same engine thunk rev drop thing when it's in neutral? I'm relatively mechanically retarded, so if I asked an idiotic question provide me with an explanation for idiots.

And no, the check engine light is not on.

[Eye of the Tiger]

How can it be transmission problems if it still shifts normally and it does the same engine thunk rev drop thing when it's in neutral? I'm relatively mechanically retarded, so if I asked an idiotic question provide me with an explanation for idiots.

And no, the check engine light is not on.

IN that case... uhh umm... is there a MAF on that car? Could also be the TPS.

[thewizard16]

IN that case... uhh umm... is there a MAF on that car? Could also be the TPS.

Explanation for idiots, not irritate idiots with acronyms.

My question about the transmission holds though, if it still shifts fine, smoothly, normally (and at pretty much the same RPMs), it's just the engine making weird noises, revving up quicker, sounding funny when trying to work and not working as well, is it likely that it's the transmission?

[Eye of the Tiger]

Explanation for idiots, not irritate idiots with acronyms.

My question about the transmission holds though, if it still shifts fine, smoothly, normally (and at pretty much the same RPMs), it's just the engine making weird noises, revving up quicker, sounding funny when trying to work and not working as well, is it likely that it's the transmission?

If the engine is still acting erratic when the transmission is in neutral, then I think it must be the engine.

MAF = Mass Air Flow sensor
TPS = Throttle Position Sensor

and another one it could be, MAP  - Manifold Absolute Pressure sensor

[thewizard16]

I don't know if it has those things. It's a 92, so it's not advanced, but it was pretty loaded for the time, so I have no clue. Wouldn't problems with those things trigger the check engine light?

[TheIntrepid]

It's your brain playing tricks on you. Camries cannot have problems.

[Eye of the Tiger]

I don't know if it has those things. It's a 92, so it's not advanced, but it was pretty loaded for the time, so I have no clue. Wouldn't problems with those things trigger the check engine light?

The MAF should trigger a CEL, but the TPS might not.
It soulds more like a TPS problem to me, too.
However, those sensors are too damn expensive to go with trial and error ($175!). I'd take it to a shop and have them diagnose it.

[thewizard16]

It's your brain playing tricks on you. Camries cannot have problems.
Honestly, it wouldn't surprise me if it was something screwed up at the last service, because it was running perfectly up until then. I haven't done anything unusual with it, and as far as a Camry goes, 118,000 miles is not a ton. Anyway, I'll see what's going on when I drive tomorrow. I'll check fluids and things tonight, but I doubt it's something that simple since a light hasn't yelled at me.

[thewizard16]

The MAF should trigger a CEL, but the TPS might not.
It soulds more like a TPS problem to me, too.
However, those sensors are too damn expensive to go with trial and error ($175!). I'd take it to a shop and have them diagnose it.

Ah. Well, I know I won't get in in the next few days, but I'll try to get it to a shop as soon as possible. Until then, I'll try to avoid driving, or steal a car, whichever seems like more fun.

[Soup DeVille]

How can it be transmission problems if it still shifts normally and it does the same engine thunk rev drop thing when it's in neutral? I'm relatively mechanically retarded, so if I asked an idiotic question provide me with an explanation for idiots.

And no, the check engine light is not on.

The torque converter is between the transmission and engine. It does not effect how the transmission shifts. What it does do is control the coupling between the two similar to what a clutch does on a manual.

Modern torque converters like yours actually have a clutch-like mechanism that will mechanically lock the engine to the transmission. That's the lock-up part I was asking about. When it is dosconnected, it is a fluid coupling and allows the engine to still turn while the wheels are stopped.

The clunk may be the lock-up engaging or disengaging tat the wrong times, and it would also explain the rev drop and the sense that the engine is working too hard.

(and yes, you will have a MAF and a TPS. I can't recall hearing of problems matching your description being caused by those, however, I'm just an amateur and by no means a Camry expert)

[thewizard16]

Could something like this be caused by bad gasoline? I filled up at a station I've never used before last week, and it's probably only been driven once or twice since then.

[Eye of the Tiger]

Ahh... if there is a "clunk", then it could either loose engine mounts combined with a bad TPS... but the malfunctioning torque converter lock-up sounds like a better idea.

[Soup DeVille]

"Taking off it revved higher than it normally needs to to get going"

[thewizard16]

As far as engine mounts, the engine doesn't really jump, I popped the hood and tried to watch for that, it just sounds like a hesitation and maybe a little shudder. None of those things sound fun though.

[thewizard16]

"Taking off it revved higher than it normally needs to to get going"

It still shifts normally though. I mean for speed. I had to get to second gear, etc. before it really was going much of anywhere. It wasn't as bad at the next stop light, it'll still shift at around 2,500 rpms if I keep it level on the accelerator, or 3,000-3,500 if I'm pressing a little harder, the engine just sounds funny. The transmission is still shifting at the right points for the amount of gas pedal it's given/etc, the engine just sounds like it's laboring.

[thewizard16]

Ahh... if there is a "clunk", then it could either loose engine mounts combined with a bad TPS... but the malfunctioning torque converter lock-up sounds like a better idea.

Would that just randomly happen, or have I done something to hurt it's feelings?

[Soup DeVille]

Would that just randomly happen, or have I done something to hurt it's feelings?

Unless you've been doing neutral slams, it probably just wore out.

If thats the problem that is.

[thewizard16]

Okay, I went and checked fluids just to see if there was something obviously wrong. The oil is clean and levels are good, and the transmission fluid is nice and pink, also good on levels. Air filter seems good as well. In park, it shakes a bit when you rev it, and it sounds lumpy, for lack of a better word, when you accelerate to move it anywhere.

[Pancor]

I'm going to recommend the basics.  Plugs, wires, and a proper injector flush.    Perhaps an Italian tune-up.

[Secret Chimp]

If you hear a thunk along with rev changes, check the idle air control valve. It may be gunked up and having trouble switching between the idle air supply and the normal-operating positions (stuck in the driving position at idle= low rpms, stuck in the idle position when driving= funny engine behavior). I just know that my IAC probably needs cleaning or fixing, as my idle shudders down and then recovers sometimes, and I can hear a clicking noise when the valve operates (coming down to idle after initial startup)

[thewizard16]

If you hear a thunk along with rev changes, check the idle air control valve. It may be gunked up and having trouble switching between the idle air supply and the normal-operating positions (stuck in the driving position at idle= low rpms, stuck in the idle position when driving= funny engine behavior). I just know that my IAC probably needs cleaning or fixing, as my idle shudders down and then recovers sometimes, and I can hear a clicking noise when the valve operates (coming down to idle after initial startup)

That actually sounds amazingly similar to what it was doing, and has just gotten worse. How would I check that (or should I just tell a mechanic to check that and hope they listen?)

[VTEC_Inside]

No one touched on the knocking.

Check for vacuum leaks and maybe an ignition problem.

A vacuum leak may even be responsible for the tranny acting up, but I'm not familiar with that car so...