Toyota Altis 2001: Falters / Chokes during acceleration

[projectlevity]

Hi guys, my first time here. Need a little help.

We have a 2001 Toyota Altis. It falters or chokes during acceleration. I also can't press the gas pedal too hard during acceleration, I don't know what it is, but is feels like when I press the gas pedal hard, the gear disengages whether I'm in 1st, 2nd, 3rd, 4th or 5th gear, and it revs up as it would when you rev a car in neutral gear without any acceleration. To make it accelerate again, I release the gas pedal and wait for the rpm meter to fall below 2K, then I press the gas pedal a little more softly to regain acceleration.

We had it checked out twice and the mechanic can't seem to figure it out. One thing we did was replace the fuel filter. But nothing changed.

Any ideas?

Many thanks

[mda]

Manual or Automatic?

With regards to the hard acceleration just seemingly revving the engine, a slipping clutch may be the reason. (EXPERTS PLS CORRECT ME IF WRONG)

[projectlevity]

Hi mda,

Thanks for the reply! Yes it is manual transmission.

As for the gear disengaging,(I don't know if "disengaging" is the right term for it), it mostly disengages when I'm in 2nd - 4th gear. It doesn't disengage when it is in 1st and/or 5th gear. So you can imagine I'm having trouble with power, I think twice when I want to overtake a slow vehicle in front of me. It "disengages" when I press the accelerator hard.

We thought of the clutch slipping since it would be the first thing that would come in to mind. But, any ideas as to why, aside from the gear disengaging, why there is an awful lack of power in the acceleration. What it does is when i press the gas pedal hard, the engine kind of chokes, you can feel the engine trying, but it just wont accelerate smoothly with power. Hindi siya talon sa makina e, more of hirap lang talaga siya umarangkada. This is one of the reasons why the mechanic considered the fuel filter to be the culprit. When we changed the fuel filter, it ran smoothly for 2 days then it went back to being faulty. Acceleration power has really gone down significantly, in all gears.

If the clutch is the cultpit, any idea how much it would cost? I would assume, since it is worn out, we would have to replace the entire thing? I'm hoping it is not the clutch, I'm assuming it would cost much.

If we leave the car as is, without fixing the problem for the meantime, any idea what the effects may be?

[niky]

First, must clarify.

What do you mean by "disengages"?

1. Engine revs keep climbing but car stops accelerating? (clutch)
2. Engine bogs and car acceleration becomes slower? (fuel filter maybe, could also be a sensor issue)
3. Engine bogs at a VERY SPECIFIC RPM:
a. above 3k rpm (may be an issue with your VVTi solenoid or control valve)
b. around 2k rpm (may be EGR or O2 sensor, or may still be VVTi issue)
c. other?
4. Engine bites then starts free revving once you push harder on the pedal? (may be clutch) Is there a sound of the gears disengaging? (May be synchro or fork issue) Worse in specific gears? (definitely gear synchro or fork issue)

Please try to describe when and how it happens. What road speeds. What pedal position... is it worse if you floor it... is it still the same whether you floor it or not?

Best to take it to a mechanic who has a scan tool and/or is familiar with your car model. It's hard to diagnose problems over the internet.

[projectlevity]

First, must clarify.

What do you mean by "disengages"?

1. Engine revs keep climbing but car stops accelerating? (clutch)
Yes. While my foot is on the gas pedal, the engine suddenly revs up but no longer accelerates. I have to release the gas pedal and wait for the rpm drop a little bit then press the gas pedal again, this time more softly, with consistent pressure so i can have the car accelerate again. This often happens from the second gear to the fourth gear.

2. Engine bogs and car acceleration becomes slower? (fuel filter maybe, could also be a sensor issue)
Yes! This is what happens exactly! This happens on first gear to second gear. But loss of power in acceleration in all gears have been very noticeable since these problems came up. Especially the lower gears.

3. Engine bogs at a VERY SPECIFIC RPM:
a. above 3k rpm (may be an issue with your VVTi solenoid or control valve)
b. around 2k rpm (may be EGR or O2 sensor, or may still be VVTi issue)
It happens mostly around 2K-3K rpm then it revs up to above 3K rpm while my foot is still on the pedal.
c. other?

4. Engine bites then starts free revving once you push harder on the pedal? (may be clutch) Is there a sound of the gears disengaging? (May be synchro or fork issue) Worse in specific gears? (definitely gear synchro or fork issue)

When I push hard on the pedal, that's the time it happens. What happens is, in first gear, the power in acceleration is significantly much slower than it used to be, then when I shift to second gear and then press hard on the pedal, the engine suddenly revs and the car stops accelerating. I have to release the pedal and press it again more softly with constant pressure for the car to accelerate again. This is what I mean when I say it "disengages". However, I don't know if it is the right term. There is no suspicious sound while these problems happen, no sound of gears disengaging. The engine just suddenly revs while my foot is on the pedal, like I described.

Please try to describe when and how it happens. What road speeds. What pedal position... is it worse if you floor it... is it still the same whether you floor it or not?

It happens in between 1st and 5th gears. Yes, when I floor it, it "disengages" after 2 seconds of the engine trying to accelerate. When I don't floor it, but press harder on the pedal, it disengages. There are no particular road speed when this happens. It happens between 1st and 5th gears so, those are the speeds that it happens. Though is still happens on 5th gear sometimes. But it doesn't happen on 1st gear. On 1st gear, you can just feel the engine is unusually trying hard to accelerate but doesn't accelerate as fast as it used to, but it does not "disengage" on 1st gear.

Best to take it to a mechanic who has a scan tool and/or is familiar with your car model. It's hard to diagnose problems over the internet.

Will do, just gathering some data before I do since I really have no idea. Would be nice to go the proper mechanic and have an idea on what they will telling me.

[niky]

While you may have some fuel system problem, it's apparent that your clutch is gone. What is happening is that when you put too much torque into the clutch, it starts to slip and spin... time to have it checked or replaced.

You can continue to drive on it... but when the friction material gives out entirely (possibly soon), it will leave you stranded and in need of a tow. Extra hassle and expense. Best to just have it fixed as soon as possible.