It could actually be true!

I recently performed a vacuum test on my 4.0l SOHC V-6 Ford to narow down the cause of an erratic idle problem. The vacuum test showed a steady 19 in/Hg at slow idle... normal.

To compare, I tested my 2.4l I-4 Toyota motor. Whoa! The needle was rapidly vibrating between 18-22 in/Hg at slow idle! This is way abnormal!
I had no idea that the Ford would do so much better on something like this.

Just some food for thought, but maybe Toyota's stealing of the car market is due to their PAST reliability that may not necessarily true now.

 

The vibrating needle was probably because its a 4 cylinder. The manifold vacuum of any 4 cylinder at idle will inherently be less steady than a 6 or 8 cylinder, because there are fewer cylinders intaking air per revolution.

I cannot see a connection between manifold vacuum and engine reliability. Put a bigger cam in and the manifold vacuum at idle will go down. Plain and simple.

 

It depends on the engine. I used to have a pos 84 mustang convertible with the 3.8L and throttle body injection and it was a hunk of junk.

I also owned a pair of 87 Supras. The 87-92 Supra Turbos had major headgasket problems where they would blow out under boost.

They all have their own set of problems.

 

I wasn't talking about reliability...I was talking about the engine being built better and tighter.

Per my Haynes manual, a healthy engine should have very little fluctuation in pressure. I think 4 in/Hg is a lot for a stock motor IMO.

 

Your Toyota 2.4L vacuum shouldn't be fluctuating like that. You might want to do a compression test on that engine. Sounds like a valve isn't seating right or something. Normal vacuum on the stock engine should be about 22-23in at idle.

 

No check engine light? I'm guessing you have a Camry 2.4. We change a lot of egr vsvs on those. Havent seen any valve problems unless the motor is sludged.