Hey,
I recently bought a 2000 Toyota Camry CE from a relative with a manual tranny and 263k miles on it and had a question about the engine shuddering/vibrates under acceleration. As this is the only manual I've driven, I'm not sure if this is normal or not.

Anyways, what has been happening is if you give it too much gas, more so at lower RPM's (under 3k), the engine shudders and there is very little acceleration. This happens all the way up to 3000-4000 RPMs depending on the gear, where I still can only have the pedal down about half. If I accelerate slowly with a light touch on the gas, everything runs smoothly. However, this isn't always an option such as when when pulling out into traffic, merging, etc. This Camry should have more horsepower than the last car I drove (2002 Honda Civic), but it accelerates a lot slower.

Now, this isn't a big issue driving around normally, but as far as highways are concerned, it makes it nearly impossible to merge safely. When I am preparing to merge, I normally start at 45mph (~3k RPMs in 3rd) and need to get up to at least 65mph. While pushing down the pedal to the limit before it shudders (about half way down), I can barely get up to 60 before the lane ends.

I had originally thought this was due to the engine just being old and having some worn parts. However, yesterday I noticed something very strange. Normally I let my car warm up for a few minutes before driving it, but yesterday I didn't have time and started driving it after a cold start. When going down the street I gunned it at around 2k RPMs in 2nd gear (put the pedal almost all the way down) which would normally have just caused the engine to shudder. However, the car hauled *** like it never had before. It accelerated as smooth as an automatic without even a single shudder. However, after a few minutes of the car warming up, it started to shudder again like it did before. I drove it from a cold start today and tried accelerating hard again and the same thing happened: it had fantastic acceleration...until it warmed up.

I find this really puzzling and have no idea what it could possibly be. Do any of you have any ideas? Any help would be much appreciated.

Thanks,
John

 

The RPM rises but there is no acceleration? What happens if you downshift?

Might check the coolant temp sensor the computer, sometimes called the ECT sensor. If the sensor is bad the engine can remain in cold start mode even after warm up.

Also check the ign system.

 

isn't the answer you're looking for, I'm sure. But I'd take to dealer and pay diagnosis fee of $75.
Probably have to leave it overnight. Then decide if you or dealer fixes it.
Sounds like a good car to me; correct this and it's 60K more miles.

Other than this comment, it seems a temp thing so I'd be sure that radiator / overflow is at full capacity,
and see if there's a bleed bolt on engine top (to get rid of any airpockets).

 

I think I explained it badly, let me try to explain with an example.
Lets say I'm driving at 2000 RPM, I can push the pedal down ~25% before it shudders.
Once I hit 2500 RPM, I can push the pedal down 30%.
Once I hit 3000 RPM, I can push the pedal down 40%
If I push the pedal down less than those percentages, the car accelerates nice and smooth (albeit slow).
If I push the pedal down more than those percentages, the car will still accelerate but it is slower than when you give it less gas. And, it isn't smooth at all as you can feel the engine shuddering throughout the whole car; it's not a violent shudder, but it is significant.

Pretty much, to get maximum acceleration in my car, I need to gradually push the pedal down as I increase RPMs (and speed).
Using the example above, if I'm at 2000 RPMs the fastest (and smoothest) way to accelerate would be pushing the pedal down 25%, and as the RPMs increase to 2500, push the pedal down 30%, as they get to 3000, push down 40%, etc.

Then, the weird thing with a cold start is I could floor it at 2000 RPMs and it accelerates A LOT faster without any shuddering.

As far as the coolant temp sensor goes, I'm pretty sure that is fine. When I first turn on the car, it idles at 1700 RPM. Then over the next ~5 minutes it gradually lowers the idle to around 400 RPM or so when it warms up.

I need to get the car inspected in about a month so I as going to wait until then to get it professionally checked out. Overall it's not a huge issue unless I need to go on the highway which I don't plan to do in the next month. I was just seeing if in the meantime it was something easily diagnosable so I could save a few bucks.

And thanks, I'll check that out.